Formulation science and technology volume 4 agrochemicals paints and coatings and food colloids thar

Page 1


Colloids Tharwat F Tadros

Visit to download the full and correct content document: https://textbookfull.com/product/formulation-science-and-technology-volume-4-agroch emicals-paints-and-coatings-and-food-colloids-tharwat-f-tadros/

More products digital (pdf, epub, mobi) instant download maybe you interests ...

Handbook of food science and technology Volume 3 Food biochemistry and technology 1st Edition Jeantet

https://textbookfull.com/product/handbook-of-food-science-andtechnology-volume-3-food-biochemistry-and-technology-1st-editionjeantet/

Coatings Formulation An International Textbook Müller

https://textbookfull.com/product/coatings-formulation-aninternational-textbook-muller/

Handbook of research on food science and technology. Volume 2, Food biotechnology and microbiology Aguilar

https://textbookfull.com/product/handbook-of-research-on-foodscience-and-technology-volume-2-food-biotechnology-andmicrobiology-aguilar/

Handbook of Research on Food Science and Technology: Volume 1: Food Technology and Chemistry 1st Edition Monica Chavez-Gonzalez (Editor)

https://textbookfull.com/product/handbook-of-research-on-foodscience-and-technology-volume-1-food-technology-andchemistry-1st-edition-monica-chavez-gonzalez-editor/

Powder

Coatings Chemistry and Technology Spyrou

https://textbookfull.com/product/powder-coatings-chemistry-andtechnology-spyrou/

Food science and technology Second Edition CampbellPlatt

https://textbookfull.com/product/food-science-and-technologysecond-edition-campbell-platt/

Handbook of Food Science and Technology 1 Food Alteration and Food Quality 1st Edition Romain Jeantet

https://textbookfull.com/product/handbook-of-food-science-andtechnology-1-food-alteration-and-food-quality-1st-edition-romainjeantet/

Polymers Coatings: Technology and Applications 1st Edition Inamuddin

https://textbookfull.com/product/polymers-coatings-technologyand-applications-1st-edition-inamuddin/

Food Science and Technology 2nd Edition Geoffrey Campbell-Platt

https://textbookfull.com/product/food-science-and-technology-2ndedition-geoffrey-campbell-platt/

TharwatF.Tadros FormulationScienceandTechnology

AlsoofInterest

HandbookofColloidandInterfaceScience. Volumes1–4

Tadros,2018

ISBN978-3-11-054050-5

SuspensionConcentrates. Preparation,StabilityandIndustrialApplications

Tadros,2017

ISBN978-3-11-048678-0,e-ISBN978-3-11-048687-2

PolymericSurfactants. DispersionStabilityandIndustrialApplications

Tadros,2017

ISBN978-3-11-048722-0,e-ISBN978-3-11-048728-2

Formulations. InCosmeticandPersonalCare

Tadros,2016

ISBN978-3-11-045236-5,e-ISBN978-3-11-045238-9

Emulsions. Formation,Stability,IndustrialApplications

Tadros,2016

ISBN978-3-11-045217-4,e-ISBN978-3-11-045224-2

TharwatF.Tadros Formulation Scienceand Technology

Volume4: Agrochemicals,PaintsandCoatings andFoodColloids

Author Prof.TharwatF.Tadros 89NashGroveLane WorkinghamRG404HE Berkshire,UK tharwattadros3@gmail.com

ISBN978-3-11-058755-5

e-ISBN(PDF)978-3-11-058800-2

e-ISBN(EPUB)978-3-11-058756-2

LibraryofCongressControlNumber:2018935454

BibliographicinformationpublishedbytheDeutscheNationalbibliothek TheDeutscheNationalbibliothekliststhispublicationintheDeutscheNationalbibliografie; detailedbibliographicdataareavailableontheInternetathttp://dnb.dnb.de.

©2018WalterdeGruyterGmbH,Berlin/Boston Coverimage:Nik_Merkulov/iStock/GettyImages Typesetting:PTP-Berlin,Protago-TEX-ProductionGmbH,Berlin Printingandbinding:CPIbooksGmbH,Leck www.degruyter.com

Preface

Thisvolumedescribesindustrialapplicationsinagrochemicals(PartI),paintsand coatings(PartII)andfoodcolloids(PartIII).Thediscussionofagrochemicalformulationsbeginswithageneralintroduction(Chapter1)describingtherequirementsofthe varioustypesofsystems.ThisisfollowedbyChapter2,whichfocusesonemulsifiable concentrates(ECs),inwhichtheactiveingredientismixed(ordissolved)inanoiland twosurfactants.Whenthisoilisaddedtoanaqueoussolutioninthespraytank,it spontaneouslyemulsifiesforminganoil/water(O/W)emulsion.Themechanismof self-emulsificationisdescribed.TheseECsarenowmostlyreplacedwithaconcentratedO/Wemulsion(Chapter3),whichprovidesanumberofadvantages,suchas usinglessoilandsurfactantandthepossibilityofincorporatinganadjuvant(which enhancesthebiologicalefficacy)inthecontinuousphase.Chapter4dealswiththe formulationofsuspensionconcentrates(SCs),whicharecommonlyusedtoreplace wettablepowders(whichcanbedustyandhazardoustotheoperator).ThemainfactorsinvolvedinSCformulationanditslong-termphysicalstabilityaredescribedwith particularreferencetotherheologicalmethodsthatcanbeappliedfortheirassessment.Chapter5describestheformulationofoil-basedsuspensions,wherebytheoil canbepolarornonpolar.Therequirementsforbothtypestoachievecolloidstability aredescribedandthisisfollowedbyadescriptionoftheuseofanti-settlingsystems innonaqueoussuspensions.Finally,theemulsificationoftheoil-basedsuspensionin aqueousandelectrolytesolutionmediaisdescribed.Chapter6describestheformulationofsuspoemulsions(mixturesofsuspensionsandemulsions)highlightingthe possibleinteractionsbetweenthesuspensionparticlesandtheemulsiondroplets. Thiscanleadtovariousinstabilityproblemssuchashomoflocculation,heteroflocculation,coalescenceofemulsiondropletsandrecrystallization.Themethodsthat canbeusedtoreduceoreliminatesuchinstabilitiesaredescribedwithparticular referencetopolymericsurfactants.Chapter7dealswiththeformulationofcontrolledreleasesystemswithparticularreferencetothemicroencapsulationofliquidandsolid AIs,controlledreleasefrommatrix-basedmicroparticlesandgranules.Chapter8describestheformulationofadjuvantsthatarerequiredtoenhancethebioefficacyofthe AISeveralfactorsmustbeconsideredwhenselectinganadjuvantforagivenAIThese includeinteractionsattheair/waterinterfaceandtheireffectonspraydropletformation,sprayimpactionandadhesion,wettingandspreading,evaporationofspray dropletsandformationofdeposits,solubilisationoftheAIbysurfactantmicellesand itseffectontransportandinteractionbetweenagrochemical,surfactantsandtarget species.

PartIIdealswiththeformulationofpaintsandcoatings.Chapter9describesthe natureofthedispersedparticle,thedispersionmediumandfilmformers,thedepositionofparticlesandtheiradhesiononsubstratesandtheflowcharacteristics(rheology)ofthepaintformulation.Chapter10describestheformulationoffilmformers

https://doi.org/10.1515/9783110588002-001

usingemulsionanddispersionpolymerization.Chapter11dealswiththeformulation ofpigmentsforpaintapplication.Topicssuchasthewettingofpowders,breakingof aggregatesandagglomerates,wetmillingandcolloidstabilizationofthepaintdispersionmustbeconsidered.Chapter12describestheprocessofenhancingparticle depositionanditsfinaladhesion.Thisisgovernedbylong-rangeforcessuchasdouble layerrepulsion(orattraction)andshort-range(surfaceforces).Chapter13illustrates therheologicaltechniquesthatcanbeappliedduringpaintformulation,whereas Chapter14showshowtheserheologicalmethodscanbeappliedduringpaintformulation.Chapter15givesexamplesoftheflowpropertiesofsomecommercialpaints.

