Semi-crystalline thermoplastics materials

Amorphous thermoplastic materials are transparent and so are available in a wider color range than semi-crystalline, thermoplastics materials. Traditionally all plastics were molded from colored granules but now, because of the ease with which color may be added at the machine, there is increasing use in the injection molding industry of color concentrates, or masterbatches, in conjunction with natural, or un-colored, material. 

C. Price, The Rapra Collection of DSC Thermograms of Semi-crystalline Thermoplastic Materials, Rapra Technology Limited, UK, 1997. 

As the natural color of the material is a translucent, ivory white, then a wide color range is possible. Being a semi-crystalline, thermoplastics material, transparent moldings are not usually possible by injection molding. Best results given by the use of fully compounded material as dry colors and mas-terbatches can sometimes give rise to streaking, due to dispersion problems. 

PVC, and its copolymers, are most often converted to TPE-type materials by melt mixing them with plasticizers (plastici ers) which are compatible with the plastics material. Both polymeric and low molecular weight plasticizers are used with PVC to give elastomeric compounds. With the semi-crystalline, thermoplastics materials, it is necessary to mfac them with rubbers/elastomers, with which they are not molecularly compatible, so as to form the required softer, elastomeric materials. This is because plasticizers are not compatible with a semi-crystalline, thermoplastics material. 

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