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Search Results: 1 - 10 of 49052 matches for " 梅长彤 "
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大室法条件下人造板的甲醛散发量

南京林业大学学报(自然科学版) , 2001, DOI: 10.3969/j.jssn.1000-2006.2001.05.013
Abstract: <正>分别用穿孔法和大室法研究了4种人造板材(胶合板、细木工板、刨花板和中密度纤维板)的甲醛散发水平。结果表明,人造板的穿孔值与其胶木比存在正比关系;胶合板、刨花板、中密度纤维板的穿孔法与大室法测试结果之间有着良好的一致性,细木工板在大室法条件下表现出较高的甲醛散发水平;大室法条件下的人造板甲醛散发速率呈指数函数规律衰减,给出了大室法条件下人造板甲醛散发量水平的预测公式。
纳米SiO2-APP对木塑复合材料界面特性及力学性能的影响
潘明珠,
北京林业大学学报 , 2013,
Abstract: 用聚磷酸铵(APP)与阻燃协效剂纳米二氧化硅(SiO2)制备了阻燃型木塑复合材料,并利用FTIR、SEM和力学性能测试仪,探讨纳米SiO2的添加量(2%、4%、6%)和APP的添加量(8%、10%、12%)对木塑复合材料的界面性能和力学性能的影响。结果表明:1)当纳米SiO2添加量为2%~6%、APP添加量为8%~10%时,两者可以均匀地分布在木塑复合材料的孔隙中,并且纳米SiO2可以与木质纤维形成Si—O—C结合,改善复合材料的界面性能;但是,APP添加量增加至12%时,纳米SiO2和APP之间会发生团聚,降低了复合材料的性能。2)当纳米SiO2添加量为2%~6%、APP添加量为8%~10%时,木塑复合材料的拉伸强度和弯曲强度均比未添加纳米SiO2、APP的有所增加,拉伸断裂伸长率基本保持不变,冲击强度降低。通过双因素方差分析可知,纳米SiO2、APP的添加量以及两者之间的交互作用对拉伸性能、弯曲性能无显著影响,但APP的添加量以及两者之间的交互作用对冲击强度有显著影响。
刨花形态及定向角度对刨片层积材性能的影响
彭明凯,*
南京林业大学学报(自然科学版) , 2009, DOI: 10.3969/j.jssn.1000-2006.2009.04.028
Abstract: 为优化刨片层积材(lsl)的生产工艺,提高刨片层积材性能,研究了速生杨木刨片层积材的刨花形态和刨花定向角度对其力学性能的影响。结果表明:刨花长度的增加有利于刨片层积材静曲强度(mor)和弹性模量(moe)的提高,但内结合强度略有下降;刨花宽度对lsl物理力学性能的影响较小;刨花厚度的增加使lsl物理力学性能下降。表层定向角对刨片层积材性能影响较大,顺纹方向上,表层定向角越小,层积材的mor和moe越大;芯层定向角度对刨片层积材性能影响较小。芯层随机铺装在一定程度上有利于层积材的内结合强度的提高。
面向21世纪的农作物秸秆材料工业
周定国,
南京林业大学学报(自然科学版) , 2000, DOI: 10.3969/j.jssn.1000-2006.2000.05.001
Abstract: <正>围绕贯彻天然林保护政策和中国木材资源短缺的实际,提出了用农作物秸秆替代木材原料发展材料工业的构想。从农作物秸秆贮量、特性和加工方法等方面探讨了开发农作物秸秆材料工业的可能性,介绍了几种农作物秸秆材料产品,如秸秆板材料、秸秆建筑材料、秸秆包装材料、秸秆模压材料等,讨论了21世纪中国农作物秸秆材料工业的发展前景。
人造板热压参数检测系统的研究与开发
周又平,刘云飞,
南京林业大学学报(自然科学版) , 2007, DOI: 10.3969/j.jssn.1000-2006.2007.01.017
Abstract: <正>在断裂力学理论基础上,应用有限元软件abaqus。采用20结点等参元有限元模、型。对路面基层裂缝进行数值计算。并采用p-m准则和paris公式预测了基层裂缝扩展寿命,分析探讨了应力强度因子k1和kz在基层裂缝扩展过程中的变化规律及路面结构参数对基层疲劳寿命的影响。计算结果真实反映路面结构的现象和规律,可为高等级公路抗裂设计提供依据。
水平密度变异对木质定向结构板性能的影响(英文)
,戴春平,周定国
南京林业大学学报(自然科学版) , 2002, DOI: 10.3969/j.jssn.1000-2006.2002.06.001
Abstract: <正>人造板产品的大部分性能指标与板材的密度有关。长期以来,为了节约成本,降低能耗,定向结构板工业界一直在探索一种既能降低定向结构板的密度,又保持其性能符合标准要求的方法,因为低密度板材意味原料需要量减少,热压压力降低。笔者分析了有水平密度差异和没有水平密度差异的两种板材的密度变化对板材胶合性能的影响,及其对用大片刨花板制成的模拟定向结构的板材性能的影响,并讨论了密度变化对板材静曲强度、内部结合强度和厚度膨胀率的影响。
天然纤维/聚合物复合材料的研究进展
黄润州, , 冒海燕, , 徐信武, WU Qinglin
南京林业大学学报(自然科学版) , 2016, DOI: 10.3969/j.issn.1000-2006.2016.03.027
Abstract: 从传统均相结构、共挤出型芯-表结构的天然纤维/聚合物复合材料、纳米纤维素及微(纳)米纤维/聚合物复合材料3个方面综述了国内外利用天然纤维增强聚合物复合材料的研究现状。芯-表结构的天然纤维/聚合物复合材料(NFPC)作为新型的绿色环保型材料已成为研究热点。使用芯-表结构可以显著改善复合材料的综合性能,大大提高复合材料的使用率,并使其在原料使用和材料性能与功能上更符合循环经济和绿色环保的原则。芯-表结构NFPC的芯层与表层间的界面性能是影响芯-表结构NFPC整体性能的主要因素。在此基础上,笔者从农作物纤维/聚合物复合材料的高值化应用的角度,分析了天然纤维/聚合物复合材料研究方向和应用方面存在的主要问题及解决思路。