PartIIIdescribestheformulationoffoodcolloids.Itstartswithageneralintroduction(Chapter16)highlightingthecomplexityoffoodsystems.Chapter17startswith adescriptionoftheinteractionbetweenfoodgradesurfactantsandthestructureof theliquidcrystallinephases.Thisisfollowedbyadescriptionofbinaryandtertiary phasediagrams,monolayerformationandtherelationshipbetweentheliquidcrystallinestructureandemulsionstability.Chapter18dealswiththeformulationoffood emulsionsusingproteins,protein/polysaccharideandsurfactant/polysaccharideinteractions.Thestructureofportentsandtheirinteractionandconformationatthe liquid/liquidinterfacearedescribed.Chapter19describestheprocessofsurfactant associationstructures,microemulsionsandemulsionsinfood.Chapter20dealswith therheologyoffoodemulsionswithparticularreferencetointerfacialandbulkrheology.Thecorrelationbetweeninterfacialrheologyandemulsionstabilityishighlighted usingtwoexamples,namelymixedsurfactantandproteinfilms.Thebulkrheologyof emulsionsisdescribedwithparticularreferencetomicrogeldispersionsandthefractalnatureoftheaggregatednetwork.Chapter21dealswithfoamformulationsinfood ofwhichwhippingcreamandbreaddougharethemostcommon.Inthefirstcase,the airbubblesarestabilizedbyfatcrystalsthatadheretoairbubblesduringthewhipping processformingaprotectivelayerandpreventingbubblecoalescence.Inthelatter case,thebreadqualityisdeterminedbyahighbreadvolumeandafinecrumbstructure.Severaltheorieshavebeenproposedtoexplainfoamstability,namely:surface viscosityandelasticitytheory,wheretheadsorbedsurfactantfilmisassumedtocontrolthemechanical-dynamicalpropertiesofthesurfacelayersbyvirtueofitssurface viscosityandelasticity;theGibbs–Marangonieffecttheory;surfaceforcestheory(disjoiningpressure π ),whichoperatesunderstatic(equilibrium)conditionsinrelatively dilutesurfactantsolutions( h < 100nm);stabilisationbymicelles(highsurfactant concentrations>cmc);stabilizationbylamellarliquidcrystallinephases,whichis particularlythecasewithnonionicsurfactantsthatproducelamellarliquidcrystalline structureinthefilmbetweenthebubbles;stabilisationoffoamfilmsbymixedsurfactantswherebyacombinationofsurfactantsgiveslowerdrainageandimprovedfoam stability;andstabilizationbysolidparticles,whichinvolvesparticlesadsorbingatthe air/liquidinterface.Chapter22looksattherelationshipbetweenrheologyandmouth feel.Afterdescribingthemainrheologicalmeasurementsthatneedtobeappliedto obtainsuchacorrelation,someemphasisisgiventothebreak-upofNewtonianand

non-Newtonianliquids.Thecomplexityofflowintheoralcavityisdescribedand subsequentlyadescriptionisgivenoftherelationshipbetweentextureandrheology. Finally,someexamplesofpracticalfoodcolloidsaregiven.

Thisbook(Volume4)givesanumberofformulationexamplesintheareasofagrochemicals,paintsandcoatingandfoodcolloids.Itisavaluabletextforformulation scientistsinvolvedintheformulationofthesesystems.Itmayalsobeusefulforacademicsinvolvedinaresearcharearelatedtoanyoftheseformulations.

TharwatTadros

May2018

Contents

Preface | v

PartI: Theformulationofagrochemicals

1Introductiontotheformulationofagrochemicals | 3

2Formulationofemulsifiableconcentrates | 9

3Formulationofemulsionconcentrates | 15

3.1Formationofemulsions 15

3.2Mechanismsandmethodsofemulsification 16

3.3Roleofsurfactantsinemulsionformation 18

3.4Selectionofemulsifiers 20

3.4.1Hydrophilic–lipophilicbalanceconcept 20

3.4.2Phaseinversiontemperatureconcept | 23

3.5Emulsionstability | 25

4Formulationofsuspensionconcentrates | 35

4.1Introduction 35

4.2Preparationofsuspensionconcentrates andtheroleofsurfactants/dispersingagents 36

4.3Controlofthephysicalstabilityofsuspensionconcentrates 40

4.4Characterizingsuspensionconcentratesandassessing oftheirlong-termphysicalstability | 50

5Oil-basedsuspensionconcentrates | 59

5.1Introduction | 59

5.2Stabilityofnonaqueoussuspensions 59

5.3Emulsificationofoil-basedsuspensions 66

5.4Polymericsurfactantsforoil-basedsuspensionsandthechoice ofemulsifiers 68

5.5Emulsificationintoaqueouselectrolytesolutions 69

5.6Properchoiceofanti-settlingsystem | 69

5.7Rheologicalcharacteristicsofoil-basedsuspensions | 70

6Formulationofsuspoemulsions | 71

6.1Introduction | 71

6.2Suspoemulsionsinvestigated 72

7Formulationofcontrolled-releasesystems 79

7.1Introduction 79

7.2Microencapsulation 79

7.3Encapsulationbyphaseseparationfromaqueoussolution | 81

7.4Microencapsulationofsolidparticles | 82

7.5Controlledreleaseofagrochemicals frommatrix-basedmicroparticles | 83

7.6Controlledreleasefromgranules | 86

8Formulationofadjuvants 89

8.1Introduction 89

8.2Interactionsattheair/solutioninterfaceandtheireffect ondropletformation 92

8.3Sprayimpactionandadhesion | 96

8.4Dropletslidingandsprayretention | 99

8.5Wettingandspreading | 101

8.6Evaporationofspraydropsanddepsoitformation | 105

8.7Solubilizationanditseffectontransport 107

8.8Interactionbetweensurfactants,agrochemicals andtargetspecies 110

References 113

PartII: Theformulationofpaintsandcoatings

9Formulationofpaintsandcoatings 117

9.1Introduction 117

9.2Dispersionparticles 118

9.3Dispersionmediumandfilmformers 120

9.4Depositionofparticlesandtheiradhesiontothesubstrate 124

9.5Flowcharacteristics(rheology)ofpaints | 124

10Formulationoffilmformers | 125

10.1Emulsionpolymerization | 125

10.2Dispersionpolymerization 135

11Formulationofpigmentdispersionsforpaintapplication 141

11.1Wettingofthebulkpowder 141

11.2Breakingofaggregatesandagglomerates(deagglomeration) 148

11.3Wetmilling(cominution) | 153

11.4Colloidstabilizationofpaintdispersions 156

11.4.1Electrostaticdoublelayerrepulsion 157

11.4.2Stericrepulsion 160

12Enhancementofparticledepositionandadhesioninpaints andcoatings | 167

12.1Particledeposition | 167

12.2Particle–surfaceadhesion | 172

13Controloftherheologyofpaintformulations 177

14Applicationofrheologicaltechniquestopaintformulations 193

15Examplesoftheflowpropertiesofsomecommercialpaints | 203

References | 207

PartIII: Theformulationoffoodcolloids

16Introductiontotheformulationoffoodcolloids 211

17Interactionbetweenfood-gradeagentsurfactantsandwaterandstructure oftheliquidcrystallinephases | 215

17.1Binaryphasediagrams | 216

17.2Ternaryphasediagrams | 222

17.3Monolayerformation 222

17.4Liquidcrystallinephasesandemulsionstability 226

18Formulationoffoodemulsionsusingproteinsandprotein/polysaccharides andpolysaccharide/surfactants 229

