Electron Beam Irradiation Modification Of PBAT-based Biodegradable Films

Plastic films endow people's life and production with significant convenience,yet,growing environmental and social concerns arises from the overuse of tranditional polyolefin-based non-degradable plastic films.To address this,it is of great importance to develop high-performance biodegradable plastic films.Among the currently available biodegradable polymers,poly(butylene adipate-co-terephthalate)(PBAT)possesses ideal mechanical,thermal and processing properties and therefore attracts conderable research interests.However,PBAT suffers from higer production cost as well as poorer water/oxygen barrier properties in compassion to polyolefins,which significantly hinder its application scopes in the fields such as food packaging and agricultural mulch films.Herein,a new methond that elagently integrates plasticizing with electron beam irradiation post-treatment technology is developed for the preparation of low-cost and highperformance PBAT-based plastic films.The processing property of PBAT as well as the flexibility of the resulting PBAT-based films were significantly improved due to the plasticizing effect of active plasticizers.Then the active plasticizers could serve as the crosslinking reagent to further improve the mechanical properties,water vapor barrier properties of the PBAT-based biodegradable films.The major works and achievements of this paper are as follows:Firstly,Triallyl isocyanurate(TAIC)was selected for an active plasticizer and blended with PBAT.The plasticized PBAT/TAIC films were modified by electron beam irradiation post-treatment technology to investigate the mechanical properties,water vapor barrier propertie of pure PBAT and PBAT/TAIC films.The experimental results revealed that pure PBAT irradiated at electron beam was weakly cross-linked.The gel fraction increased rapidly with TAIC,and the sol fraction and irradiation dose satisfied the Chen-Liu-Tang equation.The water vapor transmission coefficient(WVP)and elongation at break of PBAT/TAIC films decreased with the increase of radiation dose.The tensile strength of PBAT/TAIC films increased in the range of 0?150 k Gy.And the tensile strength of PBAT film with 2 wt%TAIC irradiated at 150 k Gy was 31.5 MPa,which increased by 23% than pure PBAT film.Secondly,the post-treatment technology of electron beam irradiation and the biaxial stretching process were organically combined to further improve the tensile strength and water vapor barrier properties of PBAT.The PBAT with 2 wt% TAIC which had the best irradiated tensile strength was selected for biaxial stretching.The mechanical strength of biaxially oriented PBAT/TAIC film was 67.1 MPa when the stretch ratio was 3.5 and the irradiation dose was 100 k Gy,which increased by 1.5 times than pure PBAT film.The WVP of it was about 40% lower than pure PBAT,which is of great importance to promote the wide application of PBAT-based biodegradable films.Finally,polylactic acid(PLA)was used to further improve the tensile strength and water vapor barrier properties of PBAT and the trimethylolpropane triacrylate(TMPTA)instead of TAIC was choosed as an active plasticizer which had higher boiling point because of the higher processing temperature of PBAT/PLA system.Then the chain extender Joncryl ADR4368 L was used to increase the compatibility between PBAT and PLA.Next,the water vapor barrier properties and mechanical properties of the PBAT/PLA/TMPTA films under electron beam irradiation were also investigated.It demonstrated that tensile strength of the film was slightly improved.And the WVP of film decreased with the increase of radiation dose.It decreased by 33% compared with pure PBAT when it was irradiated at 200 k Gy with 10 wt%TMPTA.