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Combining buffing leather fibers from industrial waste streams with ammonium polyphosphate and bentonite clay is proposed as a flame-retardant additive for polypropylene. The paper addresses how they can be processed into attractive composites with the desired mechanical properties. Buffing leather fibers function as a multifunctional bio-filler and as a synergist for the flame retardant, resulting in fire retardancy successful enough to increase the oxygen index (LOI) by up to 7 vol.-% and to achieve a V0 UL 94 classification. Impressively reduced heat release rates are obtained in the cone calorimeter at 50 kW/m2 irradiation; for instance, the maximum average rate heat evolved (MARHE) drops from 765 to below 200 kW m 2. The synergistic effects are quantified and shown to be very strong for LOI and MARHE. This work opens the door to use waste buffing leather fibers as a promising multifunctional and synergistic bio-filler.
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.
Pressure-sensitive adhesive tapes are used in several industrial applications such as con-struction, railway vehicles and the automotive sector,where the burning behavior is ofcrucial importance. Flame retarded adhesivetapes are developed and provided, however,often without considering the interaction of adhesive tapes and the bonded materialsduring burning nor the contribution of the tapes to fire protection goal of the bondedcomponents in distinct fire tests. This publication delivers an empirical comprehensiveknowledge how adhesive tapes and their flame retardancy effect the burning behaviorof bonded materials. With a special focus on the interaction between the single compo-nents, one flame retarded tape and one tapewithout flame retardant are examined inscenarios of emerging and developing fires, along with their bonds with the commonmaterials wood, zinc-plated steel, mineral wool, polycarbonate, and polymethylmethacry-late. The flame retardant significantly improved the flame retardancy of the tape as afree-standing object and yielded a V-2 rating in UL 94 vertical test and raised the OxygenIndex by 5 vol.%. In bonds, or rather laminates, the investigations prove that the choiceof carrier and substrates are the factors with the greatest impact on the fire propertiesand can change the peak of heat release rate and the maximum average rate of heatemission up to 25%. This research yielded a good empirical overall understanding of thefire behavior of adhesive tapes and bonded materials. Thus, it serves as a guide for tapemanufacturers and applicants to develop tapes and bonds more substrate specific.
The residual post-fire mechanical properties of fiber-reinforced epoxy composites are influenced by their fire residues after burning. This study uses intumescent/low-melting glass flame retardants to tailor fire residues in epoxy resin. Processibility of prepregs and their quality are analysed for transfer of the flame-retardant epoxy resins to layered glass-fiber reinforced composites. Minimal effects were found on the pre-fire flexural strengths of the composites due to low loading of the flame retardants. However, when transferred to glass-fiber reinforced composites, the fire residues diminish significantly. Further studies are required to improve theoretical and experimental estimations of the post-fire mechanics of the composites.
The residual post-fire mechanical properties of fiber-reinforced epoxy composites are influenced by their fire residues after burning. This study uses intumescent/low-melting glass flame retardants to tailor fire residues in epoxy resin. Processibility of prepregs and their quality are analysed for transfer of the flame-retardant epoxy resins to layered glass-fiber reinforced composites. Minimal effects were found on the pre-fire flexural strengths of the composites due to low loading of the flame retardants. However, when transferred to glass-fiber reinforced composites, the fire residues diminish significantly. Further studies are required to improve theoretical and experimental estimations of the post-fire mechanics of the composites.
The transfer of flame-retardant epoxy resin formulations to composites for structural and lightweight applications in the energy and transport sector can be complex and requires systematic investigation. Here, uncoated and silane-coated ammonium polyphosphate (APP, Si-APP) intumescent compounds are transferred to prepregs using a Bisphenol A diglycidyl ether (DGEBA) resin matrix to 0/90o bidirectional glass fibers with an aerial weight of 600 g/m2. Inorganic silicates (InSi) are added to improve the fire residues of the composites after combustion and the total amount of flame retardants in the resin formulations was 10% by weight. The prepregs' fiber volume content (FVC) is corroborated using in-process measurements and thermogravimetric analysis. This was found to be approximately 60% for the composites containing APP, which is ideal for load-bearing applications with high mechanical strength. However, the Si-APP containing prepregs showed an inconsistent FVC potentially due to interactions with the commercial sizing of the glass fibers. The composites subsequently prepared are analysed for potential filtration effects of the additives via SEM after immobilization in a cured resin and platinum sputtering. The inter-laminar shear strength and the mechanical strength of the composites are compared via three-point bending tests. Additionally, the fire performance of the composites is analysed using cone calorimetry. It was found there was minimal impact of the loading of the flame retardants on the delamination of the composites and the flexural strength. However, the high density of the glass fibers possibly results in a suppression of the mode of action of the flame retardants in the composites. Therefore, the fire residues of the composites are further compared using SEM, and the flame-retardant modes of action upon transfer are investigated.
Leather is a widely used material for thousands of years and in modern days it is produced on industrial scale. This production produces high amounts of organic waste during the tannery process. These fibers can become a resource and act as a multi-functional bio-filler in flame retardant composites.
This project investigates two leather fibers towards their ability to enhance the flame-retardancy in different composites. These composites use ammonium polyphosphate (APP) or aluminum trihydroxide (ATH) as flame retardants. Different silicon based synergists support polymers with ATH to reduce the load of flame retardant. The different modes of action (charring, gas phase activity, barrier effect) can be quantified of each composite.
The new composites form a stable char layer resulting in an increase in residue, lower peak heat release rates (pHRR) and higher limiting oxygen index (LOI). In addition, the ratings in the UL94-classification increased up to V-0.
Only the nano-scaled structure of the nanocomposite and the dispersion of nanoparticles within the polymer matrix harbor multifunctional potential including superior fire retardancy. Thus, this chapter focuses on the dispersion of nanoplates, based mainly on studies of layered silicates and graphene/graphene-related nanoplates. The nanostructure and properties of the nanocomposites are dependent mainly on thermodynamic and kinetic factors during preparation. Improving nano-dispersion often directly improves flame retardancy. Therefore, the modification of the nanoplates as well as the preparation of nanocomposites becomes very important to control this dispersion. The dispersion of nanoplates functions as a prerequisite for the formation of an efficient protective layer, changing the melt flow and dripping behavior, or the improvement of the char properties.
Leather is a widely used material for thousands of years and in modern days it is produced on industrial scale. This production produces high amounts of organic waste during the tannery process. These fibers can become a resource and act as a multi-functional bio-filler in flame retardant composites.
This project investigates two leather fibers towards their ability to enhance the flame-retardancy in different composites. These composites use ammonium polyphosphate (APP) or aluminum trihydroxide (ATH) as flame retardants. Different synergists support polymers with ATH.
The new composites form a stable char layer resulting in an increase in residue, lower peak heat release rates (pHRR) and higher limiting oxygen index (LOI). In addition, the ratings in the UL94-classification increased up to V-0.