Modification Of Poly (butylene Adipate - Butylene Terephthalate)

As a new class of biodegradable materials, aliphatic-aromatic copolyester has become a hot field of materials science research. Poly (butylene adipate-co-terephthalate)(PBAT) is a new kind of aliphatic-aromatic copolyester, which caused by adipic acid, terephthalic acid and butanediol. PBAT contains both of a flexible aliphatic segment and a rigid aromatic segments. Thus, PBAT has the biodegradable of aliphatic units while the mechanical properties of aromatic units. However, the mechanical properties of PBAT are poor, and the price is expensive, so its application is limited. Therefore, finding an effective way to modified PBAT, and then establishing the relationship between structure and properties is a useful way to expand PBAT applications.In this work, PBAT/CNTs composites, PBAT/PLA blends and PBAT reinforced materials with GF were prepared by melt mixing. Then the structure, mechanical properties and viscoelastic behavior of these materials were researched, in order to establish the relationship between structure and properties. Using tetrabutyl titanate (TBT) and glass fiber (GF) modified the PBAT/PLA (70/30) blends, and compared the difference of performance before and after modification, aiming at providing useful theoretical and experimental information on fabrication of biodegradable PBAT based materials with high performance.The main results are as follows.(1) PBAT/CNTs compositesAfter adding CNTs, only the modulus of the composites was increased. The presence of CNTs retards overall kinetics of creep, creep-recovery and stress relaxation of PBAT. This is attributed to highly restrained viscoelastic deformation and viscoplastic relaxation of PBAT chain coins, rather than slightly confined elastic deformation of chain segments, because the former is in the same size-scale with the CNT flocs. Such a dispersion state of CNTs is further confirmed by the structural parameters obtained by model descriptions on the dynamic rheological responses of composites.(2) PBAT/PLA blendsPBAT and PLA are the thermodynamic incompatibility system. The phase morphology of their blends highly depends on the composition ratio between them. Three typical immiscible morphologies, spherical droplet, fibrous and co-continuous structure can be seen at various composition ratios. The inversion of the system was approximately59wt%. Using tetrabutyl titanate (TBT) as a compatibilizer, the morphology of PBAT/PLA (70/30) blends was improved. The radii of the dispersed phase domains were reduced, and the interfacial adhesion was enhanced significantly. The mechanical properties of capacity system were firstly increased and then decreased. This is because that the body materials are degraded with more TBT.(3) PBAT enhanced systemOwing to the presence of GF, the performances of PBAT based materials were improved significantly, the tension strength and the Young’s modulus were increased with the GF loadings. But the toughness of the materials was decreased. The interfacial adhesion effect between GF and the matix was poor.