增强-热处理桉树木材物理力学性能分析

采用水溶性MUF树脂浸渍增强与热处理相结合的方法对粗皮桉木材进行改性处理。MUF树脂浓度25%,通过真空加压浸渍工艺处理粗皮桉木材,获得增重率为15.6%处理材。真空热处理试验选用不同温度(160℃、180℃、200℃、220℃、240℃)、不同时间(2h、4h、6h、8h、10h)处理粗皮桉素材和浸渍增强处理材。对比分析二者在不同热处理工艺条件下的物理、力学性能指标,结果表明:随热处理温度的升高、时间的延长,无论素材还是浸渍增强处理材,失重率在逐渐增大、径弦向干缩率逐渐增大、弹性模量及抗弯强度逐渐降低。但是在同样的热处理温度和时间条件下,浸渍增强处理材的各项指标明显优于素材。     

人工林杉木胶合工艺优化研究

采用SAS全因子试验设计,研究了胶粘剂类型、涂胶量、单位压力、加压时间和胶合面纹理五个因子对人工林杉木木材胶合性能的影响,并对其胶合工艺进行了优化。研究结果表明:胶粘剂类型对杉木木材常态胶合剪切强度和木破率的影响不显著,但是老化处理后API和PF的胶合剪切强度和木破率比PVAc和UF的要高;在以API为胶粘剂时,涂胶量、单位压力、加压时间和胶合面纹理对杉木胶合剪切强度和木破率的影响显著,优化的胶合工艺为涂胶量250g/cm2,单位压力1.5 MPa,加压时间50 min和胶合面纹理为弦切面-弦切面。     

磷氮硼阻燃剂处理炭化橡胶木工艺

采用水溶性磷-氮-硼复合阻燃剂,对炭化橡胶木进行了阻燃处理,分析了前真空时间、浸注压力和浸注时间对炭化橡胶木增重率和力学性能(MOE和MOR)的影响。研究结果表明:前真空时间、浸注压力和浸注时间对炭化橡胶木的增重率和MOE、MOR没有显著影响。在实验范围内,较佳的工艺条件为:前真空时间10min,浸注压力0.4MPa,浸注时间10min。     

胡萝卜片中富集植物乳杆菌的工艺优化

为将植物乳杆菌富集到胡萝卜中以制备含益生菌的果蔬功能食品,本研究首先通过单因素和正交试验优化植物乳杆菌以真空浸渍和超声浸渍的方式富集到胡萝卜片中的工艺参数,然后以常压浸渍为对照比较3种浸渍方式下胡萝卜片中富集的活菌数,以期获得较优的胡萝卜植物乳杆菌富集方式。结果表明,真空浸渍较优工艺参数为真空浸渍温度35℃、真空浸渍时间15 min、复压浸渍时间20 min;超声浸渍较优工艺参数为超声浸渍温度30℃、超声浸渍功率125 W、超声浸渍时间12 min。比较真空浸渍、超声浸渍和常压浸渍3种方式下胡萝卜中活菌数可知,真空浸渍组活菌数最多,达到10~(10) CFU/g以上;扫描电子显微镜结果显示,在真空和超声浸渍的胡萝卜组织中均观察到杆状菌体,而在常压浸渍样品的组织内部未发现菌体。3种浸渍方式下胡萝卜组织表面均有大量菌体。本研究获得了较优的胡萝卜中富集植物乳杆菌工艺参数,为乳酸菌或其他菌通过真空浸渍富集到果蔬组织中提供实验依据,也为含益生菌功能食品开发提供新思路。     

树脂型硅酸盐改性剂及改性材的制备工艺与性能分析

为了提高人工林杨木的物理力学性能和阻燃性能,采用低分子量三聚氰胺脲醛(MUF)树脂复合一定比例的硅酸钠溶液,制备出树脂型硅酸盐改性剂,对人工林杨木进行真空加压浸渍处理,以改性杨木增重率为评价指标,得到较优化的浸渍处理工艺:抽真空至-0.095MPa,保持30min,施加压力0.8MPa保持2h,木材增重率达到60%左右;通过分析不同配比改性剂的性能及其对改性杨木各项物理力学性能和燃烧性能的影响,优选出MUF树脂复合30%硅酸钠制备的改性剂,对木材的改性效果最佳,可使杨木密度由未处理材的0.39g/cm~3提高到0.55g/cm~3,抗胀率达到51.5%,弹性模量和抗弯强度比未处理材分别提高35.9%和59.4%,氧指数达到57%,比未处理材提高119.2%。     

