剪切場下聚乳酸結(jié)晶行為研究.pdf

1、西南科技大學(xué)碩士學(xué)位論文剪切場下聚乳酸結(jié)晶行為研究姓名：李旭娟申請學(xué)位級別：碩士專業(yè)：材料物理與化學(xué)指導(dǎo)教師：李忠明20080411西南科技大學(xué)碩士研究生學(xué)位論文第1I頁AbstractThesubjectsonhowtocontrolthemicrostructurefrommelttocrystallinestructure，settinguptherelationshipamongpolymercrystallizationpro

2、cess，condensedstructureandfinalproperties，especiallyforthepolymerphysicsmattersofcrystallinethermoplasticpolymermaterialsduringcrystallizationprocess，havecausedincreasingattentionofpolymerscienceworkersInthisthesis，thesu

3、bjectonthecrystallizationbehaviorsofPLLAundershearflowwasinvestigatedusingp01arizedopticalmicroscopycoupledwithlinkamshearstage，WAXD，DSCandIRTheinnuencesofshearmodel，shearrate，shearstrain，shearduration，isothermaltemperat

4、ure，processingparametersandfillersonthemicrostructureofPLLAwerecarriedoutTheresultsshowedthat：Understeadyshearflow，sheartemperature，shearrateandcoolingratehadsignificantrolesinthemicrostructureofPLLAUndergiVentemperature

5、condition，therewasthecriticalshearrate(5s1)aboVewhich，thecrystallinemorph0109ywascylindrite；belowwhich，morphol69ywasspheruliteThecrystallinemorphologyVariedftomcrylindritemorph0109ytospherulitecrystalsdependingonsheartem

6、peratureAboVecriticaltemperature(1200C)，thecylindritecrystalswereobserVed，belowsuchtemperature，f6rmationofspherulitecrystalsAsconcernedasnon—isothermalcrystallizationofPLLA，bothcoolingrateandshearratemadesignificantdiffe

7、renceonthestructureandcrystallinityWhencoolingratereached50C／min，thePLLAdidnotcrystallizeUnderoscillatoryshearflow，thestructureofPLLAwasdeterminedbyshearstrainandsheardurationDuringisothermalcrystallizationprocess，t蜓ecyl

8、indritecrystalswe’regeneratedatshearstrainofhighas100‘％；orelse，thecrystallinemorphologymaintainedspheruliteShearflowincreasedcrystaldensity，reducedinductionperiodThegenerationofcylindritecrystalsoccurredwhenshearduration