18.1Proteinstructure | 229

18.2Interfacialpropertiesofproteinsattheliquid/liquidinterface | 231

18.3Proteinsasemulsifiers | 232

18.4Protein–polysaccharideinteractionsinfoodcolloids | 233

18.5Polysaccharide–surfactantinteractions 236

19Surfactantassociationstructures,microemulsions andemulsionsinfood 239

20Rheologyoffoodemulsions | 245

20.1Interfacialrheology | 245

20.2Correlationbetweenemulsionstabilityandinterfacialrheology 247

20.2.1Mixedsurfactantfilms 247

20.2.2Proteinfilms 248

20.3Bulkrheologyofemulsions | 249

20.4Formationofnetworks | 251

20.5Rheologyofmicrogeldispersions | 253

20.6Fractalnatureoftheaggregatednetwork | 253

21Foamformulationsinfood 255

21.1Foamstability 255

21.2Foamdestabilization 261

22Foodrheologyandmouthfeel 267

22.1Introduction | 267

22.2Rheologicalmeasurements | 267

22.3Mouthfeeloffoods:theroleofrheology | 270

22.3.1Break-upofnewtonaianliquids | 272

22.3.2Break-upofnon-Newtonianliquids 273

22.4Complexityofflowintheoralcavity 274

22.5Relationshipbetweenrheologyandtexture 274

23Practicalapplicationsoffoodcolloids 279

References | 283

Index | 285

PartI: Theformulationofagrochemicals

1Introductiontotheformulationofagrochemicals

Agrochemicalformulationsincludeawiderangeofsystemssuitedtospecificapplications[1,2].Agrochemicalsareusuallyeffectiveatseveralgramstohundredsof gramsofactiveingredientper1,000m2 .Itis,however,difficulttoapplysuchasmall amountuniformlytothecrop.Theactiveingredientisalwaysfirstformulatedina suitablediluentsuchaswateroranorganicsolventandwhentheformulationisapplieditisfurtherdilutedinthespraytanktoensureuniformdepositionuponspraying.Insomecases,anagrochemicalisawater-solublecompoundofwhichparaquat andglyphosate(bothareherbicides)areprobablythemostfamiliar.Paraquatisa 2,2bypyridiumsaltandthecounterionsarenormallychloride.Itisformulatedasa 20%aqueoussolutionwhichissimplydilutedintowateratvariousratios(1:50up to1:200dependingontheapplication)uponapplication.Tosuchanaqueoussolution,surfaceactiveagents(sometimesreferredtoaswetters)areaddedwhichare essentialforanumberofreasons.Themostobviousreasonforaddingsurfactantsis toenablethespraysolutiontoadheretothetargetsurfaceandspreadoverittocover alargearea.However,thispictureisanoversimplificationsincethesurface-active agentplaysamoresubtleroleintheoptimizationofthebiologicalefficacy.Thus,the choiceofthesurfactantsysteminanagrochemicalformulationiscrucialsinceitmust performanumberoffunctions.Todate,thischoiceismadebyatrialanderrorprocedure,duetothecomplexnatureofapplicationandthelackofunderstandingofthe modeofactionofthechemical.Itistheobjectiveofthisbooktoapplythebasicprincipleofcolloidandinterfacesciencetoagrochemicalformulations,theirsubsequent application,andtheoptimizationoftheirbiologicalefficacy.

Themainpurposeofanyagrochemicalformulationistomakehandlingandapplicationoftheactiveingredientaseasyaspossible.Animportantfunctionofthe formulationistooptimizeitsbiologicalefficacy.Inmostcases,thisisachievedby controllingthephysicalcharacteristicsoftheformulationanduseofadjuvants.An importantcriterionforanyagrochemicalisitssafetybothtothecropandtheagrochemicalworker.Thisrequiresadequatecontrolofthespraydropletspectrum,reductionofanydriftandremovalofanytoxiceffectoncontactwiththeindividual.These stringentrequirementscanbeachievedthroughcarefulanalysisofalltheinterfacial phenomenathatareinvolvedinapplication.Theconceptof“PesticideDeliverySystem”(PDS)mustbeapplied,wherebytheactiveingredientsaremadeavailabletoa specifiedtargetataconcentrationanddurationdesignedtoaccomplishanintended effect,i.e.,obtainthefullestbiologicalefficacywhileminimizingvariousharmfuleffects.

Mostagrochemicalsarewater-insolublecompoundswithvariousphysicalproperties,whichhavefirsttobedeterminedinordertodecideonthetypeofformulation. Oneoftheearliesttypesofformulationsarewettablepowders(WP),whicharesuitableforformulatingsolidwater-insolublecompoundsthatcanbeproducedinapow-

https://doi.org/10.1515/9783110588002-002

derform.Thechemical(whichmaybemicronized)ismixedwithafillersuchaschina clayandasolidsurfactantsuchassodiumalkyloralkylarylsulphateorsulphonate isadded.Whenthepowderisaddedtowater,theparticlesarespontaneouslywetted bythemediumand,uponagitation,dispersionoftheparticlestakesplace.Itisclear thattheparticlesshouldremainsuspendedinthecontinuousmediumforaperiod oftimedependingontheapplication.Somephysicaltestingmethodsareavailableto evaluatethesuspensibilityoftheWP.Clearly,thesurfactantsystemplaysacrucialrole inwettablepowders.Inthefirstplace,itenablesspontaneouswettinganddispersion oftheparticles.Second,byadsorptionontheparticlesurface,itprovidesarepulsive forcethatpreventsaggregationoftheparticles.Thisprocessofaggregationincreases thesettlingoftheparticlesandmayalsocauseproblemsuponapplication,suchas nozzleblockage.

Thesecondandmostfamiliartypeofagrochemicalformulationisemulsifiable concentrates(ECs),asdescribedinChapter2.Thisisproducedbymixingoneagrochemicaloilwithanotherone,suchasxyleneortrimethylbenzene,oramixtureof varioushydrocarbonsolvents[1].Alternatively,asolidpesticidecouldbedissolved inaspecificoiltoproduceaconcentratedsolution.Insomecases,pesticideoilmay beusedwithouttheadditionofanyextraoils.Asurfactantsystem(usuallyamixtureoftwoorthreecomponents)isalwaysaddedforanumberofpurposes.First,the surfactantenablesselfemulsificationoftheoilonadditiontowater.Thisoccursby acomplexmechanismthatinvolvesanumberofphysicalchanges,suchaslowering interfacialtensionattheoil/waterinterface,enhancementofturbulenceatthatinterfacewiththeresultofspontaneousproductionofdroplets.Second,thesurfactant filmthatadsorbsattheoil/waterinterface,stabilizestheproducedemulsionagainst flocculationand/orcoalescence.Aswewillseeinlatersections,emulsionbreakdown mustbeprevented,otherwiseexcessivecreamingorsedimentationoroilseparation maytakeplaceduringapplication.Thisresultsinaninhomogeneousapplicationof theagrochemicalontheonehand,andpossiblelossesontheother.Thethirdroleof thesurfactantsysteminagrochemicalsistoenhancebiologicalefficacy.Aswewill lookatlater,itisessentialtoarriveatoptimumconditionsforeffectiveuseofagrochemicals.Inthiscase,thesurfactantsystemwillhelpspreadingthepesticideatthe targetsurfaceandmayenhanceitspenetration.

Inrecentyears,therehasbeengreatdemandtoreplaceECswithconcentrated aqueousoil-in-water(O/W)emulsions[1–3]aswillbedescribedinChapter3.This replacementprovidesseveralpotentialadvantages.Inthefirstplace,theaddedoil canbereplacedwithwater,whichisofcoursemuchcheaperandenvironmentally acceptable.Secondly,removingtheoilcouldhelptoreduceundesirableeffectssuch asphytotoxicity,skinirritation,etc.Third,byformulatingthepesticideasanO/W emulsion,itispossibletocontrolthedropletsizetoanoptimumvalue,whichmay becrucialforbiologicalefficacy.Fourth,water-solublesurfactants,whichmaybedesirableforbiologicaloptimization,canbeaddedtotheaqueouscontinuousphase. Aswewillseeinthesubsequentchapters,thechoiceofasurfactant,oramixedsur-

factantsystemiscrucialforpreparationofastableO/Wemulsion.Inrecentyears, macromolecularsurfactantshavebeendesignedtoproduceverystableO/Wemulsionswhichcouldbeeasilydilutedintowaterandappliedwithoutanydetrimental effectstotheemulsiondroplets.

Morerecently,microemulsionsarebeingconsideredaspotentialsystemsfor formulatingagrochemicals.Microemulsionsareisotropic,thermodynamicallystable systemsconsistingofoil,waterandsurfactant(s)wherethefreeenergyofformation ofthesystemiszeroornegative[4].Itisobviouswhysuchsystems,whentheycan beformulated,areveryattractive,sincetheyhaveanindefiniteshelflife(withina certaintemperaturerange).Sincethedropletsizeofmicroemulsionsisverysmall (usuallylessthan50nm),theyappeartransparent.Themicroemulsiondropletsmay beconsideredasswollenmicellesandhencetheywillsolubilizetheagrochemical. Thismayresultinconsiderableenhancementofthebiologicalefficacy.Thus,microemulsionsmayofferseveraladvantagesoverthecommonlyusedmacroemulsions. Unfortunately,formulatingtheagrochemicalasmicroemulsionisnotstraightforward sinceoneusuallyusestwoormoresurfactants,anoilandtheagrochemical.These tertiarysystemsproducevariouscomplexphasesanditisessentialtoinvestigate thephasediagrambeforearrivingattheoptimumcompositionofmicroemulsion formation.Ahighconcentrationofsurfactant(10–20%)isneededtoproducesuch aformulation.Thismakessuchsystemsrelativelymoreexpensivetoproducewhen comparedtomacroemulsions.However,theextracostincurredcouldbeoffsetbyan enhancementofbiologicalefficacywhichmeansthataloweragrochemicalapplicationratecouldbeachieved.

