Effect of copper nanoparticles on permeability, physical, and mechanical properties of particleboard

Effects of a 200 ppm nanocopper suspension, with size range from 10 to 80 nm, on the physical and mechanical properties of particleboard made on an industrial scale at the Iran-Choob Factory were studied. Nanocopper suspension was added to the mat at two levels of 100 and 150 ml/kg dry weight wood particles and compared with control boards. Results showed that hot-pressing time was reduced by 5.7 and 3.4 % when 100 and 150 ml of nanocopper were used, respectively. Also, both levels of nanocopper consumption had improving effects on physical and mechanical properties, although in some cases not significant. Permeability was significantly decreased to its lowest value in 150 ml/kg treatment. It can be concluded that 150 ml of nanocopper/kg may be used to improve the physical and mechanical properties, to reduce press time, and to decrease permeability in particleboards. For industrially accepted outcome, 150 ml/kg of nanocopper is recommended.     

原料和制备方法对醋酸酯淀粉糊化特性的影响

以三种淀粉(马铃薯、木薯和玉米淀粉)为原料,以醋酸酐、醋酸乙烯酯为酯化剂生产醋酸酯化淀粉,对其Brabendar粘度曲线图进行研究。经酯化后,淀粉的糊化特性都有明显的变化(起糊温度降低,粘度增加),但原料和酯化剂的不同,会导致变化程度的不同,另外冷热糊稳定性和凝胶性强弱变化就有更明显的差异。      

Improving physical and mechanical properties of new lignin- urea-glyoxal resin by nanoclay

To eliminate toxic formaldehyde from wood based panels, glyoxal, a low volatility and nontoxic aldehyde, was used to react with urea and lignin to prepare a glyoxalated lignin- urea-glyoxal (LUG) wood adhesive resin. Moreover, another objective of this research work was to improve the physical and mechanical properties of the new LUG resins by nanoclay addition. For the preparation of LUG resin, glyoxalated lignin (15 mass%) was added instead of second urea to the urea-glyoxal resin synthesis under acid conditions. The LUG resin so prepared was mixed with 1, 2 and 3 mass% nanoclay by mechanically stirring for 5 min at room temperature. Then, the physicochemical and structural properties of the prepared resins as well as the water absorption and the mechanical properties of the plywood panels bonded with it were measured according to standard methods. The physicochemical test results indicated that the gel time of the LUG resin was markedly slower than that of the UF resin. Plywood panels prepared with the LUG resin also presented lower water absorption as well as weaker shear strength than those prepared with the UF resin. Addition of nanoclay changed the physicochemical properties of the resins as the gelation time of the LUG resin was shorter when adding sodium montmorillonite (NaMMT). Higher shear strength values and lower water absorption were achieved by continuously increasing nanoclay proportion from 1 to 3 mass%. Furthermore, addition of nanoclay had more influence on panels bending strength than their flexural modulus. X-ray diffraction (XRD) analysis also indicated that NaMMT exfoliated completely when mixed with LUG resin.     

降低刨花板生产施胶量技术

介绍了刨花板生产中施胶量的主要影响因子。通过对施胶方式、拌胶方式和碎料计量方式对施胶量的影响关系及相关设备的研究,提出降低刨花板生产施胶量的途径和方法。     

Physical and mechanical properties of gypsum particleboard reinforced with Portland cement

High thickness swelling, high water absorption and low mechanical properties of gypsum particleboard limit its utilization in building construction. Gypsum particleboard reinforced with Portland cement could result in a product with higher mechanical properties and an acceptable resistance to moisture. Physical and mechanical properties of gypsum-cement particleboards were analyzed for specimens previously conditioned at 20?°C and 60% relative humidity and then soaked in water for 24 hours. The results showed that Portland cement incorporation increased the mechanical resistance of the boards. In the dry state, Portland cement addition generated a modulus of rupture increase ratio of 53% and an internal bond strength increase ratio of 206%. Higher increase ratios were obtained after 24 hours water soaking. An increase ratio of 642% was obtained for the modulus of rupture and 97% for hardness. Furthermore, the addition of Portland cement resulted in a reduction ratio of 21% for water absorption after 2 hours water soaking and 26% after 24 hours water soaking. Moreover, reduction ratios of 43% and 61% in thickness swelling and 33% and 46% in linear variation were observed after 2 and 24 hours water soaking. It can be concluded that Portland cement is a suitable reinforcing material for improving the performance of gypsum particleboard.     

Microstructure and mechanical properties related to particle size distribution and composition in dark chocolate

Composition in dark chocolate was varied and the effects determined on microstructure, using light microscopy, and mechanical properties of molten and tempered chocolates, using a TA.HD Plus Texture Analyser. Compositional parameters were particle size distribution (PSD) (D₉₀ of 18, 25, 35 and 50 μm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Micrographs revealed wide variations in sugar crystalline network structure and inter-particle interaction strengths related to PSD and fat level. Samples containing 25% fat had more crystal agglomerates, well flocculated with greater particle-to-particle interaction strengths than those with higher (30% and 35%) fat contents. Increasing the D₉₀ to 35–50 μm caused broadening of the PSD, with particles becoming coarser, which were similar at all fat levels. Mechanical analysis showed that PSD, fat and lecithin content significantly influenced firmness of molten chocolate and hardness of solid (tempered) chocolate with significant interactions among factors. Particle size was inversely correlated with firmness (1235–173 g) and hardness (7062–5546 g). Greatest effect of PSD was with 25% fat and 0.3% lecithin. With higher fat and lecithin contents, the PSD influence was reduced. It was concluded that PSD, fat and lecithin contents and their interactions were central to mechanical properties of dark chocolates.     

