Poly aliphatic polyesters

For an aliphatic polyester, poly(pivalolactone) has a rather high of 245°C and for such a an unexpectedly low of -10°C. It is also claimed to have good hydrolysis resistance for a polyester and this appears to be one of the reasons for its manufacture on an experimental scale by Shell with a view for use as both a fibre and as a thermoplastics moulding material. 

The activation energy of thermolysis of the azo group was measured by DSC [14]. Type II MAIs, which are composed of various prepolymers such as aliphatic polyester, poly(caprolactone), and aliphatic poly (carbonate), showed almost the same activation energy irrespective of difference in prepolymer structure, suggesting that the neighboring group only affects the active site. 

Aliphatic polyesters Poly(L-lactic acid), poly(glycolic acid), PLGA co-pol3Tners Polyfglycolic acid), polyflactic acid), and their co-polymers are the most widely used synthetic degradable polymers in medicine. 

Nakayama, A., Kawasaki, N., Arvanitoyannis, I., lyoda, J., and Yamamoto, N., 1995, Synthesis and degradability of a novel aliphatic polyester -Poly( -methyl- -valerolactone-co-L-lactide, Po/ymer 36 1295-1301. 

Song, M.J. et al., 2003. Thermosensitive sol-gel transition behaviors of poly (ethylene oxide)/aliphatic polyester/poly (ethylene oxide) aqueous solutions. Journal of Polymer Science Part A Polymer Chemistry, 42(3), 772-784. 

Upon irradiation with an electron beam the aliphatic polyester, poly(butylene adipate)diol (PBAD) undergoes predominantly scission at low doses (< 50 kGy) along with an increase in the level of crystallinity, whereas above 100 kGy both crosslinking and scission occur and the level of crystallinity decreases [157]. 

Belonging to the family of aliphatic polyesters, poly(lactic acid) or polylactide (PLA) is composed of lactic acid repetitive units, which is the simplest ot-hydro)y acid with an asymmetric carbon atom. Interestingly, the L-lactic acid monomer, and more recently the D-lactic acid monomer, can be straightforwardly obtained by bacterial fermentation from renewable resources (namely starch), making both monomers and therefore the resulting polymers environmentally friendly. Polycondensation of lactic acid and ring-opening polymerization (ROP) of lactide (LA), i.e. cyclic diesters of lactic acid, are currently used to prepare PLA polymers (Scheme 4.1). 

Chrissafis K., Paraskevopoulos K.M., Bikaris D.N. Thermal degradation kinetics of the biodegradable aliphatic polyester, poly(propylene succinate), Polym. Deg. Stab. 91 (2006) 60. 

Among unsaturated di-acids, fumaric acid is one of the most useful building blocks, since it is a naturally occurring metabolite. Aliphatic polyesters, poly(propylene fiimarates) have recently been considered as biodegradable and photo-crosslinkable polymeric material used for scaffold applications (15). 

To elucidate the degradation mechanisms of two biodegradable aliphatic polyesters, poly (propylene azelate) (PPAz) and poly(propylene sebacate) (PPSe), TGA, FTIR and a TG-GC/MS system was used. Due to the existence in both polyesters... 

Fig. 6 Chemical structure of the aliphatic polyesters poly(glycolic acid) (PGA) and pol(lactic acid) (PLA), sodium alginate, and oxidized sodium alginate...

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