利用废旧塑料制备木塑复合材料研究进展

利用废旧塑料与木质纤维制备木塑复合材料（WPC）是塑料资源重复利用、降低WPC制造成本的有效方式之一。简要介绍了废旧塑料的分类、来源以及危害,阐述了近年来利用废旧塑料制备WPC的概况,综述了利用物理和化学方法预处理木质纤维、原位增容改性等提高植物纤维/废旧塑料复合材料界面相容性的方法,并对利用废旧塑料制备WPC的前景进行了展望,以期提高废旧塑料基WPC的研发和实际应用。     

利用锯屑生产机制炭

介绍了利用木材加工剩余物—锯屑生产机制炭的全过程及产品市场供需状况，很有实用价值。     

落叶松锯屑液化技术的研究

以兴安落叶松锯屑、苯酚为主要原料,以硫酸为主要催化剂,采用均匀设计试验方法和单因子试验法,研究液化温度、液化时间以及硫酸等催化剂的用量对落叶松锯屑液化率的影响。结果表明,酚木比为2.8∶1的前提下,硫酸用量为4%,TSA用量为硫酸的5%,液化温度为135℃,液化时间为120 min时,兴安落叶松锯屑的液化率为95.60%,且液化物中游离酚含量为39.88%,可被溴化物含量为49.33%。     

工厂锯屑苯酚液化物制备工艺的优化研究

为了将工厂锯屑变废为宝,本文对工厂锯屑的苯酚液化工艺进行了研究与优化。通过正交试验的方法对:液比[n(苯酚)∶n(木粉)]、酸催化剂(浓度为30%的H2SO4)用量、液化时间以及液化温度这4个液化工艺的影响因素进行了分析研究。结果表明:液比对液化效果的影响最大,其次依次为液化时间、催化剂用量和液化温度。得到的工厂锯屑苯酚液化的优化工艺为:液比[n(苯酚)∶n(木粉)]为5、液化时间为2.5h、催化剂用量为8%、反应温度为160℃,在此工艺条件下,液化效率可达到92%。     

超声波-微波对杉木锯屑液化的强化效应研究

以正辛醇为溶剂、浓硫酸为催化剂,探讨了超声波-微波（UW-MW）辅助对杉木锯屑液化的强化作用,考察了工艺参数的影响,并对液化产物进行了表征分析。研究结果表明：超声波-微波具有很好的传质传热强化效应,与传统液化相比,杉木锯屑超声波-微波辅助液化反应时间从60 min缩短至20 min,液化率提高了5.24%。在溶剂与锯屑质量比值6、催化剂H₂SO₄浓度0.6 mol/L时,杉木锯屑液化率达到64.30%;适当添加γ-戊内酯可提高液化率,γ-戊内酯用量40%时液化率达81.17%。液化过程中,少量熔融状物质沉积在残渣（SR）表面,阻碍了原料的进一步液化;纤维素与半纤维素的降解产物主要为小分子糖类等物质,富集在水相产物（WS）中;木质素的降解产物主要由芳香族等物质组成,分布在生物油（BO）产物中。     

锯屑掺入量对快速固化水泥刨花板性能的影响

就不同的细料(锯屑)掺入量对快速固化水泥刨花板的性能的影响作了探讨,结果表明:锯屑的掺入对水泥刨花板的密度、静曲强度、内结合强度和厚度膨胀率均有一定的影响,当锯屑的掺入量占木质原料总量的20% ～ 30%时,既可以改善板的性能,又可以提高木质原料的利用率.     

SEBS-g-MAH和原位接枝MAH对木粉/废旧塑料混合物复合材料力学性能的影响研究

由聚丙烯（PP）、高密度聚乙烯（HDPE）和聚苯乙烯（PS）组成的混合废旧塑料与木粉经高速混合机混合后,采用双螺杆/单螺杆串联挤出机组制备了木粉/混合废旧塑料复合材料。探讨了马来酸酐接枝苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物（SEBS-g-MAH）和原位接枝马来酸酐（MAH）对木粉/混合废旧塑料复合材料力学性能的影响。结果表明,与使用MAH和DCP的原位反应共混相比,SEBS-g-MAH显著提高了复合材料的抗冲击性能,但对拉伸和弯曲性能的改善不如原位反应共混显著。总的来说,混合废旧塑料制备的复合材料的力学性能要低于纯塑料混合物制备的复合材料,尤其是拉伸断裂伸长率。微观形态研究表明,添加SEBS-g-MAH和原位接枝MAH均可提高木粉与塑料混合物之间的界面相容性,但与添加SEBS-g-MAH相比,原位接枝MAH能更好的改善PP、HDPE、PS与木粉之间的界面结合。原位接枝MAH可被看作是一种改善木粉与塑料混合物间界面相容性的有效途径。此外,采用动态力学分析（DMA）进一步表征了复合材料的储能模量和阻尼因子。     

