Effect of boron containing materials on flammability and thermal degradation of polyamide‐6 composites containing melamine cyanurate

Abstract

Three different boron containing materials, zinc borate (ZnB), borophosphate (BPO4), and boron and silicon containing oligomer (BSi), were used to improve the flame retardancy of melamine cyanurate (MC) in a polyamide‐6 (PA‐6) matrix. The combustion and thermal degradation characteristics were investigated using limiting oxygen index (LOI), UL‐94 standard, thermogravimetric analysis‐Fourier transform infrared spectroscopy (TGA‐FTIR), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM). All the three boron compounds showed no synergistic effect with MC, and only BPO4 at high loadings showed comparable LOI values by increasing the dripping rate. For ZnB and BSi glassy film and char formation decreases the dripping rate and sublimation of melamine and give rise to low LOI. According to TGA‐FTIR results, addition of boron compounds does not alter the gaseous product distribution of both MC and PA‐6. The addition of boron compounds affects flame retardancy through physical means. It was noted from the TGA data that boron compounds reduced the decomposition temperature of both MC and PA‐6, also affecting the flame retardancy negatively by premature degradation of MC at low temperatures. Copyright © 2009 John Wiley & Sons, Ltd.

Investigation of a combination of novel polyphosphoramide and boron-containing compounds on the thermal and flame-retardant properties of polystyrene

“…At higher magnification, a quantity of circular particles with diameter about 1.6 μm attaching on the surface of spherical intumescent char can be observed. Evidently, the circular particles could be attributed to the BP particles [21]. In the case of the char of PSPD/ZnB, the Much more continuous and intact char with few holes was observed.…”

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

“…Previous work on polyamide 6 and melamine cyanurate composite showed that the LOI value of PA6 sharply increased from 22.5 to 31.8 when 15 wt% MC was added to PA6 [23]. It has been determined that the inclusion of MC increased slightly the char yield from 0% to 0.6%.…”

“…Melamine cyanurate (MC) (Melapur MC25) was purchased from Ciba (Basel, Switzerland). PA6 and 20 and 15 wt% melamine (PA6/Me) or melamine cyanurate (PA6/MC) respectively, were mixed in a twin screw extruder at 100 rpm and 230 • C [21,23].…”

“…It has been shown that polyamide-6 (PA-6) mixed with melamine is self-extinguishing and the thermal degradation process in PA-6 is modified strongly by the presence of melamine [20]. Recently, LOI and vertical burning ratings (UL-94) for PA6 containing melamine or melamine cyanurate composites were investigated by Dogan et al [21,23]. It has been determined that addition of 20% melamine or 15% melamine cyanurate increases LOI value 22.5-31.…”

“…There have been several studies on flammability and thermal degradation of polyamide-6 composites containing melamine or melamine cyanurate [17][18][19][20][21][22][23][24][25][26][27]. Generally, PA6 decomposes primarily into caprolactam, alkyl cyanides and ammonia.…”