Horizontal burning test, polymer

Air Products, a manufacture of latex binders, has completed a comprehensive study of flame retardants for latex binder systems. This study evaluates the inherent flammability of the major polymer types used as nonwovens binders. In addition, 18 of the most common flame retardants from several classes of materials were evaluated on polyester and rayon substrates. Two of the most widely recognized and stringent small scale tests, the NFPA 701 vertical burn test and the MVSS-302 horizontal burn test, are employed to measure flame retardancy of a latex binder-flame retardant system. Quantitative results of the study indicate clear-cut choices of latex binders for flame retardant nonwoven substrates, as well as the most effective binder-flame retardant combinations available. 

Thermosetting nanocomposites exhibit a reduced rate of heat release compared to neat polymer. However, the approach to nanocomposites itself is not sufficient to comply with the actual fire test standards. For this reason, traditional flame retardants are currently used in combination with nanofillers, and researchers are focusing on the individuation of synergistic systems. As an alternative to the most common cationic clays, anionic clays show improved performance in terms of flame retardancy. Epoxy nanocomposites based on anionic clay exhibit unique self-extinguishing behavior in a UL-94 horizontal burning test never observed before in a pure nanocomposite. The formation of a continnous intu-mescent ceramic layer on the surface of a polymer during combustion reduces the heat release rate to a higher extent than do montmorillonite nanocomposites. 

Included in the horizontal tests is the horizontal burn (HB) test. This takes place on solid polymers such as plastics. Cellular elastomers are evaluated according to the horizontal foam (HE) test. Horizontal burn foam (HBF) is the minimal rating assigned in this test, followed by horizontal foam-2 (HF-2) and horizontal foam-1 (HF-1) (the most stringent). 

The test is a horizontal fire propagation test performed in a metal cabinet using 102-mm-wide and 356-mm-long polymer sample. Fire propagation rate and bnm-ing time are used as the selection criteria. A polymer that does not bum nor transmit a flame front across its surface at a rate of more than 102 mm/min (1.7 mm/s) is acceptable as a vehicle interior material. If a polymer stops burning after 60 s of heat exposure and has not burned more than 51 mm from the point where the timing was started, it is considered to meet the bum-rate requirement. 

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