Injection molding plastic materials used

Large quantities of secondary cellulose acetate are used worldwide in the manufacture of filter material for cigarettes. Because of its excellent clarity and ease of processing, cellulose acetate film is widely used in display packaging and extmded plastic film for decorative signs (see Packaging materials). Injection-molded plastics of cellulose acetate are used in toothbmsh handles, computer bmshes, and a large variety of other appHcations (7). 

Pf pressure at the tip of the screw for an injection-molding plasticator (Eq. 10.22) Q extrusion rate in kg/h O specific rate in kg/(h-rpm) for Eq. 10.21 R compression rate in the helical direction Pjs belt sheave reduction Rg speed reduction for the gearbox S support distance from the fixed end of the barrel shear strength of the material used for the screw t plasticating time in seconds (Eq. 10.21)... 

Cell Hardware. Cell jars are constructed almost exclusively of injection-molded plastics, which are resistant to the strong alkali electrolyte. The most generally used materials are modified styrenes or copolymers of styrene and acrylonitrile (SAN). Another material that has been found to increase shock resistance of cells is ABS plastic (acrylonitrile—butadiene—styrene). All of these plastics can be injection-molded, are solvent-sealable and, in general, meet operating temperature ranges up to about 70°C. For applications that require greater resistance to temperature, some of the more recent plastics such as polysulfone and poly(phenylene oxide) (PPO) injection-moldable materials able to withstand operating temperatures up to 150°C are used. 

More recently, foamable, recyclable PVC blends were disclosed. They comprise PVC plasticized with DOP and/or epoxidized soybean oil, blended with either TPU and/or EVAc. The formulation could be foamed either during extrusion or injection molding. The material is used to produce anti-slip shoe soles with good abrasion resistance [Shin etal., 1998]. 

Gotzmann et al. [12] of Bayer Plastics discussed the manufacture of metal-plastic hydride components, including injection molding plastics such as glass fiber-reinforced polyamides around a steel aluminum profile placed in the mold. Some applications of such components were examined, and computer-aided material selection, finite element analysis, and computer simulation systems developed for use in this technology are described. 

By copolymerization with alpha olefins it is possible to produce a range of very low density materials (VLDPE.) which can have a density of 0.88 to 0.91g.cm-3 (0.51 to 0.53oz/cu.in.). Can be used as an alternative to thermoplastic elastomers and for materials modification, for example, for improving the impact strength of PR The higher density materials are also used as injection molding plastics. 

Insert injection mol ding is used to manufacture snap closures for yogurt and ice cream cups and tubs and for breakfast cereal cans. In insert injection mol ding, a die-cut printed paperboard or other flat material is placed in the mold. The plastic is extmded around the insert to form a precision skeletal stmcture. 

Mold Coolers for Plastic Injection Molding. Heat pipes are used for local temperature control in the injection molding of plastics (see Polymerprocessing). A heat pipe is often used to force local cooling within a mold to speed operation, control viscosity, retention of material in a difficult mold area, or to reduce thermal stresses on cooling. 

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