Improved Toughness in Lignin/Natural Fiber Composites Plasticized with Epoxidized and Maleinized Linseed Oils.

Franco Dominici,Debora Puglia,María Dolores Samper,Francesca Luzi,Alfredo Carbonell-Verdu,Juan López-Martínez,Luigi Torre

doi:10.3390/ma13030600

Abstract

The use of maleinized (MLO) and epoxidized (ELO) linseed oils as potential biobased plasticizers for lignin/natural fiber composites formulations with improved toughness was evaluated. Arboform®, a lignin/natural fiber commercial composite, was used as a reference matrix for the formulations. The plasticizer content varied in the range 0–15 wt % and mechanical, thermal and morphological characterizations were used to assess the potential of these environmentally friendly modifiers. Results from impact tests show a general increase in the impact-absorbed energy for all the samples modified with bio-oils. The addition of 2.5 wt % of ELO to Arboform (5.4 kJ/m2) was able to double the quantity of absorbed energy (11.1 kJ/m2) and this value slightly decreased for samples containing 5 and 10 wt %. A similar result was obtained with the addition of MLO at 5 wt %, with an improvement of 118%. The results of tensile and flexural tests also show that ELO and MLO addition increased the tensile strength as the percentage of both oils increased, even if higher values were obtained with lower percentages of maleinized oil due to the possible presence of ester bonds formed between multiple maleic groups present in MLO and the hydroxyl groups of the matrix. Thermal characterization confirmed that the mobility of polymer chains was easier in the presence of ELO molecules. On the other hand, MLO presence delayed the crystallization event, predominantly acting as an anti-nucleating agent, interrupting the folding or packing process. Both chemically modified vegetable oils also efficiently improved the thermal stability of the neat matrix.

Highlights

At the present time, the use of eco-sustainable materials is becoming a required condition of worldwide interest
Tecnaro GmbH Company studied and developed a new material based on wood components that can be processed as a thermoplastic polymeric material
Epoxidized linseed oil (ELO), supplied by Traquisa S.A. (Barcelona, Spain) with a molecular weight 1.037–1.039 and an epoxy equivalent weight (EEW) of 178 g equiv−1, and maleinized linseed oil (MLO) supplied as Veomer Lin by Vandeputte (Mouscron, Belgium) with a viscosity of 10 dPa s at 20 ◦ C and an acid value of 105–130 mg KOH g−1 were used as plasticizers

Summary

Introduction

The use of eco-sustainable materials is becoming a required condition of worldwide interest. It is known that polymeric materials are derived from fossil fuels and these limited resources can be preserved if, from a sustainable perspective, biobased materials containing the maximum amount of renewable biomass derivatives will be considered. The main concern is related to the possible substitution of materials and products traditionally made from petroleum resources with biobased plastics and composites. To antedate this need, the German Fraunhofer Institute for Chemical Technology together with. Materials 2020, 13, 600 fibers (60 wt %, flax, hemp, sisal, wood) and 10% natural additives (softeners, pigments, processing agents, etc.) that make it a fully biodegradable bioplastic composite known as “liquid wood [1]”. The material properties—biodegradability and recyclability up to ten times without modifications of its features—recommended it to be the near future alternative to various traditional plastic materials [2]

Methods

Results

Conclusion