Polyethylene flame retarded with expandable graphite and a novel intumescent additive

Abstract

A novel intumescent additive was synthesized by neutralizing 3,5-diaminobenzoic acid hydrochloride salt with ammonium dihydrogen phosphate. This compound, which melts at 257°C, decomposes concurrently to release carbon dioxide gas. The flame retardant performance of this compound as a primary fire retardant and in combination with expandable graphite was evaluated by cone calorimetry. Cone calorimeter results revealed that addition of 10 wt.% expandable graphite alone lowers peak heat release rate of carbon black-pigmented polyethylene from 710 ± 109 kW m -2 to 342 ± 15 kW m -2 , while addition of 27 wt.% of the novel intumescent lowered it to 400 ± 16 kW m -2 . Combinations of these two additives were able to decrease the peak heat release rate even further. Furthermore, the novel intumescent additive reduced the flame out time from 773 ± 307 s to 537 ± 69 s although all other expandable graphite containing samples increased it.

Characterization of commercial expandable graphite fire retardants

“…This investigation and its associated projects aim to explore the use of these additives in a variety of applications ranging from flame retardants to heat storage materials [27][28][29][30]. The objective of this particular study in particular was to perform a comprehensive characterization of two commercial expandable graphite grades used in industrial polymer applications.…”

Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

“…The reason for this is not known at this stage. Differential scanning calorimetry (DSC) results (presented in but not shown here) indicated that both exfoliation events are endothermic in nature.…”

“…Mass loss continued and reached another peak value at a temperature of 465 °C. The DSC curves (not shown here but presented in ) indicated that this reaction is exothermic, while all other mass loss steps are endothermic in nature. However, in a nitrogen atmosphere, this step was also endothermic.…”

“…The d 10 , d 50 , and d 90 particle sizes of this low expansion onset temperature grade were 313, 533 and 807 µm, respectively (Mastersizer 2000, Malvern Instruments, Malvern, UK), and the density was 2.23 ± 0.01 g cm −3 . The phosphate salts of ethylenediamine phosphate (EDAP) and of 3,5‐diaminobenzoic acid phosphate (DABAP) were synthesized using the procedures previously described . The structural formulas for these two compounds are presented in Scheme .…”

Flame‐Retardant Mechanism of Benzoxazine Resin with Triazine Structure

“…It was well known that the resin was prepared by phenolic, aldehyde, and amine to form an oxazine ring structure, 10,11 which was known to have a good flame-retardant and antistatic property, but the flame-retardation mechanism of the benzoxazine resin especially the oxazine ring structure was barely reported without gas released and heat absorbed to prevent burning. [12][13][14] As almost flame-retardant benzoxazine resin contains phosphorus, which was bad for the environment and the human body, the benzoxazine resin we designed to form a flame-retardant resin without phosphorus and halogen 15,16 was of significance.…”