超支化聚乙烯亚胺聚磷酸铵对定向刨花板性能的影响
Effect of hyperbranched polyethyleneimine ammonium polyphosphate on the properties of oriented strand boards
王帅旗 1叶超宇 1段衍筠 2李万兆 1梅长彤 1潘明珠1
作者信息
- 1. 南京林业大学 材料科学与工程学院,南京 210037
- 2. 南京林业大学 机电产品包装生物质材料国家地方联合工程研究中心,南京 210037
- 折叠
摘要
本文以超支化聚乙烯亚胺(PEI)改性的聚磷酸铵(APP)为阻燃剂(PEI/APP)、以酚醛树脂(PF)为胶粘剂制备定向刨花板(OSB).采用DSC探讨了PEI/APP对PF固化过程的影响,PEI/APP能够与PF形成分子间的氢键和亚胺键(C=N)促进PF的固化过程,使其等温固化时的放热峰温度降低至 71.6℃,终止固化温度降低至 74.1℃.采用力学性能分析仪、数字图像相关(DIC)和X射线计算机断层扫描扫描仪(X-CT)探究OSB的力学性能及其增强机制.相比于APP添加量为 9wt％的定向刨花板,PEI/APP添加量为 9wt％的OSB主向(L)和次向(H)的弹性模量分别提高了 21.1％和 20.7％;主向和次向的弯曲强度分布提高了 10.8％和 19.6％,内结合强度提高了 6.9％,吸水厚度膨胀率降低了 37.9％.DIC显示,OSB在承受弯曲载荷时,应变积累主要发生在顶层和底层,然后沿着或穿过中心层传播.主向的顶层和底层结构变化为股线分层或折断,次向上仅出现折断.X-CT测试结果显示,PEI/APP和PF树脂均匀分散在OSB的表层和芯层.因此,超支化改性提高了APP与大片刨花、PF树脂之间的界面结合,使得应变沿着中心层的传递更明显,中心层吸收载荷能量,从而提高了OSB的弯曲强度.采用极限氧指数(LOI)和锥形量热仪测试了OSB的阻燃性能,当PEI/APP添加量为 9wt％时,OSB的极限氧指数为 46.3％,热释放速率峰值为 131.2 kW/m2,相比于APP添加量为 9wt％的OSB,其极限氧指数提高了 27.9％,热释放速率峰值降低了 14.2％.超支化改性APP能够促使OSB脱水炭化产生连续致密的膨胀炭层,同时产生NH3,实现气相和凝聚相的协同阻燃.阻燃高强的定向刨花板在绿色建筑、家居、交通应用领域具有十分广阔的应用前景.
Abstract
In this paper,we are using hyperbranched polyethyleneimine(PEI)modified ammonium polyphosphate(APP)as flame retardant(PEI/APP)and phenol formaldehyde resin(PF)as an adhesive to prepare oriented strand boards(OSB).Using DSC to explore the influence of PEI/APP on the curing process of PF,PEI/APP was able to form intermolecular hydrogen and imine bonds(C=N)with PF to promote the curing process of PF,so that the peak temperature of curing was lowered to 71.6℃,and the end of curing temperature was lowered to 74.1℃.Using mechanical property analyzer,digital image correlation(DIC)and X-ray computed tomography(X-CT)to understand the mechanical properties of OSB and its enhancement mechanism.Compared to OSB with 9wt％APP addition,the modulus of elasticity of OSB with 9wt％PEI/APP addition increased by 21.1％and 20.7％in the major(L)and minor(H)directions,respectively;The major and minor modulus of rupture was increased by 10.8％and 19.6％,the internal bond strength was increased by 6.9％,and the thickness swelling of the absorbed water was reduced by 37.9％.DIC shows that when OSB is loaded in bending,strain accumulation mainly occur in the top and bottom layers and then propagate along or across the central layer.Structural changes in the top and bottom layers of major specimens was either strand delamination or snap off,while only snap off is found in minor specimens.X-CT test results show that PEI/APP and PF resins are widely spread in the surface layer and core layer of OSB.Therefore,the hyperbranching modification improves the interfacial bonding between APP and the large wood shavings and PF resins,which results in making strain transfer along the center layer more pronounced.The center layer absorbs the energy of the load,which improves the bending strength of the OSB.The flame retardancy of OSB was tested using limiting oxygen index(LOI)and cone calorimetry.Its LOI increases by 27.9％and its peak heat release rate decreases by 14.2％.Hyperbranched modified APP could induce OSB dehydration charring to produce a dense and continuous expanded char layer,and at the same time produce NH3 to realize synergistic flame retarda-tion in both gas and condensed phases.Flame-retardant and high-strength OSB has a very wide application prospect in the field of green building,furniture and transportation applications.
关键词
定向刨花板/复合聚电解质/酚醛树脂固化动力学/动态应变传递/X射线计算机断层扫描Key words
oriented strand board/polyelectrolyte complex/curing kinetics of PF/dynamic strain transferal/X-CT引用本文复制引用
出版年
2024
NETL
NSTL
万方数据