General purpose polymers

I mentioned in the preface to the sixth edition that when I began preparation of the first edition of this book in the early 1960s world production of plastics materials was of the order of 9 million tonnes per annum. In the late 1990s it has been estimated at 135 million tonnes per annum In spite of this enormous growth my prediction in the first edition that the likelihood of discovering new important general purposes polymers was remote but that new special purpose polymers would continue to be introduced has proved correct. 

General-purpose polymers, being thermal insulators, cannot dissipate heat generated by mechanical work or by electronic devices and so on. If the temperature rises, the mechanical properties of the polymer decrease and ageing speeds up. Eventually, the temperature can reach the melting point. 

Manufacturers There are over 200 major manufacturers of general-purpose polymers and numerous other manufacturers of specialty polymers. 

In contrast, the viscosity increases exponentially as the molecular weight increases above the threshold molecular weight. Since more energy is required to process these high-molecular-weight polymers, an optimum or commercial range is often selected for commercial general purpose polymers. 

Chloroprene rubber (Neoprene—trade name of DuPont) was one of the earliest synthetic rubbers, first commercialized in 1932. It has a wide range of useful properties but has not become a true general purpose synthetic rubber, probably because of its cost. It does possess properties superior to those of a number of general purpose polymers, such as oil, ozone, and heat resistance but for these properties other specialized polymers excel. Polychloroprene thus is positioned between the general purpose elastomers and the specialty rubbers. 

The practical solution of these protection tasks are connected to specific chemical agents, well engineered polymer additives, elaborated mainly for the stabilization of general purpose polymers [8], The radiation stabilizers, called antirads represent only a modest, but flourishing fraction of that thermo-oxidative- and UV stabilizers. 

A general purpose polymer intermediate, which can be produced readily and in a variety of forms (i.e. low or high molecular weights, soluble or crosslinked, colloid or suspension, surface graft or coating, etc.). 

Gels, amphiphilic 3, 19 -, -, polymer-solvent compatibility 24 General purpose polymers 4 Glass transition temperature 52 Graft copolymers 3... 

The first step in the identification of polymers is a critical visual examination. While the appearance of the sample may indicate whether it is essentially a raw polymer or a compounded and processed item, learning about its form, feel, odor, color, transparency or opacity, softness, stiffiiess, brittleness, bounce, and surface texture may be important in the process of the identification of the polymer. For example, polystyrene, the general purpose polymer, is transparent and brittle, and produces a characteristic metallic tinkle when objects molded from it are dropped or struck. 

Uses Used In adhesives, textiles, and hIgh-wax polish applies. lubricant for PVC extrusion food pkg. adhesives, fexfiles defoamer In food-con-faef paper coafings, paper/paperboard Features General-purpose polymer Regulatory FDA 21CFR 175.105,176.200,176.210,177.2800 Properties Solid vise. 152 SUS (116 C) m.p. 107 C congeal pf. 93 C add no. 24 sapon. no. 42 Bareco C-4040 [Bareco Prods.]... 

Features Superior processing general purpose polymer storage stability similar to type W shrinkage resistance similar to type WB low nerve Properties Creamy wh. chips Mooney vise. 42-52 (ML1+4,212 F) Toxicology TSCA listed... 

Following are selected data for the most often used polymers. They have been divided (partly arbitrarily, because of the overlap in definitions) into four tables, numbered from 24.3 to 24.6 respectively, for general purpose polymers, engineering polymers, thermosets, and elastomers. The third colunm in each of these tables shows the values of density, the fourth of the tensile modulus, the fifth the stress at break, the sixth the elongation at break IS denotes the Izod impact strength for notched specimens. The letters A and C in the last column in Tables 24.3 and 24.4 pertain respectively to amorphous and crystalline thermoplastic polymers. 

General purpose polymers such as NR and styrene-butadiene polymers do not withstand the action of oxygen, and ozone (especially close to electrical generators), which attack the polymer chains and create cracks that soon cause failure. These effects can be suitably avoided by addition of antioxidants and/or antiozonants, often with certain microcrystalline waxes. 

General purpose polymers (natural rubber and SBR) pose no difficulty unless they are of high viscosity or conversely are of very low hardness, i.e., s 40 IRHD (NR) and styrene-butadiene rubber (SBR). 

Saturated polymers such as butyl and ethylene-propylene-diene terpolymer are more difficult to bond and generally exhibit lower bond strengths compared to those found with the general purpose polymers. Once a degree of functionality is introduced into the polymer such as with chloro or preferably bromobutyl rubber and chlorosulfonated polyethylene (Hypalon ) then the ability to bond is enhanced. 

Grades of PP of melt index 3 were employed in these studies of general-purpose polymers and special high heat ageing stabilisation. Additional studies are discussed involving pigmented materials incorporating various UV stabilisers. In these latter studies these PP... 

The reinforcement of rubber may be illustrated by examining the response of two dissimilar general-purpose polymers to the increase in filler loading (Figure 7.4). 

Those who have not accepted the historical approach in the past, should now recognize the value of the historical viewpoint for studying new developments, such as general purpose polymers and, to a greater degree, the high performance polymers. 

Man s knowledge of polymer science is so new that Professor Herman F. Mark, the author of the first Chapter and a polymer science pioneer, has lived to see the first acceptance of the concept of the existence of chain-like macromolecules, the development of a multi-billion dollar industry based on general purpose polymers, and now a higher order of polymers which includes those which outperform all other materials of construction. Since synthetic polymers are so new it is important to record each historical breakthrough by the actual inventors and that is the purpose of this book and the ACS Symposium upon which the book is based. 

Electrodeposition coatings Electrophoretic compositions General purpose General purpose Polymer-coated siliceous fillers Chlorinated copolymer for coatings... 

Our study of the literature shows there have been no new general purpose polymers developed in the last twenty years. The needs for designed polymers, for the heterogeneous materials and systems I just mentioned have been met instead by new product configurations based on existing polymers and development of new specialty polymers when needs cannot be met by older materials. The latter activity is striking. 

Manipulation of individual polymers can result in forms which meet a remarkable range of end uses in a highly functional and economic way. Polyethylene terephthalate for example, a general-purpose polymer in many fiber, film and plastic uses, can be engineered to have very special properties. As fibers, they can be hollow, sheath core or have a variety of cross-sections and surfaces. Experimenting with this almost infinite set of variables has already led to ... 

New ways to exploit the potential of polyester and the other general-purpose polymers will continue to develop as systems approaches to specific needs result in polymers and polymer shapes ingeniously tailored to give the desired properties. The challenge to bring these improvements to all parts of the world in an affordable form is continuously before us. 

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