Preparation And Performance Study Of Biodegradable PBAT Barrier Fil

A large number of plastic film products are discarded after single-use,resulting in serious "white pollution" and thus poses threat to ecological environment due to nondegradability.The use of biodegradable polybutylene adipate terephthalate(PBAT)to replace is one of the alternative solutions to address the plastic pollution problem is to replace traditional plastic film materials with biodegradable polybutylene adipate terephthalate(PBAT).However,PBAT has low resistance to water vapor and oxygen and poor crystallization properties,which hinder its applications in packaging and other fields.Therefore,improving the resistance of PBAT to water vapor and oxygen is still one of the hot topics for research.In this work,cellulose nanofibers(CNF)were employed as functional additives for PBAT.CNPH nanomaterials were prepared by surface grafting modification,MCNF nanomaterials loaded with active molecules were prepared by solution precipitation method,and a series of PBAT barrier films were prepared by solution method.The effects of CNPH and M-CNF additions on the properties of PBAT crystallization and gas barrier were investigated,and the barrier mechanism of nanomaterials in PBAT films was also explored.The results of the thesis work are as follows:(1)CNPH,a surface grafted nanomaterial,was prepared,and the optimal reaction time of the grafting reaction was determined by yield and FTIR spectroscopy;the water contact angle of CNPH was increased by 98% and the dispersion in hydrophobic matrix was improved compared with CNF;the morphology of CNF was changed after grafting as observed by TEM,and a rod-like cellulose nanomaterial was obtained,which enabled it to play a better role in PBAT.(2)The PBAT/CNPH barrier film with good biodegradability was prepared,and CNPH was uniformly dispersed in PBAT matrix.The gas barrier performance of the films was significantly improved.Compared with pure PBAT,PBAT/CNPH films showed the highest improvement in gas barrier performance at 4% CNPH loading,with32.2% improvement in water vapor barrier performance and 43.9% improvement in oxygen barrier performance;the mechanism of the effect of CNPH on the gas barrier performance of PBAT with the physical barrier effect of nanomaterials and the synergistic effect of increasing the crystallinity of PBAT was investigated.(3)M-CNF,a nanomaterial loaded with active molecule DL-α-tocopherol,was prepared,and the optimal formulation of M-CNF was determined by UV-Vis spectroscopy analysis,and its corresponding DL-α-tocopherol encapsulation efficiency and loading amount reached 83.26% and 19.51%,respectively;it was verified that MCNF has DPPH radical scavenging ability;the wettability of M-CNF was greatly improved,and the water The wettability of M-CNF was greatly improved and the water contact angle was increased by nearly 70% compared with CNF;the encapsulation effect of CNF on DL-α-tocopherol was confirmed by characterizing its microstructure using TEM.(4)PBAT/M-CNF barrier films with good biodegradability were prepared,and the presence of DL-α-tocopherol in the films was verified;good compatibility of M-CNF with PBAT was observed by SEM,and the gas barrier performance of the films was significantly improved.Compared with pure PBAT,PBAT/M-CNF films showed the highest improvement in gas barrier performance at 4% M-CNF loading,with 26.7%improvement in water vapor barrier performance and 39.2% improvement in oxygen barrier performance.Similar to the barrier mechanism in PBAT/CNPH films,the physical barrier effect of M-CNF and the increased crystallinity of PBAT lengthen the path of gas through the film,thus improving the film gas barrier performance,but the antioxidant effect on the film surface brought by DL-α-tocopherol also has an effect on the oxygen barrier performance.