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- 2018 (4) (entfernen)
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- Flame retardant modes of action (1)
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- High-Throughput Fire Tests (1)
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Eingeladener Vortrag
- nein (2)
After introducing into the activities and competence of BAM in the field of fire science, several aspects of successful and tailored flame retardancy of polyolefins are discussed. The talk gives an overview of the works relevant for developing flame retardant polyolefins performed in the working group flame retardancy of polymers. The hypothesis of conservation of effective heat of combustion is proposed. The role of charring, inert fillers, protection layer, and intumescence is assessed for flame retarded polyolefins. Distinct routes of optimization sketched. Examples of controlling the dripping and melt flow to obtain the desired fire behaviour are discussed. Finally the cable modul for the cone calorimeter is presented.
High-throughput fire tests and weathering-induced degradation behaviour of intumescent coatings
(2018)
In this work, the weathering-induced degradation of intumescent coatings was investigated by a systematic and comprehensive approach. A mechanism is revealed that is proposed to be responsible for the loss of function of intumescent coatings induced by weathering.
First, the thermal decomposition of artificially weathered intumescent coatings was examined. To get a better understanding of the weathering and ageing phenomena, the degradation behaviour of the single ingredients during the weathering process was investigated, as well as their chemical and physical interactions. For the systematic approach, the materials that are essential for intumescence (ammonium polyphosphate, pentaerythritol, titanium dioxide, melamine and the binder) are treated with moisture, elevated temperature and UV radiation.
Thermogravimetry (TG) and IR spectroscopy were used to compare the initial samples with their different grades of weathering. We demonstrate that ammonium polyphosphate, melamine and the binder are mainly responsible for the ageing process. Further, it was demonstrated that TG and IR spectroscopy are suitable measuring methods to detect the effects of weathering on intumescent coatings.
Finally, a small-scale fire test procedure is introduced. Based on the reduction of the sample size, up to 50 samples can be tested in a single fire test. The results of this fire test have the same quality as the results from standard intermediate fire tests corresponding to DIN 4102-8.
The Role of Decomposition Temperature for Flame Redartancy Mode of Action in the Condensed Phase
(2018)
Condensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. One important aspect in achieving, adjusting and optimising flame retardancy in the condensed phase is exploiting chemical reactions between the pyrolysing polymer and flame retardant at the right place, time and temperature. It is the aim of this contribution to address the role of the decomposition temperature of both flame retardant and polymer by the means of two examples: First, aryl phosphates in Polycarbonate/ Acrylonitrile-Butadiene-Styrene (PC/ABS) blends, where the reaction with the early stage decomposition products of PC is controlling the flame retardancy mechanism in the condensed phase. Second, a comprehensive set of phosphorus flame retardants in thermosets and their corresponding carbon fibre reinforced composites based on two different epoxy systems. Both examples show that key reactions between intermediate decomposition products only occur when the decomposition temperature ranges correspond to each other. The systems can be shifted towards condensed phase activity such as charring or inorganic glass formation as well as towards phosphorus release and thus flame inhibition in the gas phase. Changing the role of flame retardancy mechanisms also influence the efficiency in the achieved flame retardancy.
Der Beitrag versucht sich an der Herausforderung, trotz beschränktem zeitlichen Rahmen einen ansprechenden Spagat zwischen umfangreichem Überblick und wissenschaftlichem Verständnis und so eine unabhängige und unparteiliche Einführung in Thematik flammgeschützte PUR-Schäume zu geben. Er kann sicherlich nicht individuelle Antworten oder konkrete Entwicklungsziele wie neue Rezepturvorschläge liefern, aber hofft zum Hintergrund und als Handwerkzeugs für das Aufstellen und Überdenken von Entwicklungsstrategien beizutragen.