Formulation Science and Technology: Volume 4: Agrochemicals, Paints and Coatings and Food Colloids

301 Pages·2018·6.79 MB·English

by  Tharwat F Tadros

TharwatF.Tadros
FormulationScienceandTechnology
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Tharwat F. Tadros
Formulation
Science and
Technology
|
Volume 4:
Agrochemicals, Paints and Coatings
and Food Colloids
Author
Prof.TharwatF.Tadros
89NashGroveLane
WorkinghamRG404HE
Berkshire,UK
[email protected]
ISBN978-3-11-058755-5
e-ISBN(PDF)978-3-11-058800-2
e-ISBN(EPUB)978-3-11-058756-2
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Preface
This volume describes industrial applications in agrochemicals (Part I), paints and
coatings(PartII)andfoodcolloids(PartIII).Thediscussionofagrochemicalformula-
tionsbeginswithageneralintroduction(Chapter1)describingtherequirementsofthe
varioustypesofsystems.ThisisfollowedbyChapter2,whichfocusesonemulsifiable
concentrates(ECs),inwhichtheactiveingredientismixed(ordissolved)inanoiland
twosurfactants.Whenthisoilisaddedtoanaqueoussolutioninthespraytank,it
spontaneously emulsifies forming an oil/water (O/W) emulsion. The mechanism of
self-emulsificationisdescribed.TheseECsarenowmostlyreplacedwithaconcen-
tratedO/Wemulsion(Chapter3),whichprovidesanumberofadvantages,suchas
usinglessoilandsurfactantandthepossibilityofincorporatinganadjuvant(which
enhancesthebiologicalefficacy)inthecontinuousphase.Chapter4dealswiththe
formulationofsuspensionconcentrates(SCs),whicharecommonlyusedtoreplace
wettablepowders(whichcanbedustyandhazardoustotheoperator).Themainfac-
torsinvolvedinSCformulationanditslong-termphysicalstabilityaredescribedwith
particularreferencetotherheologicalmethodsthatcanbeappliedfortheirassess-
ment.Chapter5describestheformulationofoil-basedsuspensions,wherebytheoil
canbepolarornonpolar.Therequirementsforbothtypestoachievecolloidstability
aredescribedandthisisfollowedbyadescriptionoftheuseofanti-settlingsystems
innonaqueoussuspensions.Finally,theemulsificationoftheoil-basedsuspensionin
aqueousandelectrolytesolutionmediaisdescribed.Chapter6describestheformu-
lationofsuspoemulsions(mixturesofsuspensionsandemulsions)highlightingthe
possible interactions between the suspension particles and the emulsion droplets.
This can lead to various instability problems such as homoflocculation, heterofloc-
culation, coalescence of emulsion droplets and recrystallization. The methods that
can be used to reduce or eliminate such instabilities are described with particular
referencetopolymericsurfactants.Chapter7dealswiththeformulationofcontrolled-
releasesystemswithparticularreferencetothemicroencapsulationofliquidandsolid
AIs,controlledreleasefrommatrix-basedmicroparticlesandgranules.Chapter8de-
scribestheformulationofadjuvantsthatarerequiredtoenhancethebioefficacyofthe
AISeveralfactorsmustbeconsideredwhenselectinganadjuvantforagivenAIThese
include interactions at the air/water interface and their effect on spray droplet for-
mation,sprayimpactionandadhesion,wettingandspreading,evaporationofspray
dropletsandformationofdeposits,solubilisationoftheAIbysurfactantmicellesand
itseffectontransportandinteractionbetweenagrochemical,surfactantsandtarget
species.
PartIIdealswiththeformulationofpaintsandcoatings.Chapter9describesthe
natureofthedispersedparticle,thedispersionmediumandfilmformers,thedepo-
sitionofparticlesandtheiradhesiononsubstratesandtheflowcharacteristics(rhe-
ology)ofthepaintformulation.Chapter10describestheformulationoffilmformers
https://doi.org/10.1515/9783110588002-001
vi | Preface
usingemulsionanddispersionpolymerization.Chapter11dealswiththeformulation
ofpigmentsforpaintapplication.Topicssuchasthewettingofpowders,breakingof
aggregatesandagglomerates,wetmillingandcolloidstabilizationofthepaintdis-
persionmustbeconsidered.Chapter12describestheprocessofenhancingparticle
depositionanditsfinaladhesion.Thisisgovernedbylong-rangeforcessuchasdouble
layerrepulsion(orattraction)andshort-range(surfaceforces).Chapter13illustrates
the rheological techniques that can be applied during paint formulation, whereas
Chapter14showshowtheserheologicalmethodscanbeappliedduringpaintformu-
lation.Chapter15givesexamplesoftheflowpropertiesofsomecommercialpaints.
PartIIIdescribestheformulationoffoodcolloids.Itstartswithageneralintroduc-
tion(Chapter16)highlightingthecomplexityoffoodsystems.Chapter17startswith
adescriptionoftheinteractionbetweenfoodgradesurfactantsandthestructureof
theliquidcrystallinephases.Thisisfollowedbyadescriptionofbinaryandtertiary
phasediagrams,monolayerformationandtherelationshipbetweentheliquidcrys-
tallinestructureandemulsionstability.Chapter18dealswiththeformulationoffood
emulsionsusingproteins,protein/polysaccharideandsurfactant/polysaccharidein-
teractions. The structure of portents and their interaction and conformation at the
liquid/liquidinterfacearedescribed.Chapter19describestheprocessofsurfactant
associationstructures,microemulsionsandemulsionsinfood.Chapter20dealswith
therheologyoffoodemulsionswithparticularreferencetointerfacialandbulkrheol-
ogy.Thecorrelationbetweeninterfacialrheologyandemulsionstabilityishighlighted
usingtwoexamples,namelymixedsurfactantandproteinfilms.Thebulkrheologyof
emulsionsisdescribedwithparticularreferencetomicrogeldispersionsandthefrac-
talnatureoftheaggregatednetwork.Chapter21dealswithfoamformulationsinfood
ofwhichwhippingcreamandbreaddougharethemostcommon.Inthefirstcase,the
airbubblesarestabilizedbyfatcrystalsthatadheretoairbubblesduringthewhipping
process forming a protective layer and preventing bubble coalescence. In the latter
case,thebreadqualityisdeterminedbyahighbreadvolumeandafinecrumbstruc-
ture.Severaltheorieshavebeenproposedtoexplainfoamstability,namely:surface
viscosityandelasticitytheory,wheretheadsorbedsurfactantfilmisassumedtocon-
trolthemechanical-dynamicalpropertiesofthesurfacelayersbyvirtueofitssurface
viscosityandelasticity;theGibbs–Marangonieffecttheory;surfaceforcestheory(dis-
joiningpressureπ),whichoperatesunderstatic(equilibrium)conditionsinrelatively
dilute surfactant solutions (h < 100nm); stabilisation by micelles (high surfactant
concentrations >cmc); stabilization by lamellar liquid crystalline phases, which is
particularlythecasewithnonionicsurfactantsthatproducelamellarliquidcrystalline
structureinthefilmbetweenthebubbles;stabilisationoffoamfilmsbymixedsurfac-
tantswherebyacombinationofsurfactantsgiveslowerdrainageandimprovedfoam
stability;andstabilizationbysolidparticles,whichinvolvesparticlesadsorbingatthe
air/liquidinterface.Chapter22looksattherelationshipbetweenrheologyandmouth
feel.Afterdescribingthemainrheologicalmeasurementsthatneedtobeappliedto
obtainsuchacorrelation,someemphasisisgiventothebreak-upofNewtonianand
Preface | vii
non-Newtonian liquids. The complexity of flow in the oral cavity is described and
subsequentlyadescriptionisgivenoftherelationshipbetweentextureandrheology.
Finally,someexamplesofpracticalfoodcolloidsaregiven.
Thisbook(Volume4)givesanumberofformulationexamplesintheareasofagro-
chemicals,paintsandcoatingandfoodcolloids.Itisavaluabletextforformulation
scientistsinvolvedintheformulationofthesesystems.Itmayalsobeusefulforaca-
demicsinvolvedinaresearcharearelatedtoanyoftheseformulations.
TharwatTadros
May2018

