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Improving the Properties of Recycled Polycarbonate with Blending and Chain Extending

Ghayednazeri, Reza | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57426 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Pircheraghi, Gholamreza
  7. Abstract:
  8. Polycarbonate is one of the thermoplastic engineering polymers, which due to its desirable properties of high resistance, high toughness, thermal insulation, non-flammability and resistance to ultraviolet rays (UV) have many applications in the construction industry, medicine, transportation industry and transfer. and has electronic components. One of the disadvantages of polycarbonate is the high cost of raw materials for its production. Therefore, due to the fact that this polymer and its high volume of production and the low cost of recycling, it finds its recycling. The characteristics after recycling and during it, due to exposure to high environments and mechanical destruction and degradability and breaking of polymer chains, will have a noticeable drop, for example, the strength of recycled polycarbonate will decrease compared to virgin polycarbonate. Recycled polycarbonate is a good alternative to polycarbonate, which needs to improve its properties. Among the ways to improve the properties of recycled polycarbonate, it can be Blending with other polymers or by chain extending method. In this research, it was done by blending polycarbonate with ABS and also using chain extender to increase the properties of recycled polycarbonate. At first, the ABS-g-MA compatibilizer was produced by the reactive extrusion method, which according to the MA graft degree titration test, 1.3% was obtained, which shows that MA is well grafted to ABS. The results of the first phase have shown that the manufacture of rPC-ABS blend leads to the improvement of the mechanical properties of rPC. The impact test results for the rPC-ABS blend showed that the impact resistance is 2.3 times higher than that of rPC. Also, the results indicated the appropriate performance of the compatibilizer. By adding 1%wt to the rPC-ABS blend, it was observed that the impact resistance increased from 4.5 kJ m-2 to 24.7 kJ m-2, which increased by 448%. Also, in 3%wt, the impact resistance has reached its maximum, which was equal to 27.8 kJ m-2. In this case, the yield strength has decreased by 15% compared to rPC, but on the opposite side, the breaking point strain has increased from 6.6% for rPC to 23.9% for the blend containing 3%wt% compatibilizer. Also, the results of the melt rheology test showed that by adding a compatibilizer in the amount of 3%wt to the blend, the viscosity has increased in proportion to the rPC-ABS blend at all frequencies, which confirms the greater compatibility of the two polymer phases and the reduction of surface tension between them. In the second part of the research, chain extender was used to compensate for the reduction of yield strength observed in the blend and to maintain impact resistance. The chain extender used in this study was Joncryl ADR 4300. At first, the chain extender was added in the twin-screw extruder, and then injection molding was done. The results of the impact test showed a significant reduction in impact resistance compared to the blend without chain extender. Also, the yield strength had not changed in this case. These results indicate that the chain extension reaction does not work due to the short residence time in the twin screw extruder. Then, in order to increase the performance of chain extender, the manufacturing process was carried out in an internal mixer, and then compression molding was carried out. Compared to the blend made in the first phase, in this case, the impact resistance increased from 21.2 kJ m-2 in the blend containing 3wt% compatibilizer to 22.5 kJ m-2 in the blend containing 5wt% chain extender. The yield strength was also measured for the blend containing 3%wt of compatibilizer in this case 44.3MPa, which increased to 48.5MPa for the blend containing 5%wt% of chain extender. In this case, the yield strength of rPC was 53.6 MPa. The results obtained from the melt rheology test also confirm chain extension
  9. Keywords:
  10. Blending ; Compatibilizer ; Chain Extender ; ABS-g-MA Compatibilizer ; Recycled Polycarbonate

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