炭化杨木单板制备胶合板的氧指数和热重分析

林业工程学报,2016,1(2):17-20Doi:10.13360/isn,2096-139.2016.02.03炭化杨木单板制备胶合板的氧指数和热重分析关明杰',常馨曼',薛明慧',王炳忠2’,翟通军2(1南京林业大学材料科学与工程学院南京210037;2连云港南方木业有限公司,江苏灌南222500)摘要:通过研究不同炭化处理温度下的杨木单板制备胶合板的氧指教和热重分析,以评价其阻燃性能。分别将160,180和200℃炭化处理后的单板热压制成5层对称结构胶合板,氧指数和热重分析结果表明:炭化处理后的胶合板氧指数均高于未处理的胶合板,当炭化条件为200℃和2h时,胶合板氧指数最大值为30.3%,达到B3级难然材料标准。由TG-DIG曲线可知,炭化处理前后胶合板的TG、DTC曲线变化趋势完全一致,主要差异体现在最终的成炭率、肩峰及特征峰对应的具体温度上。炭化条件为200℃和2h时的最终成炭奉为21·04%达到最大值;肩峰对应温度随炭化温度的升高而降低,炭化处理后胶合板特征峰对应温度均小于未处理的胶合板。关键词:杨木;炭化处理;氧指数;热重分析;胶合板中图分类号:TU531.2;T653.3文献标志码:A文章编号:2096-1359(2016)02-0017-04Oxygen index and thermalgravimetric analysis ofpoplar plywood by carbonized veneerGUAN Mingjie, CHANG Xinman, XUE Minghui, WANG Bingzhong, ZHAI Tongjun(1. College of Materials Science and Engineering, Nanying Forestry Univeristy, Nanying 210037, China;2. Nanfang Wood Products Ltd. Co. Liangyungang, Guannan 222500, Jiangsu, China)Abstract: This paper aimed at investigating the effect of veneer carbonization treatment on the fire resistance propertieof poplar plywood by means of Oxygen Index(OI)and thermalgravimetric analysis. The poplar veneers carbonized in160, 180 and 200 C respectively for 2 h were used to produce five-layer plywood with melamine-urea-formaldehyderesin. a series of parameters of the carbonized plywood were tested in aspects of bonding shear strength, Modulus of Elasticity( MOE), Modulus of Rupture( MOR)and Ol Thermalgravimetric analysis was also used to analyze the thermalproperties of plywood correspondingly. The results showed that the bonding shear strength and mor decreased as the in-crease of carbonized temperature of poplar veneer, while MOE of plywood increased with the increase of carbonized temperature slightly. As a whole, bonding shear strength, MOE, MOR of the plywood from carbonized veneer declined obviously compared with those of control group. Bonding shear strength and mOR of the carbonized plywood from 200C and2 h decreased by 12. 7% and 38. 3% respectively, and MOE of the three carbonized plywood declined 26% to 30%. TheOI results showed that the oI in carbonization treatment groups were higher than that of control group. At the carbonize-tion condition of 200 and 2 h, the ol of the carbonized plywood was 30. 