Common thermoplastics

Acetal Good dimensional stability and abrasion resistance. High tensile strength. Used for water or oil-lubricated bearings. 

Acrylic Hard, transparent, fair chemical resistance. 

Cellulosic Very tough, but poor weather resistance and embrittle with age. 

Polyamide (nylon) Excellent toughness and good wear resistance. Low friction. Poor dimensional stability. 

Polycarbonate Tough, rigid, transparent. Good dimensional stability, high resistance to impact loads. 

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The housing physically holds the valve pieces together by means of a mechanical lock (crimp) and fits into the pedestal of the mounting cup. It is made from any of a number of common thermoplastics and contains the metering orifices for both the Hquid and vapor phases of the effluent. Many... 

Traditional rubbers are shaped in a manner akin to that of common thermoplastics. Subsequent to the shaping operations chemical reactions are brought about that lead to the formation of a polymeric network structure. Whilst the polymer molecular segments between the network junction points are mobile and can thus deform considerably, on application of a stress irreversible flow is prevented by the network structure and on release of the stress the molecules return to a random coiled configuration with no net change in the mean position of the Junction points. The polymer is thus rubbery. With all the major rubbers the... 

The plastics industry was launched nearly 150 years ago with the production of certain derivatives of cellulose. However, its real emergence as a growth industry of immense proportions and importance has occurred since World War II with the sustained strong growth of thermoplastics and specialty elastomers. The importance of the polymers industry in modern society is underscored by the myriad of uses already developed for these materials, with more being developed almost daily. Although there are a multitude of polymers that are derived from hydrocarbons, we will only briefly discuss the more common thermoplastics that are made from relatively simple monomers from petroleum. 

A good professional can correctly repair the most-common thermoplastic parts, such as piping, geomembranes, inflatable boats and structures, by welding or gluing patches after removal of the soiled and damaged part. 

These are the linear or slightly branched long chain molecules capable of repeatedly softening on heating and hardening on cooling. These polymers possess Intermolecular forces of attraction intermediate between elastomers and fibres. Some common thermoplastics are polythene, polystyrene, polyvinyls, etc. 

Thus, a brief survey of the current understanding of the molecular and super-molecular structures of common thermoplastics is presented first. This review starts with a brief description of the current state-of-the-art knowledge of the constitution, configuration, conformation and supermolecular structure of common glassy and semicrystalline thermoplastics. Later in this chapter, specific features of the structure-property relationships are discussed in greater detail for the most frequently filled thermoplastics. Effects of fillers on the structural variables in polypropylene, considered the most commercially important matrix, are especially emphasized. 

Table 9. Critical strain energy release rates, G ., for common thermoplastics measured under impact loading promoting brittle fracture [92]...

Among the more common thermoplastics from ring opening polymerization of interest in composite processing are polylactams, polyethers, polyacetals, and polycycloolefins. It has also been shown that polycarbonates can be produced from cyclic carbonates [22], Anionic ring opening polymerization of caprolactam to nylon 6 is uniquely suited to form a thermoplastic matrix for fiber-reinforced composites, specifically by the reaction injection pultrusion process [23-25]. The fast reaction kinetics with no by-products and the crystalline... 

However, PIB is mostly manufactured as a block copolymer. Unsaturations in the backbone are common. Thermoplastic elastomers are composed of glassy outer blocks and rubbery inner blocks. Because of the phase separation of the glassy blocks into discrete domains, these materials behave like crosslinked rubbers at low temperatures. However, at elevated temperatures they can be processed in the same way as thermoplastics (4). 

Examples of various thermoplastics are discussed in detail in the literature [6,10] and can be found in commercial materials data banks [1], Examples of the most common thermoplastic polymers, with a short summary, are given below. Ranges of typical processing conditions... 

Table 2.5 Power Law and Consistency Indices for Common Thermoplastics...

Table 2.6 Constants for Carreau-WLF (Amorphous) and Carreau-Arrhenius (Semi-Crystalline) Models for Various Common Thermoplastic...

Table 2.6 presents constants for Carreau-WLF (amorphous) and Carreau-Arrhenius models (semi-crystalline) for various common thermoplastics. In addition to the temperature shift, Menges, Wortberg and Michaeli [50] measured a pressure dependence of the viscosity and proposed the following model, which includes both temperature and pressure viscosity shifts ... 

Parts molded from polyetherimide can be assembled with all common thermoplastic assembly methods. Adhesives that are recommended include epoxy, urethane, and cyanoacrylate. However, service temperature must be taken into consideration in choosing an adhesive because PEI parts are generally used for high-temperature applications. Good adhesion can be effected by simple solvent wipe, but surface treatment by corona discharge, flame treatment, or chromic acid etch will provide the highest bond strengths. 

Blends of ASA with many of the common thermoplastic materials are state of the art. The properties of the finished products depend to a large extent on the polymer compatibility often induced by the use of reactive polymers. Only a few of these blends have reached a significant commercial status. The largest blend products in this area are ASA-PC blends followed by ASA-PBT and ASA-PC-PMMA blends. Combinations of ASA with high-Tg matrix polymers are also frequently found in commercial products. 

As emphasized above, in contrast to common thermoplastics, thermoplastic elastomers contain a very soft phase (with Tg around —50°C), which is in a liquid state at room temperature and is characterized by a viscosity closer to that of low-molecular-weight liquids rather than a solid amorphous polymer. In this respect it seems useful to recall that the molecular weight of the PTMG and PEG used is 1000, i.e. one is dealing with typical oligomer systems. For this reason it looks reasonable to accept that such a liquid will be characterized by a negligibly small microhardness, in the equation ... 

Fig. 1 Common thermoplastic resins used as the matrix phase in polymer composites.

Figure 4-3. Comparison of ten-second modulus vs. temperature curves for three common thermoplastics polyvinyl chloride (PVC), polystyrene (PS) and polyethylene (PE).

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