MWCNT-PMMA composites properties

Jin et al. (26) used melt blending to fabricate MWCNT-PMMA composites with different CNT loadings varying from 0 to 26 wt%. They used a laboratory mixing molder to disperse MWCNT in PMMA at 200°C followed by compression molding at 210°C. Their TEM studies revealed good dispersion even at high MWCNT concentration. The composites showed enhanced mechanical and thermal properties. 

Combination of solvent casting followed by compression molding is also one of the approaches to fabricate CNT-PMMA composites (21,24,57). Slobodian et al. (57) fabricated MWCNT-PMMA composites by this technique and studied electrical conductivity of composites obtained after two-time compression molding. Different percolation thresholds were found for different solvent systems. Mathur et al. (24) also reported improvement in the mechanical properties of the CNT-PMMA composite over the one prepared by simple solvent casting. The reason attributed is the removal of any solvent trapped in the cast films. 

Jin et al. (65) used poly(vinylidene fluoride) (PVDF) as a compatibilizer to assist dispersion of CNTs in PMMA. Multi-walled carbon nanotubes were first coated with PVDF and then melt-blended with PMMA. Poly(vinylidene fluoride) served as an adhesive to improve wetting of CNTs by PMMA and to increase the interfacial adhesion resulting in improved mechanical properties of MWCNT-PMMA composites. 

A number of studies on CNT-polymer composites have focused on improving the dispersion and load transfer efficiency in other words the compatibility between the CNTs and polymer matrix through covalent chemical functionalization of CNT surface (12,40). Many of the studies reported above have used acid-functionalized CNTs to fabricate MWCNT-PMMA composites with improved mechanical properties using different processing methods (24,25,27,62). Yang et. al (68) modified the acid functionalized CNTs with octadecylam-ine (ODA) to obtain ODA-functionalized CNTs. These CNTs were reinforced in a copolymer P(MMA-co-EMA) to form composites with improved dispersion and mechanical properties. 

Pande et al. (25) also reported significant improvements in the flexural properties of MWCNT-PMMA composites prepared by in-situ polymerization method. They observed a maximum reinforcing effect of CNTs at 3 wt% for a-MWCNT and at 1.8 wt% for f-MWCNT. The flexural strength for the two cases was about 90 MPa as compared to about 64 MPa from two step method... 

Tensile mechanical properties of MWCNT-PMMA composites were shown to be improved by using P3HT-g-PMMA as a... 

Velasco Santos et al. (27) measured both the dynamic mechanical behavior and tensile mechanical properties of MWCNT-PMMA composites. They observed 1135% increase in storage modulus at 90°C and increase in glass transition temperature by 40°C over neat PMMA with only 1 wt% functionalized nanotubes. The tensile... 

Mathur et al. (24) and Pande et al. (44) studied the effect of MWCNT content on the EMI shielding properties of MWCNT-PMMA composite films in the X-band (8.2-12.4 GHz). The MWCNT-PMMA nanocomposites with higher MWCNT content exhibit greater EMI shielding effectiveness (SE) (Figure 7.14). 

Park et al. [144] conducted a study in which PMMA/MWCNT nanocomposites were prepared via both in-situ bulk polymerization and suspension polymerization, using the radical initiator 2,2-azobis(isobutyronitrile) (AIBN). The electrical and electrorheological (ER) properties of the nanocomposites were investigated. The conductivity of pure PMMA and MWCNT/PMMA nanocomposites were measured, and it was shown that the conductivity of MWCNT/PMMA composites rapidly increased when MWCNTs were added to the PMMA matrix, i.e., 3.192 x 10 , 2.163 X 10 2, and 1.693 x 10 Scm for 1.5, 5 and 10wt% of MWCNT in the composites, respectively. The conductivity of insulating PMMA was about 1 X 10 2Scm [144]. 

Pande, S., Singh, B.P., Mathur, R.B., Dhami, T.L., Saini, P., Dhawan, S.K., 2009. Improved electromagnetic interference shielding properties of MWCNT-PMMA composites using layered structures. Nanoscale Research Letters 4, 327—334. 

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