摘要
分别对杨木单板进行高温加热和硅烷溶液喷淋处理,并与高密度聚乙烯(High Density Polyethylene,HDPE)薄膜胶合制备木塑复合胶合板,利用扫描电镜(SEM)和动态热机械仪(DMA)分析了两种改性方法对木塑复合胶合板抵抗水分子破坏能力的影响。结果表明:3次"湿-冷冻-热"循环对未处理和高温处理材的破坏程度较大,循环处理后胶接结构中存在明显的裂缝及脱落的HDPE碎片。硅烷处理可以显著提高木塑复合胶合板的耐湿循环能力,胶接结构中仅存在少量的裂纹。胶接结构的破坏引起了胶合强度不同程度的降低,未处理、高温处理和硅烷处理材的胶合强度保留率分别为57%,72%和84%。DMA结果表明:水分子的交替作用显著降低了未处理和高温处理材的热稳定性,而对硅烷处理材的影响较小。当环境温度达到200℃时,未处理和高温处理材的胶接界面结构完全破坏,木材单板与塑料薄膜两相完全分离。
In order to study the effects of surface modification on the wet cycle resistance of wood-plastic plywood, woodveneer surface was thermally modified in an oven at 200 ℃ or chemically modified by vinyltrimethoxysilane （silane A-171 ）. The untreated and two treated veneers were used to prepare wood-plastic plywood （WPP） with high density poly-ethylene （HDPE） films as wood adhesives by improved hot-pressing technology. The tensile strength, modulus of rupture（MOR） and modulus of elasticity （MOE） of the samples were compared. Thermal stability and the bonding structure af-ter bond durability tests （three times of water-freezing-dry circulation） were also evaluated by dynamic mechanical anal-ysis （DMA） and scanning electronic microscopy （SEM）. Both cohesive and interracial failure existed in the WPP afterbond durability experiments according to the SEM study. Obvious cracks along the interface and the fragments of HDPEwere observed in both untreated and thermal-treated samples, while there were only a little bit of break for silane-treatedsamples after the bond durability tests. Different failure kinds of the bonding structure lead to the decrease in mechanicalproperties of WPP at different levels. The retention rate of tensile strength for the untreated, thermal-treated and silane-treated samples after 3 cyclic tests were 57%, 72% and 84%, respectively, while the retention rate of MOR and MOEvalues were both higher than 80%. Thermal stability of WPP was also weakened after bond durability tests according tothe DMA results. Plastic film was totally separated from both untreated and thermal-treated poplar veneers when the sam-pies were heated up to 200 ℃. However, HDPE film could be still closely cohered with silane-treated veneer in thewhole stage and the bonding structure was not destroyed.
出处
《林业工程学报》
北大核心
2016年第1期37-41,共5页
Journal of Forestry Engineering
基金
江苏省自然科学基金项目(BK20150881)
南京林业大学高学历人才基金项目(GXL024)