As a new-generation green composite, nature fibers/ polymer composites(NFPC), mading of thermoplastics filled with nature agriculture fibers and other additives, has been recently developed and used to enhance performance characteristics of composites. In this paper, typical NFPC,core-shell structure NFPC(co-extrusion)and cellulose nanofibers(CNFs)and its filled composites have been systematically reviewed. The shell layer, mading of thermoplastics unfilled or filled with minerals or nature fibers and other additives, plays a critical role in enhancing overall composite properties. A fundamental understanding of the interactions between shell and core layers with different structural and material combinations is, however, needed to achieve desired product performance. The results of this paper can help to provide a fundamental base for developing new functional applications of NFPC
皮层对皮-芯结构木塑复合材料性能的影响
黄润州, , 徐信武, 冒海燕, WU Qinglin, 戴 翔
南京林业大学学报(自然科学版) , 2017, DOI: 10.3969/j.issn.1000-2006.201609015
Abstract: 【目的】研究在两种不同芯层材料的复合体系下,增强材料含量与皮层厚度对共挤出(皮-芯结构)木塑复合材料弯曲与热膨胀性能的影响。【方法】以共挤出技术为加工工艺,选取短玻璃纤维(SGF)为皮层的增强材料,制备共挤出型(皮-芯结构)木塑复合材料(WPC)。分析了在芯层1与芯层2两种复合体系下,不同皮层厚度(1.0、1.2及1.6 mm )和皮层填料含量(0%、10%、20%、30%和40%)对共挤出型皮-芯结构WPC的弯曲性能和热膨胀性能的影响。【结果】当表面为纯的高密度聚乙烯(HDPE)时,在芯层1和芯层2两个复合体系中,皮层越厚则复合材料的热膨胀系数(LTEC)越高,其热膨胀性能越差; 当SGF的加入量恒定时,其LTEC随着皮层厚度的增加而降低。当皮层的弯曲模量比芯层低时,共挤出木塑复合材料的弯曲模量随着皮层厚度的升高逐渐降低; 当芯层的弯曲模量比皮层低时,共挤出木塑复合材料的弯曲模量随皮层厚度的升高而升高。皮层为SGF/HDPE材料时,在芯层1和芯层2两个复合体系中,随着皮层SGF的含量从0%增加到40%时,其弯曲性能显著性提高,LTEC显著降低。当皮层的 LTEC 值比芯层大时,皮层厚度的降低可以降低共挤出木塑复合材料的LTEC; 当皮层的 LTEC 值小于芯层时,共挤出木塑复合材料的 LTEC 随皮层厚度的增加而减少。【结论】通过改性芯层可以提高皮-芯结构木塑复合材料的整体性能,其增强趋势与表层的增强趋势相似。
【Objectives】In order to investigate the effects of various GF contents in the shell layer and shell thickness changes on thermal expansion and flexural properties of coextruded WPCs. 【Methods】Co-extruded WPCs with short glass-fiber(SGF)loaded shells were manufactured, the formulations for the two-core systems and three shell thicknesses(i.e., 1.0, 1.2 and 1.6 mm)were used to make different shells. Their flexural and thermal expansion behavior was studied. It was shown that the LTEC values varied with composite structure and composition(i.e., core,shell thicknesses and materials). 【Results】The use of SGF-filled shells helped lower overall composite LTEC values. The imbalance LTEC between core and shell layer, and their modulus caused complex stress fields within a given composite system. Extruding a relatively thick, less-stiff HDPE shell with a large LTEC value over a stiff and thermally. Stable WPC core decreased overall composite modulus and increased the LTEC values. The composite modulus and strength increased and LTEC values decreased with increase of the SGF loading levels in the shell. 【Conclusions】The flexural modulus/strength of core-shell structure WPC was greatly enhanced with unfilled-and filled HDPE shells
