The Effect of Different Plant Oil Impregnation and Hardening Temperatures on Physical-Mechanical Properties of Modified Biocomposite Boards Made of Hemp Shives and Corn Starch.

Dovilė Vasiliauskienė,Renata Boris,Giedrius Balčiūnas,Arūnas Kremensas,Jaunius Urbonavičius,Agnė Kairytė

doi:10.3390/ma13225275

Abstract

In this study, tung tree and linseed drying oils, as well as semi-drying hempseed oil, were analyzed as the protective coatings for biocomposite boards (BcB) made of hemp shives, corn starch binder, and the performance-enhancing additives. The hydrophobization coatings were formed at 40, 90, and 120 °C temperatures, respectively. The physical-mechanical properties such as the compressive strength, thermal conductivity, dimensional stability, water absorption, and swelling were tested. In addition, scanning electron microscopy (SEM) was employed for the analysis of the board microstructure to visualize the oil fills and impregnation in pores and voids. It was demonstrated that the compressive strength of oil-modified BcBs compared to uncoated BcBs (at 10% of relative deformation) increased by up to 4.5-fold and could reach up to 14 MPa, water absorption decreased up to 4-fold (from 1.34 to 0.37 kg/m2), swelling decreased up to 48% (from 8.20% to 4.26%), whereas the thermal conductivity remained unchanged with the thermal conductivity coefficient of around 0.085 W/m·K. Significant performance-enhancing properties were obtained due to the formation of a protective oil film when the tung tree oil was used.

Highlights

The increased interest in plant resources as renewable materials is growing in recent years.The biological origin of raw ingredients allows the production of environmentally friendly materials, but biodestructive factors emerge during the exploitation
For the formation of the protective coating, 90 °C temperature was used. This temperature stimulates the autoxidation of the protective coating, 90 ◦ C temperature was used
This temperature stimulates the autoxidation of oil, as shown as previously [10]

Summary

Introduction

The biological origin of raw ingredients allows the production of environmentally friendly materials, but biodestructive factors emerge during the exploitation. While using this kind of materials, e.g., thermal insulation boards, moisture could accumulate at the partition walls of the building due to the hygroscopicity and lead to favorable conditions for the growth of microorganisms [1]. Previous studies have reported that hemp shives absorb a large amount of water due to the hydroxy groups present in their constituents such as cellulose, hemicellulose, and lignin. Another important factor contributing to water sorptivity of hemp shives and their-based materials is the porosity [2].

Methods

Results

Conclusion