Effect of MWCNT functionalization on thermal and electrical properties of PHBV/MWCNT nanocomposites
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Paulo Barros Machado Instituto Nacional de Pesquisas Espaciais (INPE), Laboratório Associado de Sensores e Materiais (LAS), São José dos Campos, São Paulo 12.245-970, Brazil
Dayane Batista Tada Universidade Federal de São Paulo (UNIFESP), Instituto de Ciência e Tecnologia, São José dos Campos, São Paulo 12.231-280, Brazil
Nelson Durán Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Campinas,São Paulo 13.083-970, Brazil; and Universidade Estadual de Campinas (UNICAMP), Laboratory on Nanostructures Synthesis and Biological Interactions (NanoBioss), Campinas, São Paulo 13.083-970, Brazil
Ana Paula Lemes Universidade Federal de São Paulo (UNIFESP), Instituto de Ciência e Tecnologia, São José dos Campos, São Paulo 12.231-280, Brazil; and Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Campinas, São Paulo 13.083-970, Brazil (Received 30 June 2014; accepted 29 September 2014)
Pristine multiwalled carbon nanotubes (P-MWCNTs) were functionalized with carboxylic groups (MWCNT-COOH) through oxidation reactions and then reduced to produce hydroxyl groups (MWCNT-OH). Pristine and functionalized MWCNTs were used to produce poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites with 0.5 wt% of MWCNTs. MWCNT functionalization was verified by visual stability in water, infrared and Raman spectroscopy, and zeta potential measurements. Pristine and functionalized MWCNTs acted as the nucleating agent in a PHBV matrix, as verified by differential scanning calorimetry (DSC). However, the dispersion of filler into the matrix, thermal stability, and direct current (DC) conductivity were affected by MWCNT functionalization. Scanning electron microscopy (SEM) showed that filler dispersion into the PHBV matrix was improved with MWCNT functionalization. The surface roughness was reduced with the addition and functionalization of MWCNT. The thermal stability of PHBV/MWCNT-COOH, PHBV/P-MWCNT, and PHBV/MWCNT-OH nanocomposites were 20, 30, and 30 °C higher than neat PHBV, respectively, as verified by thermogravimetry analysis (TGA). Addition of pristine and functionalized MWCNTs provided electrical conductivity in nanocomposite, which was higher for PHBV/P-MWCNTs (1.2 105 S cm1).
I. INTRODUCTION
In the last two decades, biodegradable polymers have received special attention.1 The dependence on petroleum resources can be minimized by the development of bioplastics, which can be obtained from biological and fossil resources or combinations of both.2 With correct disposal and composting, the pollution caused by nondegradable plastics can be controlled with the use of bioplastics.3 For this purpose, polyhydroxyalkanoates (PHAs) are very promising alternatives, due to a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.303 J. Mater. Res., Vol. 30, No. 1, Jan 14, 2015
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their biodegradability.4 This class of biopolymer is produced by a wide diversity of microorganisms as intracellular carbon and
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