Petrochemical-derived plastics

As an example of good choice of starting materials, NEC were interested in making wide use of biopolymers instead of petrochemically derived plastics and composites in their consumer electronics. There is a desire to use renewable materials to reduce reliance on non-renewables and to avoid the predicted rising cost of petrochemically derived materials. A range of biopolymers already exist, but they lack the performance required for products such as mobile phones, portable entertainment devices and mobile computers. 

PHAs can consist of a diverse set of repeating unit structures and have been studied intensely because the physical properties of these biopolyesters can be similar to petrochemical-derived plastics such as polypropylene (see Table 1). These biologically produced polyesters have already found application as bulk commodity plastics, fishing lines, and for medical use. PHAs have also attracted much attention as biodegradable polymers that can be produced from biorenewable resources. Many excellent reviews on the in vivo or in vitro synthesis of PHAs and their properties and applications exist, underlining the importance of this class of polymers [2, 6, 7, 12, 26-32]. 

PHB has been shown to accumulate to levels approaching 90% of the bacterial dry cell weight when these pathway enzymes have been overexpressed.345 With these efficiencies and with governmental support for developing this technology in plants, it will just be a matter of time before the production of biopolymers such as these can compete economically with the petrochemically derived plastics.345... 

Abstract Polyhydroxyalkanoates (PHAs) are natural polyesters that accumulate in numerous microorganisms as a carbon- and energy-storage material under the nutrient-limiting condition in the presence of an excess carbon source. PHAs are considered to be one of the potential alternatives to petrochemically derived plastics owing to their versatile material properties. Over the past few decades, extensive detailed biochemical, molecular-biological, and metabolic studies related to PHA... 

All petrochemical projects, either planned or under construction, are large-scale plants of international proportions. When completed, the Chinese hope to develop the capacity to manufacture a wide variety of general-use plastics, synthetic rubber, synthetic textiles and other petrochemical-derived products. 

Starch-plastic composites contain a mixture of two very different types of materials (/) hydrophobic, petrochemical-derived polymers (PE, EAA) known to be highly resistant to degradation by living organisms, and (i7) a hydrophilic, natural polymer (starch) that is easily broken down by a wide array of organisms. In the process developed by Otey (3), these fundamentally incompatible materials are forced into an intimate mixture during production of the plastic film. Since... 

Lastly we examine attempts to design structures for particular functions, namely, films that act as barriers and capsules that contain bioactive substances. In the future, we will need to create novelty in the long-term stability of products and delivery of specific molecules for a health benefit. These technologies are attracting attention not only from the food industry but also for nonfood use. Sustainable and environmentally friendly attributes of biomaterials are increasingly discussed, compared to petrochemically derived, synthetic polymers and plastics. For once, food materials scientists can teach other industries the rules of the game. ... 

Since the plastics are produced from petrochemicals derived from hydrocarbons, the motivation to reuse, recycle, or reprocess for energy recovery is primarily driven by an interest in conservation of petroleum resources. Economic factors are also important, but the potential saving of landfill space is more a perception rather than a reality [9]. Most of the categories of vinylic polymers discussed in this chapter are melt-formable, that is, they are thermoplastic materials, rather than nonmelting or thermosetting as are several of the condensation polymers discussed in Chapters 20 and 21. Thus,... 

Polylactic acid (PLA) has caught the attention of polymer scientist and proving to be a viable alternative biopolymer to petrochemical based plastics for many applications. PLA is produced from lactic acid, that is derived itself from the fermentation of corn or sugar beet and due to its biodegradation ability, PLA presents the major advantage to enter in the natural cycle implying its return to the biomass. The life-cycle of PLA is shown in Fig. 11.1. 

However, more recently, ethylene production in China has been on the rise. For example, in 2003, China s output of ethylene increased by 15%, to 3.44 million tonnes, according to the State Statistical Bureau. Ethylene consumption in the same period rose by 14%, to 3.45 million tonnes. Output of purified terephthalic acid - a key raw material in the production of many petrochemical derivatives and plastics - rose by 10%, to reach 1.47 million tonnes, while the production of benzene increased 16%, to 1.16 million tonnes. 

Benzene, toluene, and xylene are made mosdy from catalytic reforming of naphthas with units similar to those already discussed. As a gross mixture, these aromatics are the backbone of gasoline blending for high octane numbers. However, there are many chemicals derived from these same aromatics thus many aromatic petrochemicals have their beginning by selective extraction from naphtha or gas—oil reformate. Benzene and cyclohexane are responsible for products such as nylon and polyester fibers, polystyrene, epoxy resins (qv), phenolic resins (qv), and polyurethanes (see Fibers Styrene plastics Urethane POLYiffiRs). 

Until the end of World War II, coal tar was the main source of these aromatic chemicals. However, the enormously increased demands by the rapidly expanding plastics and synthetic-fiber industries have greatly outstripped the potential supply from coal carbonization. This situation was exacerbated by the cessation of the manufacture in Europe of town gas from coal in the eady 1970s, a process carried out preponderantly in the continuous vertical retorts (CVRs), which has led to production from petroleum. Over 90% of the world production of aromatic chemicals in the 1990s is derived from the petrochemical industry, whereas coal tar is chiefly a source of anticorrosion coatings, wood preservatives, feedstocks for carbon-black manufacture, and binders for road surfacings and electrodes. 

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