Durability of the flame retardance of ethylene‐vinyl acetate copolymer cables: Comparing different flame retardants exposed to different weathering conditions

Abstract

Scientific publications addressing the durability of the flame retardance of cables during their long-term application are rare and our understanding lacks. Three commercial flame retardants, aluminum hydroxide, aluminum diethyl phosphinate (AlPi-Et), and intumescent flame retardant based on ammonium polyphosphate, applied in ethylene-vinyl acetate copolymer (EVA) model cables, are investigated. Different artificial aging scenarios were applied: accelerated weathering (UV-irradiation/temperature/rain phases), humidity exposure (elevated temperature/humidity), and salt spray exposure. The deterioration of cables' surface and flame retardancy were monitored through imaging, color measurements, attenuated total reflectance Fourier transform infrared spectroscopy, and cone calorimeter investigations. Significant degradation of the materials' surface occurred. The flame retardant EVA cables are most sensitive to humidity exposure; the cable with AlPi-Et is the most sensitive to the artificial aging scenarios. Nevertheless, substantial flame retardance persisted after being subjected for 2000 h, which indicates that the equivalent influence of natural exposure is limited for several years, but less so for long-term use.

Degradation of flame retardance: A comparison of ethylene‐vinyl acetate and low‐density polyethylene cables with two different metal hydroxides

“…As stated in our previous paper, 36 the maximum UV radiative exposure in artificial weathering exposure for no more than 2000 h is roughly equivalent to about 14 months or more outdoors in Berlin (considering longer periods of high temperatures in the artificial test would further increase this equivalence). Therefore, with respect to flame retardancy there should be no problem with the application of these typical kinds of cables for several years.…”

“…The data for the EVA/MDH obtained from the cone calorimeter showed, three peaks in each HRR curve. The char layer generated in the first peak did not offer sufficient protection to prevent the subsequent combustion believed to be typical for cable rafts, 36 as apparent in the appearance of the following two peaks in the HRR curve.…”

“…Any scientific understanding resulting from developing such products in industry, such as ways to optimize the stability of the fire properties of cables, is hardly ever communicated. Thus, the starting point of our endeavor reported in both our previous paper 36 and here was the lack of comprehensive systematic direct comparisons: A comparison of the degradation of fire properties based on the use of different main flame retardants in cables; a comparison performed using real cables to which flame retardant sheet materials were applied in contact with copper.…”

“…In our previous study, 36 the fire behavior of EVA cables with different flame retardants was studied with the cone calorimeter before and after they were subjected to different weathering conditions. Comparing the results indicated that EVA flame retarded with ATH outperforms EVA with other flame retardants, such as aluminum diethyl phosphinate, with respect to durability, especially against the impact of high humidity.…”

Ammonium Polyphosphate with High Specific Surface Area by Assembling Zeolite Imidazole Framework in EVA Resin: Significant Mechanical Properties, Migration Resistance, and Flame Retardancy

“…Nevertheless, EVA resin is extremely flammable and releases a high emission of heat and smoke, making flame-retardant modification an urgent concern [4,5]. For environmental concerns, intumescent flame retardants (IFRs) with low-toxicity, low smoke, and high efficiency are acceptable halogen-free flame retardants for EVA composites [6,7]. Among the components of the hybrid IFR system, phosphor-containing flame retardants such as ammonium polyphosphate (APP) and its derivatives are the most widely used acid source [8][9][10].…”