Halloysite containing polyurethane foams as insulation materials with enhanced flame retardance

Official URL: http://risc01.sabanciuniv.edu/record=b2313571_ (Table of contents)

Rigid polyurethane foams (RPUFs) are one of the high-performance insulation materials preferred due to their superior thermal insulation properties, good chemical durability, high mechanical strength and easy processability. Nevertheless, low thermal stability and high flammability of RPUFs is a critical concern in insulation applications. Conventionally, flame retardants (FRs) are used to overcome these problems. However, typically high amounts of environmentally unfriendly FR agents are added into RPUFs to provide flame retardancy. Such FR agents can be partially replaced by alternative additives to provide safer flame retardancy. Halloysite nanotubes (HNT) are low cost, abundant clay minerals, standing as unique, environmentally friendly alternatives to numerous nanofillers. During burning, HNTs are expected to reinforce the char layer and entrap flammable decomposition products. They contribute to the formation of smaller foam cells, which reduce thermal conductivity. Yet, it is critical to obtain a homogeneous dispersion of HNTs in the RPUF matrix. This thesis focuses on the incorporation of HNTs into RPUFs and understanding of their thermal insulation and flammability behavior. HNTs that were untreated, sonicated, chemically functionalized and FR-loaded were incorporated into RPUF formulations. The morphology, thermal conductivity and flammability behavior of resulting nanocomposites were studied extensively. Halogenated FR content in the RPUF formulation was replaced with FR-loaded HNTs with much lower FR content, which resulted in nanocomposites with comparable total heat release and peak heat release rates to existing commercially available RPUFs. This project is supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK) under the grant agreement number 115M033