Thermal Degradation Behavior of Epoxy Resin Containing Modified Carbon Nanotubes.

Xiaohui Bao,Jiangbo Wang,Fangyi Wu

doi:10.3390/polym13193332

Xiaohui Bao, Jiangbo Wang + Show 1 more

Open Access

https://doi.org/10.3390/polym13193332

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Abstract

Via the surface-grafting of carbon nanotubes (CNTs) with a silicon-containing flame retardant (PMDA), a novel flame retardant CNTs-PMDA was synthesized. The flame retardancy was tested by cone calorimeter. Compared with pure epoxy resin, the total heat release (THR) and peak heat release rate (PHRR) of epoxy resin containing CNTs-PMDA were significantly reduced, by 44.6% and 24.6%, respectively. Furthermore, thermal degradation behavior of epoxy resin based composite was studied by the thermogravimetric analysis with differences in heating rates. The kinetic parameters of the thermal degradation for epoxy resin composites were evaluated by the Kissinger method and Flynn-Wall-Ozawa method. The results suggested that activation energy values of epoxy resin containing CNTs-PMDA in thermal degradation process were higher than those of pure epoxy resin in the final stage of the thermal degradation process, which was closely related to the final formation of char layer residues. Finally, the results from Dynamic mechanical thermal analysis (DMTA) and Scanning electron microscopy (SEM) measurements exhibited that the functionalization of CNTs with PMDA obviously improved the dispersion of CNTs in the epoxy resin matrix.

Highlights

Advanced improvements when compared with conventional flame retardant containing halogen, they are free of toxic smoke or corrosive fumes during combustion [8,9,10]
As shown in the pristine carbon nanotubes (CNTs) spectra at the top, the bands at around 1650 and 3500 cm−1 were attributed to the presence of carbonyl and hydroxyl groups, respectively, which means that the CNTs contained some impurities [31,32]
The reaction of CNTs with the PMDA led to the formation of an amide group, which exhibited close wavenumber bands with very close carboxylic groups

Summary

Introduction

Epoxy resins (EP) have been developed for nearly 70 years; their applications cover such varied fields as composite matrices, surface coatings, adhesives, and encapsulation of electronic components, as well as the aeronautical and astronautical industries. Flame retardants have to be used in order to fulfill the requirements of flammability tests [5,6,7]. Carbon nanotubes (CNTs) have been of interest to researchers because they frequently exhibit superior flame retardancy, mechanical and electronic properties. Carbon nanotubes can be prepared by extracting lignin from bamboo charcoal, rice straw, coconut fibre and corn straw as carbon sources. It has excellent environmentally friendly properties and recyclability [11,12,13]. The agglomeration of CNTs owing to strong van der Waals forces and π–π interactions between carbon nanotubes make it quite impossible to realize the ideal functions of CNTs in polymer nanocomposites [14,15]

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Results

Conclusion