دانلود رایگان مقاله انگلیسی مکانیک و رئولوژیک کامپوزیت های پلی کربنات تقویت شده با الیاف بازالت - الزویر 2018

abstract

To enhance the mechanical, thermal, and electrical properties and economic profits, polycarbonates (PCs) have been blended with various inorganic additives for the past few decades. Herein, we fabricated basalt fiber (BF)-infiltrated PC composites as a promising candidate for a myriad of PC applications. Mechanical robustness and rheology were examined via the precise control of BF contents (up to 12.5 phr). The incorporation of BF gradually enhanced the mechanical properties of the composites such as moduli and strengths, as determined by flexural and tensile tests. The Izod impact strength was reduced as a function of BF concentration, representing the ductile-to-brittle transition. The heat deflection temperature of the PC/BF composites was increased from 131.2
C to 138.9
C, which was in good agreement with the thermomechanical results. By contrast, the glass transition temperature measured by differential scanning calorimetry remained unchanged at ca. 143
C. The incorporation of BF in PCs enhanced the dimensional stability. The visual observation for PC/BF composites was examined via scanning electron microscopy. The rheological investigation was systematically performed by utilizing the melt flow index, and capillary and torsional rheometry with a variety of experimental conditions. These PC/BF hybrid composites with tunable mechanical and rheological properties will be employed for various applications by tailoring the PC/BF ratios.

4. Conclusion

By incorporating BFs into a PC matrix, the mechanics was significantly enhanced except for the impact strength. The rheological properties were explored by MFI, and capillary and torsional rheometry with various temperatures and a wide range of frequencies. The tensile and the flexural modulus were gradually enhanced from 2.3 to 2.2 GPa to 3.9 and 3.8 GPa, respectively, up to 12.5 phr of BF concentration. The tensile and the flexural strength were also increased from 63 to 95 MPa to 83 and 126 MPa, respectively. The impact strength was decreased due to the ductileto-brittle transition. The HDT of the PC/BF composites was increased by ca. 8
C, which is consistent with Tgs measured by TMA whereas the Tgs by DSC were almost identical for all samples due to the difference in measurement mechanisms. The visual observation for the PC/BF composites was examined via SEM. All rheological analysis tools used in this study showed higher viscosity at higher BF concentrations. Capillary rheometry showed shear thinning phenomenon for all composites at all shear rates and similar viscosity between the pristine PC matrix and the PC/BF composites at high shear rates. Torsional rheometry indicated the increased slope of G0 vs. frequency beyond ca. 0.7 s1 and a dramatic decrease in G00 at high shear rates. The BF-infiltrated polycarbonate composites can be used for various applications due to their tailorable mechanics and rheology.