Structural Construction And Properties Of GO-ODA Derivatives Compatibilized PP/PA6 In-situ Microfibrillar Composites

In-situ fibrillation technology is an important processing method to prepare polymer blends,the polymer fibrils formed in the melt process can effectively improve their mechanical properties.However,the incompatibility between the matrix and the fibril phase of in-situ microfibrillar composites(MFCs)limits the reinforcing effect.Adding traditional compatibilizers by one-step method often leads to poor compatibilization effect because of their high usage limit and low intrinsic strength.In addition,because of the excessive use of conductive fillers and their poor distribution,it is hard to obtain the balanced electrical and mechanical properties of condutive MFCs prepared by using the network structure of MFCs.Therefore,it is an important field for polymer composites that how to design a new compatibilizer and a conductive filler to effectively improve the mechanical properties of MFCs at a relatively low dosage of compatibilizer and obtain the MFCs with balanced electrical and mechanical properties at a relatively low dosage of conductive filler.In this paper,the compatibilizer polypropylene grafted by graphene oxide(PP-gGO)and heated conductive filler graphene oxide grafted octadecylamine(HT-GOODA)were prepared.PP/G-PA6 MFCs with PP-g-GO and PP/F-PA6 conductive MFCs with HT-GO-ODA had been obtained through two-step melt blend.The effects of PP-g-GO,content of fibril phase and traction rate on the fibril morphology,rheological properties,mechanical properties and non-isothermal crystallization properties of PP/G-PA6 MFCs had been investigated.The effects of HT-GO-ODA content and traction rate on the fibril morphology,rheological properties,electrical conductivity,mechanical properties,non-isothermal crystallization,photothermal conversion and thermal conductivity of PP/F-PA6 MFCs had been carried on.The main results are as follows:(1)Based on GO-ODA,the new compatibilizer PP-g-GO and conductive filler HT-GO-ODA were successfully prepared.GO can effectively restore the graphitized structure after hydrothermal reduction with ODA and heat treatment,and exhibit the high intrinsic conductivity of HT-GO-ODA.(2)The orthogonal experiments had been carried on varing with the processing parameters such as temperature,screw speed and feed speed,and the optimum processing conditions for PP/PA6 MFCs are 250 °C processing temperature,110 rmp screw speed,and 90 rmp feed speed.(3)PP/G-PA6 MFCs prepared by two-step method contain highly profiled fibrils.Compared with PP-g-MAH,PP-g-GO exihit advantanges in reducing the average diameter of fibril,reducing the fibril diameters distribution,promoting the fibril dispersion and increasing the heteromorphism degree of fibril.When the G-PA6 content is 15 wt%(including PP-g-GO 0.6 wt%)and 12.62 wt%(including PP-g-GO0.5 wt%),at 150 rmp traction rate,PP/G-PA6 MFCs show the maximum flexural and tensile strength of 39.40 and 46.35 MPa,which are 42.19% and 19.77% higher than those of pure PP,respectively.The results have confirmed the design of improving the reinforcement effect of the fibril with low compatibilizer content.(4)Three kinds of PP/PA6 MFCs show obvious gelation behavior,the sequence of fibril contents corresponding to the gel point is PP/PA6 < PP/G-PA6 < PP/M-PA6,the order of gel strength is PP/PA6 < PP/M-PA6 < PP/G-PA6.With the increase of traction rate,the fibril diameter and the gel point of three MFCs decrease continuously,the tensile and flexural strength and crystallization-inducing ability are increased,but there is no obvious effect on the degree of fibril profiled.(5)The non-polar HT-GO-ODA fillers migrate spontaneously from the interior to the surface of the fibril,construct an efficient fibril conductive "internal and external path" at low HT-GO-ODA content,and make PP/F-PA6 MFCs to obtain the lowest percolation threshold of 0.68 vol%,which is lower than most of the reported conductive MFCs percolation threshold.At the same time,the well-dispersed HT-GO-ODA fillers in the fibril improve the strength of the fibril,the HT-GO-ODA fillers on the surface of the fibril enhance the ability of matrix crystallization,improve the intrinsic strength of the matrix,and strengthen the interfacial adhesion.Therefore,the maximum tensile strength of PP/F-PA6 MFCs is 49.37 MPa at 1.8wt% HT-GO-ODA content,which is27.57% higher than that of pure PP.The fibril network structure in PP/F-PA6 MFCs can conduct heat effectively,reduce heat loss,and show better photothermal and thermal conductivity properties.