木材阻燃研究及发展趋势

近年,随着我国阻燃法规的建立健全,阻燃技术的不断发展,新型的木材阻燃剂及阻燃技术不断涌现。阐述了木材的化学组成及燃烧过程、木材阻燃剂类型、阻燃机理、木材阻燃处理方法及各种处理方法的优缺点,同时介绍了国内外木材阻燃研究的发展方向,对我国木材阻燃剂工业进一步发展提出了建议。木材阻燃的发展趋势是开发一剂多效的新型复合阻燃剂,同时深入探索阻燃机理,为组合新的阻燃体系提供有效的途径,使木材阻燃研究与市场实际需求相结合,为生产实践的应用提供了理论基础。     

胍类化合物对木材热行为的影响

用含P、N的化合物处理木材得到阻燃木材,通过用热分析,剩碳率,氧指数等一系列分析方法,对木材的热降解行为进行研究,用Braido方程计算降解反应活化能,实验表明经过阻燃处理的木材氧指数和剩碳率比未处理的木材升高,降解反应活化能和分解温度降低。     

微晶纤维素对阻燃聚乳酸复合材料力学性能、阻燃与热稳定性的影响

以经硅烷偶联剂(KH570)处理的微晶纤维素(MCC)为填料,三嗪系膨胀阻燃剂(CFA)与聚磷酸铵(APP)的复配体系为阻燃剂(C-IFR),聚乳酸(PLA)为基体树脂,采用熔融共混方法制备阻燃MCC/PLA复合材料,研究了MCC对阻燃PLA复合材料的力学、阻燃性能、热稳定性的影响。力学试验结果显示,MCC加入使PLA和阻燃PLA均比纯基体树脂的拉伸强度、弯曲强度有所降低,对悬臂梁缺口冲击强度影响小。MCC在小添加量时可以提高PLA复合体系的极限氧指数,MCC与APP具有的协同效应降低了PLA的燃烧速率,提高了材料的成炭性能。热降解动力学表明,MCC增加了PLA和阻燃PLA材料的活化能,提高了PLA复合材料的热稳定性,同时MCC降低PLA的玻璃化转变温度。     

微波超声波技术在阻燃剂浸渍处理木材中的应用

将微波处理与超声波辐射技术应用于木材阻燃处理中,利用微波加热处理改善木材构造的渗透性能,利用超声波的空化作用强化阻燃剂浸入性能。以ZR—M-301型木材阻燃剂为浸渍药液,樟子松和水曲柳为木材试样,选择常压浸渍、压力浸渍和微波处理后超声波加压浸渍3种木材阻燃处理方法,考察在生产阻燃木材的浸渍方法中引入微波和超声波技术的可行性,实验表明新的技术路线是可行的。     

新型木材阻燃剂FRW

新型木材阻燃剂FRW是一种具有阻燃、抑烟、防腐等多种效能的磷-氮-硼复合高效阻燃剂,适用于木材及其他纤维素类材料的阻燃处理,对木材的颜色、吸湿性、物理力学和加工性能基本无影响,在生产和使用过程中无环境污染。阻燃剂FRW的制备方法是由双氰胺和磷酸反应合成高纯度脒基脲磷酸盐(GUP),将GUP与硼酸和助剂复配得到产品。     

偶联剂与相容剂协同处理对马尾松木粉/PE复合材料性能的影响

为改善马尾松木粉/聚乙烯(PE)复合材料的性能,采用硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH550)、γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)、乙烯基三甲氧基硅烷(A171)对马尾松木粉进行表面处理,研究不同偶联剂与相容剂聚乙烯接枝马来酸酐(MAPE)协同处理对压制成型马尾松木粉/PE复合材料物理力学性能的影响。接触角测试与红外分析表明硅烷偶联剂成功接枝到木粉表面,且三种硅烷偶联剂处理均可降低马尾松木粉表面极性。三种硅烷偶联剂和MAPE均可提高复合材料的弯曲强度,同时会降低复合材料的吸水性和冲击强度。其中,利用KH550和MAPE协同处理制备复合材料的综合性能最好,处理后复合材料的静曲强度提高了88.55%、24 h吸水率降低了75.84%。     

