Biodegradable plastics thermoplastics

Chapters 10 to 29 consisted of reviews of plastics materials available according to a chemical classification, whilst Chapter 30 rather more loosely looked at plastics derived from natural sources. It will have been obvious to the reader that for a given application plastics materials from quite different chemical classes may be in competition and attempts have been made to show this in the text. There have, however, been developments in three, quite unrelated, areas where the author has considered it more useful to review the different polymers together, namely thermoplastic elastomers, biodegradable plastics and electrically conductive polymers. 

Thermoplastic xylan derivatives have been prepared by in-hne modification with propylene oxide of the xylan present in the alkaline extract of barley husks [424,425]. Following peracetylation of the hydroxypropylated xylan in formamide solution yielded the water-insoluble acetoxypropyl xylan. The thermal properties of the derivative quahfy this material as a potential biodegradable and thermoplastic additive to melt-processed plastics. Xylan from oat spelts was oxidized to 2,3-dicarboxyhc derivatives in a two-step procedure using HI04/NaC102 as oxidants [426]. 

Biodegradable plastics have been used on an industrial scale since the end of the 1990s when BASF launched Ecoflex . This is a fossil-based, man-made polyester but yet is completely biodegradable due to its chemical structure. This structure is also the reason why Ecoflex combines excellent mechanical properties with the good processability of synthetic thermoplastics. Ecoflex is the preferred blend partner for bio-based and biodegradable polymers, which typically do not exhibit good mechanics and processability for film applications by themselves. Ecoflex therefore is a synthetic polymer that enables the extensive use of renewable raw materials (e.g., starch). 

In examples Cy-Am 1-5 of Table 7 the monomers used were 2-propeneni-trile (107-13-1) and 2-propenamide (79-06-1). In examples Cy 1-5 of Table 7, the monomer used was 2-propenenitrile (107-13-1). The compounds in the first group are water-absorbing agents whereas those in the second group are thermoplastics and biodegradable plastics [56]. In examples MBuD 1-3 of Table 7, the monomer used was 2-methyl-1,3-butadiene (78-79-5). These materials are uncrosslinked elastomers and potential rubber additives. In examples MPrPe 1-9 of Table 7, the monomer used was 2-methyl-2-oxy-3-oxopent-4-ene (80-62-6). These materials are thermoplastics and biodegradable plastics [57]. 

Mater-Bi . [Novamont N. Am.] Thermoplastic horn natural, renewable raw materials recyclable, combustible, and biodegradable plastic for pkg. films, bags, 6-pack yokes, disposable diapers, hospital and sanitary prods. 

HUA 06] Huang M.F., Yu J.G., Ma X.F., High mechanical performance MMT-uiea and formamide-plasticized thermoplastic cornstarch biodegradable nanocomposites , Carbohydrate Polymers, vol. 63, no. 3, pp. 393-399,2006. 

Starch has been one of the first materials extensively studied for its potential as polymer for biodegradable plastics. Impetus in this direction has come from shortage of municipal landfills and pressure to reduce the visual pollution caused by plastic residues abandoned in the landscape. Despite considerable interest from both the academic and industrial sectors, production of commercially viable materials has been delayed for technical and economic reasons. The former are inherent to the chemical structure of starch itself the vast quantity of internal hydrogen bonds hampers thermoplastic behaviour, and the hydrophilic nature of the polysaccharide translates into sensitivity to the environmental humidity that, in its turn, may affect the mechanical properties of the material. 

Poly(j3-hydroxy butyric acid) is a thermoplastic polyester that is useful as a biodegradable plastics material. It is accumulated by many bacteria as an energy reserve material in the form of granules within the bacterial cells (6). 

In the biodegradable plastics market, aliphatic polyesters (in the main PLA, the present main competitor of starch thermoplastics) sell for 1.5-2.5 per kilo. Starch itself is very cheap ( 0.33 per kilo), but starch-based biopolymers such as Mater-Bi (from Novamont) are more expensive ( 2.40-3.4 per kilo) [6]. 

Thermoplastic starch (TPS) is an attractive source for the development of biodegradable plastics. It is one of the lowest cost biodegradable materials currently available in the global market (Mathew and Dufresne 2002 Shen et al. 2009). It can be found in the form of discrete semicrystalline particles, whose size, shape, morphology, and composition depend on the botanical origin (com, potato, maize. 

Union Carbide, Daicel and Interox are the three producers of poly-s-caprolactone world wide. High molecular weight poly-s-caprolactone may be processed by a variety of techniques, including film blowing and slot casting. Main application in the field of biodegradable plastics is in combination with thermoplastic starch in films, sheets and injection molded parts. 

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