Abstract
The present work deals with the study of phosphorus flame retardant microcellular acrylonitrile–butadiene–styrene (ABS) parts and the effects of weight reduction on the fire and mechanical performance. Phosphorus-based flame retardant additives (PFR), aluminum diethylphosphinate and ammonium polyphosphate, were used as a more environmentally friendly alternative to halogenated flame retardants. A 25 wt % of such PFR system was added to the polymer using a co-rotating twin-screw extruder. Subsequently, microcellular parts with 10, 15, and 20% of nominal weight reduction were prepared using a MuCell® injection-molding process. The results indicate that the presence of PFR particles increased the storage modulus and decreased the impact energy determined by means of dynamic-mechanical-thermal analysis and falling weight impact tests respectively. Nevertheless, the reduction of impact energy was found to be lower in ABS/PFR samples than in neat ABS with increasing weight reduction. This effect was attributed to the lower cell sizes and higher cell densities of the microcellular core of ABS/PFR parts. All ABS/PFR foams showed a self-extinguishing behavior under UL-94 burning vertical tests, independently of the weight reduction. Gradual decreases of the second peak of heat release rate and time of combustion with similar intumescent effect were observed with increasing weight reduction under cone calorimeter tests.
Highlights
Acrylonitrile–butadiene–styrene (ABS) is one of the most used engineering polymers due its good combination of properties and low cost, being widely used in different industrial areas such as in the automotive sector, building, and construction, as well as in electrical and electronic applications.In the automobile sector, ABS is commonly used for interior and exterior car parts due to its high thermal insulation performance and the fact that its electrical properties do not change significantly with temperature and humidity [1]
As can be seen by the characteristic low magnification scanning electron microscopy (SEM) images displayed in Figure 2, the structural foams obtained by means of Mucell® injection-molding foaming process showed a characteristic solid skin, a transition zone with decreasing density and a microcellular core structure
The skins and transition zones represented around 30–40% of the whole thickness of the part and the microcellular core around 60–70%
Summary
Acrylonitrile–butadiene–styrene (ABS) is one of the most used engineering polymers due its good combination of properties and low cost, being widely used in different industrial areas such as in the automotive sector, building, and construction, as well as in electrical and electronic applications.In the automobile sector, ABS is commonly used for interior and exterior car parts due to its high thermal insulation performance and the fact that its electrical properties do not change significantly with temperature and humidity [1]. Acrylonitrile–butadiene–styrene (ABS) is one of the most used engineering polymers due its good combination of properties and low cost, being widely used in different industrial areas such as in the automotive sector, building, and construction, as well as in electrical and electronic applications. Its high flammability with release of gases and toxic fumes during combustion significantly limits its use for this type of application. The flame retardancy enhancement of polymeric materials such as plastics, foams, resins, and adhesives has been achieved through the use of brominated flame retardant additives. These materials were introduced in the 1960s and 1970s and are very effective at low concentrations [2]. The use of such additives has been highly limited due to European environmental restrictions [3], in some cases even
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