For Plastics Elastomers

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

U. SchOnhausen, Positive List I. Additives for Plastics, Elastomers and Synthetic Fibres for Food Contact Applications, Ciba-Geigy Ltd, Basel (1993). 

Only about 5% of the fossil fuels consumed today are used as feedstocks for the production of synthetic carbon-based products. This includes the products of the chemical and drug industries with a major portion acting as the feedstocks for plastics, elastomers, coatings, fibers, etc. 

Table 7.7. Another method of producing PTFE micropowders is by controlled polymerization of TFE to a lower molecular weight [105]. Fluoroadditives are used as additives for plastics, elastomers, coatings, printing inks, paints, lacquers and lubricants, where they provide nonstick and/or sliding properties [106]. Benehts provided by PTFE micropowders are summarized in Table 7.8 [107].

The significance of synthetic polymers, on the other hand, lies more in their mechanical, electrical, or optical properties. Their use as raw materials for plastics, elastomers, or synthetic fibers is especially important. The chemical structure of these substances plays a subordinate role for their application, and it is desirable that such substances are as chemically inert as possible otherwise the useful properties could change unfavorably with time. Since the properties of plastics depend on physical quantities, the chemistry of synthetic macromolecules is bound inseparably to the physics and physical chemistry of such substances. Thus, a clear-cut division into pure preparative chemistry and pure physics of macromolecules is inadvisable. Macromolecular science represents a true interdisciplinary science. ... 

Organic peroxide initiators serve as sources of free radicals in the preparation of a variety of resins for plastics, elastomers, and coatings. Their usage in plastics processing can be divided into four fimctions ... 

However, as far as plastics are concerned, commercial interest in the use of tin-based flame retardants has only developed over the past 10 years or so. Although it is estimated that over 600 000 tonnes of chemical additives are used worldwide annually as flame retardants for s)mthetic polymers, recent concerns about the toxic nature of certain additives have led to an intensified search for safer flame retardants. Hence, the generally low toxicity of inorganic tin compounds has been a major factor in their growing acceptance throughout the 1990s as flame retardants and smoke suppressants for plastics, elastomers and other polymeric materials. 

Butanediol. 1,4-Butanediol [110-63-4] made from formaldehyde and acetylene, is a significant market for formaldehyde representing 11% of its demand (115). It is used to produce tetrahydrofuran (THF), which is used for polyurethane elastomers y-butyrolactone, which is used to make various pyrroHdinone derivatives poly(butylene terephthalate) (PBT), which is an engineering plastic and polyurethanes. Formaldehyde growth in the acetylenic chemicals market is threatened by alternative processes to produce 1,4-butanediol not requiring formaldehyde as a raw material (140) (see Acetylene-derived chemicals). 

Flame and Smoke Retardants. Molybdenum compounds are used extensively as flame retardants (qv) (93,94) in the formulation of halogenated polymers such as PVC, polyolefins, and other plastics elastomers and fabrics. An incentive for the use of molybdenum oxide and other molybdenum smoke and flame retardants is the elimination of the use of arsenic trioxide. Although hydrated inorganics are often used as flame retardants, and thought to work by releasing water of crystallization, anhydrous molybdenum oxides are effective. Presumably the molybdenum oxides rapidly form... 

Nitrile mbber compounds have good abrasion and water resistance. They can have compression set properties as low as 25% with the selection of a proper cure system. The temperature range for the elastomers is from —30 to 125°C. The compounds are also plasticized using polar ester plasticizers. The main dilemma is the selection of a heat-stable, nonfugitive plasticizer that also gives good low temperature properties. 

Ester plasticizers are used mainly in very polar elastomers, such as neoprene and nitrile mbber, to improve low or high temperature performance or impart particular oil or solvent resistance to a compound 5—40 parts are commonly used (see Plasticizers). Resins and tars are added to impart tack, soften the compound, improve flow, and in some cases improve filler wetting out, as is the case with organic resins in mineral-filled SBR. Resinous substances are also used as processing agents for homogenizing elastomer blends. 

