Thermal degradation and flammability behavior of fire-retarded wood flour/polypropylene composites

Abstract

Magnesium hydroxide, expandable graphite, and ammonium polyphosphate were used to enhance the thermal stability and fire retardant properties on wood flour/polypropylene composites. The thermal decompositions and flammability properties were investigated using modulated thermogravimetric analysis and cone calorimeter, and the activation energy of each decomposition process was also determined by modulated thermogravimetric analysis. The results showed that both expandable graphite and ammonium polyphosphate promoted thermal degradation of wood flour and char formulation, and magnesium hydroxide did not influence on the wood flour decomposition. Unlike in nitrogen atmosphere, magnesium hydroxide and ammonium polyphosphate increased the peak temperature of wood flour thermal degradation and diminished the decomposition peaks of polypropylene in air atmosphere. Cone calorimeter results showed that expandable graphite greatly reduced the heat and smoke release. A general activation energy range of 187-226 kJ mol 21 (in nitrogen), 165-206 kJ mol 21 (in air) at wood flour degradation stage, 237-262 kJ mol 21 (in nitrogen), and 185-269 kJ mol 21 (in air) at polypropylene degradation stage were proposed for wood flour/polypropylene composite with and without fire retardants.

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]…”

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

“…Therefore, the development of PP‐based WPC with advanced mechanical properties that allow easy processing with versatile applicability presents a key puzzle in polymer engineering. One main task for the utilization of WPC in the building, automotive, and electronic industries is flame retardancy . The easiest route to obtain flame‐retarded WPC is to use halogenated flame retardants.…”

“…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 .…”

Studies on intumescent flame retardant polypropylene composites based on biodegradable wheat straw

“…So, making these kind materials flame retardant is necessary. Until now, although some research have been done on flame retardancy of PP composites base on ligin, starch, bamboo, wood flour, and so on, the research on flame retardant WSP composites still lacks study.…”