Preparation And Properties Of PBAT/PGA,and PLA/PBAT Blends

Poly(butylene adipate-co-terephtaltae)(PBAT)has attracted much attention due to its excellent tensile toughness and ductility.However,the defects of its own low strength also need to be improved,and a lot of work has been done in this regard.In this paper,the rigid polyglycolic acid(PGA)was used to enhance PBAT matrix,and the multiple epoxy chain extender(Joncryl ADR-4370s)was added to control its mechanical properties and processing properties.Finally,PBAT/PGA/ADR blends with excellent performance were obtained.In addition,PBAT was used to tough PLA matrix.Further more,through the subsequent process of adjustment,the dispersed phase morphology was changed,which improved the mechanical properties of the blends.Then the relationship between micro aggregation change of dispersed phase and the macro performance were deeply discussed.(1)Biodegradable PBAT/PGA blends were prepared by melt blending technology,and the reinforcing effect of PGA on PBAT was studied.It was found that the addition of PGA could obviously enhance the PBAT matrix,but followed by a sharp decrease in tensile fracture strength and elongation at break.On this basis,the rheological properties of blends and the compatibility between PBAT and PGA were improved upon addition of chain extender ADR,the comprehensive mechanical properties of the blends were significantly improved.The micromorphology observed by scanning electron microscopy showed that ADR greatly improved the compatibility of PBAT/PGA blends and the interface adhesion between PBAT matrix and PGA dispersed phase.In addition,the water and oxygen barrier properties of the blends were also greatly improved.These above results provide important implications for the preparation of biodegradable polymer packaging materials.(2)PLA/PBAT blends were prepared by melt blending extrusion method,and a little ADR was added as melt processing stabilizer.The PLA/PBAT samples were obtained by molding method.The properties of the samples were studied by means of torque,melt flow rate(MFR),tensile tests,impact tests,scanning electron microscopy(SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),Vicat softening temperature(VST)and so on.On this basis,annealing process was introduced to improve the crystallinity of molded samples,and the relationship between the crystallinity and properties of molded samples was explored.The test results show that the toughness of the molded sample firstly increases and then decreases with the increase of the content of PBAT.When the content of PBAT reaches 15%,the elongation at break of the molded samples reaches the extreme value and then decreases.The microstructure observation shows that due to the poor interfacial compatibility of the two phases,the size of dispersed phase of PBAT gradually increases with the increase of PBAT content,which leads to the continuous decline of toughness of the molded samples.After annealing treatment,the crystallinity of the molded samples increased obviously,and the yield strength and tensile strength increased in different degrees,but the toughness decreased sharply.(3)As a comparison of PLA/PBAT molded samples,PLA/PBAT calendered samples were prepared by extrusion calendering method.Related properties of the samples were studied by tensile tests,SEM,XRD,DSC.The relationship between the morphology of the microscopic dispersed phase and the macroscopic mechanical properties of the blends was discussed.Compared with the test results of the molded samples,it is found that the tensile yield strength,tensile modulus and elongation at break of the calendered samples are increased to different degrees.According to the microstructure observation,it is found that after calendering,the dispersed phase received strong tensile and shear field,its morphology gradually changed from granular to layered,strip and fibrous.Compared with granular PBAT dispersed phase,the orientation of the PBAT dispersed phase has a higher specific surface area,the perpendicular to the tensile direction of silver grain has more efficient contact chances and termination of ability makes extrusion calender specimen tensile toughness increased significantly.After further annealing treatment,the crystallinity of extruded calendered samples is significantly increased,and they can still maintain a higher elongation at break.