Preparation And Properties Of PBAT-Based Biodegradable Blends And Their Foaming Materials

Poly（adipic acid/butylene terephthalate）（PBAT）was a biodegradable polymer with excellent processability and good mechanical properties.However,its linear molecular structure,and low molecular weight resulted in a low melt strength.In this paper,high molecular weight PBAT（E-PBAT）was obtained by modification of neat PBAT（N-PBAT）through chain expansion and binary blended with polypropylene carbonate（PPC）capped with maleic anhydride（MA）,and E-PBAT/-PPC foams were prepared by extrusion foaming.On this basis,Basalt fiber（BF）was used as filler to improve the viscosity and modulus of PBAT and the foaming property of the blends.The mechanical properties,rheological properties,phase structure and cell structure were investigated in the PBAT/PPC blended system.The rheological results showed that the complex viscosity of E-PBAT increased by 3400 Pa/s compared to that of N-PBAT,and the addition of PPC increased the viscosity significantly,reaching a maximum of 88836Pa/s at 50%PPC content.In the E-PBAT/PPC-90/10 fraction,the blend had a“sea-island”phase structure with a large cell size and a minimum number of pores,in the E-PBAT/PPC-70/30 fraction,the blend had a“quasi-continuous”phase structure with a uniform cell structure and a large number of pores,in the E-PBAT/PPC-50/50 fraction,the blend had a“bicontinuous”structure with severe collapse of vesicles due to the rapid escape of gas at the blend interface.The mechanical tests showed that the addition of PPC significantly increased the modulus of the blends,with the Young’s modulus in tension increasing from58.8 MPa（E-PBAT）to 187.74 MPa（E-PBAT/PPC-70/30）.Meanwhile,the DMA results showed that the energy storage modulus（E’）of the blends increased from 538 MPa to1650 MPa at room temperature.BF was added on the basis of the first system and the mechanical properties,rheological properties,thermal properties and vesicular structure were investigated.Both DSC and DMA curves showed that the Glass transition temperature（T_g）of PPC increased with increasing fiber content in E-PBAT/PPC-90/10 and E-PBAT/PPC-70/30 fractions,while the opposite results were obtained in E-PBAT/PPC-50/50 fractions.The rheological data revealed that the viscosity of the BF and E-PBAT blends was lower,indicating a poor binding ability.However,the binding capacity of BF with PPC was better,and in the E-PBAT/PPC-50/50 fraction,the increase of BF would improve the viscosity.DMA data results showed that BF was able to increase the E’of the blends significantly.In the E-PBAT/PPC-70/30 fraction,7 wt%BF was able to increase the E’by a maximum of 1.6times,while in the E-PBAT/PPC-50/50 fraction,5 wt%BF increased the E’by a maximum of 3.2 times.The variation of fiber content also affected the foaming performance of the blends,It can be seen from the SEM image that BF can play the role of heteronucleation point in the blends,and the cell density of the foam was greatly improved.When BF content was 5 wt%,the cell density of E-PBAT/PPC reached the maximum,which was about 7.41×10¹¹/cm³.