الفهرس 
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Abstract
The main aim of this study is to study the effect of TiO2 nanoparticles (TiO2 NPs) and Date Seed Nanoparticles (DS NPs) on the mechanical and tribological characteristics of (PMMA).To technique fabricate the composites was used cold-cured. And specimens were fabricated directly without heat treatment. Two groups of specimens were fabricated, the first group by addition of TiO2 NPs to PMMA with different weight fractions (wt.%) of 0-1.2 and 1.5 wt.%. For the second group, DS NPs were added to PMMA with the same wt.%. Effect of TiO2 NPs and DS NPs content on Vickers microhardness number (VHN), the elastic modulus, wear rate, and coefficient of friction (COF) of all nanocomposites have been investigated. The pin-on-disc tester achieved the tribological characteristics under loads 10, 20, and 30 N applied at constant sliding speed and sliding distance of 1.256 m/s and 226 m, respectively. Then, the worn surfaces were characterized by (SEM) scanning electron microscope after the wear test.
For cold (self) nanocomposites, experimental results uncovered that microhardness, the elastic modulus, COF, and wear rate were improved with increasing nanofiller content up to 1.2 wt. % of TiO2 NPs and DS NPs. Also, the wear rate increased with increasing applied loads up to 30 N, while COF decreased with increasing applied loads up to 30 N. SEM examination showed that the worn surface of pure PMMA contains many ploughed marks and deep grooves. After adding 1.2 wt. % TiO2 NPs and DS NPs into PMMA, mechanical strength of the specimen’s surface was improved and dramatically decreased wear grooves. Also, after adding TiO2 NPs and DS NPs to PMMA, more than 1.5 wt.% up to 1.2 wt. %, there were more ploughed marks and porosity on worn surfaces than PMMA at 1.2 wt.% TiO2 NPs and DS NPs.