مطالعه ازمايشگاهي خواص مكانيكي نانو كامپوزيت پلي پروپيلن- نانو لوله TiO2

mechanical properties Experimental investigation of PP-TiO2 nanotube nanocomposite

در اين مطالعه خواص مكانيكي نانوكامپوزيت هاي پلي پروپيلن در حضور نانو ميله هاي TiO2 مورد بررسي قرار گرفته است. نانوكامپوزيت ها با تركيب درصدهاي مختلف از روش اختلاط مذاب تهيه شده اند و خواص فيزيكي و مكانيكي آن از قبيل توزيع نانوميله ها در ماده ي زمينه، استحكام كششي، خمشي و ضربه، مدولي الاستيسيته و خمشي و... بررسي و تحليل شد. براي توزيع نانو ميله ها در ماده فرضيه پليمري ، از دستگاه SEM استفاده شد.مشاهده شد كه با افزايش درصد وزني نانو ميله ها، TiO2 ها به سمت توده اي شدن ميل پيدا مي كنند. براي خواص مكانيكي مشاهده شد كه مدولي يانگ و خمشي با افزايش در درصد وزني TiO2، به طور قابل ملاحظه اي بهبود يافت؛ با افزايش درصد وزني TiO2ها، مقدار مدول الاستيسته افزايش پيدا مي كند. با افزايش مقدار TiO2به ۸٪ وزني مقدار مدول الاستيسيته به شدت كاهش پيدا مي كند. هم مدول و هم استحكام خمشي نمونه ها با افزايش درصد وزني نانوميله ها افزايش مي يابد.

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using nanotubes (NTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. In this study, TiO2 commercial nanotubes were incorporated into polypropylene (PP) using melt blending technique that employs a Brabender internal mixer to prepare the nanocomposites with different concentrations. The morphological, rheological, and mechanical properties of the nanocomposites were characterized. The morphological characterization based on scanning electron microscopy has confirmed that nanotubes are distributed uniformly indicating a good dispersion of nanotubes in the PP matrix. The rheological studies were performed by a capillary rheometer, and mechanical properties of the nanocomposites were studied using a tensile and flexural tester. Both PP and its nanocomposites showed non-Newtonian behavior. At low shear rates the addition of TNT content causes an increase in viscosity; however, viscosity is less sensitive to addition of TNT content at higher shear rates. From the melt rheological analysis (frequency sweep) results, it was found that the storage modulus, loss modulus, and complex viscosity increased with increasing TNTs loading. The nanocomposites samples exhibited a higher complex viscosity than the neat PP. Flow activation energy showed that the temperature sensitivity of nanocomposites was increased by increasing of nanotube content. An increase in tensile and flexural moduli and Izod impact strength was also observed by increasing the TNT content. From rheological and mechanical tests it was concluded that the mechanical and rheological percolation threshold is at 1.5 wt%.