Investigation on effects of aluminum and magnesium hypophosphites on flame retardancy and thermal degradation of polyamide 6

Abstract

Two hypophosphites, aluminum hypophosphite (AlHP) and magnesium hypophosphite (MgHP), were applied to obtain flame retardant polyamide 6 (FR‐PA6) composites. UL‐94 and limiting oxygen index results indicated that AlHP contributed both good flame retardance and antidripping ability for PA6, while MgHP did not. Based on thermogravimetric analysis (TGA), AlHP and MgHP presented the different thermal degradation behavior. That is, the quick decomposition of AlHP took place at lower temperature than that of MgHP. AlHP promoted the early thermal degradation of PA6 and formed more char residue. The thermal decomposition mechanisms of AlHP and MgHP in nitrogen or air were suggested. Scanning electron microscope and X‐ray photoelectron spectroscopy indicated that in the existence of AlHP, the morphological structures of char residue were more homogenous, and compact, and more char residue was formed. These results well illustrated the difference of the flame retardancy between AlHP and MgHP. Mechanical properties of PA6/AlHP and PA6/MgHP were also obtained. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Investigation of thermal degradation characteristics of polyamide-6 containing melamine or melamine cyanurate via direct pyrolysis mass spectrometry

“…Weil et al discussed the currently used or promising flame retardant systems for the aliphatic polyamides [10]. The developments in the chemistry of halogen-free flame retardant polymers, effects of ammonium phosphate, aluminum and magnesium hypophosphites on flame retardancy and thermal degradation of polyamide 6 and thermal decomposition behavior of polyamide fire-retardant compositions containing magnesium hydroxide filler have been discussed [11][12][13]16].…”

“…Several studies focused on the improvement of the flame retardancy of PA6 [7][8][9][10][11][12][13][14][15][16][17]. It has been determined that various mechanisms depending on the experimental conditions contribute to thermal degradation.…”

Aluminum hypophosphite microencapsulated to improve its safety and application to flame retardant polyamide 6

“…Howbeit, AHP also has some defects including poor compatibility with polymer matrix and fire risk. Especially in the case of heating or impact, which will make AHP decompose and release phosphine [11][12][13][14], which is spontaneously flammable in air, burning with a luminous flame and even can form explosive mixtures in extreme cases. In this process, it release a lot of heat and accelerate the decomposition of AHP, which will form a cyclic process and cause even huge damage.…”

“…In the past few years, aluminum hypophosphite (AHP) has been employed as an efficient halogen-free flame retardant [10][11][12][13][14] and widely used in engineering plastics, such as PA, PET, PBT etc. Howbeit, AHP also has some defects including poor compatibility with polymer matrix and fire risk.…”

Using TG–FTIR and TG–MS to study thermal degradation of metal hypophosphites

“…Metal hypophosphite compounds, such as aluminum hypophosphite (AHP), magnesium hypophosphite, and cerium hypophosphite have attracted much attention over the decades for their high thermal and chemical stabilities, good mechanical and electrical properties, and environmentally friendly properties [1][2][3]. Especially, AHP as a novel class of phosphorous-based flame retardants, which is expected as a promising candidate for replacing halogenbased flame retardants, also it has been applied in the treatment of organic materials such as glass-filled polyamide 6 [3], polybutylene terephthalate (PBT) [4,5], poly(ethylene terephthalate) [6], and polylactide [7].…”