Plastic materials applications

ASTM Cl 921-96 Standard test methodfor particle size (sieve analysis) of plastic materials, applicable to particle size determination of plastic materials in powdered, granular or pelleted forms by dry sieving with a lower limit of measurement of about 38 pm, 212... 

Only a few of the large number of photoprotectants available produce optimum results with a wide range of plastics. Research and development efforts are therefore geared toward application-specific UV stabilizers for a number of different plastic types to facilitate plastic material applications for a market of growing variety. As a matter of course, photoprotectants are now also available in the form of nondusting, easy-handling master batches [59],... 

MACHINE FOR TREATING RUBBER AND OTHER HEAVY PLASTIC MATERIAL. APPLICATION FILED IAN. ID, IDI6. 

The above paragraphs indicate some of the major uses of plastics materials, but these materials also find applications in a variety of other areas. In addition, closely related materials such as rubbers, fibres, surface coatings and adhesives are of considerable importance. 

Whilst plastics materials have been associated with electrical and electronic applications since the early days of the electrical industry, developments over the... 

For some applications of plastics, such as in packaging where disposability has to be considered, it may be desirable for plastics materials to bum without difficulty. There are, however, a number of uses such as in building, furniture and fitting... 

For many applications the resistance to impact is the most important property of a plastics material. It is also notoriously one of the most difficult to assess. 

By the mid-1990s capacity for polyethylene production was about 50 000 000 t.p.a, much greater than for any other type of plastics material. Of this capacity about 40% was for HDPE, 36% for LDPE and about 24% for LLDPE. Since then considerable extra capacity has been or is in the course of being built but at the time of writing financial and economic problems around the world make an accurate assessment of effective capacity both difficult and academic. It is, however, appeirent that the capacity data above is not reflected in consumption of the three main types of material where usage of LLDPE is now of the same order as the other two materials. Some 75% of the HDPE and LLDPE produced is used for film applications and about 60% of HDPE for injection and blow moulding. 

The nylons have found steadily increasing application as plastics materials for speciality purposes where their toughness, rigidity, abrasion resistance, good hydrocarbon resistance and reasonable heat resistance are important. Because of their high cost they have not become general purpose materials such as polyethylene and polystyrene, which are about a third of the price of the nylons. 

Since large tonnage production is desirable in order to minimise the cost of a polyamide and since the consumption of nylons as plastics materials remains rather small, it is important that any new materials introduced should also have a large outlet as a fibre. There are a number of polyamides in addition to those already mentioned that could well be very useful plastics materials but which would be uneconomical for all but a few applications if they were dependent on a limited outlet in the sphere of plastics. Both nylon 7 and nylon 9 are such examples but their availability as plastics is likely to occur only if they become established fibre-forming polymers. This in turn will depend on the economics of the telomerisation process and the ability to find outlets for the telomers produced other than those required for making the polyamides. 

The initial use was as a blow moulded vessel for vegetable oil candles. However, because of its biodegradability it is of interest for applications where paper and plastics materials are used together and which can, after use, be sent into a standard paper recycling process. Instances include blister packaging (the compound is transparent up to 3 mm in thickness), envelopes with transparent windows and clothes point-of-sale packaging. 

With the expiry of the basic ICI patents on poly(ethylene terephthalate) there was considerable development in terephthalate polymers in the early 1970s. More than a dozen companies introduced poly(butylene terephthalate) as an engineering plastics material whilst a polyether-ester thermoplastic rubber was introduced by Du Pont as Hytrel. Polyfethylene terephthalate) was also the basis of the glass-filled engineering polymer (Rynite) introduced by Du Pont in the late 1970s. Towards the end of the 1970s poly(ethylene terephthalate) was used for the manufacture of biaxially oriented bottles for beer, colas and other carbonated drinks, and this application has since become of major importance. Similar processes are now used for making wide-neck Jars. 

The bulk of plastics materials are required to operate within the range of -30 to + 100°C. There has, however, been a steadily increasing demand for materials to operate outside of these ranges, particularly in certain aerospace, military and telecommunications applications. A considerable amount of research work has been carried out in response to this demand and many thousands of polymers, both organic and inorganic, have been prepared. Many of those which have achieved commercial use have been considered in earlier chapters but in the final part of this chapter it is intended to review the overall situation. 

With the exception of some of the natural rubber derivatives these materials were available during the first deeade of this eentury and, together with celluloid, aetually completed the range of plastics materials then in eommercial use. In spite of being ousted from important markets they have continued to find use in specialised applications, details of which will be given in subsequent sections of this chapter. The historical significance of these materials was dealt with in the first chapter of this book. 

When dry, casein is a good electrical insulator but is seriously affected by humid conditions. For this reason it can no longer compete with the many alternative plastics materials now available for electrical applications. 

Chapters 10 to 29 consisted of reviews of plastics materials available according to a chemical classification, whilst Chapter 30 rather more loosely looked at plastics derived from natural sources. It will have been obvious to the reader that for a given application plastics materials from quite different chemical classes may be in competition and attempts have been made to show this in the text. There have, however, been developments in three, quite unrelated, areas where the author has considered it more useful to review the different polymers together, namely thermoplastic elastomers, biodegradable plastics and electrically conductive polymers. 

The concept of degradable polymers arose largely from concern about the large quantities of plastics materials used for packaging and which, having fulfilled their function, were then discarded and unwanted. Interest has, however, now moved on to include medical and related applications. 

Thermoplastic elastomers have now been available for over 30 years and the writer recalls organising a conference on these materials in 1969. In spite of considerable publicity since that time these materials still only comprise about 5-10% of the rubber market (equivalent to about 1-2% of total plastics consumption). It is important to appreciate that simply being a thermoplastic material (and hence being processed and reprocessed like a thermoplastic plastics material) is not enough to ensure widespread application. Crucially the material must have acceptable properties for a potential end-use and at a finished product price advantageous over other materials. 

Plastic Material First Introduced Strength Electrical Properties Acids Bases Oxidizing Agents Common Solvents Product Manufacturing Methods Common Applications... 

Birley, A.W. and Scott, M.J. Plastic Materials Properties and Applications, Leonard Hall, Glasgow (1982)... 

The materials of construction, from the cupboard to the fan, should be inorganic and resistant to attack by perchloric acid. For the cupboard itself suitable materials include stainless steel of types, 316 or 317, solid epoxy resin, and rigid PVC. Stainless steel has been popular for this application as it is easy to form, weld, and polish. It is, however, attacked by the acid, which causes discoloration of the metal surface and the formation of iron(III) perchlorate, which can be explosive. Ductwork, separate from other extract systems, is usually made from stainless steel or plastic materials. Fire regulations may preclude the use of plastic ductwork or require it to be sheathed in an outer casing of metal or GRP. The fan casing and impeller can both be made of plastic. 

The synthesis of new polymeric materials having complex properties has recently become of great practical importance to polymer chemistry and technology. The synthesis of new materials can be prepared by either their monomers or modification of used polymers in industry. Today, polystyrene (PS), which is widely used in industrial applications as polyolefins and polyvinylchlorides, is also used for the production of plastic materials, which are used instead of metals in technology. For this reason, it is important to synthesize different PS plastic materials. Among the modification of PS, two methods can be considered, viz. physical and chemical modifications. These methods are extensively used to increase physico-mechanical properties, such as resistance to strike, air, or temperature for the synthesizing of new PS plastic materials. 

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