Asimilarconcepthasbeenappliedtoreplacewettablepowders,namelywith aqueoussuspensionconcentrates(SCs)thatwillbedescribedinChapter4.ThesesystemsaremorefamiliarthanECsandtheywereintroducedseveraldecadesago[2,5]. Indeed,SCsareprobablythemostwidelyusedsystemsinagrochemicalformulations. Again,SCsaremuchmoreconvenienttoapplythanWPs.Dusthazardsareabsent, andtheformulationcanbesimplydilutedinthespraytanks,withoutanyvigorous agitation.AswewillseeinChapter20,SCsareproducedbyatwoorthreestageprocess.Thepesticidepowderisfirstdispersedinanaqueoussolutionofasurfactant oramacromolecule(usuallyreferredtoasthedispersingagent)usingahigh-speed mixer.Theresultingsuspensionisthensubjectedtoawetmillingprocess(usually beadmilling)tobreakanyremainingaggregatesoragglomeratesandreducetheparticlesizetosmallervalues.Oneusuallyaimsataparticlesizedistributionranging from0.1to5µm.,withanaverageof1–2µm.Thesurfaceorpolymeraddedadsorbson theparticlesurfaces,resultingintheircolloidalstability.Theparticlesmustbestablymaintainedoveralongperiodoftime,sinceanystrongaggregationinthesystem maycausevariousproblems.First,astheaggregatesarelargerthantheprimaryparticles,theytendtosettlefaster.Second,anygrossaggregationmayresultinlackof dispersionondilution.Thelargeaggregatescanblockthespraynozzlesandmayreducebiologicalefficacyasaresultoftheinhomogeneousdistributionoftheparticles

onthetargetsurface.Apartfromtheirroleinensuringthecolloidalstabilityofthe suspension,surfactantsareaddedtomanySCstoenhancetheirbiologicalefficacy. Thisisusuallyproducedbysolubilizationoftheinsolublecomparedinthesurfactant micelles.Thiswillbediscussedinlatersections.Anotherroleasurfactantmayplay inSCsistoreducecrystalgrowth(Ostwaldripening).Thelatterprocessmayoccur whenthesolubilityoftheagrochemicalisappreciable(saygreaterthan100ppm)and whentheSCispolydisperse.Thesmallerparticleswillhaveahighersolubilitythan thelargerones.Withtime,thesmallparticlesdissolveandbecomedepositedonthe largerones.SurfactantsmayreducethisOstwaldripeningbyadsorptiononthecrystalsurfaces,thuspreventingdepositionofthemoleculesatthesurface.Thiswillbe describedindetailinChapter5.

Chapter6describestheformulationofoil-basedsuspensions,whicharecurrently usedfortheformulationofmanyagrochemicals,inparticularthosewhicharechemicallyunstableinaqueousmedia[2].Thesesuspensionspermittheuseofoils(such asmethyloleate)whichmayenhancethebiologicalefficacyoftheactiveingredient. Inaddition,onemayincorporatewater-insolubleadjuvantsintotheformulation.The mostimportantcriterionfortheoilusedistohavetheminimumsolubilityoftheactiveingredientotherwiseOstwaldripeningorcrystalgrowthwilloccuruponstorage. Theoil-basedsuspensionhastobedilutedinwatertoproduceanoil-in-wateremulsion.Aself-emulsifiablesystemmustbeproducedandthisrequiresthepresenceof theappropriatesurfactantsforselfemulsification.Thesurfactantsusedforselfemulsificationshouldnotinterferewiththedispersingagentthatisusedtostabilizethe suspensionparticlesinthenonaqueousmedia.Displacementofthedispersingagent withtheemulsifierscanleadtoflocculationofthesuspension.Topreventsedimentationoftheparticles(sinethedensityoftheactiveingredientishigherthanthatofthe oilinwhichitisdispersed),anappropriaterheologymodifier(anti-settlingagent)that iseffectiveinthenonaqueousmediummustbeincorporatedintothesuspension.This rheologymodifiershouldnotinterferewiththeselfemulsificationprocessoftheoil basedsuspension.Twomaintypesofnonaqueoussuspensionsmaybedistinguished:

(i)Suspensionsinpolarmediasuchasalcohol,glycols,glycerol,esters.Thesemedia havearelativepermittivity ε r > 10;inthiscase,doublelayerrepulsionplaysan importantrole,inparticularwhenusingionicdispersingagents.

(ii)Suspensionsinnonpolarmedia, ε r < 10,suchashydrocarbons(paraffinicoraromaticoils),whichcanhavearelativepermittivityaslowas2.Inthiscase,charge separationanddoublelayerrepulsionarenoteffectiveandhenceonehastodependontheuseofdispersantsthatproducestericstabilization.

Chapter7describestheformulationofsuspoemulsions[2],whicharemixturesofsuspensionsandemulsionswheretwoactiveingredientsareformulatedwithoneasan aqueoussuspensionandtheotherasanoil/wateremulsion.Thisoffersconvenience tothefarmerandmayalsoresultinsynergisminbiologicalefficacy.Awiderspectrumofdiseasecontrolmaybeachieved,particularlywithmanyfungicidesandher-

bicides.Withmanysuspoemulsions,anadjuvantthatenhancesthebiologicalefficacy isadded.Theformulationofsuspoemulsionsisnotaneasytask;onemayproducea stablesuspensionandemulsionseparatelybutwhenthesemixtheybecomeunstable duetothefollowinginteractions:

(i)Homoflocculationofthesuspensionparticles.Thiscanhappenifthedispersing agentusedforpreparationofthesuspensionisnotstronglyadsorbedandhence itbecomesdisplacedbytheemulsifier,whichismorestronglyadsorbedbutnot agoodstabilizerforthesuspensionparticles.

(ii)Emulsioncoalescence.Thiscanhappeniftheemulsifierisnotstronglyadsorbed attheO/WorW/Ointerface,resultinginitspartialorcompletedisplacement bythesuspensiondispersant,whichisnotagoodemulsionstabilizer,andthis resultsincoalescenceoftheemulsiondropletswithultimateseparationofoil (forO/W)orwater(forW/O).

(iii)Heteroflocculationbetweentheoildropletsandsuspensionparticles.Thelatter maybepartiallywettedbytheoilandresideattheO/Winterface(thisisparticularlythecaseiftheoildropletsaremuchlargerthanthesuspensionparticles). HeteroflocculationcanalsooccurwithsuspensionparticlesdispersedinaW/O emulsion.

(iv)Phasetransferandcrystallization.Thishappenswhenthesuspensionparticles havesomesolubilityintheoilphase.Thesmallsuspensionparticleswhichhave highersolubilitythanthelargerones(duetocurvatureeffects)maybecomedissolvedintheoilphaseandtheybecomerecrystallizedontothelargersuspension particles(aformofanOstwaldripeningprocess).Largeandsometimesneedle shapedcrystalsmaybeproducedasaresultofcrystalhabitmodification(that sometimesoccurswithOstwaldripening).

Animportantapplicationinagrochemicalsisthatofcontrolledreleaseformulations, asdescribedinChapter8.Severalmethodsareusedforcontrolledrelease,ofwhich microcapsules(CS)areprobablythemostwidelyused[2].Thesearesmallparticles withsizerange1–1,000µmconsistingofacorematerialandanouterwall.Thelatter isolatesthecorematerialfromtheenvironmentandprotectsitfromdegradationand interactionwithothermaterials.Thecoreactiveingredientisdesignedtobereleased inacontrolledmannerasrequired.Microencapsulationofagrochemicalsisusually carriedoutbyinterfacialcondensation,insitupolymerizationorcoacervation.Interfacialcondensation,wherebytwomonomers,oneoil-soluble(placedsayinanemulsiondroplet)andonewater-soluble,placedinthecontinuousmediumundergointerfacialpolycondensationproducingacapsulewallofpolyureaorpolyurethane.The polymerwallmusthaveappropriatemolecularweight,glasstransitiontemperature, andthicknesstoachievethedesirablecontrolledrelease.Thepolymerwallshouldnot interactwiththeagrochemical.Thispolymerwallmustnotcauseanyenvironmental damageondegradationafterapplicationandhenceabiodegradablepolymerispreferred.Thepolymerwallmustbeeasilymanufacturedandshouldalsobestableon

storageandusage.Themainadvantagesofmicrcapsuleformulatiosare:controlledor slowreleaseofthecoreactiveingredientsthusimprovingresidualactivity;reduction ofapplicationdosage;stabilizationofthecoreactiveingredientagainstenvironmentaldegradation;reductionofmammalianandfishtoxicity;reductionofphytotxicity; reductionofenvironmentalpollution.

Itcanbeseenfromtheaboveshortdiscussionthatagrochemicalformulations arecomplexmulti-phasesystemsandtheirpreparation,stabilizationandsubsequent applicationrequiretheapplicationofthebasicprinciplesofcolloidandinterfacescience,asisdescribedinseveraltextbooks[6–8].