浸胶方式对荷木重组木性能的影响

以荷木纤维化单板为研究对象,采用真空加压、常压浸渍两种浸胶方式,在相同浸胶量的条件下,分别制备不同密度的荷木重组木,并检测其物理力学性能,从而探索不同的浸胶方式对荷木重组木性能的影响。真空浸渍时PF胶液固体含量为10%,真空保持5min,然后加压至0.8MPa保持8min,浸渍量达12%;常压浸渍用PF胶液的固体含量为16%时方能保证浸胶量达到12%。结果表明:两种浸胶方式均可制备出性能优良的荷木重组木,其中真空加压法制备的荷木重组木性能更优,且使用的胶液固含量低,可节省胶耗,原因在于采用加压浸渍,有利于胶液进入木材细胞腔内,增加渗透深度和浸渍均匀性,并产生有效胶合。     

鲜荸荠真空浸渍强化钙工艺研究

为提高鲜荸荠中钙含量,以乳酸钙为强化剂,钙含量、淀粉含量、可溶性固形物和亮度L~*值为评价指标,通过单因素试验考察温度、真空度、真空浸渍时间和乳酸钙浓度对鲜荸荠浸渍钙含量的影响,并结合正交试验分析真空浸渍对鲜荸荠性质的影响,确定真空浸渍最佳条件。结果表明,真空浸渍较优工艺条件为温度40℃,真空度49 kPa,乳酸钙浓度6.0%,真空浸渍20min。此条件下浸渍鲜荸荠钙含量为64.41 mg/100 g,提高了13.64倍;淀粉含量为3.35 g/100 g,可溶性固形物含量为9.7°Brix,亮度L~*值为87.97。研究获得鲜荸荠真空浸渍强化钙工艺的最佳条件,真空浸渍可作为强化鲜荸荠钙含量的一种新方法。     

棉织物的硅溶胶/短链含氟聚丙烯酸酯复合拒水整理

为实现棉织物绿色环保拒水整理，利用硅溶胶和短链含氟聚丙烯酸酯对棉织物进行复合整理和工艺优化，赋予棉织物优异的拒水性。探讨了硅溶胶用量、短链含氟聚丙烯酸酯质量浓度、浸渍时间、预烘温度、烘焙温度和烘焙时间等因素对棉织物拒水效果的影响，得到其最佳整理工艺为：硅溶胶用量0.3%(o.w.f),短链含氟聚丙烯酸酯质量浓度30 g/L,浸渍时间20 min,预烘温度80℃,170℃焙烘2 min。利用扫描电子显微镜、傅里叶红外光谱仪、热重分析仪对整理后棉织物的表面形貌和结构进行分析，并通过表面接触角测试仪及织物风格仪测试其表面润湿性、耐酸碱性和风格变化。结果表明：复合整理后棉织物表面形成硅溶胶/短链含氟聚丙烯酸酯疏水层，最大接触角为155.6°,经50次洗涤后，接触角仍大于90°;对强酸(pH值为3)和强碱(pH值为12)液滴的接触角分别可达100°和93°,具有良好的耐酸碱性；整理后棉织物折皱回复率提升约20%,热稳定性及柔软度也略有改善。     

专利技术信息

★难燃木材浸渍新工艺本发明难燃木材浸渍新工艺涉及的是一种制造难燃木材的浸渍加工工艺，难燃木材浸渍工艺为：（１）将干燥木材计量装入浸渍筒，灌满常温阻燃液；（２）计量压入常温阻燃液，排除浸渍筒内气体；（３）计量常温阻燃液加压压力，压力按木材不同材质分别为...     

浸渍热压工艺对碳纸结构性能的影响及机理研究

本研究通过探究碳纸浸渍和固化过程中酚醛树脂的分布及形态结构,研究浸渍热压工艺对碳纸性能的影响。结果表明,当浸渍时间为4 min,浸渍液浓度为11%时,预固化后碳纸中所含的树脂最多,浸渍量可达154.9%。当热压温度为160℃,热压时间为20 min,热压压力为3.0 MPa时,制备的碳纸热压纸性能最好,电阻率仅27.1 mΩ·cm,抗张强度达103.9 N/cm。     

等离子体改性对玄武岩/聚丙烯复合材料性能的影响

采用等离子体改性技术对玄武岩纤维进行表面改性处理,通过SEM对改性后的纤维表面形貌进行表征,研究真空度、处理时间和功率对玄武岩/聚丙烯复合材料力学性能的影响,从而确定最佳处理工艺,并研究等离子体处理对复合材料结晶性能的影响。结果表明:纤维经等离子体处理后,等离子体对纤维表面产生刻蚀作用,使纤维表面变得粗糙;当真空度、处理时间和功率分别为20 Pa、5 min、100 W时,复合材料的力学性能最佳,此时拉伸强度为247 MPa,抗弯强度为49.319 MPa;改性处理能促进聚丙烯的异向成核,使其结晶度增加。     