3%, reaching grade B, standard of refractorynaterials according to the classification for burning behavior of building materials and products( GB 8624-2012) Fromthe TG-DTG analysis curves, the variation tendency of the four groups were consistent, the differences were mainly inthe specific temperatures of final char yield, the acromion and characteristic peaks. Under the condition of 200C andh, the final char yield was 21. 04%, reaching the maximum value among four plywood groups. The temperature of acromion decreased with the rising of carbonization temperature, and the temperature of characteristic peaks in the carbon-ized groups were lower than that of control plywood. Generally, carbonization treatment on veneer improves the final charyield and Ol of plywood. It is supposed to be a new way to improve the fire resistance of plywood without any chemicalKey words: poplar; carbonization treatment; oxygen index; thermalgravimetric analysis; plywood修回日期:2015-11-03中国煤化工收稿日期:2015-07-3基金项目:苏北科技发展计划-科技型企业技术创新项目(BC2013425);江苏高校优势学利CNMHG作者简介:关明杰,女,副教授研究方向为竹木材的加工利用。 E-mail; mingjieguand@ hotmailcom林业工程学报第1卷杨树是重要的速生树种,基本密度为0.35g/汽对单板进行炭化处理。炭化时间均为2h时,设cm3,颜色浅,含水率高极易加工,我国南北方均定炭化温度分别为160,180和200℃,分别标记为有广泛种植。但杨木单板材质软尺寸稳定性差,a、b、c组,另设对照组d(表1)。制成的胶合板易吸湿产生变形,因此其应用受到广表1杨木单板炭化分组泛限制。为充分利用杨木资源,增加产品的附Tab,1 Carbonization treatment group of poplar veneer加值,需要对杨木单板进行改性处理。目前常用的炭化时间/h炭化温度/℃改性方法包括物理和化学改性方法,物理改性方法中常用的是炭化改性,化学改性方法则包括乙酰化单板浸渍等方法23)。由于化学改性方法引入未处理了其他化学成分,会对杨木单板的胶合产生消极影响污染大且后期处理工艺复杂。而炭化处理是通122杨木胶合板制备过对木材进行热处理降低其组分中吸水羟基的密单板涂胶量为220g/m2(双面),涂胶后的板度,从而减弱木材的吸湿性及内应力加强木材的坯采用5层对称结构组坯陈放热压。热压工艺尺寸稳定性4。炭化处理很少添加化学药剂,污为100℃、1.0MPa、1min/mm,自然冷却在20染问题少、处理工艺简单且炭化后木材具有良好的℃、(65±2)%的调制箱中调质平衡,制得与表1耐老化性能、尺寸稳定性及安全、环保等突出优对应试验编号下的胶合板每组胶合板试验张数为点。而国内外对炭化木质材料的物理、力学、化5张。学性能研究主要集中在炭化木材上70,对炭化单1.23杨木胶合板物理力学性能测试板制备的胶合板的可燃性能评估关注极少。参照GB/T17657-2013《人造板及饰面人造笔者通过炭化杨木单板制备胶合板,测试胶合板理化性能试验方法》测定杨木胶合板的胶合强板的极限氧指数,并对其进行热重分析,以期找到度、弹性模量和静曲强度等物理力学性能。炭化处理工艺对胶合板性能的影响规律,从而为今1.2.4杨木胶合板氧指数(OD)测定后国内外对炭化木质复合材料燃烧性能研究提供将制得的杨木胶合板锯制成尺寸为100mm技术参数,为速生材的综合利用开发、产出高附加10mm(厚度<10.5mm)的试样,每组试件数量15值产品提供技术指导参考。个,在每个试件距离一端50mm处划线做标记。