Polyhydroxybutyrate-valerate

After many years of research initiated in the 1970s, ICI introduced polyhydroxybutyrate-valerate copolymers in 1990. Because of their particularly interesting manufaeturing technology, these materials are dealt with in depth separately in the next section. 

Table 31.3 Some selected properties of polyhydroxybutyrate-valerate copolymers (Biopol—Zeneca)...

Metabolix s PHBV (polyhydroxybutyrate valerate) was initially developed by ICI. PHBV and related copolymers are made in a pilot plant using different bacteria to create compositions with up to 70% crystallinity. Elongation can be manipulated from 5% to 100%, and melting points range between 135 and 185 °C (275-365 °F). 

Polyhydroxybutyrate-valerate copolymer Biodegradable polyester used in degradable plastic... 

Another important family of biobased polyesters is the polyhydroxyalkanoates (PHAs) the most common members of this family are polyhydroxybutyrate (PHB) and its copolymer, polyhydroxybutyrate-valerate (PHBV). 

A more recent biodegradable polymer is polyhydroxybutyrate-valerate copolymer (PHBV) from ICI Americas Inc.. These copolymers are produced through biochanical means. In fact, these natural thermoplastics are derived from bacteria. They are fully degradable in many microbial environments. Other biodegradable polymers include Konjac, a water-soluble polysaccharide produced by FMC Chitin, another polysaccharide that is insoluble in water and Chitosan, which is soluble in water. 

Polyhydroxybutyrate-valerate is produced under BIOPOL trade mark by Monsanto, with a production capacity of about 500 ton/year. 

A more recent biodegradable polymer is polyhydroxybutyrate-valerate copolymer (PHBV). These copolymers differ from many of the typical plastic materials in that they are produced through biochemical means. It is produced commercially by ICI using the bacteria Alcaligenes eutrophus, which is fed a carbohydrate. The bacteria produce polyesters, which are harvested at the end of the process. When the bacteria are fed glucose, the pure polyhydroxybutyrate polymer is formed, while a mixed feed of glucose and propionic acid will produce the copolymers. Different grades are commercially available that vary in the amount of hydroxyvalerate units and the presence of plasticizers. The pure hy-... 

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