Thermoset-cellulose nanocomposites: Flammability characteristics

Abstract

Fire resistant thermoset-cellulosic fibre composite materials are taking over in advanced engineering applications. As they are high-performance materials, these composites are used in automotive, aerospace, military, safety and security fields. They have remarkable combination of properties including light weight, high mechanical, thermal and thermo-mechanical characteristics, excellent dielectric properties, dimensional stability and are easy to process. Furthermore, these composite materials show high levels of fire safety (i.e. little smoke production and emissions of toxic gases if exposed to fire). In this way, they protect the novel end-product, infrastructure, the environment and mainly aid at preventing loss of lives to fire. To achieve this, additives or fillers called flame retardants (FR) are incorporated into thermoset-fibre composites to prevent or minimize fire from causing damage. Generally, flame retardants are based on halogen, phosphorus, minerals and nanometric compounds. They are incorporated into thermosets through the use of either a) normal additive FR or b) reactive additive FR agents. In the case of natural fibres, solution impregnation or surface treatment are methods of incorporating FR agents. Fire retardancy of natural plant fibres is based on wood and non-wood, both main sources of cellulose. Recently, cellulose materials such as nano-fibres and nano-crystals are of research interest and are used as bio-reinforcements for biopolymers, bio-based polymers, thermoplastics and thermoset matrices. In this way, a look at different studies on thermosets reinforced with nanocellulose materials in the presence of FR agents is required. The aim of this chapter is to discuss flammability characteristics of nanocellulose reinforced-thermoset nano-composites. The work presents the background on fire retardancy, thermosettings, cellulose and nanocellulose materials, thermoset-cellulose nanocomposites, strategies to impart flame retardancy into thermoset-cellulose nanocomposites, their fire resistance performance based on various characterization techniques, and possible industrial applications of thermoset-cellulose nanocomposites. Some concluding remarks on discussed works are given and finally the list of references presented.