| Poly（butylene Succinate）（PBS）is a synthetic aliphatic polyester that has attracted much attention in recent years.PBS has excellent mechanical and physical properties,excellent production and processing properties and complete biodegradability.Thus,it is the most one of the potential biodegradable polymer materials.However,PBS has poor strength and poor thermal performance feature,it is difficult to fully meet the needs of actual production and using;In recent years,conductive polymer composites（CPCs）have gradually developed into a hot spot in the field of materials science.Among them,doped polymer composites such as graphene,carbon nanotubes,and nano silver wires can not only improve the mechanics and crystallization,but also give the material a certain functional effect.In this paper,MWCNTs is used as the conductive filler and PBS is the matrix.The surface of MWCNTs was modified first,and MWCNTs/PBS conductive composites were prepared by melt blending.On the basis of MWCNTs/PBS conductive composites,the second phase PLA was introduced to make MWCNTs select distributed in PBS and obtain the MWCNTs/PLA/PBS conductive composite material with percolation structure,in order to reduce the percolation value of composite material.And,and the PBS-based composites were carried out accelerated aging experiment under simulated ultraviolet environment;Main research contents:first,MWCNTs were modified to improve their dispersion in the PBS matrix,and then a series of MWCNTs/PBS composites were prepared by melt-compounding,and the influences of MWCNTs with different surface treatment methods on the crystallinity,mechanical properties and electrical properties of the composites were systematically analyzed.Second,by introduction of the second phase PLA,distributing MWCNTs selectively in PBS through melt blending to construct MWCNTs/PLA/PBS conductive composites with double percolation structure was performed,and the effect of phase evolution on the crystallization and thermal stability and conductivity of materials were also studied.Third,a series of MWCNTs/PLA/PBS composite materials were subjected to accelerated ultraviolet aging,and the effect of aging time on the crystallization and conductivity of the composite materials was explored.The results show that:an appropriate amount of MWCNTs can act as an obvious heterogeneous nucleating agent to increases the nucleation rate of PBS.When the addition amount of MWCNTs is too high,a large amount of agglomeration will occur in the PBS matrix to inhibit the crystallization of PBS;after surface modification,The modified composite material can better promote the nucleation process of PBS;Calculated by the classical percolation threshold theoretical model,the percolation threshold of MWCNTs/PBS composite material is 0.47 wt%;When the content of MWCNTs is 1.0 wt%,the conductivity of the MWCNTs/PBS composite material after oxidation modification is 5 orders of magnitude lower than that of the unmodified composite material.MWCNTs-COOH-KH570/PBS composite material has better mechanical properties than MWCNTs-COOH-PVP/PBS composite material,its tensile strength,impact strength and flexural strength are respectively increased by 11.8%,25.8%and 24.3%compared with pure PBS.Moreover,when the PLA content is 50 wt%,it can be seen that an obvious double percolation structure is formed in the composite material,and the composite material has the best electrical conductivity;Based on the classic theoretical model of percolation threshold,the percolation threshold of MWCNTs/PLA/PBS composite material is 0.049 wt%;After modification,the percolation threshold of the MWCNTs-COOH/PLA/PBS composite is 2.31 wt%calculatedby the classical theoretical model of percolation threshold.Forethermore,with the increase of UV aging time,in the MWCNTs/PBS composite material,the crystallinity of PBS increases,and its thermal stability increases.When the aging time is 192 h,the conductivity of the composite material tends to be flat,which is increased by 1.64×10-6 S/m compared with the original.In the MWCNTs/PLA/PBS composite material,the crystallization performance of PBS is improved,the crystallization performance of PLA is first improved and then decreased,the thermal stability performance is first improved and then decreased,and the conductivity is increased by 1.80×10-5 S/m;In the MWCNTs-COOH/PLA/PBS composite material,the thermal stability of the composite material is gradually reduced,and the electrical conductivity of the composite material is increased by 5.4×10-6 S/m compared with the unaging. |
