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The dripping behaviour of polymers is often observed experimentally through the UL94 flammability standard test. In this work, polymeric dripping under fire is investigated numerically using particle finite element method. A parametric analysis was carried out to observe the influence of a single property on overall dripping behaviour via a UL94 vertical test model. Surrogates and property ranges were defined for variation of the following parameters: glass transition temperature (T g), melting temperature (T m), decomposition temperature (T d), density (ρ), specific heat capacity (Cp), apparent effective heat of combustion of the volatiles, char yield (µ), thermal conductivity (k), and viscosity (η). Polyamide, poly(ether ether ketone), poly(methyl methacrylate), and polysulfone were used as benchmarks. Simulated results showed that specific heat capacity, thermal conductivity, and char yield allied with viscosity were the properties that most influenced dripping behaviour (starting time and occurrence).

Although numerous investigations study the improvement of flame retardancy of epoxy resins using additives, maintaining the flame retardant (FRs) modes of action present in the resins upon transfer to composites is challenging. In this study, ammonium polyphosphate (APP) and inorganic silicate (InSi) are loaded at 10%, 30%, and 50% by weight, in a diglycidyl ether of bisphenol A (DGEBA) resin cured with dicyandiamide and transferred to bidirectional (BD) glass fiber (GF) composites. Although a 50% loading of the FRs impacts the curing kinetics of the resin system, the effect on the glass transition temperature of the resin system remains negligible compared to reactive FRs in the state of the art integrated into the resin's chemical structure. Increasing the FR content improved the heat release characteristics in both the resins and composites. However, the charring mode of action is completely suppressed in the formulation with 10% APP + InSi. A 30% concentration of the FRs restored the charring action in the composite and the GFs provide increased protective layer action upon transfer to the composites. This study highlights the importance of accounting for the changing dynamics related to processing and flame retardancy upon transferring FRs from resins to composites. [ABSTRACT FROM AUTHOR]

To curtail flammability risks and improve material properties, flame retardants (FRs) and fillers are mixed into rubbers. High loadings of aluminum trihydroxide (ATH) and carbon black (CB) are the most used FRs and reinforcing additive, respectively, in rubbers. To reduce loading without losing mechanical properties, partial substitution of ATH as well as CB by low amounts of multilayer graphene (MLG) nanoparticles is investigated. The high aspect ratio MLG is made of ten graphene sheets. In polybutadiene/chloroprene (BR/CR) nanocomposites 3 phr MLG replaced 15 phr CB and/or 3 phr ATH. Material and mechanical properties as well as fire behavior of the nanocomposites are compared to BR/CR with 20 phr CB both with and without 50 phr ATH. MLG appears as a promising nanofiller to improve the functional properties: replacement of CB improved rheological, curing, and mechanical properties; substitution of ATH improved nanocomposite properties without affecting flame retardancy.

Ethylene propylene diene monomer (EPDM) rubbers with the flame retardants tris(2-ethylhexyl)phosphate, ammonium polyphosphate, polyaniline, and aluminum trihydroxide were prepared and analyzed in this study. The homogenous dispersion of the fillers in the rubber matrix was confirmed by scanning electron microscope. To investigate the interplay of the different flame retardants, the flame retardants were varied systematically. The comprehensive study sought combinations of flame retardants that allow high loadings of flame retardants without deterioration of the physical and mechanical properties of the EPDM rubber. The eight EPDM rubbers were investigated via thermogravimetric analysis and pyrolysis gas chromatography coupled with a mass spectrometer (Py-GC/MS) to investigate the potential synergistic effects. In the Py-GC/MS experiments, 27 pyrolysis products were identified. Furthermore, UL 94, limiting oxygen index, FMVSS 302, glow wire tests, and cone calorimeter tests were carried out. In the cone calorimeter test the EPDM rubbers R-1AP and R-1/2P achieved an increase in residue at flameout of 76% and a reduction in total heat evolved of about 35%. Furthermore, the compounds R-1AP and R-1/2P achieved a reduction in MAHRE to about 150kW[m.sup.-1], a reduction of over 50% compared to the unprotected rubber R., INTRODUCTION Ethylene propylene diene monomer (EPDM) rubber is the most widely used synthetic rubber for nontire applications, such as automotive, construction, and electrical insulation. EPDM rubbers offer usage at low [...]

