分子筛前驱体对定向刨花板性能的影响

人造板阻燃研究中常将分子筛用作阻燃添加剂或协效剂,但合成分子筛通常使用水热方法,耗能大、流程复杂。本研究采用LTA型分子筛的合成前驱体浸渍处理刨花并制备阻燃定向刨花板(OSB)。通过热重分析(TGA)和极限氧指数(LOI)测试对浸渍处理刨花的热分解行为和燃烧性能进行考察,采用锥形量热测试和力学性能测试探究了分子筛前驱体处理刨花对OSB阻燃性能和力学性能的影响,并考察了残炭的微观形貌和元素组成。结果表明:分子筛前驱体浸渍处理提高了刨花的成炭性能和热稳定性,浸渍处理刨花的LOI由19.1%提升到44.0%,达到难燃级别。浸渍处理刨花制备的OSB第1、第2热释放速率峰值分别降低了48.1%和32.2%,总热释放量和总烟释放量较对照组分别降低了42.4%和47.0%。浸渍处理OSB的可燃气体产量减少、残炭量明显提升,同时在刨花表面生成Na₂CO₃和α-Al₂O₃等物质,提升了炭层稳定性,表明分子筛前驱体在气相和凝聚相方面均能起到阻燃作用。分子筛前驱体在刨花表面的沉积使刨花含水率提高、胶层的胶接性能下降,导致浸渍处理刨花制备的OSB各项力学性能均有所下降,但仍满足定向刨花板行业标准LY/T 1580—2010中OSB/3型刨花板的性能要求。

Effect of zeolite precursor on properties of oriented strand board

Oriented strand board(OSB) is a rapidly developed new wood-based composites in China.However,the flammability of OSB brings serious threat to personal and public safety and restricts its applications.Zeolites were frequently applied as additives or synergists of flame retardants of wood composites,showing excellent improvement on the fire retardancy.As inorganic silicate crystal,zeolites are usually synthesized by hydrothermal method,which is rather sophisticated and consumes large amount of energy.To address this challenge,in this work,the precursor of LTA zeolite was prepared without hydrothermal treatment and applied to impregnate wood flakes.Flame-retardant oriented strand board(FROSB) was fabricated using the treated wood flakes.The thermal degrade behavior and combustion behavior of zeolite precursor treated samples were evaluated by the thermogravimetry analysis(TGA),limited oxygen index(LOI) test and cone calorimetry test(CCT).The mechanical properties of FROSB were also investigated.To investigate the fire-retarding mechanism,the micro-morphology and elemental composition of char residue were further analyzed.The results showed that the zeolite precursor deposited on the surface of wood flakes,leading to an increase of hygroscopicity.The LOI value of impregnated flakes was accordingly increased from 19.1% to 44.0%.TGA results showed that the precursor enhanced the char-forming performance and increased the thermal stability of flakes.The residue of treated wood flakes at 600℃ was increased from 22.43% to 45.21% due to the dehydration effect of zeolite precursor.Compared with the control group,the first and second heat release rate peaks during the combustion of FROSB decreased by 48.1% and 32.2%,respectively.The total heat release and total smoke production of FROSB were decreased by 42.4% and 47.0%,respectively.Furthermore,the average effective heat of combustion(av-EHC) was reduced,indicating that the less combustible gas was produced.Na₂CO₃ and α-Al₂O₃ were observed in the residue,which would enhance the thermal stability of the char.It was suggested that the zeolite precursor played an important role in both gas-phase and solid-phase fire-retarding mechanism.The mechanical properties of FROSB were decreased due to the deposition of the precursor,but still meet the requirements of mechanical properties of OSB/3 class according to LY/T 1580-2010 standard.This research provides a promising method for improving the fire safety of wood composites.