To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a o...To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a one-step solvent-free modification method.The effects of KH560 as a compatibilizer on the morphology,chemical structure,crystallization behavior,thermal degradative behavior as well as mechanical strength of the PLA/lignin composites were analyzed in detail.It was found that,after modification by KH560,the fractured surfaces of composites became smooth,suggested sufficient bonding between the lignin and PLA in the composites with KH560 coupling agent molecules.This result further proved by 1H NMR and ATR spectra of the composites that lignin and PLA formed stable chemical bonds with KH560.Due to the toughening effect of KH560,mainly affect the molecular chain mobility,the thermodynamic properties of LG-KH560/PLA composites were all reduced.When compared to the conventional solution modification method of adding silane coupling agents into PLA/lignin,the composites were synthesized via a single-step reactive extrusion modification procedure in this work showed relatively low tensile strength,which mainly because the existence of the free radicals due to coupling agents result in the composite’s deterioration and subsequent weakening of the tensile properties.展开更多
In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified....In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified. The effects of growth factors on the degradation of PBAT and the lipase activity of PBAT-degrading bacteria were assessed. The degradation mechanism was analyzed using scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, Xray diffraction, and liquid chromatography-mass spectrometry. The results showed that Stenotrophomonas sp. YCJ1 had a significant degrading effect on PBAT. Under certain conditions, the strain could secrete 10.53 U/m L of lipase activity and degrade 10.14 wt.% of PBAT films. The strain secreted lipase to catalyze the degradation of the ester bonds in PBAT, resulting in the production of degradation products such as terephthalic acid, 1,4-butanediol, and adipic acid. Furthermore, the degradation products could participate in the metabolism of YCJ1 as carbon sources to facilitate complete degradation of PBAT, indicating that the strain has potential value for the bioremediation of PBAT in the environment.展开更多
基金funded by the National Key Research and Development Program of China(grant number:2019YFD1101201)the National Natural Science Foundation of China(grant numbers:51773005 and 21905008)the Beijing Natural Science Foundation(grant number:2194071).
文摘To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a one-step solvent-free modification method.The effects of KH560 as a compatibilizer on the morphology,chemical structure,crystallization behavior,thermal degradative behavior as well as mechanical strength of the PLA/lignin composites were analyzed in detail.It was found that,after modification by KH560,the fractured surfaces of composites became smooth,suggested sufficient bonding between the lignin and PLA in the composites with KH560 coupling agent molecules.This result further proved by 1H NMR and ATR spectra of the composites that lignin and PLA formed stable chemical bonds with KH560.Due to the toughening effect of KH560,mainly affect the molecular chain mobility,the thermodynamic properties of LG-KH560/PLA composites were all reduced.When compared to the conventional solution modification method of adding silane coupling agents into PLA/lignin,the composites were synthesized via a single-step reactive extrusion modification procedure in this work showed relatively low tensile strength,which mainly because the existence of the free radicals due to coupling agents result in the composite’s deterioration and subsequent weakening of the tensile properties.
基金financially supported by the National Natural Science Foundation of China (21905009)the 2023 Beijing Technology and Business University graduate research capacity improvement program project。
基金supported by the Research Fund at the Shaanxi Provincial Science and Technology Department of China (No. 2018SF-375)Beijing Key Laboratory of Plastics Health and Safety Quality Evaluation Technology, Beijing Technology and Business University (No. TQETJP2018 004)。
文摘In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified. The effects of growth factors on the degradation of PBAT and the lipase activity of PBAT-degrading bacteria were assessed. The degradation mechanism was analyzed using scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, Xray diffraction, and liquid chromatography-mass spectrometry. The results showed that Stenotrophomonas sp. YCJ1 had a significant degrading effect on PBAT. Under certain conditions, the strain could secrete 10.53 U/m L of lipase activity and degrade 10.14 wt.% of PBAT films. The strain secreted lipase to catalyze the degradation of the ester bonds in PBAT, resulting in the production of degradation products such as terephthalic acid, 1,4-butanediol, and adipic acid. Furthermore, the degradation products could participate in the metabolism of YCJ1 as carbon sources to facilitate complete degradation of PBAT, indicating that the strain has potential value for the bioremediation of PBAT in the environment.