木材及木塑复合材料的阻燃性能研究进展

木材阻燃机理主要有覆盖理论、热理论、不燃气体冲淡理论、自由基捕集理论、炭量增加和挥发物减少理论;人造板阻燃处理主要是在生产工序中添加阻燃剂和成板处理两种方法,高压处理法是目前最重要的工业化方法;以FRW阻燃剂、BL-环保阻燃剂为代表的磷-氮-硼系阻燃剂仍旧是木材阻燃剂的主流。对于木塑复合材料的阻燃研究尚处于起步阶段,一般采用对木纤维和基体分别阻燃的手段;研制高效膨胀型木材阻燃剂和将纳米技术应用于木材阻燃剂制造,开发阻燃效率高、低烟、低毒、环境友好等多功能复合阻燃剂将是今后阻燃剂研究领域的发展方向。     

木材构造对木材化学阻燃浸渍处理方法的影响

从木材构造对化学阻燃浸渍处理工艺影响的角度,指出在木材化学阻燃浸渍处理过程中,影响阻燃剂在木材中渗透性的木材主要微观构造有浸提物、纹孔等,分析了木材中水分的存在状态和木材中水分的移动与木材化学阻燃浸渍处理工艺的关系。探讨了强化木材化学阻燃浸渍处理的方法。采用微波技术提高木材的渗透性,采用超声波技术强化阻燃剂的浸渍。实验表明是一条可行的技术路线。     

聚磷酸铵疏水改性及其阻燃聚乙烯的性能研究

利用十八烷基胺对聚磷酸铵（APP）进行表面修饰改性,通过静态接触角对改性后的APP进行润湿性能的测试,其接触角达到了136°,说明改性后的APP具有良好的疏水性能。将改性的APP与成炭发泡剂（CFA）以4:1的比例进行复配后加入到聚乙烯（PE）中,制备阻燃PE材料,并通过氧指数（LOI）和垂直燃烧研究了材料的阻燃性能,通过拉伸和弯曲测试研究了材料的力学性能,通过水煮的方法研究了阻燃材料的耐水性。测试结果表明,与未改性的APP相比,APP的表面改性使得阻燃PE材料的阻燃性能略有降低,但提高了阻燃剂与聚合物的相容性,阻燃PE的力学得到了提高,同时阻燃材料的耐水性能得到了大幅度的提高,其阻燃剂的水抽出率大大降低,当阻燃剂的添加量为25%时,阻燃材料的抽出率仅为0.12%。     

木材阻燃浸渍处理方法及新的技术

介绍了国内外目前在木材阻燃浸渍处理行业普遍使用的常压处理方法和真空一加压处理方法，在回顾传统木材阻燃浸渍处理方法的基础上，从生产设备小型化、连续化、操作简单化的角度介绍了具有一定应用前景的木材阻燃浸渍处理新技术，如微波处理技术和超声波处理技术等。     

Wood fiber surface treatment level effects on selected mechanical properties of wood fiber-cement composites

The objective of this study was to determine the effects of sodium (N) silicate, potassium (K) silicate, and silane (Si) treatment levels on newspaper and unbleached kraft fibers for enhancing selected mechanical properties of wood fiber-cement composites compared to untreated wood fiber-cement composites. Both wood fiber types were treated with selected aqueous solution strengths, air dried, and mixed with water and cement. The bending and compression properties of the specimens were determined after 28 days of hydration. Results of this study indicated that the aqueous chemical treatments of the wood fibers enhanced some of the mechanical properties of wood fiber-cement composites compared to the untreated wood fiber-cement composites. The enhancement depended on chemical treatment and wood fiber type. All three chemical treatments of newspaper fiber enhanced the normalized toughness values compared to the untreated newspaper fiber-cement composites. In addition, higher treatment levels using N silicate with newspaper fiber improved the compressive strength and bending modulus of the composites compared to the untreated newspaper fiber-cement composites. Kraft fiber treated with all three chemicals enhanced the compressive strength, bending modulus and bending strength compared to the untreated kraft fiber-cement composites. However, only silane-treated kraft fiber improved the normalized toughness values compared to the untreated kraft fiber-cement composites. The results of the study indicated that certain chemical treatments react better with different wood fiber types resulting in selected mechanical property enhancements.     