材料与方法参照GB/T2406-2009,将试件未划线一端固定在燃烧筒中,使氧氮混合气流由下向上流过,用1.1试验材料点火器点燃试样顶端,同时观察并记录试件燃烧时杨木单板500mm×500mm×2mm,取自江苏间及燃烧长度。试件燃烧时间达到3min或者燃省灌南县,单板气干含水率为7%-10%;三聚氰胺烧长度超过50mm时,所需最低氧气浓度即为试改性脲醛树脂,固含量52.6%,黏度190mPa·s,由件氧指数。经反复测试,找出达到临界值的氧气浓江苏舜天利华木业有限公司提供。度,得到试件的氧指数。炭化箱,南京恒裕仪器设备制造有限公司,型1.2.5杨木胶合板热重分析号THX-3;电加热蒸汽锅炉,上海捷士服装机械有将制得的杨木胶合板研磨成粉末并过60目限公司,型号DZC-4.5E。JF-3氧指数测定仪,南(0.25mm)筛网,将所得粉末置于高纯动态氮气京市江宁区分析仪器厂;TG209F3 Tarsus型热重内,从室温升至700℃(升温速率为10℃/min),分析仪,德国 NETZSCH公司。进行热重分析。1.2试验方法1.2.1杨木单板炭化2结果与分析由电加热蒸汽锅炉提供炭化处理过程中所需2.1胶合板物理力学性能的过热蒸汽作为保护气体,隔绝氧气的同时参与部杨木胶合板的胶合强度、弹性模量和静曲强度分加热,使温度过高时木材不致燃烧损毁。测试结果见表2。随着炭化温度的升高,胶合板的将杨木单板放入炭化箱中调节炭化箱温度至胶合强度和静rV凵中国煤化工弹性模量却预设温度。温度达到后,打开电加热蒸汽锅炉维略有提高这可CNMH板的表面润持蒸汽压力0.2MPa,持续向炭化箱中通入过热蒸湿性降低胶液渗透少,形成的胶层更厚胶层为脆第2期关明杰,等:炭化杨木单板制备胶合板的氧指数和热重分析性多孔高密度层,可提高胶合板的弹性模量,但对规定:B1级为难燃材料,B2级为可燃材料,B1级氧强度的贡献不大。因此,随着炭化温度的升高,处指数O≥30%,B2级氧指数OI≥26%。由图1可理后的单板压制的板材抗弯弹性模量有增高的现知,C组的氧指数达到B级难燃材料的标准,而A、象,但与对照组相比,炭化单板所制胶合板的3项B、D组均为B2级可燃材料。单板炭化处理可以在性能指标都有明显下降,抗弯弹性模量的下降最明定程度上提高胶合板燃烧的氧指数,从而降低胶显,降幅达到26%~30%,而C组的静曲强度下降合板的燃烧性能达到38.3%,胶合强度的下降达到12.7%。表2炭化单板胶合板的基本物理力学性能Tab 2 Basic physical and mechanical properties ofplywood by carbonized veneer/M编号胶合强度弹性模量静曲强度A2.2244.33B2.14C2.06D2.36673753.17图1胶合板氧指数Fig 1 Oxygen index of plywood2.2胶合板氧指数胶合板的氧指数如图1所示,D组的氧指数为2.3胶合板热重分析9.2%,A组为29.8%,B组为29.5%,C组为采用热重法得到程序控制温度,各组试件的质30.3%,即炭化组胶合板的氧指数均大于对照组,量随温度变化的曲线(TG曲线)及对热重曲线进但测试出的炭化组之间氧指数差异不明显。根据行一次微分所得的微商热重曲线(DTG曲线)如图GB8624202《建筑材料及制品燃烧性能分级》2所示。80A组2.580B组TO7.5§240-10.02010020030040050060070012500200300400500600700温度/℃80+C组TO80D组DTG50004005006000100200300400500600700温度/℃C温度/℃图2各组试件的TG-DIG曲线Fig 2 TG-DTG curves of carbonized groups and control group由TG和DTG曲线可看出:在室温至100℃范是由于残余木质素的热解。4组试件在280~295围内出现一个失重峰,此阶段主要是杨木胶合板的℃之间均出现一个肩峰,该峰值说明以半纤维素和水分析出,当温度达到80℃时已基本完全失重;在木质素为主要的聚合物在此温度阶段达到热解最100-400℃范围内出现一个较大失重峰,这是由大程度,杨木胶合板进入以纤维素和木质素为主要于大量的挥发分析出,温度达到400℃时,胶合板热解聚合物的20-35,之间,DTG曲的失重率约为70%;温度高于400℃后,随着温度线出现一个牛中国煤化质素出现热的增加,失重速率逐渐放缓,这时木材的失重主要解高峰1,互,曲线变化趋势20林业工程学报第1卷完全一致,主要差异体现在最终的成炭率、肩峰及nal of Central South University of Forestry Technology, 2014特征峰对应的具体温度上。34(3):99-1034组胶合板热解的最终成炭率、肩峰及特征喹[2]雷得定,周军浩,刘波,等.木材改性技术的现状与发展趋势[J].木材工业,2009,23(1):37对应温度见表3,未处理组最终成炭率为20.55%,Lei DD, Zhou J H, Liu B, et al. 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