Correlation between molar mass changes and CO2 evolution from biodegraded 14C-labeled ethylene-vinyl alcohol copolymer and ethylene polymers

Abstract

The biodegradation of 14 C-labeled poly(ethylene-co-vinyl alcohol) (EVOH), 14 C-labeled LDPE mixed with starch and a metal salt and 14 C-labeled LDPE was studied. A comparison was made between samples exposed to UV irradiation for 60 h before inoculation and those that were not pre-aged. The samples were inoculated with a mixture of Penicillium simplicissimum and Fusarium redolens. The amount of evolved 14 CO 2 was measured by liquid scintillation counting (LSC). The changes in molar mass, crystallinity and amount of carbonyls were determined. After 498 days the pre-aged EVOH samples exposed to the fungi had the largest amount of evolved 14 CO 2 . Pure LDPE was the least degraded of the three materials compared. The EVOH samples did not, however, show any changes in molar mass, crystallinity or number of functional groups as compared to an unaged sample. The pure LDPE and LDPE/MB samples showed a difference between the pre-aged samples and the non pre-aged samples. A small increase in number average molar mass (M -n ) was seen for the inoculated samples as compared to the sterile samples, indicating that the low molar mass part of the polymer had been assimilated by microorganisms.

High-Performance Dual-Action Polymer−TiO2 Nanocomposite Films via Melting Processing

“…Figure depicts the cumulative effect of light irradiation up to 2 months of simulated sunlight exposure in the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum of the 2 wt % sample. While UV light is known to have a rather limited aging effect on EVOH polymers,13a the progressive degradation of the polymer matrix is evidenced in the case of the TiO 2 -containing nanocomposites by the spectra displayed in the figure. At the initial part of the treatment, only small bands at 1711 and 1594 cm -1 can be discerned as new features.…”

“…The treatment effect accelerates after 2/3 of the time period scanned. The corresponding FTIR spectra show important alterations in the O−H stretch (3500−3000 cm -1 ) and bending/deformation (1590/1390 cm -1 ) modes with a parallel increase in the 1725−1710 cm -1 band intensity related, as mentioned, to the appearance of carbonyl groups . These observations evidence the strong degradation of the hydrophilic part of the polymer attained in the last third of the treatment, with a parallel and modest modification of the ethylene groups, as suggested by small changes in the 2900−2800 (symmetric/asymmetric CH 2 stretching modes) and 1400 (bending CH 2 mode) cm -1 zones.…”

“…These observations evidence the strong degradation of the hydrophilic part of the polymer attained in the last third of the treatment, with a parallel and modest modification of the ethylene groups, as suggested by small changes in the 2900−2800 (symmetric/asymmetric CH 2 stretching modes) and 1400 (bending CH 2 mode) cm -1 zones. The speed of the TiO 2 -assisted polymeric matrix degradation reported in Figure is clearly competitive with that observed by using biodegradation procedures. 13b,g

6 ATR-FTIR spectra of the nanocomposite containing 2 wt % of TiO 2 during an aging treatment under simulated sunlight for 2 months. Spectra showed slides at different cumulative exposure times up to the end of treatment (marked as 1 in the figure).

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