2Formulationofemulsifiableconcentrates

Manyagrochemicalsareformulatedasemulsifiableconcentrates(ECs),which,when addedtowater,produceoil-in-water(O/W)emulsionseitherspontaneouslyorbygentleagitation[1].Suchformulationsareproducedbytheadditionofsurfactantstothe agrochemicalifthelatterisanoilwithreasonablylowviscosityortoanoilsolution oftheagrochemicalifthelatterisasolidoranoilwithhighviscosity.Asdiscussed below,spontaneousemulsificationrequiresanumberofcriteriathatmustbemetto controlthepropertiesoftheinterfacialregion,inparticularproducingalowinterfacialtension.Thelatterisgenerallyproducedbyusingamixedemulsifiersystem,e.g.a mixtureofcalciumdodecylbenzenesulphonateandanethoxylatednonionicsurfactant,aswillbedescribedbelow.Withsuchanemulsifiermixture,5%concentration maybesufficienttoproducespontaneousemulsification.Insomeagrochemicals,specificemulsifiersystemshavetobeusedtoensurethespontaneityofemulsification. OneofthemainproblemswithECsisthebatch-to-batchvariationoftheagrochemicalandemulsifiersystemswhichmayresultinlackofspontaneityofemulsification. Thus,tosuccessfullyformulateanEC,onemusthaverigorousqualityassuranceand useseveraltestssuchaseffectofwaterhardness,temperature,agitationinthespray tank,etc.Quantitativeevaluationoftheformulationisrequiredusinginterfacialtensionmeasurements,dropletsizeanalysisoftheresultingO/Wemulsion,subjecting theECtostresstests,e.g.temperaturevariation,etc.

Inmostcases,ECsareformulatedbyasimpletrialanderrorapproach,byscreeninganumberofemulsifiersystemsforaspecificagrochemicalformulation.Unfortunately,thehydrophilic–lipophilicbalance(HLB)methodthatiscommonlyusedfor selectionofemulsifiers(Chapter3)isinadequateforselectingemulsifiersforECs[9]. Otherindicessuchasthecohesiveenergyratioconcept(CER),describedbyBeerbower andHill[10],mayprovideabetteroption.Essentially,themethodinvolvesselecting suitableemulsifiersbybalancingtheinteractionsoftheirhydrophobicpartswiththe oilphaseandthehydrophilicpartswiththeaqueousphase.Thisrequiresknowledge ofthesolubility,polarandhydrogenbondingparametersofthevariouscomponents. Unfortunately,theseinteractionparametersareonlyavailableforasmallnumberof emulsifiersandhencetheirapplicationtothewidevarietyofemulsifiersusedinECsis limited.ThisdiscussionclearlyshowsthatselectingemulsifiersforECsstillrequiresa largenumberofexperimentalscreeningtoproduceaproductthatsatisfiesthespontaneityofemulsificationandstabilityunderpracticalconditions.Inaddition,with manyECs,othercomponentssuchascrystalgrowthinhibitors(forsolutionofsolids inoil),defoamersandotherstabilizersareaddedandthisrequiresinvestigationof theirpresenceonthefinalformulationproperties.

ThemostcommonprocedurefortestingECsisbasedontherecommendationof theWorldHealthOrganization(WHO),whichstatesthat“anycreamingoftheemulsionatthetop,orseparationoftheemulsionatthebottom,ina100mlcylindershall

https://doi.org/10.1515/9783110588002-003

notexceed2mlwhentheemulsionistestedasfollows”.Intoa250mlbeakerhavingan internaldiameterof6–6.5cmand100mlcalibrationmarkandcontaining75–80mlof standardhardwater(containing342ppm,calculatedascalciumcarbonate,prepared using0.304ofanhydrousCaCl2 and0.39gMgCl2 ·6H2 Otomake1lusingdistilledwater),5mlofECisadded,usingaMohr-typepipette,duringstirringwithaglassrod (4–6mmindiameter),atabout4revolutionspersecond(rps).TheECshouldbeadded atarateof25–30ml/min,withthepointofthepipette2cminsidethebeaker;theflow oftheconcentrateshouldbedirectedtowardthecentre,andnotagainsttheside, ofthebeaker.Thefinalemulsionismadeto100mlwithstandardhardwater,stirringcontinuously,andthenimmediatelypouredintoaclean,dry100mlgraduated cylinder.Theemulsioniskeptat29–30°Cfor1handexaminedforanycreamingor separation.BothtemperatureandwaterhardnesshaveamajoreffectontheperformanceoftheEC.ThisisillustratedinFig.2.1andFig.2.2,whichshowtheeffectof waterhardnessontheamountofcreamthatseparatesfromatypicalformulation.

Fig.2.1: Effectofwaterhardness ontheamountofcreamseparated asafunctionoftimeforatypicalEC.

Fig.2.2: Amountofcreamseparated asafunctionofwaterhardness.

Fig.2.1showsthattherateatwhichtheamountofcreamreachesequilibriumisfairly independentfromthewaterhardness.Thismeansthatmeasuringtheseparated creamatanarbitrarytimeof1hisadequateforrelativecomparisonofthevarious formulations.ThebestperformanceforthisparticularECappearstobeobservedat awaterhardnessof300ppm,butthismaynotbegeneralizableforallotherECs.

Fig.2.2showsthatthestabilityoftheproducedemulsionimprovesaswaterhardnessincreases,reachingamaximumat ≈ 500ppm,abovewhichthestabilityofthe emulsiondecreaseswithfurtherincreaseinwaterhardness.

Fig.2.3showstheeffectoftemperatureonthestabilityoftheemulsionproduced fromanEC.

Effectoftemperatureonthestability ofanemulsionproducedfromanEC.

ItcanbeseenfromFig.2.3thattemperaturevariationsencounteredinpracticehave asignificanteffectonemulsionstability.Generallyspeaking,increasingtemperature shiftstheoptimumperformancetosofterwaterandloweringithastheoppositeeffect. Thisreflectstheeffectoftemperatureonthesolutionpropertiesoftheemulsifiers,in particularthoseofthenonionicethoxylatetype.Thelatterbecomeslesswatersoluble asthetemperatureorelectrolyteconcentrationincreases,asaresultofthedehydrationoftheethoxylatechain(breakingofhydrogenbondsbetweenethyleneoxideand water).ThisamountstoadecreaseoftheHLBnumberoftheemulsifierwithincrease oftemperatureandelectrolyteconcentrationresultinginreductionoftheemulsion stability.

SeveralmechanismshavebeenproposedtoexplainthespontaneityofemulsificationofECs.Thefirstmechanismisduetointerfacialturbulencethatmayoccuras aresultofmasstransfer,schematicallyrepresented[1,2]inFig.2.4

(Na as ppm CaCo3)(ppm CaCo3)
Fig.2.3:

Fig.2.4: Schematicrepresentationofspontaneousemulsification:(a)interfacialturbulence; (b)diffusionandstranding;(c)ultralowinterfacialtension.

Inmanycases,theinterfaceexhibitsunsteadymovement;streamsofonephaseare ejectedandpenetrateintothesecondphaseasisillustratedinFig.2.4(a),which showslocalizedreductionininterfacialtensioncausedbythenon-uniformadsorptionofthesurfactantmoleculesattheO/Winterface[11]orbythemasstransferof thesurfactantmoleculesattheO/Winterface[12,13].Withtwophasesthatarenotin chemicalequilibrium,convectioncurrentsmaybeformed,conveyingliquidrichin surfactantstowardsareasofliquiddeficientofsurfactant[14,15].Theseconvection currentsmaygiverisetolocalfluctuationsininterfacialtension,causingoscillations oftheinterface.Suchdisturbancesmayamplifythemselvesleadingtoviolentinterfacialperturbationsoreventualdisintegrationoftheinterface;whenliquiddroplets are“thrown”intotheother[16].

Thesecondmechanismthatmayaccountforspontaneousemulsificationisbased ondiffusionandstrandingasillustratedinFig.2.4(b).Thisisbestillustratedbycarefullyplacinganethanol-toluenemixture(containingsay10%alcohol)ontowater. Theaqueouslayereventuallybecometurbidasaresultofthepresenceoftoluene droplets[17].Inthiscase,interfacialturbulencedoesnotoccur,althoughspontaneous emulsificationapparentlytakesplace.Ithasbeensuggested[18,19]thatthealcoholmoleculesdiffuseintotheaqueousphase,carryingsometolueneinasaturated three-componentsubphase.Atsomedistancefromtheinterface,thealcoholbecomes sufficientlydilutedinwatertocausethetoluenetoprecipitateintheaqueousphase. Thisphasetransitionmightbeexpectedtooccurwhenthethirdcomponentincreases themutualsolubilityofthetwopreviouslyimmisciblephases.

Thethirdmechanismofspontaneousemulsificationmaybeduetotheproductionofanultralow(ortransientlynegative)interfacialtension[20],asillustratedin Fig.2.4(c).Thismechanismisthoughttobethecauseofformationofmicroemulsions.

