Shanghai Daoqin Plastics Co., Ltd.

degradation: polymer in processing process in, need to high temperature, strong/high force and other function, in this strong/high function lower, polymer/macromolecule need generate 断链, molecular weight decline, this is degradation.

一, degradation classification

1.自由基连锁 degradation reaction

由 hot, force and other material factors degradation. in hot or force effect/influence lower, polymer degradation usually is random selection 进行. this is is polymer in has chemical can amount separation 接近 关系.

in this material factors function lower, degradation mechanism its versus 似, usually is through formed 自由基 in steps 按连锁 reaction mechanism 进行, active property in generate, 链转移 and fracture, 链终止 several stage/phase.

2.逐步 degradation

this type of degradation main/primary is in processing high temperature lower, polymer has micro amount water separation, acid or alkali and other 杂志进行 has selection degradation, degradation generally in carbon -杂链（如C-N, C-O, C-S, C-Si and other ）处, this is is carbon -杂链键 can relatively small, stability property relatively 差 缘故.

degradation tool has reaction 特征, 每一步 tool has property, in material stability, machine molecular weight increase large increase large, therefore degradation reaction 逐步进行, polymer molecular weight decrease small meanwhile, its molecular weight dispersion property 也逐步 decrease small. has amine, ester, shrink aldehyde polymer easy in high temperature lower hydrolysis, ester understanding, acid understanding, amine understanding and other degradation reaction.

temperature degree high, degradation fast; in high temperature lower time long, degradation 越厉害. processing process has oxygen gas in, oxygen in high temperature lower can make polymer oxidation formed oxidation material structure, oxidation material easy separation understanding generate 自由基, from 而引发连锁 degradation reaction, is hot oxygen degradation, make polymer degradation main/primary 历程.

processing process in, polymer need 反复受 to force function （以剪切应 force is 主）, 当剪切应 force can amount ultra- 键 can 时, 就引起 chemical fracture, generate degradation. function and hot function 一起, for polymer degradation strong/high degradation promote function.

micro amount water separation is has polymer degradation main/primary factors, 如PC, nylon （PA）, ABS, polyester and other. therefore processing front drying is 必备 工序.

二, solution measures

polymer in processing process in degradation rear, products appearance 变差, inner in quality reduce, use lifespan shrink short. therefore processing process large more 数情况 lower 都应设 method amount decrease/reduce and polymer degradation. therefore usually can using/adopting below/following measures:

• 严格 control Raw Materials technology indicators, amount remove polymer in catalytic agent and other 杂质.

• use front for polymer 进行严格 drying, especially is polyester, polyether, polyamide (PA) and other polymer process easy from gas in water separation, use front usually make water separation content reduce to 0.01-0.05% below/following.

• 确定 combined processing process and processing conditions, make polymer can in easy generate degradation conditions lower processing molding.

• processing equipment and mold has good structure. main/primary remove equipment in and polymer 接触 部 separation can can in or 缝隙, decrease/reduce long runner, improvement add hot plant/unit, improve/increase temperature degree plant/unit degree and cooling system cooling efficiency.

• in formulation in use antioxidant, stabilizer and other add strong/high polymer for degradation resistant can force.

has lower, can utilizing polymer in processing process in degradation 效应, 如橡胶 开炼（塑炼）, reduce molecular weight, improve/increase processing property; polymer blending material, utilizing 剪切效应 generate 自由基, can is types or multiple polymer generate grafting, copolymer and other reaction, from improve/increase blending material property can.