| With the increasing use of agricultural mulch,the "white pollution" of soil is becoming more and more serious.Biodegradable film is the fundamental way to solve such problems.Therefore,more attentions are focused on the biodegradable mulching films.Poly(butylene adipate-coterephthalate)(PBAT)is a well-known biodegradable plastic with good flexibility and expected to be used for producing mulch.However,pure PBAT is difficult to blow film owing to its high melt viscosity.Therefore,blending PBAT with other biodegradable polymer provide a useful solution.Polylactic acid(PLA)has been considered a good alternative to enhance the processibility of mulching film based on PBAT resin due to its high elastic modulus and rigidity.To improve the compatibility between PBAT/PLA blends and further use as mulching films,we choose two type of reactive chain extender to react with PBAT and PLA during the blending process.The morphology and properties of the PBAT/PLA blends and films were also characterized.The main research work and the results are as follows.1.The CE-SZ01 and ADR4370 S which contain epoxy groups are used as reactive chain extender to modify PBAT/PLA blends by melting blends,respectively.The PBAT: PLA ratio is 80:20,and the addition of CE-SZ01 is 0%,0.4%,0.6%,0.8%,1.0% and 1.2%;and the ADR4370 S portion is 0%,0.2%,0.4%,0.6%,0.8% and 1.0%.The CE-SZ01 was melting reacted and blended with PBAT and PLA under 190 ℃.After blending for 8min,the obtained PBAT/PLA/CE-SZ01 blends were pressed into film by plate vulcanization machine.The PBAT/PLA/ADR4370 S blends were prepared using double screw extruder via melt blending with the melting section under 190 ℃.Then blends were blowing molded into film with 10μm,and the temperature of each extruder sections are 130 ℃,140 ℃,150 ℃ and 135 ℃.2.A series of performance characterizations were used to analyze the morphology and properties of PBAT/PLA/CE-SZ01 and PBAT/PLA/ADR4370 S,such as melt flow rate(MFI),scanning electron microscopy(SEM),Fourier transform infrared(FTIR),X-ray diffraction(XRD),differential scanning calorimetry(DSC),thermogravimetric analysis(TG),dynamic thermodynamic analysis(DMA)),tensile and optical test.3.The SEM of PBAT/PLA/CE-SZ01 shows that the island morphology of the modified blends is transformed into a coherent structure,which indicates that the introduced CE-SZ01 improves the compatibility between the PBAT and PLA.The thermal analysis of DSC,TG and DMA showed that the addition of chain extender did not affect the thermal stability of PBAT/PLA blends.Tensile testing shows that the material of elongation at break increased 287%,and the modulus of elasticity decrease 58.9%,when the chain extender addition amount of 1.2%.This presents that the chain extender modified PBAT/PLA blends became softer and toughen and more suitable for blowing thin film.4.Comparing to unmodified PBAT/PLA blend,the melt flow rate of PBAT/PLA/ADR4370 S blends decreased with increasing ADR4370 S content which indicated that the epoxy groups reacted successfully with PBAT and PLA.The SEM results proved that the interface between PBAT and PLA is gradually blurred involving with chain extender,and the particle size of the dispersed PLA gradually decreases.The XRD results indicated that the addition of chain extender did not cause a significant change in the crystal morphology of the matrix.The tensile test showed that when the addition of chain extender was between 0.4% and 0.8%,the anisotropy of the film was weakened.The transverse and longitudinal tensile strength of the degradable mulching film with 0.8% ADR4370 S increased by 30.0% and 30.0% respectively,and the nominal tensile strain at break increase from 53.6% to 130.1%.It is noted that the tear strength in vertical and horizontal direction are 132 and 133 N/mm,respectively,and the consistent data demonstrated that the modified PBAT/PLA biodegradable film has good mechanical properties.Optical performance test show that the haze of the thin film increased with increasing chain extender content and this may be due to the light scattering and diffusion of uniform dispersed PLA in the matrix leading... |
PDF Full Text Request