The plastic flow cae analysis in the injection mold

Abstract

Consulta en la Biblioteca ETSI Industriales (7614)

[EN] Plastics are an important part of everyday life; products made from plastics range from sophisticated products, such as prosthetic hip and knee joints, to disposable food utensils. One of the reasons for the great popularity of plastics in a wide variety of industrial applications is due to the tremendous range of properties exhibited by plastics and their ease of processing. Plastic properties can be tailored to meet specific needs by varying the atomic makeup of the repeat structure; by varying molecular weight and molecular weight distribution; by varying flexibility as governed by presence of side chain branching, as well as the lengths and polarities of the side chains; and by tailoring the degree of crystallinity, the amount of orientation imparted to the plastic during processing and through copolymerization, blending with other plastics, and through modification with an enormous range of additives (fillers, fibers, plasticizers, stabilizers). Given all of the avenues available to pursue tailoring any given polymer, it is not surprising that such a variety of choices available to us today exist. [2] Polymeric materials have been used since early times, even though their exact nature was unknown. In the 1400s Christopher Columbus found natives of Haiti playing with balls made from material obtained from a tree. This was natural rubber, which became an important product after Charles Goodyear discovered that the addition of sulfur dramatically improved the properties. However, the use of polymeric materials was still limited to natural¿based materials. The first true synthetic polymers were prepared in the early 1900s using phenol and formaldehyde to form resins Baekeland's Bakelite. Even with the development of synthetic polymers, scientists were still unaware of the true nature of the materials they had prepared. For many years scientists believed they were colloids aggregates of molecules with a particle size of 10¿ to 1000nm diameter. It was not until the 1920s that Herman Staudinger showed that polymers were giant molecules or macromolecules. In 1928 Carothers developed linear polyesters and then polyamides, now known as nylon. In the 1950s Ziegler and Natta¿s work on anionic coordination catalysts led to the development of polypropylene, high¿density linear polyethylene, and other stereospecific polymers.