Plastic material synthetic polymers

The intensity of microbial growth on plastic material depends on the type of synthetic polymer, but also on the type of additives, especially plasticizers used to improve the processing characteristics of the polymer. There are plasticizers such as fatty acid esters and long-chain dicarboxylic acid esters which are most susceptible to fungal growth while phthalate and phosphate esters with alkylol substituents are generally resistant. However, as plastic materials in operation are always subject to contamination with traces of nutrients for micro-organisms. 

Examples of microbicides which fulfil these requirements are  

A review of the biodeterioration and biodegradation of naturally occurring and synthetic plastic polymers has been presented by Seal (1988). 

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Most of the plastics and synthetic polymers that are used worldwide are produced from petrochemicals. Replacing petroleum-based feedstocks with materials derived from renewable resources is an attractive prospect for manufacturers of polymers and plastics, since the production of such polymers does not depend on the limited supply of fossil fuels [16]. Furthermore, synthetic materials are very persistent in the environment long after their intended use, and as a result their total volume in landfills is giving rise to serious waste management problems. In 1992,20% of the volume and 8% of the weight of landfills in the US were plastic materials, while the annual disposal of plastics both in the US and EC has risen to over 10 million tons [17]. Because of the biodegradability of PHAs, they would be mostly composted and as such would be very valuable in reducing the amount of plastic waste. 

Modem plastics are synthetic polymers, derived from oil. Early plastics were based on a variety of natural materials, including sugar cane, cotton, mbber and coal tar. The following attempts to give a brief outline of the early plastics most used in connection with organic gem materials. 

Polymeric materials are easy to synthesize. Therefore, the final products are substantially more economical than other t) es of building materials. Synthetic polymers are widely used in the construction industry. Some of the organic polymer materials used in the building industry are fibers, rubber, plastics, adhesives, sealants, coatings, and caulking compounds. Polymers are also used as modifiers to improve the properties and performance of some construction materials, such as roofing and road asphalt. 

The use of flame retardants came about because of concern over the flammabiUty of synthetic polymers (plastics). A simple method of assessing the potential contribution of polymers to a fire is to examine the heats of combustion, which for common polymers vary by only about a factor of two (1). Heats of combustion correlate with the chemical nature of a polymer whether the polymer is synthetic or natural. Concern over flammabiUty should arise via a proper risk assessment which takes into account not only the flammabiUty of the material, but also the environment in which it is used. 

Until the 1960s, reclaimed mbber was an important raw material in molded and extmded mbber products, eg, tires, mbber mats, and hard mbber battery cases. With the advent of vinyl, other plastics, and less expensive oil-extended synthetic polymers, reclaimed mbber sales stabilized and decreased. In 1973, the oil embargo and rising energy costs increased costs of the energy-intensive mbber reclaiming process to the point where they matched virgin polymer costs. Increased radial tire production required crack resistance that could not be provided by reclaimed mbber compounds (46). 

This article discusses traditional hull ding and construction products, ie, not made from synthetic polymers (see Building materials, plastic), including wood, asphalt, gypsum, glass products, Pordand cement, and bricks. The article presents information about each basic material, the products made from it, the basic processes by which the products or materials are produced, estimates of the quantity or doUar value of the quantities produced or used in the United States, and some pertinent chemical or physical properties related to the material. More detailed chemical and physical property data can be found in articles devoted to the individual materials (see Asphalt Cement Glass Wood). 

Whereas celluloid was the first plastics material obtained by chemical modification of a polymer to be exploited, the phenolics were the first commercially successful fully synthetic resins. It is interesting to note that in 1963, by a merger of two subsidiary companies of the Union Carbide and the Distillers organisations, there was formed the Bakelite Xylonite Company, an intriguing marriage of two of the earliest names in the plastics industry. 

