Polymer-based industries

Until the 1920s and 1930s, the several industries that produced polymeric materials were independent of one another for the most part and were based on natural or modified natural materials. These industries can be identified in a broad sense as follows  

In fact, it was not until after World War II that the dividing lines became so blurred as to make it difficult to classify some companies. 

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The following examples highlight selected polymer-based industries with a particularly high potential for atmospheric emissions. These selections do not, of conrse, present a comprehensive coverage of all such applications. 

Two other polymer-based industries are found to depend more on one class than the other. The rubber industry uses both carbon chain and heterochain polymers. A generic classification of elastomers suggested by the American Society for Testing and Materials (ASTM) indicates no bias toward carbon chain polymers [1]. However, the seven heterochain rubbers listed in Appendix 16.A probably constituted less than 5% of the total rubber produced in 2000. The reasons for this situation appear to be economic and historical rather than fundamentally physical or chemical. Heterochain polymers of excellent strength, resilience, and durability have been designed, but never at a price that attracted widespread use. 

Transesterification has a number of important commercial uses. Methyl esters of fatty acids are produced from fats and oils. Transesterification is also the basis of recycling technology to break up poly(ethylene terephthalate) [25038-59-9] to monomer for reuse (29) (see Recycling, plastics). Because vinyl alcohol does not exist, poly(vinyl alcohol) [9002-89-5] is produced commercially by base-cataly2ed alcoholysis of poly(vinyl acetate) [9003-20-7] (see Vinyl polymers). An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate) [24991-31-9]. 

Alkali/polymer based multifunctional formulation for hard water MU (up to 50 ppm CaCOf) in LP steam or light-industrial FT boilers. Includes a metal passivator. 

Aliphatic polyesters based on monomers other than a-hydroxyalkanoic acids have also been developed and evaluated as drug delivery matrices. These include the polyhydroxybutyrate and polyhydroxy valerate homo- and copolymers developed by Imperial Chemical Industries (ICI) from a fermentation process and the polycaprolactones extensively studied by Pitt and Schindler (14,15). The homopolymers in these series of aliphatic polyesters are hydrophobic and crystalline in structure. Because of these properties, these polyesters normally have long degradation times in vivo of 1-2 years. However, the use of copolymers and in the case of polycaprolactone even polymer blends have led to materials with useful degradation times as a result of changes in the crystallinity and hydrophobicity of these polymers. An even larger family of polymers based upon hydroxyaliphatic acids has recently been prepared by bacteria fermentation processes, and it is anticipated that some of these materials may be evaluated for drug delivery as soon as they become commercially available. 

After the war, Carothers work spread to American universities and became the prototype for science-based industrial research. Polymer scientists, including Flory and Staudinger, won four Nobel Prizes. The prize is not awarded posthumously but, had Carothers lived, he might well have shared one of their prizes. 

Polymers are integral parts of mankind as building blocks of himself (protein, nucleic acids), his clothing (wool, cotton, polyester), building materials (wood, polystyrene), in the accumulation of knowledge (paper, ink), etc. The polymer industry today is at parity with the total metal-based industry and employs more chemists than all the other areas of chemistry combined. 

Produced diallyllsilazanes and polymers based on them were used for the modification of the properties of some industrial polymer composites based on polymers with functional groups. 

Polymer membranes are the most common commercial membranes for separations [1]. They have proven to operate successfully in many gas and liquid separations. For example, polymer membrane-based gas separation processes have undergone a major evolution since the introduction of the first polymer membrane-based industrial hydrogen separation process about two decades ago. The... 

The dental industry is currently accepting the International Standards Organization (ISO) standard for Polymer-based filling and restorative materials. This standard will require testing of the following properties ... 

In some industrial processes, exposure to HDI may occur in the presence of its hydrolysis products, namely 1,6-hexamethyleneaminoisocyanate and HDA, both of which may also cause adverse respiratory effects (Beard and Noe 1981). In a study to evaluate isocyanate exposures of automobile repair workers involved in welding activities, which could lead to pyrolysis of HDI polymer-based paint, the atmospheric concentration ranges of HDI, 1,6-hexamethyleneaminoisocyanate, and HDA were found to be 0.18-1.3 mg/m (0.027-0.20 ppm), <0.004-0.24 mg/m (<0.0006-0.036 ppm), and <0.004-0.10 mg/m (<0.0006-0.015 ppm), respectively, 25 cm from the source (Sharping et al. 1988). Concentrations of 1,6-hexamethyleneamino-isocyanate and HDA were on the order of 15% of the HDI concentrations. 

Polyesters, specifically polylactides and poly(lactide-co-glycolide)s have played a critical role in the development of polymer-based CR technologies. The biocompatibility and the well-established safety profiles of PLA and PLGA polymers have made them the polymer of choice for CR applications. However the off-patent status of these polymers makes them freely available for research in industry as well as academia. This has led to a vast number of patents covering various applications of these polymers within the drug delivery sector. Due to these issues, very limited scope remains to utilize these polymers to reformulate generic, off-patent drugs. 

The important feature of polymers based on vinyl monomers is their transparency in the visible part of the spectrum. This is why the most important articles produced from these materials are organic glasses, which are used in the aircraft, automobile and ship-building industries as engineering materials, and also in civil engineering, and the optical, chemical, food industries, etc. The main technical characteristics of poly (methyl methacrylate) are given in Table 1.1. 

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