3Formulationofemulsionconcentrates

Manyagrochemicalshavebeenformulatedasoil-in-water(O/W)emulsionconcentrates(EWs).Thesesystemsoffermanyadvantagesoverthemoretraditionallyused emulsifiableconcentrates(ECs).ByusinganO/Wsystem,onecanreducetheamount ofoilintheformulationsinceinmostcasesasmallproportionofoilisaddedtothe agrochemicaloil(ifthishasahighviscosity)beforeemulsification.Insomecases,if theagrochemicaloilhasalowtomediumviscosityonecanemulsifytheactiveingredientdirectlyintowater.Withmanyagrochemicalswithlowmeltingpoints,which arenotsuitableforthepreparationofasuspensionconcentrate,onecandissolvethe activeingredientinasuitableoilandtheoilsolutionisthenemulsifiedintowater.EWs whichareaqueous-basedproducelesshazardtotheoperator,reducingskinirritation. Inaddition,inmostcasesEWsarelessphytotoxictoplantswhencomparedtoECs.The O/Wemulsionisconvenientfortheincorporationofwater-solubleadjuvants(mostly surfactants).EWscanalsobelessexpensivecomparedtoECssincealowersurfactant concentrationisusedtoproducetheemulsionandalsoonereplacesagreatproportionofoilbywater.TheonlydrawbackofEWscomparedtoECsistheneedtouse highspeedstirrersand/orhomogenizerstoobtaintherequireddropletsizedistribution.Inaddition,EWsrequirecontrolandmaintenanceofitsphysicalstability.Aswill bediscussedlater,EWsareonlykineticallystableandonehastocontrolthebreakdownprocessthatoccuronstoragesuchascreamingorsedimentation,flocculation, Ostwaldripening,coalescence,andphaseinversion.

Inthissection,wewillstartwiththeprinciplesofformationofemulsionsandthe roleofthesurfactants[3].Thisisfollowedbyasectionontheproceduresthatcan beappliedtoselecttheemulsifiers.Thethirdsectionwilldealwiththebreakdown processesthatmayoccuronstorageandmethodsoftheirprevention.Thelastsection willdealwiththeassessmentandpredictionofthelong-termphysicalstabilityofEWs.

3.1Formationofemulsions

Considerasysteminwhichanoilisrepresentedbyalargedrop2ofarea A 1 immersed inaliquid2,whichisnowsubdividedintoalargenumberofsmallerdroplets(1)with totalarea A 2 ( A 2 ≫ A 1 )asshowninFig.3.1Theinterfacialtension γ 12 isthesame forthelargerandsmallerdropletssincethelatteraregenerallyintheregionof0.1to fewµm.

ThechangeinfreeenergyfromstateItostateIIismadefromtwocontributions [3]:Asurfaceenergyterm(thatispositive)thatisequalto∆ Aγ 12 (where∆ A = A 2 A 1 ). Anentropyofdispersionstermwhichisalsopositive(sinceproducingalargenumber ofdropletsisaccompaniedbyanincreaseinconfigurationalentropy)whichisequal to T ∆ S conf .

https://doi.org/10.1515/9783110588002-004

(flocc. + coal.)

Fromthesecondlawofthermodynamics,

Fig.3.1: Schematicrepresentationofemulsion formationandbreakdown.

Inmostcases,∆ Aγ 12 ≫ T ∆ S conf ,whichmeansthat∆ G form ispositive,i.e.theformationofemulsionsisnon-spontaneousandthesystemisthermodynamicallyunstable. Intheabsenceofanystabilizationmechanism,theemulsionwillbreakbyflocculation,coalescence,Ostwaldripening,oracombinationofalltheseprocesses.Inthe presenceofastabilizer(surfactantand/orpolymer),anenergybarrieriscreatedbetweenthedropletsandthereforethereversalfromstateIItostateIbecomesnoncontinuousasaresultofthepresenceoftheseenergybarriers.Thisisillustratedin Fig.3.2.Inthepresenceoftheaboveenergybarriers,thesystembecomeskinetically stable[3].AsdiscussedinChapters7and8ofVol.1,theenergybarriercanbecreated byelectrostaticand/orstericrepulsionwhichovercomestheeverlastingvanderWaals attraction.

Fig.3.2: Schematicrepresentationoffreeenergypathforbreakdown(flocculationandcoalescence) forsystemscontaininganenergybarrier.

3.2Mechanismsandmethodsofemulsification

Toprepareanemulsionsoil,water,surfactantandenergyareneeded[3].Thiscanbe consideredbylookingattheenergyrequiredtoexpandtheinterface,∆ Aγ (where∆ A is theincreaseininterfacialareawhenthebulkoilwitharea A 1 producesalargenumber

GII GV

Another random document with no related content on Scribd:

literary revolutionaries of an earlier age, Joseph and Thomas Warton.” A. L. H.

Ath p1031 O 17 ’19 1600w

Booklist 16:234 Ap ’20

“It is altogether likely that these essays will fail to please the modern school of literary pencillers who scorn scholarship, and who fancy that verbal smartness and triviality is the only method of criticism. Mr Gosse writes with a light and pleasant touch. He is by no means a dry-as-dust because he is serious, and here he has written a series of papers that are a distinct contribution to the literature of criticism.” E. F. E.

Boston Transcript p6 Ja 28 ’20 1300w

“As a literary man-of-the-world, unbewildered and unprejudiced, Mr Gosse goes forth to pay his calls here and there down the centuries, and returns to his club in Victoria street to chat with his intimates. He is correct in dress and manner, discreet in speech; he says the right thing to every one, and nearly always of every one. A Major Pendennis of literature, one might say, he plays an important part in the world which he has so long cultivated.” R. M. Lovett

Dial 68:777 Je ’20 1550w

“Mr Gosse is bravely determined not to be a mere praiser of time past. His poise is beautiful; he is immensely urbane to the younger critic and grants the latter’s contentions right and left. But he cannot hide the sadness in his heart at the thought of the cold young men with something inscrutable in their faces who despise so much that is venerable and beautiful to him.” Ludwig Lewisohn

Nation 110:690 My 22 ’20 1250w

“Suggestive and entertaining.” R: Le Gallienne

N Y Times 25:151 Ap 4 ’20 3100w

“He gives us a delightful collection of essays, distinguished in that it is handsome in tone and written like a fine old English gentleman.”

Review 2:487 My 8 ’20 800w

“Mr Gosse’s essays on Sterne and the two Wartons are pure belles lettres, but of the best brand.”

Sat R 128:316 O 4 ’19 1200w

“The charm of his infectious admiration pervades nearly all the essays that make up the volume now before us. The best and most characteristic pages are those devoted to ‘Three experiments in portraiture’; and of these the sketch of Lady Dorothy Nevill is easily the most striking.”

Spec 123:504 O 18 ’19 1400w

The Times [London] Lit Sup p529 O 2 ’19 1100w GOULDING,

*$3 Van Nostrand 677

This is a British work based on studies made for the Imperial institute. It is issued as one of the Imperial institute series of handbooks to the commercial resources of the tropics, with a preface by Wyndham R. Dunstan, director of the institute. Contents: Introductory; Cotton; Cotton production in the principal countries and the chief commercial varieties; Cotton growing in British West Africa and other parts of the British empire; Flax, hemp, and ramie; Jute and similar fibres; Cordage fibres; Miscellaneous fibres. A list of principal publications on fibres occupies nine pages and there is an index.

GOWAR, EDWARD. Adventures in Mother Goose land. il *$2.25 Little

20–16169

Noel was a little boy who wished to be put into a book and because he made his wish in the time of the blue moon it came true. And the book was all about Mother Goose, and his adventures in her country, where he met the little man all dressed in leather, the old woman who lived in a shoe and all the rest of them, are told in this story. There is humor both in the telling of the story and in the illustrations, which are by Alice Bolam Preston.

+

Ind 104:376 D 11 ’20 90w

“His tale is cleverly contrived and attractively illustrated.”

N Y Evening Post p10 S 25 ’20 100w

“It is entertainingly told and charmingly printed.” Hildegarde Hawthorne

N Y Times p9 D 19 ’20 50w

Springf’d Republican p7a N 21 ’20 70w

GOWIN, ENOCH BURTON. Developing

executive ability. il $3 Ronald 658

19–11576

“A very simply written book for the young or prospective executive. It deals mainly in developing attention to general matters of routine, good working habits, office equipment and devices, rules for mental and physical economy which will establish a spirit and habit of order. Developed from lectures before commercial associations and business classes. Bibliography. Index.” Booklist

“Designed primarily for the young executive, the book brings a wealth of ideas before him, which only await application that they may yield him a goodly return in economies of time, energy, and money. ”

+ + + +

Am Econ R 9:829 D ’19 130w

Booklist 16:192 Mr ’20

+ Pittsburgh 24:456 O ’19 30w

GRAÇA ARANHA, JOSÉ PEREIRA DA.

