Vermiculite Filler Modified with Casein, Chitosan, and Potato Protein as a Flame Retardant for Polyurethane Foams.

Karolina Miedzińska,Krzysztof Strzelec,Sylwia Członka,Anna Strąkowska

doi:10.3390/ijms221910825

Karolina Miedzińska, Krzysztof Strzelec + Show 2 more

Open Access

https://doi.org/10.3390/ijms221910825

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Abstract

In this study, polyurethane (PU) composite foams were modified with 2 wt.% of vermiculite fillers, which were themselves modified with casein, chitosan, and potato protein. The impact of the fillers on selected properties of the obtained composites, including their rheological (foaming behavior, dynamic viscosity), thermal (temperature of thermal decomposition stages), flame-retardant (e.g., limiting oxygen index, ignition time, heat peak release), and mechanical properties (toughness, compressive strength (parallel and perpendicular), flexural strength) were investigated. Among all the modified polyurethane composites, the greatest improvement was noticed in the PU foams filled with vermiculite modified with casein and chitosan. For example, after the addition of modified vermiculite fillers, the foams’ compressive strength was enhanced by ~6–18%, their flexural strength by ~2–10%, and their toughness by ~1–5%. Most importantly, the polyurethane composites filled with vermiculite filler and modified vermiculite fillers exhibited improved flame resistance characteristics (the value of total smoke release was reduced by ~34%, the value of peak heat release was reduced by ~25%).

Highlights

(the value of total smoke release was reduced by ~34%, the value of peak heat release was reduced by ~25%)
To assess the effect of the vermiculite fillers modified with casein/chitosan/potato protein on the thermal stability of the polyurethane composites, thermogravimetric analysis (TGA) and derivative thermogravimetry analysis (DTG) were performed
The vermiculite fillers modified with casein/chitosan/potato protein were used as reinforcing fillers in the synthesis of the polyurethane composites

Summary

Introduction

(the value of total smoke release was reduced by ~34%, the value of peak heat release was reduced by ~25%). They can be produced in various forms, including elastomers, adhesives, coatings, and porous materials, which are divided into two main groups—rigid polyurethane foams (RPUFs) and flexible polyurethane foams (FPUFs) [1,2,3,4] This enables the use of polyurethane products in many applications, such as thermal and electrical insulation materials, construction, packaging, furniture, or biomedical applications [5,6,7,8,9]. The cellular structure of rigid polyurethane foams has a high closed-cell content This determines the good dimensional stability of the obtained products and their low thermal conductivity [13].

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