Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams.

Sylwia Członka,Agnė Kairytė,Anna Strąkowska

doi:10.3390/ma13122687

Sylwia Członka, Agnė Kairytė + Show 1 more

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https://doi.org/10.3390/ma13122687

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Abstract

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

Highlights

IntroductionPolyurethanes (PUR) are one of the most important classes of polymeric materials and they are widely used in different applications, such as furnishing, packaging, and building construction [1,2]
Polyurethanes (PUR) are one of the most important classes of polymeric materials and they are widely used in different applications, such as furnishing, packaging, and building construction [1,2].PUR are synthesized from two basic compounds—polyols and isocyanates [3,4]
The results have shown that the application of bio-polyols in the production of PUR foams results in materials with comparable mechanical, thermal, and insulating properties to those that were synthesized from the petrochemical polyol

Summary

Introduction

Polyurethanes (PUR) are one of the most important classes of polymeric materials and they are widely used in different applications, such as furnishing, packaging, and building construction [1,2]. PUR are synthesized from two basic compounds—polyols and isocyanates [3,4]. The main concern that is connected with PUR materials is their petroleum-dependent synthesis, since both polyols and isocyanates are petroleum-derived [3]. The development of bio-based compounds has attracted great interest due to environmental issues and fluctuations in oil prices. The preparation of bio-polyols that are based on different kinds of oils, such as canola oil [5], sunflower oil [6], and rapeseed oil [7,8], have already been reported

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