AH of the polyether elastomers, like other vulcanizable elastomers, can be compounded with processing aids, fillers, plasticizers, stabilizers, and vulcanizing agents to make useful mbber products. A typical compounding recipe for epichlorohydrin elastomer is as follows ... 

The modulus term in this equation can be obtained in the same way as in the previous example. However, the difference in this case is the term V. For elastic materials this is called Poissons Ratio and is the ratio of the transverse strain to the axial strain (See Appendix C). For any particular metal this is a constant, generally in the range 0.28 to 0.35. For plastics V is not a constant. It is dependent on time, temperature, stress, etc and so it is often given the alternative names of Creep Contraction Ratio or Lateral Strain Ratio. There is very little published information on the creep contraction ratio for plastics but generally it varies from about 0.33 for hard plastics (such as acrylic) to almost 0.5 for elastomers. Some typical values are given in Table 2.1 but do remember that these may change in specific loading situations. 

Electron and optical microscopes are being used to see blend homogeneity. Elastomer-plastic blends are somewhat easier to identify than elastomer-elastomer blends because normal staining techniques, e.g., osmium tet-raoxide, can be used in the case of plastic-elastomer blends. Normally, there are two methods that are followed for examining the blend surface by electron microscopy. 

It is possible to distinguish between SBR and butyl rubber (BR), NR and isoprene rubber (IR) in a vulcan-izate by enthalpy determination. In plastic-elastomer blends, the existence of high Tg and low Tg components eases the problems of experimental differentiation by different types of thermal methods. For a compatible blend, even though the component polymers have different Tg values, sometimes a single Tg is observed, which may be verified with the help of the following equation ... 

Plastic elastomers are generally lower-modulus flexible materials that can be stretched repeatedly and will return to their approximate original length when the stresses are released. The rubber materials have been around for over a century. They will always be required to meet certain desired properties, but thermoplastic TPEs are replacing traditional TS natural and synthetic rubbers (elastomers). TPEs are also... 

POLYMAT light POLYMAT light Materials Data for Plastics is a manufacturer independent, materials database for plastics and contains properties of thermoplastics, thermoplastic elastomers and blends. In total, data from approximately 13,000 commercial products of 170 manufacturers are available products and data can be retrieved via searching in 35 different numerical properties and 15 text fields. 

Polymer-bound antioxidants must be molecularly dispersed (i.e. infinitely soluble) and cannot be physically lost from the substrate. High-MW phenolic AOs are preferred for applications requiring FDA approval, minimal discoloration, and long service life at high temperatures. Antioxidants are used for protection of polymers, plastics, elastomers, foods, fuels and lubricants. 

Chemical reactions are used to modify existing polymers, often for specialty applications. Although of considerable importance for plastics, very few polymer reactions (aside from crosslinking) are important for elastomers. Chlorination and bromination of Butyl rubber to the extent of about one halogen atom per isoprene unit yields elastomers which are more easily crosslinked than Butyl rubber. Substitution occurs with rearrangement to yield an allylic halide structure... 

Materials and articles intended to come into contact with foodstuff are generally regulated in the EU in the Framework Directive 89/109/EEC. Under this Directive Single Directives are released, such as for Plastic Material (90/128/EEC), Cellulose Films (83/229/EEC), Elastomers and Rubber (93/11/EEC) and others. 

Global demand for thermoplastic elastomers (TPEs) is estimated at 2 million tonnes in 2005 and is forecast to increase by 6% per year. TPEs as a whole represent roughly 10% of elastomers or 1% of plastics. Consequently, economic statistics are rare and we can only make some assumptions concerning the consumption of each family ... 

As a result of needs for plastics and elastomers which are more stable to high temperatures and more resistant to degrading chemical reaction than presently available polymers, a study has been made of polymer structure with units consisting of oxadicizole rings connected by per-fluoroalkyl chains 17a). 

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