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1、塑料的内应力控制改性(Internalstresscontrolofplastics)InternalstresscontrolofplasticsInternalstressofplasticsreferstoaninherentstressproducedbytheprocessofmeltingofplasticsduetotheorientationofmacromoleculechainsandcoolingandshrinkage・Theesseneeofinternalstressisnotbalaneed
2、conformationofmolecularchainformedinthemeltingprocess,theimbalanceintheconformationofcuringnotimmediatelycoolingreturntotheequilibriumconfonnationandadapttoenvironmentalconditions,theimbalanceofhighelasticdeformationoftheconfonnationisakindofreversible,highelasti
3、cdeformationandtheusualtofreezeenergystoredinplasticproducts,undersuitableconditions,theforcedunstableconformationwilltransformtotheconfonnationalfreedomofthestabilityofthepotentialenergyintokineticenergyrelease・Whentheforcebetweenthemacromolecularchainsandthefor
4、cesofentanglementcannotwithstandthiskineticenergy,theinternalstressbalanceisdestroyed,andtheplasticproductswillcausestresscrackingandwarpage・Almostallplasticproductswi11havevaryingdegreesofinternalstress,especiallyplasticinjectionproductsaremoreobviousstress・Thee
5、xisteneeofinternalstressnotonlycauseswarpageandcrackingofplasticproductsduringstorageanduse,butalsoaffectsthemechanicalproperties,opticalproperties,electricalpropertiesandappearancequalityofplasticproducts・Forthisreason,wemustfindouttheinternalstressesandtoelimin
6、ateinternalstressandreducethestressinsidetheplasticproducts,andtheresidualstressintheplasticproductsaredistributedasevenlyaspossible,toavoidthephenomenonofstressconcentration,therebyimprovingtheplasticmechanicalthermalproperties1.CausesofinternalstressinplasticsT
7、herearemanyreasonsfortheinternalstress,suchasplasticmeltbystrongershearinthemachiningprocess,orientationandcrystallizationprocessinthepresenceofmelt,allpartsofthecoolingspeedisextremelydifficulttoachieveuniformandnonuniformplasticization,demolding,whichwillleadto
8、internalstress・Accordingtothecausesofinternalstress,stresscanbedividedintothefollowingcategories・(1)orientationinternalstress;Theorientationinternalstressisaki