Canaan. *$2 (3c) Four seas co.

20–4216

Graça Aranha is a cultured Brazilian, prominent in the affairs of his country, and a writer of many books, of which, says Guglielmo Ferrero in his appreciative introduction: “‘Canaan’ is the most beautiful.” The hero of the story is Milkau, a German colonist who, disillusioned by the hypocrisies, hidden immoralities, and social and legal injustices of the civilizations of Europe, imagines that here, in a new country where the soil is virgin, unbroken, and the natives of childlike simplicity, exists a golden state of human happiness, of joy and work ideally blended, and little evil. For months his illusion remains intact. Then, a wronged and persecuted young woman ’ s misfortunes unveil for him the malicious injustices, cruelty, and cupidity lurking here in the ideal country of his dreams. The close of the story is vague we do not know just what happens to Milkau and Mary, but the scenes evoked in the last chapter are especially powerful, ending in Milkau’s fervent dream and hope of a promised land of justice and beauty yet to come through toil and faith. The novel is translated from the Portuguese by Mariano J. Lorente.

“There is a distinctly noble flavor to the work, and certainly a large humanity that marks it as something more than exclusively Brazilian in significance. Indeed, for the thinking American of the north, between Canada and the Rio Grande, the theme is of primary importance. Millions have sought their ‘Canaan’ here and have been

no more successful than Milkau. And for similar reasons. ” I: Goldberg

Bookm 51:232 Ap ’20 560w

“‘The great American novel,’ Anatole France is said to have called this book, which comes to us from Brazil. Whoever reads the first hundred pages will be inclined to agree with him. Thereafter, it must be confessed, the spell relaxes. Nevertheless, ‘Canaan’ leaves behind it a powerful, memorable, beautiful impression. It is a book for both the Americas.”

Freeman 1:261 My 26 ’20 1050w

“As a piece of writing, due allowance being made for a wretched translation, the book is amorphous in a curiously old-fashioned way. In spirit and structure it goes back to the first generation of the romantic writers. What gives its value to the book is the picture which, largely by means of discussion, Aranha presents of the Brazilian civilization of today.”

Nation 110:337 Mr 13 ’20 950w

“As pure literature the book must take a lower rank than it commands as a work of philosophy. It requires too attentive reading for Simon-pure fiction. The author’s canvas is overcrowded with ideas. His book is notable for the purity of its psychological analysis, for its powers of characterization, for the vivid beauty of its descriptive passages and for its scenes of tremendous dramatic power as much as it is for the light it throws into the depths of an unusually reflective mind.”

“Aside from the compelling interest of so vast a theme, and the fascinating portrayal of Brazilian life, either of which place the book in the first rank of modern novels, the intrinsic fineness of the book lies in the exquisite poetry of its style.”

− + N Y Times 25:174 Ap 11 ’20 1650w

Springf’d Republican p6 Je 3 ’20 850w

GRAHAM, ALAN. Follow the little pictures!

(2½c) Little

20–13547

Two branches of an old English family are involved in this exciting treasure hunt and the treasure itself could be located by deciphering the puzzle picture left by the American ancestor to the only remaining survivor of his family. The English representation of the family is an irascible Scotch laird, the ingredients of whose character are cunning and venom and a passion for recovering the treasure. He outwits all the others that have gradually been let into the secret, but had not reckoned on his son ’ s Belgian wife, a descendant of a Belgian servant of the original Lord Tanish, who also has come into possession of a document revealing the spot, and has married Roy Tanish on the strength of it without loving him. She gets away with the loot, the laird and Roy are killed in the wild pursuit, while the other persons involved take the loss of the gold lightly, having found more precious treasures.

Booklist 17:32 O ’20

“A good mystery story.”

Boston Transcript p6 Jl 3 ’20 240w

N Y Times p26 Ag 1 ’20 300w Sat R 130:40 Jl 10 ’20 50w

“The developments of the plot are ingenious.”

Spec 124:798 Je 12 ’20 20w

“Readers fond of mystery will find the tale to their liking.”

Springf’d Republican p11a Jl 11 ’20 180w

“The author has chosen to set his scene in nowadays, and, to be sure, a motor chase figures in it. But the story would have been as well served by galloping horses. The dominant figure the villain would have been so much more at home in a heavy wig and jackboots.”

The Times [London] Lit Sup p257 Ap 22 ’20 200w

GRAHAM, JAMES CHANDLER. It happened at Andover; well, most of it did, anyway. il *$1.90 (3½c) Houghton

20–15954

A series of stories and sketches of life at Phillips academy, Andover, written by one of the teachers. Among the titles are: The unappreciated; The transformation; The ringer; A new boy; The infirmary; The foreign-born; A Napoleon of finance; Parents; The spy; The landlady; An affaire du cœur; Taking a chance; The vamp.

“Boys, and girls too, will like these tales, but so will older readers. A charming strain of humor enriches the sketches.” Hildegarde Hawthorne

N Y Times p8 D 12 ’20 70w

“One quite believes of the sketches and tales that ‘boys between the ages of twelve and eighteen will find them absorbing and diverting’; but largely as an illuminating and slightly scandalous glimpse into a teacher’s mind. It is a book for adult non-combatants, retired teachers or superannuated parents or ‘old boys’ who recall their school days as a delightful lark.” H. W. Boynton

Review 3:502 N 24 ’20 220w

GRAHAM, JOHN WILLIAM. Faith of a Quaker. *$8 Macmillan 289.6

(Eng ed 20–23038)

“The author is principal of Dalton Hall, the hall of residence for Quaker students attending the University of Manchester, England, the author of an excellent ‘Life of William Penn,’ and other works, and is also a Quaker minister. The first four chapters, ‘The foundations,’ set forth the ideas of the author concerning God and man and the relation they bear to each other. Dissertations on the ‘Son,’ the ‘Living Christ,’ and the ‘Personality of man ’ follow, all based on what precedes. The essay on war, which has been previously published, is a presentation of the incompatibility of war with the spirit of Christianity.”—N Y Evening Post

“The essentially mystical basis of Quakerism is well pointed out, and some useful distinctions are drawn between the somewhat vehement assertions of the early pioneers and the results of modern thinking. The community of Quakers is not likely to object to the reverent, but discriminating, analysis which is here given of many current practices.”

Ath p50 Jl 9 ’20 370w

“The book is written in a spirit of fair-mindedness and not of partisanship.”

Int J Ethics 31:116 O ’20 120w

“The book, as a whole, is badly arranged and loses thereby in force. But the chief error of the author is that he has set forth as an exposition of the Quaker faith that which the vast majority of the Friends of England, as well as in America, would unhesitatingly disown, and thus he gives a wrong impression of the teachings of the

body. Had the work been published as the faith of an individual seeker after truth it would merit commendation as an earnest, strong, thoughtful presentation.” A. C. Thomas

N Y Evening Post p12 O 23 ’20 720w

“It is when we come to intellectualize their position that the problems arise. This is the point which Mr Graham does not seem sufficiently to have apprehended, and yet it is surely the key to the whole position. His explanations and argumentations are in consequence too often extraneous, too often weakened by irrelevancies.” The Times [London] Lit Sup p434 Jl 8 ’20 1400w

GRAHAM, STEPHEN. Soul of John Brown (Eng title. Children of the slaves).

*$3 Macmillan 326.1

20–21927

This is an English observer’s report on the condition of the negro in America today. He came to America to study the problem. He traveled south by way of Baltimore and Washington to Virginia, passed on to Georgia where he followed the track of Sherman’s march, went thru Alabama and Mississippi and to New Orleans and then followed the river north. He talked with negro workmen, preachers, teachers and doctors, visited their schools, churches and theaters, and he reports on lynching, the southern point of view, the effects of the war on the negro, etc., and writes of the world aspect of the problem. He finds that slavery left its taint on the white man as

well as on the negro and says it is a mistake to view this American problem as exclusively a negro problem.

“The fact that in this book, as elsewhere, Mr Graham’s observations are more valuable than his reflections, does not detract from its simple, unescapable effect.”

Ath p615 N 5 ’20 570w

“Mr Graham has, with remarkable clearness of vision, analyzed our problem of race relations. He has fallen into error in a few instances, but the great bulk of his book is filled with a correct interpretation of the innermost thoughts and aspirations of twelve million Americans who seek to be free.” W.

