Polyhydroxybutyrate applications

If the homopolymer decomposes at the fabrication temperature another approach is to make a copolymer that can be melt processed at a lower temperature. For example, polyhydroxybutyrate decomposes at the processing temperature (190°C), whereas the copolymer with valeric acid can be processed at 160°C without decomposition. These aliphatic polyesters are biodegradable and most importantly, the decomposition products are not toxic, hence their use in medical applications (e.g., sutures). 

There are two principal ways by which polymer chains can be hydrolyzed, passively by chemical hydrolysis or actively by enzymatic reaction. The latter method is most important for naturally occurring polymers such as polysaccharides and polyfhydroxy alkanoate)s, e.g., polyhydroxybutyrate and polyhydroxyvaler-ate [121,125]. Many synthetic aliphatic polyesters utilized in medical applications degrade mainly by pure hydrolysis [121]. 

Polyhydroxyalkanoic acids (PHAs) have been extensively researched since the 1970s because of the potential applications of these compounds as biodegradable substitutes for synthetic polymers. The most successful PHA products are the polyhydroxybutyrates (PHBs). The bacterium... 

Polyhydroxyalkanoates, Polyhydroxybutyrate, History, Bacterial synthesis. Chemical synthesis. Genetic engineering. Mechanical properties. Thermal transitions. Crystallization, Plasticizers, Thermal degradation. Processing, Applications... 

The simplest PHA is polyhydroxybutyrate (PHB), whose formula is shown in Fig. 22.1. This polymer and its copolymer with polyhydroxy valerate seem to be, at present, the only PHAs relevant for practical applications. 

Nanocomposites based on polyhydroxybutyrate and hydroxyapatite have been proposed for application in bone repair and regeneration. The hydroxyapatite nanoparticles acted as nncleating agent during PHB crystallization. ... 

Yasin, M. and B.J. Tighe, Strategies for the design of biodegradable polymer systems Manipulation of polyhydroxybutyrate-based materials, Plastics, Rubber and Composites Processing and Applications, 19 (199,3) 15-27. 

Other applications of AFM to the characterisation of polymers include polythiophene [9], nitrile rubbers [10], perfluoro copolymers of cyclic polyisocyanurates of hexamethylene diisocyanate and isophorone diisocyanate [11], perfluorosulfonate [12], vinyl polymers [13], polyhydroxybutyrate [14], polyacrylic acid nanogels [15], acrylic copolymers [16, 17], polyurethanes [18, 19], ethylene methacrylate copolymer [4, 20], polyamides [21], polyvinyl pyrrolidone [22], and polyethyl methacrylate dispersions [23], acryloyl chloride [13], aniline-4-sulfonic acid [24], ethylene propylene 5-ethylidene-2-norbornene terpolymer [25] and butylene adipate - butylene terephthalae [26]. 

Cheap methanol may be used as a carbon source to replace carbohydrate in the microbial production of chemicals. For example, polyhydroxybutyrate (PHB), a biodegradable thermoplastic material, can be produced by microbial fermentation. However, its hi cost restricts large-scale application. The cost of the substrate is an important contributing factor to the overall cost of production. The use of methanol to produce PHB, if successfully developed without sacrificing the molecular weight, would significantly improve process economics and increase its practical application. Recent studies have shown promising results [58, 84, 85]. 

---