塑料内应力是指在塑料熔融加工过程中由于受到大分子链的取向和冷却收缩等因素而产生的一种内在应力。内应力的本质为大分子链在熔融加工过程中形成的不平衡构象,这种不平衡构象在冷却固化时不能立刻恢复到与环境条件相适应的平衡构象,这种不均衡构象的实质为一种可逆的高弹形变,而冻结的高弹形变平时以位能情势储存在塑料制品中,在合适的条件下,这种被迫的不稳定的构象将向自在的稳固的构象转化,位能改变为动能而开释。
The internal stress of plastics is an internal stress caused by the
orientation of macromolecular chains and cooling shrinkage during the
melting process of plastics. The essence of internal stress is the
unbalanced conformation formed in the melting process of macromolecular
chain. This kind of unbalanced conformation can not be restored to the
equilibrium conformation suitable to the environmental conditions
immediately when it is cooled and solidified. The essence of this
unbalanced conformation is a kind of reversible high elastic
deformation, while the frozen high elastic deformation is usually stored
in plastic products in the form of potential energy under suitable
conditions A forced unstable conformation will be transformed into a
free stable conformation, and the potential energy will be changed into
kinetic energy.
当大分子链间的作用力和相保定平面设计培训 保定空调维修 保定管道通风 包装盒定做 化粪池模具 废旧电缆回收 不锈钢铸件互缠结力蒙受不住这种动能时,内应力平衡即受到破坏,塑料制品就会产生应力开裂及翘曲变形等现象。
When the force and entanglement force between macromolecular chains can
not bear this kinetic energy, the internal stress balance will be
destroyed, and the plastic products will have stress cracking and
warping deformation.