日本利用锯屑的简况

锯屑的多、少,与使用锯的厚、薄很有关系;如果使用薄锯,一方面提高了出材率;一方面减少了锯屑。并且在同样的原木锯割,锯割薄板材与锯割大方材,其锯屑量自有不同。因此,要估计日本全国究竟能     

木塑复合百叶窗的生产

介绍了木塑复合材百叶窗的性能、结构及制作工艺。     

木塑复合材料的研究

木塑复合材料,是以高分子材料中的热塑性树脂为母体,加入木材纤维素和木质素,以及多种化学助剂,经高温混炼而成的一种新型复合材料。它可代替木材和部分金属,广泛用于各个领域。1 国内外对木塑复合材料的研究与进展60年代初,世界各国就开始了木塑复合材料的研究,产品刚一问世,即受欢迎,取     

Aerodynamic sound and self-excited vibration of circular saw with step thickness I: Comparison of dynamic characteristics between the common circular saw and the circular saw with step thickness

The natural frequencies, aerodynamic noise, whistling noise, and self-excited vibration between the common circular saw with uniform thickness and the circular saw with step thickness (thin on its outer part and thick on its inner part) were researched during idling. The natural frequencies of the circular saw with step thickness increased with an increase in the thickness and in the radius of the thick part. The frequencies of the circular saws with step thickness (thick at the inner part) were higher than that of the thin circular saw with a uniform thickness of 0.5mm. The aerodynamic sound pressure level induced from circular saw teeth increased with an increase in the tooth thickness. The whistling noise and self-excited vibration easily occurred in the thick circular saws (1.5, 2.0, and 2.5mm). The whistling sound pressure level and the vibration amplitude increased with an increase in the thickness of the saw. None of the designed circular saws with step thickness generated whistling noises or self-excited vibration during idling.Part of this report was presented at the 45th annual meeting of the Japan Wood Research Society at Tokyo, April 1995 and the 12th International Wood Machining Seminar at Kyoto, October 1995     

跑车带锯机列的电气改造

本文通过对木工跑车带锯机列摇尺制动和摇尺操纵的电器改造，实现了摇尺自控和跑车摇控。提高了木材出材率，改善了工人的劳动条件。     

油锯采伐与手锯采伐经济效益分析

本文通过对油锯采伐与手锯采伐方式的经济效益对比分析得出 ,不论是人工林 ,还是天然林 ,油锯采伐方式的经济效益均高于手锯采伐方式。     

Theoretical and experimental analysis of circular saw tensioning

Summary Tensioning is the saw prestressing procedure most commonly used in the forest products industry to increase the stability of thin circular saws. This procedure stiffens the saw blade by introducing favorable in-plane residual stresses either by local plastic deformation or by local heating. In industry today, rolling is the standard procedure for introducing such stresses.The first part of this paper is concerned with a method of tension evaluation. The method examined consists of measuring saw blade modal stiffness, and it correlates the elastic stiffness of the saw, which approximates the vibration modes, and the natural frequencies associated with these modes. The predictions of the saw frequency shift due to stiffness variations were found to agree closely with experimentally determined frequencies. The method thus offers a practical procedure for tension evaluation and could replace the currently used technique of measuring the light gap under a straightedge placed along the saw diameter.The second part of this paper theoretically analyzes the relationship between the rolling load and the resulting tensioning stresses. The procedure followed in the theoretical model determines the identation load by equating the external power of loading with the power of storing in the elastic zones and of internal dissipation in the plastic zone.The residual stresses obtained by superpositioning the stresses due to unloading were generally in good agreement with the experimentally determined tensioning stresses outside the rolled region. The theory developed can be very useful in predicting tensioning stresses for a given rolling load and roller geometry.List of Symbols a, b Inside and outside saw disc radii - A, B Arbitrary constants - c Saw disc tensioning radius - c_i, c₀ Inside and outside rolling/indentation radii - c_n Neutral radius - d Track width - E Modulus of elasticity or strain energy - E_ext External power of the loading - E_p Power dissipation due to plastic deformation - E_d Power dissipation due to velocity discontinuity - E_e Power stored in elastic zones - f_n Resonant frequency of a saw disc n — nodal diameters - f _n ^TM Measured resonant frequency - f _n ^TC Resonant frequency calculated from the variation in the saw disc stiffness - F Rolling load - H Half saw disc thickness - K_n Modal stiffness, n=number of nodal diameters - K _n ^* Conventional or bending stiffness - K _n ^** Geometric or tensioning stress stiffness - K _n ^T Modal stiffness of a tensioned saw disc - M_n Modal mass, n=number of nodal diameters - M, N Integration constants - P_ave Average indentation pressure - p, p, p' Radial pressures at elastic-plastic boundaries; loading, unloading and residual - p_i, p_O Radial pressures inside and outside the elastic-plastic boundaries The Authors would like to express their gratiude to C. H. Zierdt and J. Rhemrev for assistance in the experimental investigations. The authors are also grateful to Hanchett Co. and California Saw Knife and Grinding, Inc. for supplying stretcher rolls and experimental saw discs, respectively. They are also grateful for the financial support of the project from the U.C. Forest Products Laboratory, California Cedar Products Co., California Saw Knife and Grinding, Inc., Hudson Lumber Co., MacMillan Bloedel Research Ltd., Potlatch Corp., Simpson Timber Co., Sun Studs, Inc. and Weyerhaeuser Co. Finally, the authors thank the National Science Foundation for its generous support of the research     

