The efficiency of ammonium polyphosphate in different biocomposites was compared. For the comparison flame retarded lignocellulosic filler reinforced biocomposites were prepared using polypropylene ...(PP), polyurethane (PUR) and fully biodegradable starch matrices. The compatibility of wood flake with PP was improved by application of an alkoxy silane based reactive surfactant. The silylation improved not only the compatibility but also the thermal stability of the wood flake according to TG measurements. Raman spectroscopic analysis of the silylated product showed that the improved thermal stability is the result of reduced ratio of the amorphous phase of cellulose. The phosphorus additives in flame retarded PUR biocomposites, comprising waste bio fillers and recycled polyol, proved to be very effective because both the matrix and the filler components participate in mechanism of flame retardancy. Plasticised thermoplastic starch could be flame retarded efficiently by as little as 10% ammonium polyphosphate. After their service life the biocomposites can be utilised as chemical fertilizer.
A mathematical model, simulation results and laboratory experiments are reported to describe the degradation of fire retardant polymeric materials.
The model describes the heat and mass balances of a ...polymer layer with finite thickness. The degradation is initiated by a constant heat flux at the top of the layer. It is assumed that the polymer degrades to a fixed mass of char and volatile gas in an instantaneous step, at the moment when the temperature reaches a critical value. The most important heat transport mechanism is conduction, which dominates the temperature profile. The mass transport of gas is described by Darcy's law, with a simplifying condition that the overall solid volume is constant during degradation. The transport processes have been modelled in one spatial dimension.
Calculations and experiments have been carried out to establish the effects of critical parameters such as layer thickness, heat flux and material properties.
Common consideration and classification of surface and interface phenomena in wide areas of material science are discussed through three examples: basalt fiber reinforced composite; flame retarded ...polypropylene and polyorganosiloxane nanocomposite. Interface-related characteristics of polymer composites and biomaterials are discussed using uniform principles. A new classification of the interphases is introduced including the compatible, adaptive and smart interfacial layers. In case of basalt fiber reinforced polypropylene reactive interface modification is performed in a new and economic way using reactive surfactants. These additives accomplish the compatibilization of the phases during reactive compounding/processing. The fire retardancy of polypropylene system containing ammonium polyphosphate and clay nanoparticles is enhanced by adaptive polysiloxane interphase. Clay additive provides thermal and pH responsive character to silicone based biomaterial thus it can be applied for forming smart interphases.
Fire retarded polymer nanocomposites Marosföi, B.; Matko, Sz; Marosi, P. Anna Gy
Current applied physics,
02/2006, Letnik:
6, Številka:
2
Journal Article
Recenzirano
Nanocomposite structure of polymer intercalated montmorillonites was formed in ethylene vinyl acetate copolymer/magnesium hydroxide flame retarded polymer system. Generally the presence of magnesium ...hydroxide flame retardant particles disturbs the structural analysis of such systems. Raman microscopic method was successfully applied for evaluating the distribution of components in presence of high concentration of flame retardant additives. The interphase formed around the nanoparticles influences the structure and the temperature dependency of the rheological characteristics, which was evaluated by thermal Scanning Rheometer. Surprisingly the combination of unmodified and modified montmorillonites provided the most advantageous rheology profile for improving the fire retardancy (reducing dripping and increasing the char-stability).
