난연제를 함유한 고무 혼합물의 물리적 특성과 난연성에 관한 연구

Abstract

Elastomers are widely used in our current society, however, their applications are restricted due to safety issues regarding flammability. Therefore, it is important to develop a composite performance such as flame retardance in the rubber industry. Some rubbers have defects in their mechanical properties. Accordingly, rubber blends are used to compensate for these defects. As a result of adding the sufficient amount of a flame retardant to ensure flame retardance, the mechanical properties and heat resistance were decreased. The mechanical properties were improved by using nanocomposites, however, research is also needed on the reduction of the calorific value during combustion. Therefore, studies on the environmentally friendly flame retardants with improved mechanical properties and efficient flame retardance are reviewed in this experiment. The objectives of this experiment are to improve the mechanical properties and to obtain the optimum flame retardance by employing non-halogen type flame retardants and nanoclay. Firstly, styrene butadiene rubber(SBR)/montmorillonite(MMT) nano- composites with various contents of chlorinated paraffin wax(CPW) as a flame retardant were prepared, and then, investigated for their mechanical properties and the flame retardance properties of the nanocomposites. The mechanical and thermal properties of SBR/MMT nanocomposites than those of the SBR compound added with flame retardants were increased. In addition, the increasing of CPW composition resulted in a decrease of the mechanical properties. The results of limited oxygen index(LOI) for the SBR/MMT nanocomposite, The limited oxygen index(LOI) value of CPW composition less than 20 phr represented 22.3∼26.4 %, and also that of 30 phr CPW composition improved to 30.2 %. In the UL 94 measurement test, the SBR/MMT nanocomposites with flame retardant content of 30 phr demonstrated excellence in flame retarding characteristics equivalent to UL 94 V-0 grade. Secondly, blends of the ethylene vinylacetate rubber(EVM) with the vinylacetate(VA) composition greater than 40 wt% and ethylene propylene rubber(EPM) were prepared by mechanical mixing; the number of parameters of the blends, including oil resistance, morphological and dynamic mechanical properties and flame retardance were subsequently measured. In the oil resistance test, for both ammonium polyphosphate(APP)/ dipentaerythritol(DPER)/expandable graphite(EG) and aluminum tri- hydroxide(ATH, Al(OH)3) flame retardants showed an increase in volume change with increasing EPM composition. For the ATH system, the dispersion shape was coarse and aggregation was observed. The results of a dynamic mechanical test showed slightly higher E’ and E" for the APP/DPER/EG than ATH systems. The limited oxygen index(LOI) tests performed at increasing content of EPM showed a LOI value higher than 30 indicating excellent flame retardance. Thirdly, this study has examined the mechanical properties and the flame retardance properties of chloroprene rubber(CR) containing inorganic flame retardant with various compositions of aluminium trihydroxide(ATH). It was found that increasing the amount over 30 phr resulted in decreasing the mechanical properties. On the other hand, the oxygen index measurements T1 sample showed a value of 38.6 %, indicating the improvement of flame retardantce properties showed a value of 49.7∼64.2 %. In burn test, it was confirmed that CR rubber containing over ATH 50 phr composition showed the performance corresponding to that of first grade fire retardantce.