Synergistic effects of polyethylene glycol and ammonium polyphosphate on intumescent flame‐retardant polypropylene

Abstract

A novel flame-retardant system of isotactic polypropylene (iPP) is prepared using polyethylene glycol (PEG) and ammonium polyphosphate (APP). The flammability of iPP/PEG/APP composites containing 20 wt% APP improves with the increase of PEG concentration in the range of 3-15 wt%. The limit oxygen index (LOI) of iPP/ PEG/APP composites reaches up to 30% with 15 wt% PEG concentration in the composites. At the same time, the mechanical properties of iPP/PEG/APP composites demonstrate that PEG can enhance toughness of iPP/APP composites. The results of cone calorimetry prove the synergistic effects of PEG and APP on intumescent flame-retardant iPP, and those of the thermogravimetric analysis(TGA) reveal that iPP/PEG/APP samples decompose faster than iPP/APP composites. Investigated by scanning electronic microscopy (SEM), the morphology and structures of residues generated during LOI tests confirm the formation of effective char layer, and that the improvement of the flame retardancy and the impact strength of the composites are thanks to the presence of PEG. POLYM. ENG. SCI., 53:410-416, 2013. ª FIG. 3. HRR curves (a) and THR curves(b) of iPP and iPP/PEG/APP composites under a heat flux of 35 kW/m 2 . FIG. 4. TG (a) and DTG (b) curves of iPP and iPP/PEG/APP composites (Inset(a): A zoomed-in image).

Intumescence: Tradition versus novelty. A comprehensive review

“…APP/ polyethylene glycol combination has proved to impart both good flame retardancy and toughness to iPP [223]. Finally, a novel organophosphorus containing spiro and caged bicyclic phosphate was found to have good interactions with both APP [224] and melamine [225].…”

Improvement of the impact strength of ethylene‐propylene random copolymers by nucleation

“…Since earlier experience and also the conclusions drawn in previous sections indicate that increasing crystallinity and lamella thickness results in decreasing fracture resistance, we must assume that nucleation induces the rearrangement of the phases or some changes in the mobility of amorphous molecules as proposed by some groups 15,20 . We therefore carried out a dynamic mechanical analysis of the samples.…”

“…They observed that the degree of phase separation and crystalline morphology varied considerably as a result, which led to changing hardness and predictably also modified impact resistance. Other groups prepared blends from PP and poly(ethylene glycol) (PEG) and studied the effect of processing conditions 19 as well as annealing 20 on structure and properties. Annealing was shown to change phase structure in PP/PEG blends resulting in a large increase in toughness.…”

Study of using aluminum hypophosphite as a flame retardant for low‐density polyethylene

“…The LDPE degrades in the way of random chain scission, and some hydroxyl groups are generated on the backbone after dehydrogenating and oxidizing of LDPE . Besides, when the temperature increases, AHP first releases phosphine, and then part of phosphine is quickly oxidized into phosphoric acid.…”