Mg（OH）2/包覆红磷对阻燃聚丙烯性能的影响

研究了Mg（OH）2和Mg（OH）／包覆红磷复配阻燃聚丙烯的性能及阻燃剂的阻燃机理,对阻燃聚丙烯进行力学性能测试、阻燃性测试．用扫描电镜二次电子成像分析试样的拉伸断口。结果表明：Mg（OH）／包覆红磷复配物比Mg（OH）2阻燃的聚丙烯的阻燃效果要好,但阻燃聚丙烯力学性能下降幅度大。     

Effect of High-Temperature Treatment on the Mechanical Properties of Rowan (Sorbus aucuparia L.) Wood

Heat treatment is a wood modification method that has been used to some extent in improving timber quality. The high temperature thermal treatment of wood is an environmentally friendly method for wood preservation. This technique has attracted considerable attention both in Europe and in North America in recent years.

This article presents the results of experimental studies on influence of heat treatment on the mechanical properties of Rowan (Sorbus aucuparia L.) wood performed in order to understand its role in wood processing. Samples were exposed to temperature levels of 120, 150, and 180°C for time spans ranging from 2 to 10 h. Mechanical properties including compression strength, modulus of elasticity, modulus of rupture, Janka hardness, impact bending strength, tension strength perpendicular to grain, tension strength parallel to grain, shear strength, and cleavage strength of heat-treated samples were determined. Maximum reduction values of 34.12, 28.40, and 26.37% were found for impact bending strength, tension strength parallel to grain, and cleavage strength for the samples exposed to 180°C for 10 h, respectively. Overall, the results showed that treated samples had lower mechanical properties than those of the control samples. Statistically significant difference was determined (P = 0.05) between mechanical properties of the control samples and those treated at 180°C for 10 h.     

Effect of wood species on the mechanical and thermal properties of wood–plastic composites

The effect of wood species on the mechanical and thermal properties of wood–plastic composites (WPCs) was explored. Various wood species, including cherry, sweet gum, hickory, yellow poplar, Osage orange, walnut, eastern red cedar, pine, maple, and red oak, were compounded with virgin isotactic polypropylene in a 50 : 50 weight ratio and injection‐molded. The tensile strength of WPCs made with cedar and hickory was higher than that of WPCs made with maple, oak, and Osage orange. The tensile modulus of WPCs made with gum and walnut was higher than that of oak WPCs. The tan δ peak temperatures and peak values from dynamic mechanical analysis indicated that pine and hickory WPCs had higher amorphous or void contents than walnut and cherry WPCs. The induction time during isothermal crystallization suggested that red cedar, cherry, and gum WPCs had higher nucleation density than walnut, pine, and oak WPCs. Dynamic mechanical properties of the WPCs appeared to be related to the crystallization behavior of the wood flour, which depends on the surface roughness. Although there were statistically significant differences in mechanical properties among the species, the differences were small, implying that wood flours from many species can be used successfully as raw materials for WPCs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The Effects of Heat Treatment on Some Mechanical Properties of Juvenile Wood and Mature Wood of Eucalyptus grandis

Heat treatment is a well-known method for modifying wood that is applied in different ways, and treatment schedules change from tree to tree. This treatment improves the physical properties of wood but, in general, it reduces the mechanical properties of wood. The effects of heat treatment on the mechanical properties of juvenile and mature wood of the same tree species have not been well-defined. Therefore, we focused our study on the differences in the mechanical properties of juvenile wood and mature wood of Eucalyptus grandis after both were subjected to heat treatment. Wood samples were treated at temperatures of 120, 150, and 180°C for 4, 6, and 8 h. The test results showed that decreases in the mechanical properties of juvenile wood (e.g., modulus of elasticity (MOE), modulus of rupture (MOR), compression strength (CS), and impact bending (IB)) were greater than the decreases that occurred in mature wood that was heat treated at the same conditions.     

