| Polylactide(PLA) has a lot of advantages, such as biodegradability, biocompati- bility, processibility, etc, it can be composed into water and carbon dioxide. Compared to the costly and flammable of PLA, which limit its widely applications, the high yield Cassava with its low costs and renewable character can be blended with PLA to prepare biodegradable material to reduce the material cost and relieve the pressure of oil resources, further promote the development of local economy. Further, Maleic anhydride(MA) is solubilizing agent to improve the availability of starch / PLA blends compatibility, due to its excellent chemical and physical properties.In this paper, Maleic anhydride esterified cassava starch(MS) was prepared by reactive blending with cassava starch(CS) as raw material, Maleic anhydride(MA) as esterifying agent. The effect of the reation temperature, reation time, rotational speed and maleic anhydride dosage on substitution degree(DS) of esterified starch(MS) was studied. The results showed that DS of MS increased gradually with the increase of reaction temperature, reaction time duration and rotational speed. When the temperature reached 130℃, or when the reaction time duration was extended to 12.5 min, the substitution degree of esterified starch tended to be stable, and when the speed of blend reached 70R/min, the DS was the highest, and the DS was growth along with the increment of MA amount. However, excessive MA will enable the processing inconvenience. It is evident from another experiment that there is an obvious increase in DS after ionic liquid into the esterified cassava starch, especially [AMIM]Cl. FTIR analysis showed that maleic anhydride grafted onto the starch chain.PLA/MS blends was prepared by melt blending with maleic anhydride esterified cassava starch(MS) and polylactide(PLA). The effect of the mechanical properties, water resistance, thermal stability and microstructure of PLA/MS composite materials with different mass ratio. The results showed that the tensile strength of 7:3 PLA/MS blents was about 22.7 MPa which was increased nearly 54% of the same ratio PLA/TPS with 40 wt% glycerol as plasticizer. Further, the materials section microscopic structure were more rough, and the glass transition temperature of the material slightly shifts to low temperature, It implied that the complatibility and fabricability of the blends were improved. In a further experiment, we found that the water resistance and thermal stability of the blends were improved also.Intumescently flame retardant polyactide composites(PLA/MS/APP/MCA) were prepared by melt blending PLA/MS with ammonium polyphosphate(APP) and melamine cyanurate(MCA). The experimental results of PLA/MS/APP/MCA blends system show: the increase of the flame retardant content can make the oxygen indexrising, have a good collaborative flame retardant performance. When the complex contained MS/APP/MCA at weight ratio of 4/9/3 and the addition amount of complex in PLA was 20 wt%, the PLA composites showed LOI values of 32.2 and passed UL 94 V-0 rating, and LOI value increases from 32.2 to 41.4 for flame-retarded PLA with the flame retardant conten was increased to 45 wt%. Thermogravimetric analysis shows that the improved flame retardancy is due to increased char residue a thigh temperature. A good interfacial interaction between MS and PLA can allow stress transfer at the interface level; however, the flame retardant coated on the surface of the MS hinders the interaction between MS and PLA, resulting in the decrease of mechanical properties for flame-retarded PLA. |
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