核壳结构木塑复合材料抗紫外老化性能试验
徐兵, , , 潘明珠, , 雍?k, 王珂
- , 2017, DOI: 10.13360/j.issn.2096-1359.2017.02.006
Abstract: 以高密度聚乙烯(HDPE)和木粉为主要原料,采用传统木塑复合材料(WPC)制备工艺和共挤出生产工艺,分别制备出均一结构和核壳结构WPC。核壳结构WPC芯层原料配比与均一结构WPC相同(木塑质量比为6:4),表层则为纯HDPE塑料。将两组材料进行紫外光加速老化试验,并对两组试件的表面颜色、表面形貌、化学基团及抗弯性能分别进行测试和表征。研究结果表明:经2 500 h紫外光照射后,均一结构与核壳结构的WPC表面颜色色差ΔE值分别增加17.59和9.40,核壳结构WPC的抗紫外色变能力明显优于均一结构WPC; 电镜照片显示,与核壳结构WPC相比均一结构WPC表面粗糙,在紫外光作用下更容易出现表面裂纹和粉化现象; 傅里叶红外光谱分析证明核壳结构WPC表面羟基与羰基基团变化明显低于均一结构WPC,HDPE表层有效延缓了WPC的光氧降解; 随着紫外光老化时间延长,两组试件的抗弯性能均呈现下降趋势,经2 500 h老化试验后,核壳结构和均一结构WPC的弯曲强度保留率分别为58.1%和49.7%,弹性模量保留率分别为43.2%和 38.0%,表明聚乙烯壳层结构对维持WPC强度有一定的积极作用。
Using the high density polyethylene(HDPE)and wood powder as the raw materials together with a small amount of chemical agents, the uniform structure and core-shell structure wood plastic composites(WPCs)were prepared with the traditional extrusion method and co-extrusion method. The core of the core-shell WPC shared the same composition with the uniform structure WPC, in which the ratio of wood powder to plastic was 6:4. The shell material was pure HDPE. Specimens of the type of WPCs were subjected to the accelerated ultraviolet aging test. The surface color, morphology, and chemical composition of specimens were characterized before and after the UV exposure, as well as the mechanical bending strength were examined. The results showed that ΔE values of the two types of WPCs increased by 17.59 and 9.40 after 2 500 h UV exposure, which indicated that the surface color change of uniform structure WPC was more distinct than that of core-shell WPC. The scanning electron microscope(SEM)revealed that, compared with core-shell WPC, uniform structure WPC was sensitive to the UV aging due to its rough surface. As UV aging processing, the change of the contents of hydroxyl group and carbonyl group in WPC of the core-shell group was less than that in uniform structure WPC, showing that the HDPE shell can delay the photo-oxidation and aging. Mechanical properties were significantly affected by the accelerated ultraviolet aging. After 2 500 h exposure, the retention rate of the bending strength of core-shell structure WPC and uniform structure WPC were 58.1% and 49.7% respectively, as well as the retention rates of elastic modulus of those two types of WPCs were 43.2% and 38.0%, respectively
木质人造板吸水过程中内部单元体尺寸及相对位置的变化
李万兆,詹先旭,杨勇,
