Shanghai Daoqin Plastics Co., Ltd.

         plastics internal stress is in plastics melt processing process in due to to large separation orientation and cooling shrinkage and other factors generate types inner in force. internal stress essence is large separation in melt processing process in formed balanced 构象, this type of balanced in cooling solid 化时不 can 立刻恢复 to and ring conditions versus balanced 构象, this type of 不均衡构象 实质 is types can high elastic 形变, 而冻结 high elastic 形变平时以位 can 情势储存 in plastics products in, in combined conditions lower, this type of by unstable will toward in solid 构象转化, can is can 而开释. large separation 子链间 function force and versus 互缠结 force 蒙受不住 this type of can 时, internal stress balanced to bad, plastics products generate force cracking and warpage deformation and other phenomenon.

         plastics internal stress generate 起因

        1, orientation internal stress

         orientation internal stress is plastics melt in flow and holding pressure material process in, large separation 子链沿 flow direction 排列定 toward by 冻结而 generate types internal stress. orientation force generate detailed process is: runner melt cooling speed degree fast formed outer melt viscosity increase high, from make melt in type core speed high table/sheet speed, melt internal and between to 剪切应 force function, generate flow direction orientation. orientation large separation understanding in plastics products inner 也就象征 its in in 未松弛 can high elastic 形变, therefore orientation force is large separation from orientation force 求 渡 to orientation inner force. use hot methods, can reduce or troubleshooting plastics products inner orientation force.

         plastics products orientation internal stress distribution is from products table/sheet to inner 层越 越 small, 并呈抛 material 线变化.

        2, cooling internal stress

         cooling internal stress is plastics products in melt processing process in cooling type shrinkage non-uniform generate types internal stress. especially is for thick plastics products, plastics products outer 层首先 cooling solid shrinkage, its inner can can still is hot melt, this 徉芯层就会限 degree table/sheet shrinkage, 导致芯层处于 pressure force 状况, table/sheet 层处于拉应 force 状态.

         plastics products cooling internal stress distribution is from products table/sheet to inner 层越 越 large, 并也呈抛 material more..

         another, belt/tape metal parts plastics products, is metal and plastics hot 胀系数 versus relatively large, easy formed shrinkage 不一平匀 internal stress.

         remove upper types important internal stress outer, also has below/following how much types internal stress: for crystallization plastics products 而言, its products internal 各部位 crystallization 构造跟 crystallization degree different 也会发生 internal stress. another also has type inner 应. force and demolding internal stress and other, is its internal stress specific gravity very small.

         effect/influence plastics internal stress generate factors

        1, separation rigid property

         separation rigid property large, melt viscosity high, polymer separation 子链运动 property 差, for/regarding generate can high elastic 形变恢复 property 差, easy generate internal stress 口例如, separation in has ring polymer, 如PC, PPO, PPS and other, its versus products internal stress large.

        2, separation 子链 极 property

        一 separation 子链 极 property large, separation versus 互吸引 function force large, from make separation 子间互 versus 挪动艰苦 increase large, can elastic property 形变 程 degree decrease small, 导致残余 internal stress large. 例如, separation in has 羰基, ester 基, and other property plastics types type, its versus products internal stress relatively large.

        3, 代替基团 位 retardant 效应

         large separation 子侧基取代基团 体积越 large, 则妨害 large separation 子链自由 active 动导致残余 internal stress add large. 例如, polystyrene (PS) 取代基团 苯基体积 relatively large, polystyrene (PS) products internal stress relatively large. types Common polymer internal stress large small 次序如 lower: PPO>PSF>PC>ABS>PA6>PP>HDPE