Particular thermal properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers

Abstract

Telechelic hydroxylated poly(3-hydroxybutyrateco-3-hydroxyvalerate)s (PHBV-diols) were synthesized by transesterification with ethylene glycol, which could be used as the macromonomers for synthesis of block copolymers. PHBV-diols owned particular thermal properties. PHBV-diols had much lower the melting temperatures (T m s) and better thermal stability than original PHBV. With the decrease of molecular weight, T m s of PHBV-diols decreased gradually and maximum degradation temperatures (T max s) increased gradually. T max -T m of PHBV-diol could increase by 57.9°C in comparison with original PHBV. It was meaningful that PHBV block in the block copolymers based on PHBV-diol owned the good thermal stability and low melting temperature of its precursor PHBV-diol, which widened greatly the meltprocessing window of PHBV. In addition, thermal degradation kinetics was studied by Ozawa method, the integration method and Kissinger method. The results showed that the thermal degradation of original PHBV and PHBV-diols proceeded by at least two steps including a random degradation process and subsequent thermal degradation process due to the autoaccelerated degradation reaction.

Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate): Structure, Property, and Fiber

“…It can be seen from Table 1 [52] that the melting temperature of commercial P(3HB-co-3HV) was beyond 150 ∘ C. In addition, P(3HB) and P(3HB-co-3HV) were unstable above 160 ∘ C mainly by nonradical, random chain scission (cis-elimination) reaction, which resulted in a drastic reduction in molecular weight during melt processing. Therefore, the melt processing window of P(3HB) and P(3HB-co-3HV) was narrow [2,62]. P(3HB) and P(3HB-co-3HV) are brittle materials, which makes them unsuitable for some applications.…”

Application of 2K Experimental Design and Response Surface Methodology in the Optimization of the Molar Mass Reduction of Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PHBHV)

“…Moreover, commercial PHBHV shows some disadvantages, such as poor thermal stability and high melting temperature. PHBHV´s thermal degradation temperature is close to 160°C and their melting temperature is around 150°C, resulting in a small processing window [39].…”

“…Liu,Q. et al [39] synthesized telechelic PHBHV-diols with various molar mass by trans-esterification with ethylene glycol. The results showed that PHBHV-diol was more stable than original PHBHV and the melt-processing window increase gradually with molar mass decrease.…”

Síntese de nanopartículas de poli(3-hidroxibutirato-co-3-hidroxivalerato) modificadas com aminosilanos para aplicação em engenharia de tecidos

“…Esse fenômeno de redução da T m com a inserção de hidroxilas terminais e diminuição da massa molar também foi observado por Liu et al (2012) (DAGNON et al, 2009). Após a análise do efeito dos parâmetros do processo de síntese de nanopartículas de PHBHV no diâmetro hidrodinâmico e índice de polidispersidade, realizou-se o estudo da estabilidade das dispersões dessas partículas ao longo do tempo.…”

“…De acordo com os autores, a redução nos valores de T m foi consequência da redução na perfeição dos cristais do PHBHV-diol.Além das diferenças nos valores obtidos para as T m , no termograma do PHBHVdiol, o primeiro pico de fusão ficou mais evidente, quando comparado com o PHBHV (M n = 121kDa, Ð= 1,90), como pode ser observado pela Figura 9 e pelo valor da entalpia de fusão (ΔH m1 ) da Tabela 3, que se relaciona com o valor da área do pico. Esse resultado também foi obtido porLiu et al (2012). Os autores concluíram que isso ocorreu, pois, o PHBHV-diol possui maior concentração de grupos terminais hidroxila.…”