利用转基因番茄生产葡激酶的研究

利用农杆菌介导的方法,将葡激酶(Staphylokinase,SAK)基因导入番茄中。经PCR、Southern杂交和Northern杂交检测,葡激酶基因已整合到再生番茄植株基因组中,共获得8个转基因株系。经ELISA检测,转基因番茄的果实和叶片均能表达SAK蛋白,SAK蛋白在果实和叶片可溶性蛋白中的比例最高分别为3.42%和2.47%。转基因番茄中的SAK蛋白具有一定的溶栓活性,溶栓比活力为3 866 AU·mg-1。     

手提式电锯的现状与发展

手提式电锯广泛使用于贮木场移植式造材作业中。本文对手提式电锯进行了客观的分析，并阐述了其发展前景。     

用“塑料环”防治落叶松毛虫技术

1松毛虫的生活史及习性 松毛虫的生活史一年一代，大部分以3～4龄在树干基部枯枝落叶层下卷曲过冬，翌年4月中旬日平均气温达10℃时，越冬幼虫开始上树为害，一般在4～5月份上树为害。6～7月份老熟幼虫在树上结茧化蛹，7～8月份羽化为成虫，数天后产卵，卵期约10～12d孵化成幼虫，8～10月份新生幼虫开始上树为害。11月份下树越冬。     

Potential and measured evaporation in saw timber piles of pinus sylvestris

The objective of this investigation was to determine the relationship between potential evaporation, according to the Penman‐Monteith evaporation formula, and measured evaporation in saw timber piles of Scots pine (Pinus sylvestris L.). The local climate and the water balance of a timber pile were investigated at two geographically different experimental sites, one in southern Norway and one in central Sweden. The results showed that the relationship was significant at both experimental sites, showing a correlation coefficient of 0.71 in Norway and 0.52 in Sweden. At both experimental sites, the potential evaporation had higher average values and between‐day variations than measured evaporation, probably because the Pen‐man‐Monteith formula is too sensitive to variation in meteorological variables. The formula overestimated the evaporation during periods with high evaporation demand, which might be explained by the stronger feed‐back between evaporation and cooling of the air at saw timber piles than at the position of the climate station. A seasonal variation of standard residuals between potential and measured values was observed at both experimental sites. The Penman‐Monteith evaporation formula estimated the evaporation well during July and August, whereas overestimation occurred during June and September.     

The effect of rotation speed on the power consumption and cutting accuracy of guided circular saw: Experimental measurement and analysis of saw critical and flutter speeds

ABSTRACT

This paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process.     

Analysis of roll tensioning and its influence on circular saw stability

Summary In a typical sawmill, about 12% of the wood which is cut is reduced to sawdust. Further material is lost during subsequent planing. A substantial part of this large loss of a costly natural resource can be saved by the use of thin, stable sawblades, but only if proper saw tensioning conditions are developed. The thickness of a stable sawblade can be minimized through optimal tensioning, an increasingly urgent objective because of sharply rising raw material costs. A theoretical model is presented which accurately describes the development of residual stresses in a roll tensioned circular sawblade and the resulting changes in saw critical speed. This model is essential for the reliable prediction of optimal tensioning conditions for any given saw operating state, and for the development of automated control of the tensioning process. An example is presented of an optimally tensioned circular sawblade for which a 40% thickness reduction is achieved compared with an equivalent untensioned sawblade with the same critical speed.Paper awarded First Place Wood Award Price, Forest Products Research Society, June 1981