Preparation And Application Of Thermal Conductive Poly(p-phenylene Sulfide)/polyamide Blends

Poly(p-phenylene sulfide) (PPS) is a semi-crystalline, aromatic polymer with outstanding high frequency, rigidness, dimensional stability and radiation resistance. PPS has been widely used in electric motors, television, integrated circuit and other electronic applications. Thermal conductive property of PPS is very important for emissing hear, improving accuracy and prolonging service life of the electronic devices.In order to improving thermal conductiviy of PPS, in this paper, we established a triple continuous structure on the basis of co-continuous structure Poly(p-phenylene sulfide)/Polyamide 66 (PPS/PA66) blends. PA66 phase with selectively located thermal fillers is a conductive phase while PPS phase provides mechanical strength. In this case, the conductive path was only formed in one component other than the entire polymer matrix, allowing for the formation of conductive path at low fillers content and improving the mechanical strengths of PPS/PA66 blends.In this paper, nano-alunmia (Al2O3) was used as thermal filler and modified by 3-glycidoxypropyltrimethoxysilane (KH560). Our special focus was paid on the effects of reactive condition on modification. The effects of modification on Al2O3 were evaluated by TG, FTIR, XPS, and TEM methods and the results demonstrated the ideal reactive condition. The dispersive solvent is petroleum ether. Reactive temperature is 80oC. Reactive time is 10h. The content of KH560 is 50% weight fraction of Al2O3 (KH560-g-Al2O3 (50wt%)) and KH560 is pre-hydrolyzed.In order to analyse the effects of modification on the thermal conductivity of polymer matrix, the modified alumina was mixed with PA66 by twin screw extrusion. The thermal conductive testing revealed that, by adding 10% volume fraction of alumina, the thermal conductivity of KH560-g-Al2O3 (12.5wt%) and KH560-g-Al2O3 (50wt%) were 0.611W/(m·K),0.581W/(m·K), increasing 50.8% and 43.5% when compared with PA66/untreated alumina, respectively.Then, we foucs on the phase morphology of PPS/PA66 blends, detecting the co-continuous structure range of PPS/PA66 blends. Poly (phenylene sulfide) (PPS) was blended with PA66 in a wide range of compositions by using a co-rotating twin-screw extruder. Scanning electron microscopy and solvent extraction were employed to detect phase morphology of PPS/PA66 blends. The results demonstrated that the phase morphology of PPS/PA66 blends changed from PA66 dispersed phase in PPS matrix to co-continuous phase, and then PPS dispersed phase in PA66 matrix with the increase of PA66 content. The fully co-continuous range spaned from 50 to 60wt% PA66 in PPS/PA66 blends. Rheological dynamic analysis and dynamic mechanical analysis were futher used in determination of the co-continuous phase. In addition, the mechanical properties of PPS/PA66 blends can also be used to identify the dispersed/matrix phase or co-continuous phase morphology.Finally, we proved the modified alumina preferred to locate in the PA66 phase through thermodynamics, kinetics and processing methods. Further the triple continuous structure PPS/PA66/Al2O3 blends was demonstrated by SEM, EDS as well as RDA. The thermal properties, mechanical properties and rheological propeties of this novel blends were discussed in detail. The results shows that the thermal conductivity of triple continuous PPS/PA66/Al2O3 blends was increased 30% or more when compared with traditional blends without severely sacrificed the mechanical strengths. The tensile strength, bending strength and the notched impact strength of triple continuous PPS/PA66/Al2O3 blends decrease 8.2%, 9.1%, 8.5%, respectively.