Contents
Preface|v
PartI:Theformulationofagrochemicals
1 Introductiontotheformulationofagrochemicals|3
2 Formulationofemulsifiableconcentrates|9
3 Formulationofemulsionconcentrates|15
3.1 Formationofemulsions|15
3.2 Mechanismsandmethodsofemulsification|16
3.3 Roleofsurfactantsinemulsionformation|18
3.4 Selectionofemulsifiers|20
3.4.1 Hydrophilic–lipophilicbalanceconcept|20
3.4.2 Phaseinversiontemperatureconcept|23
3.5 Emulsionstability|25
4 Formulationofsuspensionconcentrates|35
4.1 Introduction|35
4.2 Preparationofsuspensionconcentrates
andtheroleofsurfactants/dispersingagents|36
4.3 Controlofthephysicalstabilityofsuspensionconcentrates|40
4.4 Characterizingsuspensionconcentratesandassessing
oftheirlong-termphysicalstability|50
5 Oil-basedsuspensionconcentrates|59
5.1 Introduction|59
5.2 Stabilityofnonaqueoussuspensions|59
5.3 Emulsificationofoil-basedsuspensions|66
5.4 Polymericsurfactantsforoil-basedsuspensionsandthechoice
ofemulsifiers|68
5.5 Emulsificationintoaqueouselectrolytesolutions|69
5.6 Properchoiceofanti-settlingsystem|69
5.7 Rheologicalcharacteristicsofoil-basedsuspensions|70
6 Formulationofsuspoemulsions|71
6.1 Introduction|71
6.2 Suspoemulsionsinvestigated|72