PVC/锯末塑木材料的研制

以锯末和PVC胶粘剂为主要原料，用高速混合机制备了PVC／锯末塑木材料，并通过平板硫化机热压成型，制备出了新型的PVC／锯末塑木板材；测试了塑木板材的拉伸强度，弯曲强度，冲击强度，拉伸弹性模具，弯曲弹性模量等力学性能，讨论了增塑剂和胶粘剂用量对塑木板材性能的影响，实验结果表明：随增塑剂用量的增大，PVC／锯末塑木板材的刚性下降，韧性升高；随胶粘剂用量的增大，PVC／锯末塑木板材的力学性能和耐水性均有提高。     

PVC/α-MSAN共混物的性能研究

采用机械共混法制备了PVC与α-甲基苯乙烯类-丙烯腈共聚物(α-MSAN)共混材料,探讨了α-MSAN用量对共混材料的力学性能、耐热性能和加工性能的影响。结果表明:α-MSAN可以改善共混材料的耐热性能和加工性能;随着α-MSAN用量的增多,共混材料的热变形温度(最大弯曲正应力分别为1.80 MPa和0.45MPa)、拉伸强度、弯曲强度、弯曲模量和熔体流动速率上升,而冲击强度、断裂伸长率下降。综合考虑性能与成本等因素,α-MSAN用量为30份最佳,此时,共混材料的热变形温度由72.4℃提高至81.6℃(最大弯曲正应力为1.80 MPa)。     

无机-有机物包覆红磷的制备与应用研究

以红磷为囊芯,Mg(OH)2和聚氯乙烯为囊材,采用沉淀法制备无机-有机物包覆红磷(IOERP)。通过FESEM、XPS、TG等分析手段对其表征。结果表明:FESEM显示红磷表面包覆层均匀,XPS表明红磷表面包覆率达到97.18%,TG结果显示经包覆后的红磷着火点提高到430℃。以阻燃性能和力学性能为指标,考查红磷和IOERP对丙烯腈-丁二烯-苯乙烯塑料的阻燃和力学性能影响。测试结果显示:IOERP比红磷阻燃ABS的效果好,且力学性能有所提高。     

木粉改性处理与木塑复合材料性能研究

通过对木粉进行改性处理,研究了不同改性剂及处理条件对高密度聚乙烯木塑复合材料物理力学性能的影响。结果表明:改性剂使木粉的玻璃化温度降低,纤维素的结晶度提高;随着改性剂用量的增加,木塑复合材料的弯曲强度、拉伸强度、弹性模量都有所提高,吸水率也略有升高;50℃下处理48h的木粉制备的木塑复合材料的物理力学性能较好;改性剂C处理的木塑复合材料综合性能较好。     

聚酯型双键封端聚氨酯预聚物的合成及其在团状模塑料中的应用

以高附着力耐温二元醇（XC-488）、甲苯二异氰酸酯（TDI）、甲基丙烯酸羟乙酯（HEMA）为原料,合成了聚酯型双键封端的聚氨酯预聚物（HPU）,然后将不同含量的HPU与不饱和聚酯树脂、短切玻璃纤维、碳酸钙、阻燃剂等进行共混,用于团状模塑料（BMC）的制备。通过傅里叶变换红外光谱、差示扫描量热仪、力学性能、吸水率、熔体流动性、耐酸碱性、耐老化测试和扫描电子显微镜进行测试。结果表明,当HPU的含量为6 %（质量分数,下同）时,BMC复合材料的综合力学性能最好,此时复合材料的拉伸强度、弯曲强度、冲击强度分别为（47.24 ±0.42） MPa、（117.76±0.65）MPa、（33.8±0.2） kJ/m²。