Boston Transcript p8 F 2 ’21 1100w

“He saw nothing, of course, that informed Americans do not know already, but as an Englishman he saw from a new point of view, and ‘The soul of John Brown’ has the interest of a genuine freshness which Mr Graham’s mystical habits of thought and expression do not obscure.”

Nation 111:736 D 22 ’20 110w

“Mr Graham is an Englishman and may be forgiven for his mistakes in American history, except in the case of his opening chapter, which is lurid and dangerously misleading. It is entirely inconsistent with subsequent chapters.”

N Y Times p22 D 12 ’20 1600w

“We are more impressed by what he saw and heard than by his arguments. Sometimes, indeed, the latter are based on lack of knowledge.” E. C. Willcox

Outlook 127:109 Ja 19 ’21 1050w

“His report of what he saw and heard is of unusual interest because it gives the observations of a man who began his study of the race question in the South without prepossessions and with the simple desire to learn the truth.”

R of Rs 63:112 Ja ’21

100w

“The mischief of this sort of book is the fact that it cannot possibly help forward the cause which the author has earnestly at heart. Like most people who think with their hearts rather than with their heads, Mr Graham seems to have taken very little trouble to learn more than his own side of the question.”

Sat R 130:438 N 27 ’20 1050w

Spec 125:703 N 27 ’20 3000w

“Written with that easy yet glowing eloquence of which he is a master. But the picture that he gives is more notable for generous sympathy than for exact knowledge. It is, in important respects, onesided and misleading. The book is written in the spirit of the DuBois propaganda, and again and again Mr Graham has taken the propagandist’s view of certain matters which sociological investigators interpret differently.”

Springf’d Republican p6 D 20 ’20 650w

The Times [London] Lit Sup p727 N 11 ’20 2500w

GRANDGENT, CHARLES HALL. Old and new.

*$1.50 Harvard univ. press 814

20–14542

“‘Old and new, sundry papers, ’ is the title of a volume containing eight essays and addresses by Professor C. H. Grandgent, of Harvard university. Though covering a rather wide range of subjects, the papers included ‘have this in common, that they treat, in general, of changes in fashion, especially in matters of speech and of school.’ (Preface)” (Mod Philol) “‘Nor yet the new, ’ is an address to the Smith college chapter of the Phi Beta Kappa on May 17, 1919. The other chapters are Fashion and the broad A, The dog’s letter, Numeric reform in Nescioubia, Is modern language teaching a failure? The dark ages, New England pronunciation and School.” (Springf’d Republican)

“Against everything contemporary he easily generates animosity so intense that it strikes one as bizarre. On the pronunciation of English as she is spoke in America, Professor Grandgent is popular and amusing.”

Ath p811 D 10 ’20 240w

“‘Fashion and the broad A,’ ‘The dog’s letter,’ and ‘New England pronunciation’ are scholarly yet delightful essays on subjects which should interest every student of language. If there were more

philologists like Professor Grandgent, Mr H. L. Mencken would have less occasion to complain that American college professors investigate forgotten dialects to the neglect of living English.” T. P. Cross

Mod Philol 18:55 Ag ’20 500w

“Miscellaneous essays and addresses which, often thin as to argument, are at times rich in illustration.”

Nation 111:695 D 15 ’20 60w

“Most readers will agree that what these essays and addresses have in common is their author’s wealth of reading and of reflection and his brilliant wit, rather than any unity of theme.” J: Erskine

N Y Evening Post p5 N 6 ’20 1350w

Reviewed by Brander Matthews

N Y Times p2 Ja 16 ’21 1050w

Review 3:322 O 13 ’20 300w

“Prof. Grandgent’s witty impatience at new poetry extends to so many departments of life that one need not fear challenge in fastening upon him the epithet ‘conservative.’ The lighter papers of Prof. Grandgent’s combining wit and scholarship, are meant to give pleasure and will do so. ”

Springf’d Republican p9a Ag 15 ’20 680w

The Times [London] Lit Sup p706 O 28 ’20 70w

GRANTHAM, MRS A. E. Wisdom of Akhnaton.

*$1.25 Lane 822

20–17687

A poetic drama based on incidents drawn from the life and reign of Pharaoh Akhnaton, son of Amenhotep III, as read in the sculptures and inscriptions brought to light by modern excavations. These evidences reveal in the young ruler a new attitude toward life, a reversal of all inherited values. “There was no room for greed and hate and war in his conception of man ’ s destiny.... The episode chosen for dramatization is the conflict between the claims of peace and war and Akhnaton’s successful struggle to make his people acquiesce in his policy of peace. ” (Preface)

“His portrayal of the ruler who acts in defiance of his military chiefs is managed with a good deal of skill and entire sympathy. The verse is adequate throughout, and the climax might easily be made by stage presentation into an impressive spectacle.”

p783 Je 11 ’20 160w

“A poetic drama of some merit. If certain passages with too modern a ring, which make his Pharaoh seem almost a President

Wilson in Egyptian robes, were brought into harmony with the tone of the period, the play might have a success in representation.”

+

The Times [London] Lit Sup p290 My 13 ’20 450w

GRATTAN-SMITH, T. E. True blue. il *$1.50 (2½c) Holt

20–14285

An Australian story for young people. Mel is a fourteen year old girl, Ned is her brother, and Jim Stanley is their chum. The three are expert in all outdoor sports, including surf riding, and Mel holds her own with the boys. The story opens on Ned’s birthday, with a hydroplane for a birthday gift. A few days later war is declared and the new hydroplane plays an important part. Altho the war-time plot is the now familiar one, involving the capture of German spies, the story has an added interest in its descriptions of Australian sports.

“Up-to-date boys and girls will revel in this wholesome book, and, unless we are mistaken, grown-ups will not wholly pass it by.”

With some exceptions the stories are comic and the title story tragic. A typical Englishman, whose boast it was that he never had been in a scrape with a woman, left England to escape the charms of one and betook himself to Spain. Immediately on his arrival he finds himself defending a woman against an infuriated mob. She is a famous dancer who has incurred the hatred of her native town. As he is conducting her to her home where she is seeking her mother’s reconciliation, they are run down by a stampede of bulls. The girl is killed, he almost. Later, when sufficiently recovered from his injuries he finds that it was the sister who was killed and that the vilified girl has slipped into the former’s place with the blind mother.

“On the whole, the book well sustains her reputation.”

Cath World 112:553 Ja ’21 70w

Outlook 126:67 S 8 ’20 40w

“These narratives are unmistakably the work not only of a ‘born story-teller,’ but of a careful artist. There is a quality in the title-story which, with whatever apologies and misgivings, we can only suggest by the word ‘style.’” H. W. Boynton

Review 3:253 S 22 ’20 210w

“The medium of the short story is not very favorable to the work of ‘Richard Dehan.’”

Spec 125:280 Ag 28 ’20 40w

GRAVES, FRANK PIERREPONT.

What did Jesus teach? an examination of the educational material and method of the Master. *$1.75

Macmillan 232

19–18243

“The Christian association of the University of Pennsylvania started a campaign a year ago to enroll 2000 students in Lenten Bible study. The leaders were faculty men, secretaries, older students and outsiders, and these were all taught in a normal class by Frank Pierrepont Graves, dean of the school of education. Prof. Graves has yielded to a strong demand for the publication of the study material, and it appears as ‘What did Jesus teach?’ The book is based on the gospel of Mark, and is arranged in such form as to be available for other classes in college or out. Beginning with a study of the historical sources for the teachings of Jesus, the book goes on with eight chapters on Jesus as a teacher, his method of teaching, his ideas of God and man, the ideals and reconstruction of life, the future, the kingdom and the church, and modern society. A bibliography adds to the value of the book.”—Springf’d Republican

“This book is an experiment in pedagogy rather than a contribution to theological science. As an introductory book upon the subject, it should prove useful for many readers.” S. J. C.

Am J Theol 24:475 Jl ’20 150w

“The book is noteworthy on two accounts. The first is the arrangement of the material. The running margin makes it possible to grasp the content of pages and paragraphs clearly and quickly. Also the paragraphs bear interesting headings; there are suggestive chapter summaries; the references to literature are excellent. The second feature is the substance of the studies. The prevailing accent is upon the ethical content of the teaching.”

Bib World 54:647 N ’20 240w

Booklist 16:220 Ap ’20

20–6375

To quote from one of the poems, “Love, fear and hate and childish toys are here descreetly blent.” It is the first and the last that predominate. The other elements are to be found in the small group of war poems called “Retrospect” that come at the end. Titles are: A frosty night; A song for two children; The boy out of church; True Johnny; Advice to lovers. Among the war poems are: Haunted; Here they lie; Country at war; Hate not, fear not. This is Mr Graves’s second book of verse. “Fairies and fusiliers” was published in 1918.

Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.