锯齿形三维机织间隔复合材料的弯曲性能

为解决层合间隔复合材料易开裂和整体性差的问题,采用绿色环保的玄武岩低捻长丝作为经、纬纱,合理设计经向截面图和组织图,并在普通织机上织造3种不同间隔高度的锯齿形三维机织间隔织物。以所织得的锯齿形三维机织间隔织物作为增强材料,环氧乙烯基树脂作为基体,利用真空辅助成型工艺,制备锯齿形三维机织间隔复合材料,同时对三维机织间隔复合材料进行三点弯曲性能测试,得到弯曲载荷-位移曲线、能量吸收图和破坏模式。结果表明:复合材料的纬向是主要承力方向;组织循环个数越多的材料表现出更好的弯曲性能;在一定间隔高度范围内,间隔高度越高的锯齿形三维机织间隔织物承受的弯曲载荷和吸收的能量也越高;锯齿形三维机织间隔复合材料的破坏模式是材料上表层受压,下表层受拉,而连接层受压;在作用力下材料只是出现明显的变形,但并未出现材料整体的破坏。     

Parametric study of a yellow birch surface impregnation process

Wood is a renewable resource that has been used as a material in appearance products for years. Despite its acceptable mechanical resistance, different modification processes were developed to enhance wood’s hardness and make it an even more durable material. Impregnating wood pores with monomers under vacuum-pressure cycle is a common method for that purpose. However, most implemented processes are long and mostly submerge wood into a monomer formulation (Bethell’s full-cell process). For that, they can be considered wasteful on the quantity of materials used, energy consumed and on process duration. The objective of this paper was to evaluate the parameters that influence the penetration of monomers into the tangential surface of Yellow birch (Betula alleghaniensis Brit.) samples. The analyzed factors were the monomer formulation’s viscosity, the surface temperature, the vacuum level applied to the process, the anatomy of samples, and the absorption time. After impregnation, the weight gain of the samples was calculated. Monomer penetration depth was calculated and visualized using density profiles and micro X-ray tomography imaging. Results showed that using a low viscosity monomer formulation allied to a certain level of vacuum and absorption time can considerably increase the impregnation into the wood.

     

Effects of Wood Particle Size and Mixing Ratios of HDPE on the Properties of the Composites

The main goal of this research is to innovate wood-plastic composites by using various wood particle sizes and different mixture ratios (weight ratio) of HDPE (High Density Polyethylene). After mixing the wood particles (recycled wood waste) and the plastic powder, we use a molding and pressing process to make composites with a thickness of 12 mm. By doing so, the wood particle content can be increased to 75%. This kind of composite provides excellent dimensional stability, its moisture content is under 2.5%, and the thickness swelling rate after 24 hr water absorption is under 7.5%. The maximum static bending strength of this composite reaches 20.7 N/mm², and is better than that of general commercial particleboards. The composite made of larger sized wood particles has better strength properties. In addition, when the plastic content ratio increases, the dimensional stability of the composite will increase as well. After the soaking process in boiling water, the static bending strength of wet composite remained at 50%; this shows the good weather resistance of the composite. The surface veneer overlaid peeling strength of the composite showed 1.02–1.63 N/mm. After the evaluation of processing, cost of material and strength properties of the composite, we would suggest that the use of 70% of wood particles and 30% of plastic powder is practical to produce proper sized composites.     

The mechanical properties of densified VTC wood relevant for structural composites

The mechanical properties of densified wood relevant for structural composites were studied. Low density hybrid poplar (Populus deltoides × Populus trichocarpa) was densified using the viscoelastic thermal compression (VTC) process to three different degrees of densification (63, 98, and 132%). The modulus of rupture (MOR) and the modulus of elasticity (MOE) of the control (undensified) wood and of the VTC wood were determined. The bonding performance of the control and VTC wood, using two phenol-formaldehyde (PF) adhesives, was studied. Four different 3-layer composites were also prepared from undensified and VTC wood, and tested in four-point bending. The results showed that the bending properties of the VTC wood (MOR and MOE) were significantly improved due to the increased density. The bonding performance of VTC wood with PF adhesives was comparable with or better than in the case of the control wood. Increased density of the face layers in the 3-layer VTC composites was advantageous for their mechanical performance.     

