聚β－羟基烷酸酯热分解行为的直接裂解质谱研究

THERMAL DECOMPOSITION PROCESSES IN POLY (β-HYDROXYALKANATES) INVESTIGATED BY DIRECT PYROLYSIS MASS SPECTROMETRY

用ＤＰＭＳ、ＴＧ、ＤＴＡ等方法研究了聚β－羟基丁酸酯（ＰＨＢ）及其共聚物Ｐ（ＨＢ－ｃｏ－ＨＶ）的热分解行为和某些结构性质．能提供多至７个链节重复单元的裂解碎片．可较好地反应共聚物的组成和分布．结果表明：聚β－羟基烷酸酯的热分解具有较高的选择性，通过β－Ｈ转移反应形成由羧基和烯烃结尾的齐聚物．齐聚物准分子离子可进一步脱去一分子水．

Thermal decomposihon processes in poly(β-hydroxybutyrate)(PHB) and Poly (β-hydroxybutyrate-co-β-hydroxyvalerates) [P(HB-co-HV)s] with composihon ratios HB/HV of 96:4 and 82:18 were investigated by direct pyrolysis mass spectrometry (DPMS). It can provide up to hoptelner pyrolynates and estimate the composition and sequence distribution of copolymers. The results indicate that the thermal degradation of PHB and P(HB-co-HV) occurs quite selctively through a β-Hydrogen transfer process, with formation of oligomers bearinng carboxyl and olefin end-groups. Oligomeri groducts corresponding to dehydrated monomer up to heptamer were also identified both in the case of PHB and P(HB-co-HV).