Thermal, Morphological, and Mechanical Properties of Regular and Waxy Maize Starch Films Reinforced with Cellulose Nanofibers (CNF)

Vanessa Soltes De Almeida,Lucca Malucelli,Ivo Mottin Demiate,Luiz Gustavo Lacerda,Marco Aurélio Da Silva Carvalho Filho,Luís Antonio Pinheiro,Vivian Cristina Ito,Bárbara Ruivo Válio Barretti

doi:10.1590/1980-5373-mr-2019-0576

Abstract

Abstract Biodegradable films were prepared using regular and waxy starch and reinforced with cellulose nanofibers (CNF) from eucalyptus. Both films were characterized by their optical, structural, barrier, thermal and mechanical properties. The films presented a homogeneous, smooth surface without bubbles or cracks and good handling characteristics. Both films showed a mixture of B and V-type diffraction patterns. The water solubility of the samples decreased after the incorporation of nanocellulose. The water vapor permeability for both sources significantly reduced after incorporating nanocellulose at 0.5% and 1%. It is possible to observe that the addition of CNF increased the thermal stability of the starch films. On the other hand, the incorporation of nanocellulose improved either the mechanical resistance of the starch films.

Highlights

Global ecological and environmental challenges, such as the increase in non-biodegradable waste material and the difficulty in recycling most of the synthetic packaging have been demanding the need for renewable sources to be increasingly used[1,2]
The lowest values found were for N2 and W2, which contained 1% of nanocellulose compared to their controls (Table 1)
It is possible to observe that the addition of cellulose nanofibers (CNF) increased the thermal stability of the CNF-composite films provided that only up to 1% CNF is added

Summary

Introduction

Global ecological and environmental challenges, such as the increase in non-biodegradable waste material and the difficulty in recycling most of the synthetic packaging have been demanding the need for renewable sources to be increasingly used[1,2]. Starch films are a class of promising biodegradable polymers in the market, as alternatives to the use of petrochemical derivatives[3]. Starch is the most widely employed in the elaboration of films, due to its low cost and abundance in nature[4]. Features great capability to form a colorless and transparent polymer matrix, and it is a heterogeneous material containing different concentrations of amylose and amylopectin[5]. According to Wang et al (2015)[7] amylose content is important for the structural stability of starch and the formation of biodegradable films, with linear chains and a network stabilized by hydrogen bonds. The polymeric chains of amylopectin can be highly tangled together due to their branching and shorter length, leading to the formation of inter-chain hydrogen bonds[5]

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Results

Conclusion