Viscous properties of microparticulated dairy proteins and sucrose

Slurries of whey protein concentrate (WPC) or sodium caseinate (Na-CN) mixed with sucrose (36% T.S.) were subjected to microparticulation by a high shear homogenizer operated at 27,000 rpm for 2, 4, and 6 min to facilitate gel formation. After microparticulation treatment, the milk protein and sucrose slurries were evaporated at 85 degrees C for 60 min under a partial vacuum (20 to 45 mm of Hg) to form composite gels. Particle sizes and viscoelastic properties were determined before microparticulation treatment. Microparticulation reduced the particle size of WPC-sucrose slurries from an average size of 330 to 188 nm after 4 min and NaCN-sucrose slurries from 270 to 35 nm after 2 min. The WPC-sucrose composites were gel-like, but NaCN-sucrose composites did not gel. Viscoelastic properties of heated WPC-sucrose composites were liquid-like, exhibiting significant reduction in storage modulus and complex viscosity. Microparticulation reduced particle sizes, which resulted in softer gels as time of shearing increased.     

An economical treatment schedule for boron impregnation of Eucalyptus grandis wood: Commercial trial of partially dried material

Being non-durable, Eucalyptus grandis wood needs treatment with preservative chemicals. As vacuum-pressure impregnation treatment being more suitable for commercial applications, and boron chemicals being environment-friendly for indoor uses, an economical treatment schedule (15 minutes initial vacuum of -85 kPa followed by a pressure of 1300 kPa for 15 minutes and a final vacuum of -85 kPa for 5 minutes) developed at the Kerala Forest Research Institute was tested for its commercial suitability for treating E. grandis wood with boron chemicals. A pooled mean dry salt retention (DSR) of 7.7 kg m ^-3 was achieved for wood in partially dried condition with average moisture content of around 32%, using a 6% boric acid equivalent (BAE) solution. This confirms the success of the schedule for commercial application, as the DSR achieved is much higher than the standard specification of many countries.     

Effect of a vacuum-leaching technology on the proteins and lipids of lean sardine (Sardina pilchardus) mince

A study on the effect of the vacuum level and leaching time on the washing of lean sardine (Sardina pilchardus) mince was carried out. An experimental design was performed according to the statistical model of central composite design of response surface methodology. Proximate composition, water-holding capacity (WHC) and soluble protein were determined in the mince. Lipid classes and fatty acids were further analysed in the minces and in the extracted solutions. The WHC was greatest in the mince washed at atmospheric pressure for 40 min, and corresponded to the lowest fat content. The highest soluble protein extraction was obtained at intermediate values of pressure (382 mmHg) and time of washing (20 min). The fat initial content (4.6 %) was reduced by approximately 50% and was significantly affected by extreme vacuum levels (4 mmHg and 760 mmHg) and longer washing periods. Triacylglycerols were extracted the most, mainly at intermediate pressure values and increased washing periods. Polar lipids were next in abundance and were not extracted during washing. Polyunsaturated fatty acids were the major group of fatty acids, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) the most representative, being predominantly extracted at extreme pressure levels and increased periods of washing. DHA was more abundant in the washed mince, whereas the level of EPA was proportionally higher in the emulsions.     

玻璃纤维增强复合材料在水环境中的性能

为了解玻璃纤维增强材料在水环境中的性能变化,利用真空辅助树脂注入方法制作了2层和3层的玻璃纤维/不饱和聚酯树脂复合材料板材。在经过一定时间蒸馏水的浸泡后,对材料的拉伸及弯曲性能进行了测试,并对经水浸泡前后复合材料的显微照片进行了分析。测试结果表明:随着浸泡时间的增加,材料的拉伸强度呈下降趋势;板材的弯曲强度也有一定程度的下降。     

Einfluß der Espenholzdichte und-entnahmezone auf ausgewählte Eigenschaften des Holz-Polystyrol-Systems

The quality of aspen wood polystyrene composites is decisively influenced by the stem position and the height of the tree trunk from which the wood was selected. Wood density is only of secondary imporance. To produce wood polymer composites, aspen wood taken from sapwood areas is particulary suitable. Aspen wood taken from the heartwood zone is not suitable for producing composites due to lack of styrene saturation. This fact is caused by the presence of thyloses in vessels of these areas. The number of annual rings comprising heartwood zone in the specimen ranged from 12 rings at breast height diameter to 5 rings at a stem height of 15 m. In the alburnous aspen wood polystyrene composite narrow cell lumina are completely filled. However, large diameter tracheids are covered only by a thick polystyrene layer. The presence of polystyrene was also observed within cell walls. During composite production using higher density sapwood layers a higher temperature peak occurs during the polymerization process. Dimensional stability of the aspen polystyrence composite depends mainly on the place in the trunk crossection from which the sample was taken. The highest dimensional stability was shown by a composite of sapwood layers containing the greatest amount of polystyrene. Bending strength of the aspen wood polystyrene composite depends not only on the polystyrene content in the wood but also on the original strength of the wood itself. Composite producted from wood of higher density are characterized by higher bending strength. Hardness of the aspen wood polystyrene composite is, in principle, dependent on the polystyrene contents. An increase in polystyrene content imporves composite hardness compresive in particular perpendicular to grain.