Some Brief Discussion on Melt Rheology and Processing

2 SOME BRIEF DISCUSSION ON MELT RHEOLOGY AND PROCESSING 

Thermoplastics, by the very definition of the word, denotes polymeric materials which can be made to soften and take on new shapes by the application of heat and pressure. In their original raw material form, themu iastics are available in solid state as chips, granules, or powder. These are melted and reshaped to form various plastic products. For details regarding engineering aspects and properties of plastics, readers could refer to some of the available hancRxwks [168-171]. 

Melt rheology is concerned with the description of the deformatitm of the material under the influence of stresses. Deformation and flow naturally exist when the thermoplastics are melted and then reformed into solid products of various shapes. All polymer melts are viscoelastic materials that is, their response to external load lies in varying extent between that of a viscous liquid and an elastic solid. In an ideal viscous liquid, the energy of deformation is dissipated in the form of heat and cannot be recovered just by releasing the external forces whereas, in an ideal elastic solid, the deformation is fiilly recovered when the stresses are released. 

Quality control of raw materials, manufacturing processional product 

The sensitivity of the rheological properties to structural differences in materials forms a handy aid to the quality control engineer when deciding whether to accept or reject an incoming material. 

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