Characteristics of plastic materials

Processability. The term is used generally to describe the flow characteristics of plastic materials during fabrication. 

The concept of quasi-brittle fracture implies that some materials that exhibit the characteristics of plastic materials at standard test, collapse in tests of the sample with a crack due to the quasi-brittle mechanism, that is, plastic deformation is concentrated in a narrow layer near the tip of a crack. For such materials, Griffith s criterion is relevant instead of the value of the surface energy to introduce the work of plastic deformation at the crack tip. 

In addition to the permeability coefficient, other parameters are also used to express the barrier characteristics of plastic materials. These include permeance (R), gas transmission rate (GTR), water vapor transmission rate (WVTR), and thickness normalized flow. The relationship between these parameters is shown in Fig. 14.3. 

ON THE GRAVIMETRIC DETERMINATION OF THERMAL CHARACTERISTICS OF PLASTIC-MATERIALS. 

Corona discharge treatment is a form of Plasma pre-treatment, operated at atmospheric pressure, used widely for enhancing the adhesive characteristics of plastic materials. It is very widely used for treating plastic films (specially polyolefin films) and conical containers (tubs) but also finds application in other areas snch as wire coatings and moulded composite parts. 

This chapter has covered some of the stress loading situations other than simple tensile, compressive and bending loads encountered by plastics parts. The unique characteristics of plastic materials of certain types make them especially suited to resist the specific stress conditions. With proper part design, material selection and modification the designer can make parts that will perform well under unique stress conditions. 

Brandsch, J. and Piringer, O. G. Characteristics of Plastic Materials. In Plastic Packaging Interactions with Food and Pharmaceuticals, O. G. Piringer and A. L. Baner (Eds.), Wiley-VCH Verlag GmbH Co. KGaA Weinheim, pp. 15-60 (2008). 

Coupling agents Improves the bonding characteristics of plastic materials. Improves the mechanical and electrical properties of die plastic material. 

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