Enzymatic Degradation Tests Research Articles

Mechanical degradation and mechanochemical copolymerization of hydroxyethyl cellulose

Ultrasonic degradation of hydroxyethyl cellulose (HEC) in aqueous solution was investigated. The degradation rate of this polymer was found to follow the Baramboim kinetic equation. Rate constants and the generating rates of radicals produced by ultrasonic irradiation were calculated, and the results showed their dependence on polymer concentration. Copolymers of methyl methacrylate/HEC and acrylic acid/HEC were prepared by ultrasound-induced polymerization. Biodegradability of the resultant polymers was assessed through enzymatic cellulase degradation tests. The two kinds of copolymers were found to be susceptible to the cellulase degradation.

Synthesis of Biodegradable Polyesters by Ring-Opening Copolymerization of Cyclic Anhydrides Containing a Double Bond with 1, 2-Epoxybutane and One-Pot Preparation of the Itaconic Acid-Based Polymeric Network

Ring-opening copolymerizations of itaconic anhydride (IAn) or citraconic anhydride (CAn) with 1,2-epoxybutane (EB) were carried out using aluminium triisopropoxide (Al(OiPr)3) and magnesium diethoxide (Mg(OEt)2). The resulting copolymers were characterized for molar composition and sequences by FT-IR, 1H and 13C NMR spectra. The copolymers obtained using Al(OiPr)3 initiator were found to contain homosequences of EB, i.e., copolyesterethers (1a and 2a), while those produced by Mg(OEt)2 Were alternating copolymers, i.e., polyesters (1b and 2b), irrespective of various feed monomer ratio. Differential scanning calorimetry analysis of the copolymers revealed a relationship between the glass transition temperature and the structure. One-pot preparation of itaconic acid-based highly cross-linked polymer was achieved through cleavage of exo-type double bond of IAn unit in the copolymers. Enzymatic degradation test for the films of cross-linked poly(IAn-co-EB) by Pseudomonas sp. and Rhizopus delemar lipase indicated that EB homosequence aided the enzymes to access the ester linkage in the cross-linked copolymers. The cross-linked poly(IAn-co-EB) films degraded moderately for 120 days in soil.

Radiation crosslinked poly(butylene succinate) foam and its biodegradation

The gel fraction (%) for poly(butylene succinate) (Bionolle) blended with blowing agents was found to be higher than the pure Bionolle due to the presence of other component that also underwent crosslinking. It was also found that the cell diameter of the Bionolle foam produced from irradiated Bionolle blend decreases as the gel fraction increases, because the crosslink density increases and thus it retards the bubble growth. Lower gel fraction, less than 5% was effective enough to give sufficient melt strength for production of foams. It was found that the biodegradability of Bionolle foam in the enzymatic degradation test and soil burial test was higher than that of crosslinked Bionolle (before foaming) because it contained many bubbles.

Citrate esters as plasticizers for poly(lactic acid)

Citrate esters were used as plasticizers with poly(lactic acid) (PLA). Films were extruded using a single-screw extruder with plasticizer contents of 10, 20, and 30% by weight. All of the citrate esters investigated were found to be effective in reducing the glass transition temperature and improving the elongation at break. It was observed that the plasticizing efficiency was higher for the intermediate-molecular-weight plasticizers. Hydrolytic and enzymatic degradation tests were conducted on these films. It was found that the lower-molecular-weight citrates increased the enzymatic degradation rate of PLA and the higher-molecular-weight citrates decreased the degradation rate as compared with that of unplasticized PLA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1507–1513, 1997