Polypropylene/Polyamide 6 in situ Composite

Abstract

ABSTRACT:The in situ composite consisting of polypropylene (PP) and polyamide 6 (PA6) was obtained with extrusion method in a single screw extruder. It was found that P A6 being the dispersed phase could fibrillated in PP matrix and fibrillation occurred in the channel of the extruder. The notched impact strength increased with the increasing content of PA6 while the tensile strength decrease. The average diameter of the fibrils chai:tged hardly with the changing content of PA6 under the investigated condition. Increasing the draw rate and the impact strength and tensile strength increased obviously. When increasing the rotating speed of screw the dimension of the fibrils also became finer. The mechanical properties decreased with the increasing processing temperature and the average diameter of fibrils increased.KEY WORDS In Situ Fibrillation Composite/ Polypropylene/ Polyamide 6 /Thermoplastic/ Processing Condition/ When a suspension of fluid droplets is subjected to flow, it tend to be deformed and oriented along the flow direction. For two incompatible polymers when the effect of viscous force is larger than that of the interfacial tension, the dispersed phase in flowing blend can form ellipsoids, rods, or fibrils under different viscosity ratio of two components. 1 The well-known example is the system of liquid crystalline polymer (LCP) and thermoplastic where the dispersed phase is LCP with rigid molecular chain. Many papers had reported the formation of LCP/polymer in situ composites,2 and their mechanical properties, rheological property, and so on had been discussed in these papers. 3 • 4 For two flexible thermoplastics the dispersed phase can form fibrils in matrix although these fibrils will relax and retract easily because of its flexibility of molecular chain. If the melting temperature of dispersed-phase-formed fibrils is higher than that of the matrix and the composite is molded below the Tm of fibrils, in situ composite with the fibrils is obtained.To generate the fibrillar morphology three major methods have been used: fiber spinning, extrusion, and injection molding. It has been found that fiber spinning is particularly advantageous because the elongational force field in the spinning process is more effective for producing the fibrillar morphology than the shear force field. Polypropylene (PP)/polyamide 6 (PA6) in situ composite obtained with spinning process had been studied in some papers. 5 • 6 Under spinning condition both PP and PA6 could form fibers in the composite. It had not been reported that PP/PA6 in situ composite was obtained under ordinary extrusion processing condition. In the present study, PP/PA6 in situ composite was obtained with a single screw extruder. In this paper it was studied that how the composition and processing conditions influenced the morphology and mechanical properties of the composite.1 Supported by the National Science Foundation of Guangdong Province. tt Corresponding author. EXPERIMENTAL MaterialsBoth PA6 and PP are commercially available. PA6 is the pro...

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