Effects of Various Types of Expandable Graphite and Blackcurrant Pomace on the Properties of Viscoelastic Polyurethane Foams.

Joanna Ryszkowska,Monika Auguścik-Królikowska,Joanna Bartoń,Małgorzata Gzik,Grzegorz Budzik,Mariusz Oleksy,Rafał Oliwa

doi:10.3390/ma14071801

Joanna Ryszkowska, Monika Auguścik-Królikowska + Show 5 more

Open Access

https://doi.org/10.3390/ma14071801

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Abstract

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.

Highlights

Due to the possibility of modifying the properties of polyurethane foams (PUFs), they have been used in many industries for many years, including construction, automotive, furniture, etc. [1]
The results presented in [72] confirm that decrease in the reactivity of polyurethane (PUR) systems with expandable graphite is associated with an increase in the viscosity of polyol graphite blends
We analyzed the effects of expandable graphite (EG) with different particle size and expansion ratio and blackcurrant pomace on the viscoelastic properties of polyurethane foams

Summary

Introduction

Due to the possibility of modifying the properties of polyurethane foams (PUFs), they have been used in many industries for many years, including construction, automotive, furniture, etc. [1]. European Union regulations recommend the use of halogen-free compounds for flame retardancy [4] These materials are subject to various requirements: limiting flammability, reducing the amount of smoke released, and no effect on the toxicity of gaseous combustion products, or its reduction; their introduction should not significantly affect the functional properties of the foams [1,4]. Li et al [36] showed the addition of 30 parts per hundred of polyol by weight of graphite with an average particle size of 960, 340, and 70 μm, resulting in semirigid polyurethane foams with flammability class V0, V1, and HB75. A better flame-retardant effect for foams with larger grain size graphite results from the formation of a greater amount of char residue [32,37]. The main mechanism to improve the flame resistance is to increase the char yield [46,47,48]

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