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1、塑料内应力控制InternalstresscontrolofplasticsTime:2007-04-2410:03source:Alibabaforumtextselection:largeandsmallplasticplasticstressisakindofinternalstressintheplasticmeltintheprocessbecauseoftheorientationandthecoolingshrinkagefactorofthemolecularchainandthering・Thee
2、ssenceofinternalstressisnotbalaneedconformationofmolecularchainformedinthemeltingprocess,theimbalanceintheconformationofcuringnotimmediatelycoolingreturntotheequilibriumconformationandadapttoenvironmentalconditions,theimbalanceofhighelasticdeformationoftheconf
3、ormationisakindofreversible,highelasticdeformationandtheusualtofreezeenergystoredinplasticproducts,undersuitableconditions,theforcedunstableconformationwilltransformtotheconformationalfreedomofthestabilityofthepotentialenergyintokineticenergyrelease・Whenthefor
4、cebetweenthemacromolecularchainsandtheforcesofentanglementcannotwithstandthiskineticenergy,theinternalstressbalaneeisdestroyed,andtheplasticproductswillcausestresscrackingandwarpage・Almostallplasticproductswillhavevaryingdegreesofinternalstress,especiallyplast
5、icinjectionproductsaremoreobviousstress・Theexistenceofinternalstressnotonlycauseswarpageandcrackingofplasticproductsduringstorageanduse,butalsoaffectsthemechanicalproperties,opticalproperties,electricalpropertiesandappearancequalityofplasticproducts・Forthisrea
6、son,wemustfindouttheinternalstressesandtoeliminateinternalstressandreducethestressinsidetheplasticproducts,andtheresidualstressintheplasticproductsaredistributedasevenlyaspossible,toavoidthephenomenonofstressconcentration,therebyimprovingtheplasticmechanicalth
7、ermalproperties1.CausesofinternalstressinplasticsTherearemanyreasonsfortheinternalstress,suchasplasticmeltbystrongershearinthemachiningprocess,orientationandcrystallizationprocessinthepresenceofmelt,allpartsofthecoolingspeedisextremelydifficulttoachieveuniform
8、andnonuniformplasticization,demolding,whichwillleadtointernalstress・Accordingtothecausesofinternalstress,stresscanbedividedintothefollowingcategories・(1)orientationinternalstress:T
