Nano‐engineering of high‐performance PA6.6 nanocomposites by the integration of CVD‐grown carbon fiber on graphene as a bicomponent reinforcement by melt‐compounding

Thermal, electrical and mechanical properties of carbon fiber/copper powder/carbon black reinforced hybrid Polyamide 6,6 composites

The development of low electrical and thermal properties of Polyamide (PA), which is used in place of metals in engineering applications, draws attention to the developments in various industrial disciplines. In this study, the effects of metal and carbon based fillers on the properties of Polyamide 6,6 (PA 6,6) were investigated. Especially, copper powder (Cu), carbon black (CB), carbon fiber (CF) and hybrid fillers (Cu/CB/CF) reinforced composites based on PA 6,6 were prepared by twin-screw extruder followed by injection molding. In the microstructure investigation, it was observed that the dispersion properties of used fillers were different in the PA 6,6 matrix. Both electrical and thermal conductivity of the PA 6,6 composites prepared were higher than pure PA 6,6. The highest electrical and thermal conductivity values were obtained as 7.97x10−2 S/cm and 0.73 W/mK for PA 6,6/CB30 and PA 6,6/CF/CB/Cu 10, respectively. The effects of the fillers on melting and crystallization behaviors and mechanical properties that affect the performance of PA 6,6 composites are also discussed. In general, the results showed that the mechanical properties of PA 6,6 composites were improved with the increase in the amount of hybrid filler. The highest tensile and notched Charpy impact strength were obtained as 252 MPa and 8.84 kJ/m2 in PA 6,6 composite with 30% carbon fiber reinforcement by volume. As a result, the tensile properties of PA 6,6 hybrid composite were found to be superior to PA 6,6/CF composite with the same amount of carbon fiber content.

Experimental and Numerical Investigation of Flow and Alignment Behavior of Waste Tire-Derived Graphene Nanoplatelets in PA66 Matrix during Melt-Mixing and Injection

Homogeneous dispersion of graphene into thermoplastic polymer matrices during melt-mixing is still challenging due to its agglomeration and weak interfacial interactions with the selected polymer matrix. In this study, an ideal dispersion of graphene within the PA66 matrix was achieved under high shear rates by thermokinetic mixing. The flow direction of graphene was monitored by the developed numerical methodology with a combination of its rheological behaviors. Graphene nanoplatelets (GNP) produced from waste-tire by upcycling and recycling techniques having high oxygen surface functional groups were used to increase the compatibility with PA66 chains. This study revealed that GNP addition increased the crystallization temperature of nanocomposites since it acted as both a nucleating and reinforcing agent. Tensile strength and modulus of PA66 nanocomposites were improved at 30% and 42%, respectively, by the addition of 0.3 wt% GNP. Flexural strength and modulus were reached at 20% and 43%, respectively. In addition, the flow model, which simulates the injection molding process of PA66 resin with different GNP loadings considering the rheological behavior and alignment characteristics of GNP, served as a tool to describe the mechanical performance of these developed GNP based nanocomposites.