Thermal degradation and combustion properties of most popular synthetic biodegradable polymers

Abstract

Various products made from biodegradable polymers have been increasing rapidly in the market since the use of non-biodegradable materials has been banned, particularly for the disabled packaging materials. Burning remains the most popular method that is increasingly used in treating city wastes. The impact of these polymers on environmental during thermal degradation and combustion is an important issue for city waste management. In this work, the thermal degradation and combustion behaviours of the most popular synthetic biodegradable polymers in the market, poly(lactide acid) (PLA), poly(e-caprolactone) (PCL), poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT) and polyhydroxyalkenoates (PHA), are investigated. Both isothermal and non-isothermal thermal decomposition in oxygen and nitrogen environment were studied using thermogravimetric analysis combining with differential scanning calorimeter and coupled with Fourier transform infrared spectroscopy and gas chromatograph/mass spectroscopy. The combustion behaviour was investigated by a combustion colorimeter. The study results show that thermal degradation temperatures are PCL > PBS > PLA > PBAT > PHA. The thermal decomposition of all the polyesters started from scission reaction ( cis-elimination), and then a stereoselective cis-elimination, which resulted in the formation of trans-crotonic acid and its oligomers. They all decomposed into CO2 and water in excess oxygen environment above 800°C. Various chemical products with smaller molecules were detected under oxygen-free conditions, including oligomers and unsaturated carboxylic acid. The order of the total heat release of the materials from high to low is as follows: PHA > PCL > PBAT > PBS > PLA. The combustion values of these polyesters are lower than those of polyolefins; thus, they will not damage furnace used currently. The results provide some important and useful data for managing these new city waste.

Characterization of extruded films based on poly (butylene succinate) blends to utilize a partially degraded poly (butylene adipate‐co‐terephthalate)

“…Sample F3 revealed a thermal decomposition event at approximately 520°C that did not occur in the other samples (Figure 4b). This thermal event could be related to the heterogeneity of the constituents in F3 (PBS/PBAT, 70:30), similar to that reported by Cobo et al 42 in PLA/PBAT blends, or even to an obvious decomposition of aromatic copolyester (terephthalic acid), as reported by Chen et al 39 in advanced PBS and PBAT decomposition studies using DSC, TGA‐FTIR, and TGA‐GC‐MS.…”

“…When sufficient heat is applied, the polymer chains typically break down into their basic building blocks, followed by reaction intermediates that recombine until they form gaseous products and char. Both PBS and PBAT decompose along basic pathways involving intramolecular ester exchange and cis ‐elimination 39 …”

Recent advances in metal-family flame retardants: a review

“…and poisonous gases are released, 8,9 making reghting and rescue work difficult. Therefore, various ame retardants are typically added to the polymeric matrix to increase the re safety of polymeric materials.…”

“…These polymers are highly susceptible to airborne combustion, 6,7 which significantly limits their application. Furthermore, when polymers burn, a large amount of smoke and poisonous gases are released, 8,9 making firefighting and rescue work difficult. Therefore, various flame retardants are typically added to the polymeric matrix to increase the fire safety of polymeric materials.…”

High-Pressure Depolymerization of Poly(lactic acid) (PLA) and Poly(3-hydroxybutyrate) (PHB) Using Bio-Based Solvents: A Way to Produce Alkyl Esters Which Can Be Modified to Polymerizable Monomers

“…The first two processes do not generate any usable material and the mechanical recycling of PLA results in the production of a polymer with considerably worse properties than the original one. The reason for this outcome is that the thermal and photochemical degradation takes place during the mechanical processing of the PLA polymer, which leads to the decrease in molecular weight of the material [ 2 , 7 , 13 , 14 ]. Poly(3-hydroxybutyrate) (PHB) is a biopolymer that is produced by various microorganisms and can be degraded by living systems as well.…”