PHBV/MWCNT Films: Hydrophobicity, Thermal and Mechanical Properties as a Function of MWCNT Concentration

Ana Paula Lemes,Thaís Larissa Do Amaral Montanheiro,Nelson Durán,Ana Paula Da Silva

doi:10.3390/jcs3010012

Abstract

The introduction of multi-walled carbon nanotubes (MWCNTs) into polymer matrixes has been an important tool to alter and improve some properties in polymer nanocomposites, including biodegradable polymers such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). In this work, PHBV nanocomposites with 0.05, 0.50, 1.00, 1.50 and 2.00 wt % of MWCNTs were produced by solvent casting. MWCNT morphology and structure were characterized by Raman spectroscopy, and transmission electron microscopy (TEM). It was observed that MWCNTs have a considerable amount of amorphous carbon (AC) onto their surface and a wide distribution of the tube diameter. MWCNTs act as the nucleating agent in the PHBV matrix, as verified by differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) showed that thermal stability was not significantly affected. The nanofiller dispersion into the PHBV matrix was not effective for concentrations from 1 wt % according to the micrographs obtained in scanning electron microscopy (SEM). The contact angle was changed with the introduction of MWCNTs, turning the nanocomposites hydrophobic and improving the mechanical tensile properties of the PHBV matrix.

Highlights

Given the difficulty of treating solid urban waste—which presents increasing quantities of polymeric materials—the use of biodegradable polymeric materials has been increasing in recent years
This work aims to evaluate the effect of carbon nanotubes (CNT) concentration on the thermal proprieties of the PHBV matrix through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), on morphology by scanning electron microscopy (SEM), on hydrophilicity of the films through their contact angle and on mechanical proprieties using uniaxial tensile tests
The D band is attributed to disordered carbon present in the structure of multi-walled carbon nanotubes (MWCNTs), and the G band is attributed to the ordered carbon, analogous to the bands observed for the graphite band [32,33,34]

Summary

Introduction

Given the difficulty of treating solid urban waste—which presents increasing quantities of polymeric materials—the use of biodegradable polymeric materials has been increasing in recent years These polymers have a shorter life cycle when compared to the life cycle of conventional polymers, which come from fossil sources. Living organisms can degrade biodegradable polymers and, when discarded under favorable biodegradation conditions, they remain for a short time in the environment, for weeks or even months [1,2] With this in mind, biodegradable polymers, such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), have been studied and tested for industrial applications, aiming at the replacement of plastics from fossil sources [3]. PHBV is a straight-chain semicrystalline copolymer belonging to the polyhydroxyalkanoate (PHA) family. One of the alternatives to improve such properties is the production of nanocomposites

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