Fossil fuels polymers from

Therefore the development of environmentally friendly materials will result in huge benefits to the environment and will also contribute to reduced dependence on fossil fuels. Polymers produced from alternative... 

Rayon is unique among the mass produced man-made fibers because it is the only one to use a natural polymer (cellulose) directly. Polyesters, nylons, polyolefins, and acryflcs all come indirectly from vegetation they come from the polymerization of monomers obtained from reserves of fossil fuels, which in turn were formed by the incomplete biodegradation of vegetation that grew millions of years ago. The extraction of these nonrenewable reserves and the resulting return to the atmosphere of the carbon dioxide from which they were made is one of the most important environmental issues of current times. CeUulosic fibers therefore have much to recommend them provided that the processes used to make them have minimal environmental impact. 

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. 

The foregoing summary of the history of polyesters to date illustrates the diversity of chemical structures available and the wide range of uses to which they have been put, although it is far from being exhaustive. There can be no doubt that polyesters will continue to be one of the most important classes of polymer. Predictably, as the supply of cheap fossil-fuel-based chemical primaries declines, biological sources can be persuaded to yield appropriate intermediates and even polyesters themselves. 

As fossil fuel resources dwindle, there is growing interest in developing new raw materials for future polymers [121]. As A. Gandini has stated polymers from renewable resources are indeed the macromolecular materials of the future [122]. Between the different renewable resources, carbohydrates stand out as highly convenient raw materials because they are inexpensive, readily available, and provide great stereochemical diversity. 

In spite of the high level of commercial success of inorganic semi-conductor based photovoltaic cells, they are unlikely to challenge seriously electricity generation from fossil fuels because they are costly to manufacture and it is also difficult to make large area cells. These difficulties have spurred on research into organic alternatives, especially those that can be incorporated into or be part of a polymer, thus making cell construction easier. 

Plastics are polymers made from various hydrocarbons found in fossil fuels. Different types of plastics have different ingredients in their polymers, but nearly all of them are chains of carbon atoms bonded to hydrogen and other elements. 

Hydrocarbons are required in our modern-day life not only as energy sources, including convenient transportation fuels for our cars, tracks, airplanes (see Section 1.8.2) but also to produce commonly used products ranging from polymers to textiles to pharmaceuticals. At the beginning of the twenty-first century we can look back with substantial satisfaction at our technological and scientific achievements. We should, however, also realize that we continue to deplete the nonrenewable resources of our planet, particularly fossil fuels and hydrocarbons and at the same time create ecological and environmental problems. As mentioned earlier, dire predictions of the early exhaustion of our natural hydrocarbon sources by the... 

Since 1980, there has been rapid development of SFE, for the extraction of fossil fuel and environmental samples such as pesticides, hydrocarbons, phenolics [12,13], food products including hops, fats and lipids from butter, perfumes and flavors from natural products [14], and oligomeric materials or additives from polymers [IS]. 

Polymers prepared from these kinds of monomers are desirable in principle for two reasons. First, the monomers come from renewable sources such as com, wheat, rice, or even agricultural waste. (The fossil fuels petroleum,... 

In contrast to the polymeric products derived from fossil fuels, the production of synthetic polymers from biomass—the rayons and cellulose acetates—is quite small despite the fact that cellulose is one of the world s most abundant raw materials. The rayons are any of a variety of regenerated celluloses manufactured via intermediates such as alkali salts and cellulose xanthates. The process... 

Recycling polymers The starting materials for the synthesis of most polymers are derived from fossil fuels. As the supply of fossil fuels is depleted, recycling plastics will become more important. Thermosetting polymers are more difficult to recycle than thermoplastic polymers because only thermoplastic materials can be melted and remolded repeatedly. 

Joanna D Underwood takes us into the world of commercial products in Section 7.2.2. It is too easy to see the chemical industry as quite distant from the local toy store or furniture maker. However, in a world where commodities are increasingly made from petrochemicals and polymers, which are derived from fossil fuels, the resulting products are often a puree of scores of chemicals, many added to control and tame the reactivity and decomposition of the fuel. Underwood notes how frequently many of these substances are persistent, bioaccumulative, and toxic, a combination of factors that when present in domestic products sets ripe conditions for human and ecological harm. She concludes that many of these substances have no place in a sustainable chemical industry. 

Burnham and Braun [99] have provided a valuable review of the approaches used in the kinetic analysis of decompositions of complex materials such as polymers, minerals, fossil fuels and biochemicals. Mathematical characterization of these reaction systems, recognized as being too complex to be characterized in any fundamental way, is termed global kinetic analysis. One of its main objectives is to predict the reactivities of such materials at temperatures different from those for which kinetic measurements were made (see Section 5.5.13.). 

Figure 1.18 Polymer innovation based on fossil-fuel building blocks. Source adapted from Kamm et al. [101],...

Solid-state MAS NMR spectroscopy has had much success in examining amorphous insoluble polymers [59]. In recent years, however, there has been some debate on the reliability of quantitative data derived from CP experiments [60] and work on fossil fuels in particular has highlighted the problem [61,62]. Undoubtedly, the issues arise in the analysis of polymers as well [63-66]. While CP results in signal-to-noise enhancement and hence reduced accumulation times, carbon atoms present with no proximal protons tend to have their peak intensities reduced relative to other signals. Quaternary aromatic carbons are likely to suffer badly in this respect. The modulation of the dipolar interactions by the motion of some moieties can also introduce quantitative errors [67]. The rotation of the methyl group about its 3-fold axis of symmetry is a good example of this. Single pulse excitation (SPE) [60] however overcomes the problems that are associated with CP,... 

Starting materials are often referred to as feedstocks. Most of the starting materials (monomers) employed in the synthesis of synthetic polymers like polystyrene, polyethylene, and nylons are derived indirecdy from fossil fuels. The term fossil fuels refer to materials formed from the decomposition of once-living matter. 

---