等规聚丙烯微注塑制品结晶形态和制品收缩的-研究

《等规聚丙烯微注塑制品结晶形态和制品收缩的-研究》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、ABSTRACTWiththedevelopmentofscienceandtechnology,micro—electromechanicalsystems(MEMS)andmicro—systemstechnology(MST)havebeensuccessivelyappliedtomanyfields．Micro-injectionmolding(MIM)isoneofthemostimportantprocessesforreplicatingmicrostructuredpartsandmicropartswithhighprecision．Becauseoftheapp

2、licationinhigh—grade，precisionandadvancedfieldsofmicroinjectionmoldedparts，thehigherpropertyofthepartsisdemand．Themorphologyofstructureplaysamajorroleinmasteringthefinalpropertiesoftheproducts，therefore，investigationofmorphologyofthemicropartshasimportantsignificance．Inthiswork，theiPPmicroparts

3、withtwodifferentthicknesswerechoseninthestudy．TheinfluenceofprocessingparametersonmorphologyandshrinkageoftwokindsofmicropartsWasinvestigatedbasedonthemicroinjectionmoldingexperiments。Theworkincludes：1．Theinfluenceofscaleeffectonmorphologyofthemicroparts．Bymeansofpolarizedlightmicroscopy(PLM)an

4、dwideangleX—raydiffraction(WAXD)，themorphologyevolutionofmicropartswasinvestigated．PLMobservationsindicatedthatmorphologyalongthethicknessdirectionofmicropartsexhibitedasimilarskin—corestructureasmorphologyofthetraditionalinjectionparts．Therearethreestructuresinthemicropartsincludingskinfrozenl

5、ayer,shearlayerandcorelayer,andshearlayerpresentedalargefractionofthethicknessinmicroinjectionmoldedparts．Thecorelayerinthetraditionalinjectionpartspresentedalargefraction．There’Shardlyany13-crystalintwokindsofmicroparts．Thedegreeofcrystallinityofthemicropartsisdifferentatdifferentlocation．Thed

6、egreeoforientationinmicropartwiththicknessof0．5mmishigherthatmicropartswiththicknessof1．0mm．2．Theinfluenceofinjectionspeedonmorphologyofmicroparts．Bymeansofpolarizedlightmicroscopy(PLM)andwideangleX-raydiffraction(WAXD)，theinfluenceoftheinjectionspeedonmorphologyevolutionofmicropartswasinvestig

7、ated．Theresultsshowthattwokindsofmicropartsexhibitedthesimilarskin—corestructureatlowinjectionspeed．Withtheinjectionspeedincreasing，theIIIABSTRACTfractionofshearlayerhaslittlechange．Themicropartsexhibitaspecificcore—freemorphology