Intumescent mechanisms of fire-retarding polyurethane systems and development of graphite/polymer nano-composites

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Yuan, Q., 2004. Intumescent mechanisms of fire-retarding polyurethane systems and development of graphite/polymer nano-composites. PhD, Nottingham Trent University.

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Abstract

As an effective and environmentally friendly fire retarding approach, intumescence has been applied to design better fire retarding polymer systems for different applications. However, intumescent mechanisms have not been well understood. This has hindered the further development of intumescent fire retarding polymer systems. This research investigated the intumescent mechanisms of three commercial fire retarding polyurethane products and developed a new generation of fire retarding products based on graphite/polymer nanocomposites.

The three commercial products were studied using a single direction well-ventilated natural burning method and a series of intumescent char characterisation techniques developed in this research. The natural burning method was designed to show the protection and protection efficiency of intumescent chars. The protection efficiency was measured by the difference of char yields between natural burning and furnace burning. The intumescent chars produced by natural burning were investigated for their char structures, gas permeability, bulk strength and reactivity using microscopic methods, open porosity, durometer hardness and X-ray diffraction, respectively. Experimental results show that the three commercial products contain inert inorganic additives. The charring ability of the polymers is important in producing integrated chars by binding the inert additives together, and in strengthening the chars. An integrated char with lower open porosity has higher protection efficiency. The lower porosity also results in the char with higher strength.

Graphite/polymer nanocomposites were synthesised by solution intercalation and in situ polymerisation methods. Five graphites were modified into graphite oxides (GO) by oxidation. A chosen GO was intercalated with a polyethylene oxide (PEO), polyethylene glycol Mn300 (PEG1500) or polyvinyl pyrrolidone (PVP) in water. The GO and its PEG1500 or PVP intercalated compounds as nano-structured graphites were used in the synthesis of polyurethane nanocomposites. The nanostructured graphites were intercalated with the polyol polyethylene glycol Mn300 (PEG300), and then polymerised with the tolylene diisocyanate (TDI). The graphite/polyurethane nanocomposites synthesised contain 5.0 wt.% of GO or equivalent.

The fire retardant study of all the nanocomposites showed a non-dripping and slow burning process. The burning produced integrated chars with improvement in not only char morphology but also char yield. The chars have graphitised structure, which is ideal in terms of anti-oxidation of the char. Graphite/polymer nanocomposites are a new generation of intumescent fire retarding polymer systems.

Item Type:

Thesis

Creators:

Yuan, Q.

Date:

2004

ISBN:

9781369313291

Identifiers: