Plastics amorphous thermoplastics

Advanced Thermoplastics Materials. Thermoplastics and linear plastics of finite molecular weight that can be fabricated into very complex stmctures by hot melt or injection mol ding are different from the thermoset materials that require cross-linking to build up infinite molecular weight to form network (cross-link) stmctures. Advances in thermoplastic engineering materials include amorphous thermoplastics, crystalline thermoplastics, Hquid crystal thermoplastics, and fluorinated thermoplastics (see Engineering plastics). 

Fig. 18.8 Typical stress-strain curve of amorphous thermoplastics below their glass transition temperature. Area under the curve is small compared with many crystalline plastics and hence the impact strength is usually low...

Plasticised amorphous thermoplastics Certain plastics may be mixed with high-boiling low-volatility liquids to give products of lower T. The most important example occurs with p.v.c. which is often mixed with liquids such as di-iso-octyl phthalate, tritolyl phosphate or other diesters to bring the below room temperature. The resultant plasticised p.v.c. is flexible and to some degree quite rubbery. Other commonly plasticised materials are cellulose acetate and cellulose nitrate. 

Polyvinyl chloride (p.v.c.) P.V.C. is one of the two most important plastics in terms of tonnage and shows many properties typical of rigid amorphous thermoplastics. More individually, it softens at about 70°C, burns only with difficulty and is thermally unstable. To reduce this instability, stabilisers are invariably compounded into the polymer. 

In this report we will only consider type 3, i.e. mixtures of a rigid amorphous thermoplast with small amounts of an elastomer which is the underlying principle for all rubber toughened plastics to improve impact behavior. 

POLYMERS] (Vol 19) - [ELASTOMERS, SYNTHETIC - SURVEY] (Vol 8) - [ACRYLIC ESTERPOLYMERS - SURVEY] (Vol 1) -of amorphous thermoplastics [PLASTIC PROCESSING] (Vol 19) -effect of supercritical fluid on [SUPERCRITICAL FLUIDS] (Vol 23)... 

Polyether-imide (PEI) is an amorphous thermoplastic, with an excellent balance of physical properties and dimensional stabilities. PEI can be nsed with the fnll spectrum of sterilisation methods. Surgical probes that are subjected to repeated cleaning and sterilisation are their typical preferred application as a medical plastic. 

Thermoplastics are uncrosslinked plastics up to their decomposition temperature. Flow or melting (Fig. 2) occurs above the softening point of the amorphous structure in amorphous thermoplastics and above the melting temperature of semicrystalline thermoplastics. In this thermoplastic state, the viscous liquid can be processed. Form strength is achieved by cooUng. Meltdown, solidification, and crystallization can be repeated any number of times. 

TPE are multiphase plastics with molecular segments characterized by elastic deformability into which fusible amorphous thermoplastics are integrated, rendering them thermoplasticaUy deformable. 

Fig. 2 Temperature-dependence of the modulus of elasticity (Young s modulus) of plastics (diagram). As an alternative to this modulus, tension a can also be plotted against constant elongation e or viscosity i), or other properties [2]. MSRe x,d- main softening range of elastomers, thermoplastics, duroplastics, Tgt associated glass transition temperature, Tfi flow point of the amorphous thermoplastic, //////// application range, application range...

Amorphous amorph = formless) thermoplastics are similar to glass with respect to molecular structure. They are distinguished from semi-crystaUine thermoplastics, which have a milky, opaque appearance. When a plastic is as transparent as glass, it is usually safe to assume that it is an amorphous thermoplastic. 

The individual functions of the plasticating and injection unit are described here as they apply to the molding of Compact Disks, produced from a crystal clear material, so that the laser can read the information. The CD is therefore made from an amorphous thermoplastic. Being opaque-apart from other material properties-disqualifies thermosets and elastomers from CD production. 

Poly ethersulphone. An amorphous thermoplastic with a chemical structure as shown in Figure 1.3. Transparent in its original form. Service temperature of end-products is up to approximately 180 °C. Examples of applications transparent parts of household articles and appliances, switches, hot water meter components, electronic parts. Trade name Victrex PES (UK). The industrial plastic polysulphone is also a poly-ethersulphone in the chemical sense. 

SAN, styrene I acrylonitrile plastics. Copolymer of styrene and acrylonitrile. An amorphous thermoplastic, transparent in the original form, which is tougher, less brittle, somewhat more heat stable than the standard polystyrene. Applications transparent covers of car and signal lamps, machinery and instrument parts, and various consumer goods. Trade names Kostil (I), Luran (FRG), Lustran (USA), Tyril (USA). 

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