دراسة تاثير تركيزانابيب الكاربون النانوية متعددة الطبقات على الخصائص الفيزيائية لمتراكبات الايبوكسي == Study The Effect of Multi Walled Carbon Nanotubes (MWCNTs) Concentration on Physical properties of Epoxy composites
Author name:
الفت احمد محمود
Supervisor name:
خالد رشاد الراوي | عدوية جمعة حيدر
Abstract:
Multi wall carbon nanotubes (MWCNTs) have excellent mechanical, electrical, and thermal properties. When MWCNTs incorporated in to polymer, that’s leads to better improvement in mechanical, electrical, and thermal properties result at low MWCNTs content. Due to the change in the electrical and mechanical properties MWCNTs / Epoxy composites have attracted significant research interest specially due to their potential for application in active control of strain sensing in composites structure or as strain sensor .Different type of MWCNTs, long and short (L - MWCNTs & S - MWCNTs) were used as reinforcement in epoxy resin with volume fraction ( 0.1,0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 ,4.5, & 5%) respectively were used to prepare epoxy composites in order to examine and study some of their mechanical properties ( tensile strength, Young's modulus, flexural strength, fracture toughness, flexural modulus, Impact strength, and microhardness ), conductivity properties (AC conductivity, thermal conductivity), and morphology properties (SEM,FTIR). Direct mixing processes use to prepared (Epoxy / MWCNTs) composites, its involved use ultrasonic and magnetic stirrer bar mixing process to disperse the MWCNTs into the epoxy resin system. The results shown an improves in the mechanical, thermal, and electrical properties with increase volume fraction (0.1 to 2%), and then decreased with further increasing the MWCNTs content but stay higher than of pure epoxy. At (1.5%) we observed enhancement in tensile strength (28.19%, 15.74%) and Young's modulus (35.71%, 30.95%) for L - MWCNTs and S - MWCNTs respectively, and the higher enhancement in flexural modulus and flexural strength due to 2% vol. fraction of L - MWCNTs reached to (71.43 %, 102.26 %). The high impact strength and microhardness values result at (1. 5%L - MWCNTs) reached to (823.996%), and (41,102%) respectively.Better improvement in thermal conductivity and AC conductivity result at 2% volume fraction for both MWCNTs types compare with pure epoxy. The high thermal conductivity values due to L - MWCNT reached to (369.31%) or three times from the thermal conductivity of pure epoxy, compare with the value of enhancement for S - MWCNTs (183.39 %).Investigations of electrical properties of MWNT/polymer show a significant increase of electrical conductivity with the increase of the MWCNTs content. The AC. electrical conductivity of the sample with 2 % vol. fraction L - MWCNTs reached to four orders of magnitude higher than that of the pure polymer at a frequency range of (5E 4 to 5 E6) Hz, its present(9.66E - 7 to 5.78E - 5 Ω/cm) compare with the AC. electricalconductivity for S - MWCNTs ( 6.57 E - 11 to 2.24E - 5 Ω/cm) at same volume fraction and frequency range and with the electrical conductivity of pure epoxy (4.5E - 12 to 6.2E - 9 Ω /cm).Scanning Electron Microscope images illustrate the morphology of tensile fractured surface of EP/MWCNTs composites, although the morphologies of tensile fractured surface show ductile fracture with dispersed stresses in more than one crack propagation. Increased roughness and ductile behavior shown with increased volume fraction of MWCNTs. Above 2% vol. fraction of MWCNTs we shown increase the agglomeration that’s lead to decrease in properties of epoxy composites.
الية تكون وانهيار الطلاء الالوميني بوجود بعض اكاسيد العناصر النادرة (TiO2,Dy2O3,Y2O3) على السبائك المحسنة == Formation And Degradation Mechanisim Of a Aluminide Coating with Some of Rare - Earth Metals (Y2O3,Dy2O3,TiO2) on Supper Alloys