配料比对木塑复合刨花板性能影响的探讨

探讨了木材刨花与聚丙烯塑料的配料比(W∶W)对板材的主要物理力学性能的影响。     

乙酰化己二酸交联机械活化木薯淀粉的制备及性能研究

以机械活化木薯淀粉为原料,己二酸为交联剂,醋酸酐为酰化试剂,无水硫酸钠为膨胀抑制剂,对乙酰化己二酸交联机械活化木薯淀粉的制备工艺及性能进行研究,考察反应温度、反应时间、pH值、混合酸酐与淀粉质量比对乙酰化己二酸交联机械活化木薯淀粉冷黏度的影响.结果表明,各因素对机械活化木薯淀粉的乙酰化己二酸交联反应均有影响,对于机械活化1.0h的木薯淀粉,在无水硫酸钠溶液质量分数为3％、反应时间1h、pH8、混合酸酐质量分数为7％、反应温度50℃的条件下,所制备的机械活化木薯交联酯化淀粉糊的冷黏度由活化淀粉的847mPa·s提高到1502 mPa·s,淀粉糊液黏度的稳定性、抗酸性、抗老化性显著提高.利用红外光谱证明机械活化木薯淀粉与混合酸酐确实发生了交联酯化反应.     

Weight reduction of microfibre polyester fabric and the effect on its physical and mechanical properties

For the present work, a heat‐set microfibre polyester woven fabric was treated with five different sodium hydroxide concentrations in similar conditions. Their physical and mechanical properties were studied and discussed. Changes in eight properties due to the weight reduction, i.e. surface properties, tear strength, crimp, compression, pressure recovery, crease recovery, abrasion and weave density which are reported in this work were not available for any type of weight reduced polyester fabrics in the cited literature. Results show that the weight reduction decreases yarn and fabric strength, fabric abrasion resistance, fabric tear strength and bending stiffness. On the other hand, it increases fabric thickness under low pressure, crease recovery angle, air permeability and drape of the fabric. The treatment showed no significant effect on the surface properties of the samples.     

牛蒡渣膳食纤维微粒结构及物性的研究

采用酶法制备牛蒡渣膳食纤维,对不同粒度牛蒡渣膳食纤维的膨胀力、持水力进行测定,同时采用扫描电镜、X射线衍射等分析方法对膳食纤维微粒结构进行研究.结果表明:在355～250μm范围内,牛蒡渣膳食纤维持水力和膨胀力基本不变;在250～150μm范围内,纤维粒度减小,牛蒡渣膳食纤维的持水力和膨胀力逐渐降低;在150μm～225nm范围内,膨胀力和持水力小幅度交替升降.通过扫描电镜及X射线衍射对不同粒度的牛蒡渣膳食纤维微粒结构进行研究,分析了牛蒡渣膳食纤维微粒结构与物性之间的关系.     

The effect of fine strands in core layer on physical and mechanical properties of oriented strand boards (OSB) made of beech (Fagus sylvatica) and poplar (Populus tremula)

This paper discusses the influence of three different content levels of fine strands in the core layers on the physical and mechanical properties of European beech and poplar oriented strand boards (OSB). The results show that increasing the fines content in the core layer from 10 to 50 %, based on total board weight has no significant effect on bending strength and modulus of elasticity (MOE). All panels exceeded the minimum requirement for bending strength and MOE set by EN standards. The highest modulus of rupture (MOR) and modulus of elasticity (MOE) was determined for panels solely made of poplar with different level of fines content. Increasing the amount of fines in the core layer raised the internal bond (IB). Panels made with 30 % fines in the core layer showed highest internal bond strength values. As the fines content increased from 10 to 50 %, thickness swelling decreased. Water absorption after 24 h showed the same declining trend as thickness swelling.     

刨花板生产线的刨花计量与控制技术

与国外同类人造板生产线相比,我国的调供胶技术相对落后,未能很好地解决刨花与胶量定量配比施胶问题.本文通过对刨花体积计量和重量计量不同方案的结构、控制、特点及应用情况的详细分析和比较,提出了选用刨花计量与控制方案的建议.     

杉木间伐材物理力学性质与改性研究

分析杉木间伐材的物理力学性质,通过与天然杉木材性的比较,表明杉木间伐材物理力学性质较差。对杉木间伐材实施脲醛树脂填充的改性试验研究,结果表明杉木间伐材物理力学性质得到显著提高。     

Relative effect of particle size on the physical properties of corn meal extrudates: Effect of particle size on the extrusion of corn meal

Corn meal of various particle sizes ranging from 180 to 710 μm were processed in a twin-screw extruder to produce directly expanded extrudates. The extrusion process effects on the specific mechanical energy (SME), expansion indexes (radial, longitudinal and volumetric), pasting viscosity, water absorption index (WAI) texture properties, and microstructure were determined. Increasing the particle size decreased the SME input. Extrudates produced with corn meal of higher particle sizes expanded more than extrudates produced with smaller particle sizes. For all treatments there was no peak viscosity at 95 °C. But expanded corn meal extrudate from the 180 μm fraction showed a discontinuous gel matrix phase. Increasing corn meal particle size decreased WAI values. The mechanical resistance of the extrudates from the smallest particle size was significantly higher (p < 0.05) than that of the largest particle size. The microstructure of raw corn meal revealed large fractured particles with small rounded particles adhering to the surface.