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

Abstract

Summary Low‐density polyethylene was flame retarded by combinations of expandable graphite with either ethylenediamine phosphate or 3,5‐diaminobenzoic acid phosphate. Cone calorimeter, laser pyrolysis, and open flame exposure tests (supported by video and infrared camera data capture and analysis) were conducted to assess ignition and burn behavior. Cone calorimeter results indicated substantial reductions in the peak heat release rates for all flame‐retarded samples but with reduced ignition times and increased flame out times. Smoke generation was suppressed in the presence of expandable graphite. Infrared and video data from open flame fire tests indicated cohesive bonding of expanded strings and thermal shielding properties in all binary systems. All binary systems delivered fire retardation exceeding any of the single fire retardant compounds. They were also able to withstand higher temperatures before ignition, burn through, or sag occurred. All ethylenediamine phosphate‐containing binary systems prevented sample burn through, maintaining structural integrity of samples until eventual melting of the polymer media occurred. Thermogravimetric analysis laser pyrolysis results confirmed the good thermal shielding imparted by the intumescent additives. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of different size‐modified expandable graphite and ammonium polyphosphate on the flame retardancy, thermal stability, physical, and mechanical properties of rigid polyurethane foam

“…In order to prevent burning and delay fire spread, flame retardants (FRs) are commonly used in polymers . The graphite intercalation compound (GIC), namely expandable graphite (EG), is known as a new generation of intumescent flame retardant, which is halogen‐free, nondripping, and low smoke . In the event of a fire or thermal shock, EG will instantly expand and form “worm‐like” expanded graphite.…”

Influence of nano silica hybrid expandable graphite on flammability, thermal stability, and mechanical property of polypropylene/polyamide 6 blends

“…Expandable graphite (EG) is a novel type of intumescent flame retardant. Due to its excellent flame retardancy, EG has been used for many times in flame‐retardant polyolefins, 19–21 poly(methyl methacrylate), epoxy resin, 22 and polyurethane (PU) 23–25 . When EG is heated to about 200°C, EG expands rapidly and becomes a swollen and multi‐voided “worm‐like” structure, resulting in a large amount of charred residue covering the polymer surface 26 .…”

Anisotropy of expandable graphite to explain its behavior as a flame-retardant

“…4 Afterward, many studies were carried out on different polymers. EG is used as the only FR in the polymer matrix [5][6][7][8][9] or in synergy with other FRs, such as modified ammonium polyphosphate (AP), [10][11][12][13][14] red phosphorus, 15,16 or aluminum tri-hydroxide. 17,18 In a previous article, we studied the fire behavior of polypropylene (PP) blended with FRs: EG and AP, alone or combined in different ratios.…”