Research On Foaming Of Poly(Butylene Adipate-co-terephthalate)

In this paper,chain-extended Poly(butylene adipate-co-terephthalate)(PBAT)and PBAT/wood powder composites were prepared by melt blending method.Then PBAT foaming materials,chain-extended PBAT foaming materials and PBAT/wood powder composite foaming materials were prepared by the compression molding foaming way with chemical foaming agent azodicarbonamide(AC)and physical foaming agent expandable microsphere Expancel 951DU120.The rheological properties and crystallization properties of chain-extended PBAT and PBAT/wood powder composites were studied,then the properties and morphological structures of the foamed materials were studied.The results showed that:(1)The introduction of nucleating agent talc powder in the foaming process of pure PBAT with AC foaming agent can reduce the cell size,increase the cell density,and make the cell distribution more uniform as well as increasing the apparent density slightly.(2)Both Joncryl ADR-4370s and THYOSIL CXP5045 chain extenders can extend the chain of PBAT successfully.The melt flow rate of pbat is reduced,the melt viscoelasticity is enhanced,and the melt strength is improved.Compared with pure PBAT,the crystallinity of chain-extended PBAT decreased,and the crystallization temperature and melting temperature increased.Chain extenders can reduce the apparent density and cell size of foamed materials and increase cell density greatly.When the dosage of CXP is 1.2phr,the apparent density of PBAT foam material reaches the minimum value of 0.271g/cm³.The nucleating agent Ca CO₃ can improve the foaming effect of chain-extended PBAT,increase the cell density of the chain-extended PBAT foam material,and decrease the apparent density slightly.(3)The microsphere foaming material of PBAT has the best foaming effect at 180?.The apparent density of the foamed material decreases with the increase of the amount of microspheres.After the amount of microspheres reaches 8 phr,the matrix has been fully foamed.(4)The melt elasticity,viscosity and crystallization temperature of PBAT/wood powder composites increased with the increase of wood powder content.The obtained composite foams have closed-cell structure and uniform cells.PBAT/wood powder composite foam with a density of 0.212 g/cm³ can still be obtained when the content of wood powder was 40 phr.When the content of wood powder was below 30 phr,with the increase of wood powder content,the cell density of foamed materials increased gradually.And the apparent density and foaming ratio increased slightly.But the cell size changed little.When the content of wood powder exceeded 30 phr,the cell density and the apparent density decreased suddenly,But the cell size and the foaming ratio increased suddenly.Wood powder reduced the compressive strength of foamed materials.When the content of wood powder increased to 30 phr,the compressive strength was almost the same as that of pure PBAT foamed materials.