Thermal decomposition of fire-retarded wood flour/polypropylene composites

Abstract

The influence of magnesium hydroxide (MH), expandable graphite (EG), and ammonium polyphosphate (APP) on the kinetic property and degradation mechanisms of wood flour/polypropylene composites (WPPC) was investigated using thermogravimetric (TG) analysis. The kinetic parameters were determined using Kissinger and Flynn-Wall-Ozawa (F-W-O) methods. Criado method was used to investigate the probable degradation mechanisms. Thermogravimetric results indicated that EG and APP accelerated the degradation process of wood flour and promoted an increase in the conversion value at low temperatures. The activation energy values obtained through Kissinger and F-W-O methods were 161-178 kJ mol -1 (wood flour degradation stage) and 234-305 kJ mol -1 (polypropylene degradation stage) for WPPC with or without fire retardants. The degradation mechanism of wood flour occurred by diffusion in three-dimensional processes when the conversion value was below 0.8. Polypropylene and fire retardants had no direct influence on the degradation mechanism of wood flour. In the polypropylene decomposition stage, the degradation of WPPC without fire retardant followed phase-boundarycontrolled reaction mechanism. However, the behavior of WPPC incorporation of MH, EG, or APP was governed by nucleation and growth mechanism.

Holz‐Kunststoff‐Verbundwerkstoffe

“…Neben der Verbesserung der mechanischen Eigenschaften und der Haltbarkeit bei Außenanwendungen gehört das Brandverhalten zu den Schlüsselherausforderungen für diese Produktklasse in Hinblick auf Anwendungen im Transportwesen und im Bauwesen, insbesondere bei konstruktiven Anwendungen im Baubereich. Werkstoffeigenschaften wie Entflammbarkeit, Brandausbreitung und Wärmefreisetzung können durch gezielte Flammschutz‐Zusätze optimiert werden . Durch die gezielte Verbesserung der brandtechnischen Eigenschaften können WPC vielfältig und auch für Applikationen mit einem erhöhten Brandrisiko eingesetzt werden .…”

“…Erzielt werden diese Eigenschaften durch eine Kombination von chemischen und physikalischen Mechanismen in der kondensierten Phase und/ oder der Gasphase [7-9, 11, 15, 16]. Die unterschiedlichen Wirkprinzipien sind: [7][8][9][10][11][12][13]. Durch die gezielte Verbesserung der brandtechnischen Eigenschaften können WPC vielfältig und auch für Applikationen mit einem erhöhten Brandrisiko eingesetzt werden [12,13]…”

Fibers and fiber cocktails to improve fire resistance of concrete

“…At first the polymer melted (endothermic DTA peak at 177 °C), then between 230 and 500 °C the sample decomposed and burnt in overlapping reaction accompanied with the release of H2O, CO2 and several other fragments in a wide mass range (see the ion current curves in Fig. 2 and their assignment in Table 5) [22,23]. The decomposition of PP was endothermic, while the combustion was exothermic; and the net DTA peak was exothermic.…”

Routes to halogen‐free flame‐retardant polypropylene wood plastic composites

“…The flammability of different phosphorus‐based flame‐retardant systems and expandable graphite (EG) in PP was investigated, also with pretreated wood WPC, and the best results were achieved with multicomponent mixtures. The fire behavior of WPC containing intumescent flame‐retardant mixtures with APP and different char‐forming agents was studied .…”

“…[24][25][26] Thus, using nanofillers as adjuvants in combination with conventional flame retardants is the only successful "nano" route. [27][28][29] The flammability of different phosphorus-based flame-retardant systems and expandable graphite (EG) in PP 7,30,31 was investigated, also with pretreated wood WPC, 32,33 and the best results were achieved with multicomponent mixtures. The fire behavior of WPC containing intumescent flame-retardant mixtures with APP and different char-forming agents was studied.…”