Thermal analyses of poly(3‐hydroxybutyrate), poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Abstract

Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by T o ϭ 0.75B ϩ 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was T p ϭ 0.91B ϩ 320, and the temperature at which degradation was completed was T f ϭ 1.00B ϩ 325. In the thermal degradation of P(HB-HV) (70:30), T o ϭ 0.96B ϩ 308, T p ϭ 0.99B ϩ 320, and T f ϭ 1.09B ϩ 325. In the thermal degradation of P(HB-HHx) (85:15), T o ϭ 1.11B ϩ 305, T p ϭ 1.10B ϩ 319, and T f ϭ 1.16B ϩ 325. The derivative thermogravimetry curves of PHB, P(HB-HV), and P(HB-HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures T o , T p , and T f relative to those of PHB by 3-12°C (measured at B ϭ 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C.

Precise Depolymerization of Poly(3-hydoxybutyrate) by Pyrolysis

“…Several thermoanalytical procedures have been used to investigate the thermal degradation behavior of PHB, including thermogravimetry (TG) for the analysis of weight loss behavior (Kopinke et al, 1999;Galego & Rozsa, 1999;Li et al, 2001;He et al, 2001;Lee et al, 2001;Aoyagi et al, 2002;Carrasco et al, 2006;Kim et al, 2006;Kawalec et al, 2007;Liu et al, 2009;Ariffin et al, 2008Ariffin et al, , 2010, differential scanning calorimetry (DSC) for monitoring the heat of reaction (Kopinke et al, 1996), fast atom bombardment mass spectrometry (FAB-MS) (Ballistreri et al, 1989), electrospray ionization mass spectrometry (ESI-MS) (Kawalec et al, 2007), pyrolysis-mass spectrometry (Py-MS) (Abate, 1994;Kopinke et al, 1996), pyrolysisgas chromatography (Py-GC) (Lehrle, 1994), pyrolysis-GC/mass spectrometry (Py-GC/MS) (Kopinke et al, 1996(Kopinke et al, , 1997Aoyagi et al, 2002;Ariffin et al, 2008Ariffin et al, , 2010, TG/Fourier transform infrared spectroscopy (TG/FTIR) (Li et al, 2003), NMR (Melchiors et al, 1996;Kopinke et al, 1996;Ariffin et al, 2009), and pyrolysis-GC/FTIR (Li et al, 2003;Gonzalez et al, 2005), for the analysis of volatile products, and size exclusion chromatography (SEC) (Grassie et al, 1984;Kunioka & Doi, 1990;Nguyen et al, 2002;Kim et al, 2006) for the analysis of changes in molecular weight of residual PHB. (Kopinke et al, 1996;Galego & Rozsa, 1999;Li et al, 2001;…”

Influence of cooling rate on the thermal behavior and solid‐state morphologies of polyhydroxyalkanoates

“…5 However, they also have some disadvantages, including poor thermal stability, [6][7][8][9] narrow processing windows and brittleness [10][11][12] (especially for poly (3-hydroxybutyrate) (PHB)). These disadvantages can be improved by changing processing conditions, 13,14 by changing their chemical structures 15 (e.g., side chain length) and by adding particles, 16 stabilizers, 11 compatibilizers 17 or plasticizers, 18 all of which can influence the solid-state morphologies. Ultimately a molecular level understanding of structure and properties of PHAs will facilitate control over their properties.…”

Miscibility and morphology of chiral semicrystalline poly‐(R)‐(3‐hydroxybutyrate)/chitosan and poly‐(R)‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/chitosan blends studied with DSC, 1H T1 and T1ρ CRAMPS

“…6 For example, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-co-HV)] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-coHHx)] show a wide range of mechanical and physical properties depending on the HV or HHx content. [7][8][9] So far, many blends containing PHB have been studied, including binary blend and ternary blend systems; [1][2][3][4] however, not all of them are totally biodegradable. Chitosan [poly-␤(1-4)-d-glucosamine] is a chiral material suitable for asymmetric separation of racemic mixtures, and for biomedical applications.…”