Development of Intumescent Flame Retardant for Polypropylene: Bio-epoxy Resin Microencapsulated Ammonium-polyphosphate

Abstract

As polypropylene (PP) has no charring ability on its own due to the lack of hydroxyl functional groups, the flame retardant system needs the addition of carbonizing agent in a relatively great amount. Ammonium-polyphosphate (APP), a conventional flame retardant additive was modified by microencapsulation with a sorbitol-based bioepoxy resin shell to create an intumescent flame retardant system with enhanced charring ability for PP. The flame retardant efficiency of the microencapsulated additive, which contains all the components needed in an effective intumescent flame retardant system, was evaluated in PP matrix at different loadings.When compared to the physical mixture of the component, the microencapsuated form of APP (MCAPP) was found to have improved flame retardant efficiency in PP. The LOI values of the MCAPP containing PP samples increased by 8–11 V/V% besides achieved V-0 classification according to the UL94 test. During cone calorimeter tests, the burning intensity was reduced (peak of heat release rate decreased by 20–35% and shifted in time), increased amount of charred residue was obtained, and based on the calculated Flame Retardancy Index (FRI) “Excellent” fire performance was achieved when MCAPP was used. The improved flame retardant performance is attributed to the effective interaction between the APP core and the readily available carbonizing shell, which promoted the formation of increased amount of char accompanied with improved heat protecting and barrier efficiency.

Preparation and Characterization of Microencapsulated Ammonium Polyphosphate with Polyurethane Shell and Its Flame Retardance in Polypropylene

“…In the literature, many different types of flame retardants have been investigated and considered to improve the fire properties of PP, and one of the most current approaches is the application of novel microencapsulated ammonium polyphosphate (MCAPP). The microencapsulation of ammonium polyphosphate (APP) has the advantage of improving water resistance [5,6], increasing the interfacial compatibility between APP and the polymer matrix [7,8] and creating a complex formulation of an all-in-one intumescent flame-retardant system [9].…”

Synergistic Effect of Nano-Silica and Intumescent Flame Retardant on the Fire Reaction Properties of Polypropylene Composites

“…As one of the important halogen-free candidates, intumescent flame retardant (IFR) has been widely used to enhance the flame retardancy of polypropylene composites. Thanh et al, synthesized an efficient intumescent flame retardant via microencapsulation of ammonium polyphosphate using a bioepoxy resin shell [ 7 ]. When the microencapsulated form of ammonium polyphosphate was introduced to the polypropylene matrix, the heat release rate of the matrix decreased by 35% and an increased amount of charred residue was obtained during cone calorimeter tests.…”

Eco-friendly Synthesis of Novel Phosphorus Flame Retardants for Multiple Purposes

“…The P-species entering the gas phase are typically less harmful than the degradation products of the halogen-based FRs [7]. In the solid phase, a stable char layer is usually formed by the reaction between the phosphoric acid and the degraded polymer [8,9].…”