Bisphenol-A–Carbon Nanotube Nanocomposite: Interfacial DFT Prediction and Experimental Strength Testing

Abstract

Epoxies, their derivatives, and composites, due to superior specific strength, are preferred for many potential applications in the field of automobiles, aircraft, bonding of structures, protective coatings, water filtration, etc. As structural members in automobiles and aircraft, the epoxy-based components are exposed to various static/dynamic mechanical loading conditions during their service life. The interfacial interactions, between the matrix and reinforcement, greatly affect the final properties of the composites. The present study demonstrates that the solvent used for the preparation of the composite can also contribute toward interfacial interactions. Present research systematically finds out a suitable solvent (acetone) and reinforcement type [multi-walled carbon nanotube (CNT)] for epoxy [bisphenol-A (BPA)] nanocomposites. Dynamic and static strengths of the as-prepared epoxy–CNT nanocomposites were carefully investigated. Well dispersed CNTs in acetone were mixed with an ester of BPA under constant magnetic stirring conditions. Samples of tablet shape were prepared for testing static and dynamic performance of the composite using a nano-indentation technique. Considerable enhancement by 55 and 22% in the static elastic modulus and hardness of BPA–CNT composites, respectively, was observed (compared with that of pristine BPA). The storage modulus and tan-delta of the nanocomposites were also improved by 14 and 46%, respectively. Improved static and dynamic performance, reported in this work, significantly enhances the scope of utilization of BPA–CNT-based nanocomposites under severe static and dynamic loading conditions simultaneously. Static and dynamical analysis of CNT-reinforced epoxy provides more realistic understanding of the mechanical performance of the nanocomposite. Density functional theory (using QuantumATK software) simulations were performed to investigate and identify the alterations in the atomic morphology of CNTs during interfacial interaction with the acetone molecule and epoxy matrix. The calculations predicted that CNTs with mild defects as compared to pristine CNTs were better suited for synthesis of the nanocomposite and also assisted in a homogeneous distribution of CNTs in BPA without aggregation (with acetone as the solvent). Furthermore, structural changes in CNTs after treatment with BPA and the curing agent and the role of defects are studied in detail.

Physical property characterizations of natural rubber nanocomposites through experimental techniques, models and CRR concept

“…To finely probe the matrix/filler interactions, Donth's approach was used 56 allowing to estimate the CRR size in terms of N α number of structural units moving together at the glass transition temperature T α . The Donth's approach is based on calorimetric measurements and has often been used to study the effect of nanofillers on molecular mobility in nanocomposites 19–21 . N α can be calculated from Equation (). where T α is the glass transition temperature, k B is the Boltzmann constant, C p is the heat capacity at constant pressure, M 0 is the molar mass of one structural unit (68.12 g/mol in this work), 37 and δT the mean temperature fluctuation associated to the glass transition temperature of an average CRR.…”

“…The Donth's approach is based on calorimetric measurements and has often been used to study the effect of nanofillers on molecular mobility in nanocomposites. [19][20][21] N α can be calculated from Equation (11).…”

“…In particular, it has been reported that graphitic structures have excellent mechanical strength and functional tailorability. [18][19][20][21][22][23] Coupling fillers can moreover offer more versatility in the tuning of mechanical properties. [24][25][26] Indeed, the addition of nanofillers to NR matrix to successfully increase the tensile strength and modulus, may be detrimental for toughness and strain at break.…”

“…A less pricey solution could be the introduction of layered fillers like graphene oxide and graphite that will improve the compatibility between the rubber matrix and the silica while maintaining interesting mechanical properties. In particular, it has been reported that graphitic structures have excellent mechanical strength and functional tailorability 18–23 …”

Surface Structure Analysis and Formaldehyde Removal Mechanism of Lotus Shell Biochar: An Experimental and Theoretical Perspective

“…As a well-established method in quantum chemistry, density functional theory (DFT) has been used to obtain insights into the microscopic mechanisms of pollutant–material interfaces. − HCHO-molecularly imprinted polymers have been designed and synthesized for HCHO removal with the assistance of DFT calculations . Both experimental studies and DFT calculations have been conducted to identify the adsorption behavior of HCHO on resin-based carbons and amine-modified diatomite. , The integration of experimental and DFT methods has emerged as a crucial strategy to identify the fundamental mechanisms involved.…”