To ensure fire safety, polymers are filled with flame retardants and smoke suppressants. To meet the highest requirements, it is essential to understand the decomposition of those polymeric materials. This study reveals interactions between polymer, smoke suppressants, and flame retardants, and discusses their impact on the materials' flame retardancy, smoke emission, smoke toxicity, and particle emission in conventional loadings to provide deeper general understanding. Low melting oxide glass, melem, spherical silica, sepiolite, melamine polyphosphate, and boehmite in an aluminum diethylphosphinate flame-retarded polyamide 6.6 were investigated. All smoke suppressants improve the protective layer and act as an adjuvant. Silica and melem performed best under forced flaming conditions. Spherical silica reduces the peak of heat release rate by 39% and the total heat evolved by 14%, whereas 10 wt% melem lowers the total smoke production by 41%. Melem alters the mode of action of aluminum diethylphosphinate from gas to more condensed phase activity. This change reduces flame inhibition and hence smoke toxicity, but further improves the protective layer due to charring reactions in the decomposition mechanism. In addition, the sizes of the smoke particles decrease because of the prolonged time in the pyrolytic zone. This study highlights that interactions between polymer, flame retardants, and smoke suppressants can significantly determine the smoking and burning behavior. [ABSTRACT FROM AUTHOR]

Pressure‐sensitive adhesive tapes are used in several industrial applications such as construction, railway vehicles and the automotive sector, where the burning behavior is of crucial importance. Flame retarded adhesive tapes are developed and provided, however, often without considering the interaction of adhesive tapes and the bonded materials during burning nor the contribution of the tapes to fire protection goal of the bonded components in distinct fire tests. This publication delivers an empirical comprehensive knowledge how adhesive tapes and their flame retardancy effect the burning behavior of bonded materials. With a special focus on the interaction between the single components, one flame retarded tape and one tape without flame retardant are examined in scenarios of emerging and developing fires, along with their bonds with the common materials wood, zinc‐plated steel, mineral wool, polycarbonate, and polymethylmethacrylate. The flame retardant significantly improved the flame retardancy of the tape as a free‐standing object and yielded a V‐2 rating in UL 94 vertical test and raised the Oxygen Index by 5 vol.%. In bonds, or rather laminates, the investigations prove that the choice of carrier and substrates are the factors with the greatest impact on the fire properties and can change the peak of heat release rate and the maximum average rate of heat emission up to 25%. This research yielded a good empirical overall understanding of the fire behavior of adhesive tapes and bonded materials. Thus, it serves as a guide for tape manufacturers and applicants to develop tapes and bonds more substrate specific. [ABSTRACT FROM AUTHOR]

We report the selective ring opening copolymerisation (ROCOP) of oxetane and phthalic thioanhydride by a heterobimetallic Cr(III)K catalyst precisely yielding semi-crystalline alternating poly(ester-alt-thioesters) which show improved degradability due to the thioester links in the polymer backbone. [ABSTRACT FROM AUTHOR]

Low amounts (10 wt%) of spherical amorphous Si[O.sub.2] (sSi[O.sub.2]) has been used successfully as adjuvants in commercial polymeric materials flame retarded with metal hydroxide. The combination of LS and Si[O.sub.2] is investigated in different thermoplastics with respect to their fire behavior, particular to overcome the restrictions in maximum and minimum filler contents know for the single additives. The aim was to check the potential of combinations of the inert fillers in absence of a real fire retardant. The combination of LS and sSi[O.sub.2] harbors the potential for flame retardancy effects close to superposition or even synergy, due to an improved structure of the fire residue. LS-sSi[O.sub.2] combinations are proposed to work as adjuvants superior to LS and sSi[O.sub.2] in flame retarded polymeric materials., INTRODUCTION For several decades now demand has been increasing for developing novel flame retardants that are efficient and environmentally friendly at the same time. In the past, environmental concerns regarding [...]