Definition of the Plastic

Definition of the plastic is fundamental to the prediction of the lifetime of a plastic component. 

Definition of the plastic should include, where possible, details of ... 

Shear yielding in the bulk of the material is incorporated through the constitutive law presented in the previous section. The definition of the plastic strain rate CP together with the expression for the driving stress 6 specifies the energy dissipation rate per unit volume G D< = /2tY . The energy balance in the material can then be written as... 

Plasticisers are also used in products such as lacquers and adhesives that fall outside the definition of the plastics industry. Dicyclohexyl phthalate is used in nitrocellulose lacquers polyethylene glycol and its monostearate are compatible with cellulose nitrate. Dibutyl maleate is compatible with polyvinyl acetate, and di- -hexyl adipate, diethylene glycol di-2-ethyl butyrate or dibutyl sebacate can be used in polyvinyl butyral. Benzoates are recommended for... 

The definition of the plastic deformation and A.4 state that P is related to an unstressed state of a certain neighbourhood of X. 

FIG. 26-39 Definition of the venting capability EF of an explosion door in comparison with a plastic foil rupture disk. 

Although it is very difficult and probably of little value to produce an adequate definition of the word plastics , it is profitable to consider the chemical structure of known plastics materials and try to see if they have any features in common. 

It is the prediction of performance in its broadest sense, including all the characteristics and properties of materials that are essential and relate to the processing of the plastic. To the designer, an example of a strict definition of a design property could be one that permits calculating product dimensions from a stress analysis. Such properties obviously are the most desirable upon which to base material selections. 

How much the ecology question contributed to the impetus for developing plastic beverage bottles is debatable. I know from personal contacts this was originally a major factor. In part the uncertainty results from the need for clearer definition of the relation of packaging to environmental control. 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

There is a definite need for further work on the compatibility of additives from the perspective of their interfering with biological or chemical processes that are needed to disrupt the plastic matrix. Although additives are valuable components when they improve the properties of a plastic, their use cannot be sanctioned if they prevent degradation of the plastic. 

These glasses differ macroscopically in volume and, therefore, in structure. This mental experiment intends to point out, that correctly speaking, there does not exist a glass of definite structure. A glass of the composition x at the temperature T can be produced in different ways which result in glasses of different structure. The characteristic behavior of the plasticizer in its molecular interaction with the chain molecules determines structure and macroscopic behavior of the glass. 

Polymerization products with internal plasticization have the advantage that there is no migration or efflorescence of the plasticizer on storage. On the other hand, the mechanical properties—above all, flexibility at low temperatures—are decreased in comparison with the products with low molecular plasticizers. This is because mobility in the solvatized molecules is diminished. The same refers to tensile strength, which is often decreased with internally plasticized polymers. In this respect they are inferior to externally plasticized products, which also have an advantage in that type and quantity of plasticizer can be varied widely. Internally plasticized products must have a definite ratio of components. These are reasons why combinations of both types of plasticizers are preferred. 

Testing with a Gieseler plastometer (ASTM D-2639) gives a semiquantitative measurement of the plastic property, or apparent melting of coal when heated under prescribed conditions in the absence of air. The chemical nature of the constituents that account for a coal s plastic properties is not known. The material thought to be responsible for the plastic properties of coal has been removed from coal successfully by solvent extraction, leaving a nonplastic residue. Such residue has been rendered plastic by returning to it the extracts obtained by the solvent extraction. No definite relationship has been established between the amount of extract and the plastic properties of the coal. 

A noteworthy point is that in certain cases, it is convenient to speak in terms of function. For example, the main function of the plastic film is to keep the food fresh for a specific duration of time. In cases where a comparative study is commissioned, and alternatives are required, the function definition is important to clearly state what the product is meant to do, so alternatives can be sought. 

An important advantage of the plastic is that in thermal processing the finish on the surface of the tool—whether it be matt, leather grain, jazzy pattern, or what you will—can be transferred directly to the workpieces. One proviso when a design is applied in this way is that the tool should not wear quickly (which will result in loss of definition of the decoration) or, worse, that it be scratched or damaged so that the unwanted mark is carried over to the products. 

ISO 472 ( Plastics—Vocabulary ) provides the following definition of the first word in the title of this book ... 

For the definition of the terms yield value and flow see also Bingham, Fluidity and Plasticity. This abstract of Bartell and Hershberger s paper differs from that given by the authors, but it seems to be justified on a careful analysis of the data recorded. 

A precise definition of reinforced plastics can be difficult (or impossible) to formulate because of the scale factor. At the atomic level all elements... 

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