چكيده به لاتين
Polylactic acid (PLA) is a biodegradable and environmentally friendly polymer. With the passage of time and the increase in pollution caused by petrochemical-based polymers, PLA became a popular polymer to replace other polymers; But there are limitations for the wide use of this polymer, especially in the packaging industry. PLA is a very fragile material with low toughness, and it is not very stable in terms of heat, and its thermal distortion temperature (HDT) is low coMPared to other polymers. Mineral particles such as talc powder can be used to improve the mechanical and thermal properties of PLA. To improve the interaction between micron talc particles and polymer, these particles were surface modified by polyethylene glycol (PEG). For this purpose, talc particles were first modified by the silane coupling agent tetraethyl orthosilicate (TEOS), in order to increase the -OH functional groups on the surface. In the second step, it was prepared through the reaction between PEG and 3-triethoxysilyl propyl isocyanate (IPTES) as an additional compound. Further, this compound was attached to these particles through the reaction with –OH groups on the surface of talc. After the modified talc particles were prepared, in the next step, the particles were identified and analyzed by Fourier Infrared Spectrometer (FTIR) analysis. Pure talc and modified talc particles were added to PLA in percentages of 1%, 3% and 5% by weight through an internal mixer. The final modified talcum powder was called TTIP. Then differential scanning calorimetry (DSC), tensile test, iMPact strength, scanning electron microscope imaging (SEM) and HDT were performed. The results of DSC analysis showed an increase in Tg from 63.44 ℃ for pure PLA to 67.27 ℃ for TTIP3%/PLA, and the percentage of crystallization increased from 21.10% for pure PLA to 31.60% for PLA/5%TTIP. Tensile strength from 40.3MPa for pure PLA to 49.49 MPa for PLA/3%TTIP, Young's modulus from 1809MPa for pure PLA to 2350MPa for PLA/5%TTIP and toughness from 480 (Mj/m3) for pure PLA to increased 679(Mj/m3) for PLA/3%TTIP. The elongation at break did not change significantly with the addition of talc and modified talc. Also, the iMPact strength for pure PLA was 32.85 (J/m), which reached 40.33 (J/m) for PLA/3%TTIP. The SEM results confirmed the proper dispersion and adhesion of modified talc particles in PLA. HDT for pure PLA was equal to 56.9℃, which increased to 68.1℃ by adding 5% by weight of talc.
