Effects of residual metal compounds and chain-end structure on thermal degradation of poly(3-hydroxybutyric acid)

Precise Depolymerization of Poly(3-hydoxybutyrate) by Pyrolysis

“…However, if the plot of the calculated E a value against w shows a slope in the range of w, it indicates that multiple reactions are proceeding in a mixed manner. By using the multiple constant heating rate method, Aoyagi et al (Aoyagi et al, 2002), Kim et al (Kim et al, 2006), and our group (Ariffin et al, 2008 reported the E a value of PHB thermal degradation as being in a relatively narrow range of 111-140 kJ·mol -1 . It was proposed that this small variation in E a value was due to the influence of residual metal ions such as Ca 2+ , Mg 2+ and Zn 2+ .…”

“…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;…”

“…(Kopinke et al, 1996;Galego & Rozsa, 1999;Li et al, 2001;Carrasco et al, 2006;Liu et al, 2009), 2) 111-140 kJ·mol -1 calculated with multiple constant heating rate methods based on weight loss (Aoyagi et al, 2002;Kim et al, 2006;Ariffin et al, 2008Ariffin et al, , 2010, and 3) 178-247 kJ·mol -1 calculated with non-auto-catalytic random degradation analysis based on changes in molecular weight (Grassie et al, 1984;Kunioka & Doi, 1990;Kim et al, 2006).…”

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

“…At the moderately low temperature (170~200°C), PHB degraded into a well-defined oligomer containing one unsaturated end group, predominantly a trans-alkenyl end group, as well as a carboxylic end group [50]. The dominant thermal degradation occurred via a random chain scission (cis-elimination) with a six-membered ring ester intermediate [51][52][53][54]. If 2,2!-bis(2-oxazoline) was introduced in the thermal degradation, a hydroxyl-terminated PHBV was achieved with an improved thermal stability [55].…”

Preparative synthesis of Poly[(R)-3-hydroxybutyrate] monomer for enzymatic cell-free polymerization

“…By thermal degradation, P(3HB) can be converted into crotonic acid with a high yield. 10,11 Furthermore, the intermolecular dehydration of two crotonic acids generates crotonic anhydride. Recently, it has been shown that crotonic anhydride is generated as a minor product from P(3HB) by thermal degradation.…”