In addition to plastics materials, many fibres, surface coatings and rubbers are also basically high polymers, whilst in nature itself there is an abundance of polymeric material. Proteins, cellulose, starch, lignin and natural rubber are high polymers. The detailed structures of these materials are complex and highly sophisticated in comparison the synthetic polymers produced by man are crude in the quality of their molecular architecture. 

Thermoplastic polyurethane (TPU) is a type of synthetic polymer that has properties between the characteristics of plastics and rubber. It belongs to the thermoplastic elastomer group. The typical procedure of vulcanization in rubber processing generally is not needed for TPU instead, the processing procedure for normal plastics is used. With a similar hardness to other elastomers, TPU has better elasticity, resistance to oil, and resistance to impact at low temperatures. TPU is a rapidly developing polymeric material. 

The term plastic comes from the Greek word to form. It identifies many different plastic materials. Polymers, the basic ingredients used in practically all plastics, can be defined as high molecular weight organic compounds, synthetic or natural substance... 

The term s plastic, polymer, resin, elastomer, and reinforced plastic (RP) are some-what synonymous. However, polymer and resin usually denote the basic material. Whereas plastic pertains to polymers or resins containing additives, fillers, and/or reinforcements. Recognize that practically all materials worldwide contain some type of additive or ingredient. An elastomer is a rubberlike material (natural or synthetic). Reinforced plastics (also called composites although to be more accurate called plastic composites) are plastics with reinforcing additives, such as fibers and whiskers, added principally to increase the product s mechanical properties. 

Nowadays, a strategic area of research is the development of polymers based on carbohydrates due to the worldwide focus on sustainable materials. Since the necessary multi-step synthesis of carbohydrate-based polymers is not economical for the production of commodity plastics, functionalization of synthetic polymers by carbohydrates has become a current subject of research. This aims to prepare new bioactive and biocompatible polymers capable of exerting a temporary therapeutic function. The large variety of methods of anchoring carbohydrates onto polymers as well as the current and potential applications of the functionalized polymers has been discussed recently in a critical review [171]. Of importance is that such modification renders not only functionality but also biodegradability to the synthetic polymers. 

In disinfection of instruments, the chemicals used must not adversely affect the instruments, e.g. cause corrosion of metals, affect clarity or integrity of lenses, or change texture of synthetic polymers. Many materials such as fabrics, rubber, plastics are capable of adsorbing certain disinfectants, e.g. quaternary ammonium compounds (QACs), are adsorbed by fabrics, while phenolics are adsorbed by rubber, the consequence ofthis being a reduction in concentration of active compound. A disinfectant can only exert its effect ifit is in contact with the item being treated. Therefore access to all parts of an instrument or piece of equipment is essential. For small items, total immersion in the disinfectant must also be ensured. 

Engineering polymers generally comprise a high performance segment of synthetic plastic materials that exhibit premium properties. In this paper, engineering thermoplastics developed for advanced applications, and particularly for enhanced thermal stability are considered. 

True synthetic polymers came into use when Bakeland came from Belgium and applied his knowledge of the formation of a moldable plastic from phenol and formaldehyde to give the product named Bakelite. This was about 1914. This product, under heat and pressure, set up to a thermo-setting resin and had useful properties especially as an insulating material for electrical items. 

Polymers that can be heated and moulded into specific shapes and forms are commonly known as plastics. All plastics are synthetic (artificially made) polymers. For example, polyethene is a common synthetic polymer that is used to make plastic bags. Ethene, CH2 = CH2, is the monomer for polyethene. Adhesives, rubber, chewing gum, and Styrofoam M are other important materials that are made from synthetic polymers. 

Some important everyday items that are made from polymers with widely different properties Include billiard balls, plastic dishes, soda bottles, barrier and decorative films, egg cartons, polymeric drinking glasses, foam seats, and automotive tires. These applications for synthetic polymers have developed over about 150 years. As shown in Table 2.1, modern polymer material science and technology can be traced back to as early as 1770 [1]. Some Important advances In the understanding of polymer production were developed before World War II. 

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