چكيده به لاتين
Nowadays due to the expansion of the application and use of petroleum-based polymers in various industries such as the manufacture of storage containers, packaging films and the problems caused by their environmental pollution, as well as due to the establishment of strict rules for the reduction of non-biodegradable polymers, uses of the biodegradable polymer materials have received a lot of attention from researchers and industrial owenes. Among the biodegradable polymers, PLA is one of the semi-crystalline polymers that is widely used due to its good transparency and good processability. It has received a lot of attention for the production of polymer parts and film industry, packaging containers and injection parts. However due to low mechanical properties of PLA such as brittle, Impact strength and low Heat deflection temperatur (HDT), the expansion of its application in the industry is associated with serious limitations. In this research, in order to improve the mechanical and impact properties of PLA, mixing its melt with commercial core-shell rubber particle (CSR) prepared in Tabriz Petrochemical with a core structure of poly butadiene (PB) and a shell Styrene/acrylonitrile (SAN) copolymer graft on the core was used. Also in order to improve the distribution of rubber particles in the matrix of PLA, poly methyl methacrylate (PMMA) as a possible compatibilizer with values of 0.5,1 and 1.5 percent by weight compared to the total weight of polylactic acid and rubber core - shell particles and micron particles of talc filler in the amount 5 percent by weight compared to the total weight of polylactic acid and rubber core-shell particles were used. In this research, differential scanning calorimetry (DSC), scanning electron microscope (SEM) to analyze the structure and fracture surface of polymer composite samples and notched Izod impact strength, tensile and Heat deflection temperature were used to investigate the effect of rubber particles, compatibilizer and filler particles on the properties of the samples. The results of mechanical tests showed that the mixture containing 0.5 weight percent of PMMA and 10% of rubber particles (P90/CS10/PM0.5) has the highest impact and tensile strength due to the improvement interfacial adhesion between the dispersed and continuous phase and good dispersion of rubberparticles in the PLA matrix. In this mixture, the impact strength of 44.9 J/m forneat PLA increased to 215.2 J/m (%379 increase ) and elongation at break increased from %5.3 to % 33.3 (%528 increase) .On the other hand, with a further increase in the amount of PMMA and talc, the impact and tensile properties decreased. This behavior can be attributed to the accumulation of rubber particles and filler particles due to the reduction of compatibility with the polymer matrix. On the other hand, increasing the amount of PMMA more than % 0.5 has also led to a possible decrease in its compatibility effectiveness between rubber particles and polymer matrix. Also, micron particles of talc filler along with rubber core-shell particles and PMMA were used as nucleating agent in addition of annealing process to increase the heat deflection temperature. The obtained results showed that the addition of talc and Annealing process at 120 C fo 6 hours reduced the cold crystallization temperature, increased the percentage of crystallization, and changed the shape of polylactic acid crystals from a less regular to a more regular type. and this has caused a significant improvement in the Heat deflection temperature. For example, Heat deflection temperature from58C for neat PLA to 88.8 ℃ for the sample with 5% talc ( P90/CS10/PM1.5/T5) increased. In the Scanning Electron Microscope (SEM) image of fracture surface of the samples, the creation of external cavitation and the formation of micro holes and crazing in the matrix of poly lactic acid in the sample containing rubber particles was observeed
