21-08-2012, 12:51 PM
TESTING & IDENTIFICATION OF PLASTICS
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ABSTRACT
The characterstics of plastics are influenced by temperature changes,and therefore testing should also be done at high and low temperature extremes.Temperature and environmental chambers provide the condition necessary for such testing.However,the focus is shifted in carriying out various tests to find out out different properties of plastics.This paper gives a brief experimentation of flame behaviour testing for plastics along with other tests.Identification of plastics plays an important role in designing the data sheets of plastics in various industries.It is also briefly discussed with desire needs of testing.
.INTRODUCTION
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 wellas the lengths and polarities of the side chains; and by tailoring the degree of crystallinity, the amount of orientation imparted to the plasticduring processing and through copolymerization, blending withother plastics, and through modification with an enormous range ofadditives (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.
Analytical data associated with structural features
Analytical data associated with structural features includes molecular parameters like molecular weight, molecular weight distribution, tacticity, branching or chemical heterogeneity, morphological features like degree of crystallinity, etc. Such data are intended for material design and customer support and typically not shared broadly due to the proprietary nature of the data. Characterization of the analytical data is essential for establishing the structure-property relationships, which is useful in tailoring products designed to yield desired performance characteristics.
Data needed to aid in material preselection
Invariably every resin supplier provides a technical datasheet for each product that is commercially offered. These datasheets typically list a general set of 10 to 15 properties that are intended to represent the types of characteristics in each product, as illustrated in Fig1.
Since the primary purpose of the datasheet is a sales tool, the data reported in the datasheets generally focus on single-point data only, which is adequate for initial screening or intermaterial comparison. By their very nature, such data are inadequate for design and engineering analysis, as they bear little relevance to the end-use performance of the product and provide very little insight into how well the plastics will perform in service.