Biodegradation of Aliphatic and Aromatic Polycarbonates

Abstract

Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

BPA qualtitative and quantitative assessment associated with orthodontic bonding in vivo

“…The BPA configuration assembles a bulk, stiff chain that provides low susceptibility to biodegradation as well as significant strength and rigidity in BPA based dimethacrylate polymers based on monomers like Bisphenol--A glycidyl dimethacrylate (BisGMA), its ethoxylated analogue (BisEDMA), Bispenol--A dimethacrylate (BisDMA) and urethane--modified BisGMA [8]. Although BPA is not used as a raw material in dental resin composites, it is likely to be present as an impurity from the chemical synthesis procedure [9,10].…”

Silver effect on the biodegradation process of styrene-ethylene/butylene-styrene based thermoplastic elastomers compounds upon weathering exposure

“…The characteristics of the polymer such as crystallinity, molecular weight, functional groups, plasticizers, and additives have relevance in the degradation process (Artham & Doble, 2008). In styrene-ethylene/butylene-styrene (SEBS)-based TPE matrices, the metal particles have the tendency to remain in the SEBS/oil phase (Tomacheski et al, 2016).…”

Aliphatic-aromatic poly(ester-carbonate)s obtained from simple carbonate esters, α,ω-aliphatic diols and dimethyl terephthalate

“…Furthermore, polycarbonates have lower degradation rate than polyesters [28,29], which would be advantageous in the applications where relatively higher stability is desired.…”