Properties of plastics

Poly(vinyl chloride) as previously discussed in Sec. 10.3, Formulas and Key Properties of Plastic Materials, has the following structures ... 

An extensive new Section 10 is devoted to polymers, rubbers, fats, oils, and waxes. A discussion of polymers and rubbers is followed by the formulas and key properties of plastic materials. Eor each member and type of the plastic families there is a tabulation of their physical, electrical, mechanical, and thermal properties and characteristics. A similar treatment is accorded the various types of rubber materials. Chemical resistance and gas permeability constants are also given for rubbers and plastics. The section concludes with various constants of fats, oils, and waxes. 

Tris(2-ethylhexyl) phosphate shows good compatibiUty with PVC and also imparts good low temperature performance in addition to good fire retardancy. 2-Ethyhexyl diphenyl phosphate has widespread use in dexible PVC appHcations due to its combination of properties of plasticizing efficiency, low temperature performance, migration resistance, and fire retardancy. 

Steps 1 and 2 can be described as physical plasticization, and the precise details of how this is carried out depends on the appHcations technology involved, ie, suspension or paste PVC. The rate at which step 2 occurs depends on the physical properties of plasticizer visocity, resin porosity, and particle size. 

Mechanical properties of plastics can be determined by short, single-point quaUty control tests and longer, generally multipoint or multiple condition procedures that relate to fundamental polymer properties. Single-point tests iaclude tensile, compressive, flexural, shear, and impact properties of plastics creep, heat aging, creep mpture, and environmental stress-crackiag tests usually result ia multipoint curves or tables for comparison of the original response to post-exposure response. 

ASTM D638, Test Methodfor Tensile Properties of Plastics, Vol. 8.01, ASTM, Philadelphia, Pa., 1991. 

Light-focusing plastic rods and other optical devices with graduated refractive indexes may use DADC and other monomers (29). Preparation and properties of plastic lenses from CR-39 are reviewed in reference 30. 

Determining and Reporting Dynamic Mechanical Properties of Plastics... 

Zinc dust is used in the sherardizing process where work pieces are tumbled with zinc dust in rotating steel dmms which are heated electrically or by gas to 370—420°C (149). The steel parts are uniformly coated with zinc. In the chemical and metallurgical industries, zinc dust is used as a reducing agent, in the manufacture of hydrosulfite compounds for the textile and paper industries, and to enhance the physical properties of plastics and lubricants (2). 

The carbon blacks used in plastics are usually different from the carbon blacks used in mbber. The effect of carbon black is detrimental to the physical properties of plastics such as impact strength and melt flow. Electroconductive grades of carbon black have much higher surface areas than conventional carbon blacks. The higher surface areas result in a three-dimensional conductive pathway through the polymer at much lower additive levels of the carbon black. The additive concentrations of electroconductive carbon blacks is usually j to that of a regular carbon black (132). 

Properties of plastic LDPE LLDP E HDPE PP PVC (flexible ) PS ABS Polyacryhc (glazing) Polycarbonat e (glazing) Epoxy (minera 1 fihed) Acetal homopolym er... 

Syndiotactic Polybutadiene. Syndiotactic polybutadiene is a unique material that combines the properties of plastic and mbber. It melts at high (150—220°C) temperatures, depending on the degree of crystallinity in the sample, and it can be molded into thin films that are flexible and have high elongation. The unique feature of this plastic-like material is that it can be blended with natural mbber. 1,4-Polybutadiene and the resulting blends exhibit a compatible formulation that combines the properties of plastic and mbber. 

Bert, C.W., Mills, E.J., Gideon, D.N., and Stein, R.A., Preliminary Survey on Hypervelocity-Impact Properties of Plastics and Plastic Laminates, Battelle Memorial Institute Special Report, Columbus, OH, 24 pp., June 1963. 

Finally mention may be made about the influence of humidity on the electrical insulating properties of plastics. Once again the polymers may be classified into two groups, those which do not absorb water and those which do. The nonabsorbent materials are little affected by humidity whereas the insulation characteristics of the absorbent materials deteriorate seriously. These latter materials are generally certain polar materials which all appear capable of forming some sort of bond, probably a hydrogen bond, with water. Three reasons may be given for the deleterious effects of the water. 

A crude approximation to computer-based systems can be achieved by considering tables of properties of plastics materials such as those published annually in the Modern Plastics Encyclopaedia. Since the tables are to be marked, the following exercise should be carried out on photocopies ... 

Fluorinated rubbers, copolymers of hexafluoropropylene and vinylidene-fluorides, have excellent resistance to oils, fuels and lubricants at temperatures up to 200°C. They have better resistance to aliphatic, aromatic and chlorinated hydrocarbons and most mineral acids than other rubbers, but their high cost restricts their engineering applications. Cheremisinoff et al. [54] provide extensive physical and mechanical properties data on engineering plastics. A glossary of terms concerned with fabrication and properties of plastics is given in the last section of this chapter. 

Property of plastics that permits the material to undergo deformation permanently and continuously without rupture from a force that exceeds the yield value of the material. 

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