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Effect of 3-hydroxy valerate content on some physical and mechanical properties of polyhydroxyalkanoates produced by Azotobacter chroococcum

2000; Elsevier BV; Volume: 36; Issue: 5 Linguagem: Inglês

10.1016/s0032-9592(00)00235-1

1873-3298

Ludmila Savenkova, Z Gercberga, I. Bibers, M.M. Kalnin',

Microplastics and Plastic Pollution

This paper presents a study on the effects of phosphate concentration and carbon sources on the polyhydroxyalkanoates comonomer composition produced by Azotobacter chroococcum 23. Physical and mechanical characteristics of the purified samples of poly(3-hydroxybutyrate) (P(3HB)) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) were determined with an aim to obtain polymers with improved mechanical characteristics. The P(3HB) and P(3HB-co-3HV) copolymers with the 3HV content from 0 to 20 mol% were isolated from A. chroococcum 23 cultures. The values of melting temperature (Tm) of the analyzed P(3HB-co-3HV) copolymers decreased from 180.0 to 123.0°C and glass transition temperature (Tg) from 3.1 to −6.3°C with an increase of the 3HV content in the copolymers from 0 to 20 mol%. The elasticity of the copolymers was much higher than that of the homopolymer and reached about 180% of extension at break for the copolyester sample with 20 mol% HV.