- , 2018, DOI: 10.13360/j.Issn.2096-1359.2018.03.004
Abstract: 吸水易导致木质人造板物理力学性能的变化。为探讨木质人造板吸水后内部单元体尺寸及相对位置的变化,使用X射线断层扫描仪检测吸水前后4种中密度纤维板(MDF)、2种定向刨花板(OSB)和1种胶合板(PW)的内部单元体尺寸及相对位置的变化,分析了吸水导致人造板内部单元体尺寸及相对位置变化的原因,深入剖析了胶黏剂、添加剂和组坯方式对人造板结构稳定性的影响。结果表明,人造板吸水后尺寸增加主要集中在厚度方向。三聚氰胺改性脲醛树脂胶黏剂和石蜡添加剂,二苯基甲烷二异氰酸酯胶黏剂能有效保持MDF内部单元体间相对位置的稳定。吸水后,酚醛树脂胶黏剂所制OSB易发生胶层分离。PW的内部组成结构可更好地保持人造板的尺寸稳定性和结构完整。试验结果为优化人造板生产工艺和指导人造板的合理使用提供了理论依据。
Wood-based panels have been widely used as basic decorative products and construction materials for decades. They play an increasing important role due to the multiple advantages, such as raw material compatibility, ease of implementation, adaptability to continuous processing and standardization of the products. Physical properties of wood-based panels are prone to be influenced by water uptake, which limits the application field of wood-based panels. Generally speaking, the water uptake could lead to dimensional instability and decrease in mechanical strength of wood-based panels. Understanding the variation of internal unit during the water uptake process, therefore, is essential for optimizing the production and application of wood-based panels. In order to investigate the size and relative position of the internal unit changes induced from the water uptake, specimens prepared from four types of medium density fiberboard(MDF), two types of oriented strand board(OSB)and one type of plywood(PW)were scanned before and after the water uptake process by using an X-ray CT scanner. The reasons of size and relative position changes caused by the water uptake in wood-based panels were studied. The influence of glue, additives and the way of mattress on the structural changes of wood-based panels was discussed during the water uptake. The results showed that the X-ray CT scanning could timely visualize the 3D internal structure of wood-based panels. The dimensional increase in wood-based panels after the water uptake mainly occurred in the thickness direction. The application of melamine modified urea formaldehyde(MUF)resin, paraffin emulsion and methane-diisocyanate(MDI)resin could improve the stability of internal structure of the MDF. The glue line detachment in phenol-formaldehyde(PF)glue line was prone to occur in OSB after the water uptake. The way of mattress in the PW could better stabilize the dimension and internal structure of wood-based panels during the water uptake. The results obtained from this study can be used in optimizing the processing technology and application approaches of wood-based panels
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