高分子材料加工成型(第二章添加剂)

1、Stabilizers are almost invariably added to improve the heat and light stability of the polymer. Metallic salts of lead(铅盐铅盐), barium(钡钡), tin（锡）（锡）, or cadmium（镉）（镉） are used. Oxides（氧化物）（氧化物）, hydroxides（氢氧化物）（氢氧化物）, or fatty-acid salts（脂肪酸（脂肪酸盐）盐） are most effective. Epoxy plasticizers aid materia

2、lly in stabilizing the resin. Free radical acceptance appears to be a prominent mechanism of stabilization. HCl acceptors have been used.salts of leadEpoxy External plasticization is achieved through incorporation of a plasticizing agent into a polymer through mixing and/or heating.Internal plastici

3、zation can be produced through copolymerization giving a more flexible polymer backbone or by grafting another polymer onto a given polymer backbone，altering the molecular structure of the polymerPlasticizers should be relatively nonvolatile, nonmobile, inert, inexpensive, nontoxic,and compatible wi

4、th the system to be plasticized. 第三节第三节 润滑剂润滑剂lubricantLubricants are added to improve the flow characteristics of a material during its processing. They operate by reducing the melt viscosity or by decreasing adhesion between the metallic surfaces of the processing equipment and the material being

5、processed.一、一、作用与分类作用与分类作用：主要是降低熔体之间和熔体与作用：主要是降低熔体之间和熔体与加工机械之间的摩擦及粘附，改善流动加工机械之间的摩擦及粘附，改善流动性，提高加工性能。性，提高加工性能。分类：分类：内润滑剂内润滑剂Internal lubricants 外润滑剂外润滑剂external lubricants Internal lubricants reduce molecular friction, consequently decreasing the materials melt viscosity and allowing it to flow more e

6、asily. External lubricants act by increasing the flow of the material by decreasing the friction of the melted material as it comes into contact with surrounding surfaces. In reality, lubricants such as waxes, amides, esters, acids, and metallic stearates act as both external and internal lubricants

7、.Initiators such as benzoyl peroxide are used not only for the initiation of chain reaction polymerization but also for the curing of polyesters and ethylene-propylene copolymers and for the grafting of styrene on elastomeric polymer chains. Peroxides such as 2,5-dimethyl-2,5-di(t-butylperoxy) hexyn

8、e-3 (特丁基过氧化物)are used for crosslinking HDPE. Since these compounds contain weak covalent bonds, precautions must be taken in their storage and use to prevent explosions. Free radicals for crosslinking may also be produced by electrons, rays, or UV irradiation. The latter is more effective in the pre

9、sence of additives such as the methyl ether of benzoin（安息香胶）.Unsaturated polymers such as alkyd resins may be cured or “dried” in the presence of oxygen, a salt of a heavy metal, and an organic acid called a drier. The commonly used metals are cobalt, lead, and manganese(Mn), and the most common org

10、anic acids are linoleic(亚麻酸) and tall oil fatty acids.a filler is a relatively inert material added to a plastic to modify its strength, permanence, working properties, or other qualities or to lower costs.wood flour, calcium carbonate a reinforced plastic is one with some strength properties greatly superior to those of the base resin resulting from the presence of high-strength fillers embedded