Effects of surface performance on bamboo by microwave plasma treatment

Abstract Surface treatment of bamboo was carried out by microwave plasma (MWP), surface contact angle of the sample was measured using glycerin and urea-formaldehyde resin (UFR) liquid, and the effects on the surface performance of the bamboo sample was evaluated. The results show that the surface contact angle of the sample presented a generally decreasing trend when prolonging the MWP treatment time and shortening the distance between the sample and the resonance cavity. The surface contact angle of the sample decreased by 49%–59% under the following conditions: MWP treatment for 30 s, the distance between the sample and resonance cavity at 40 mm, and measurement at 15 s after dripping with glycerin. The surface contact angle of the sample measured with the glycerin was lower than that with UFR. No matter whether we used glycerin or UFR, the contact angle of the sample at 15 s after dripping was lower than that at 5 s after dripping. The grinding treatment had little effect on the surface contact angle of the sample after MWP treatment, and the modification effect ofMWP treatment after grinding was better than that of sole MWP treatment. __________ Translated from Journal of Nanjing Forestry University (Natural Sciences Edition), 2007, 31(4): 33–36 [译自: 南京林业大学学报(自 然科学版)]     

Surface energy of preservative-treated southern yellow pine (Pinus spp.) by contact angle measurement

In this study, the contact angles of four different reference liquids (including distilled water, diiodomethane, formadide and glycerol) formed on the surfaces of wood, treated with chromated copper arsenate (CCA) and two other emerging copper-based water-borne systems (commercial names: NW and NS) were measured with sessile drop method. Based on the contact angle data, the surface energy was obtained from the acid-base approach. The total surface energy consisted of Lifshiz-van der Waals parameter and acid-base parameter. Results showed that the NW and CCA treatments made the wood surface more hydrophobic while the NS treatment had the reverse effect on the wood surface mainly owing to the increased penetration of earlywood. By using three liquids, diiodomethane, formamide and distilled water, the total surface energy obtained for untreated earlywood, untreated latewood, CCA-treated earlywood, CCA-treated latewood, NW-treated earlywood, NW-treated latewood, NS-treated earlywood and NS-treated latewood were 43.1, 44.5, 43.4, 45.1, 49.4, 40.6, 46.0 and 40.9 mJ/m², respectively. The surface energy of CCA-treated wood was almost the same as untreated wood. After NW and NS treatments, the surface energy of both earlywood and latewood changed a little. However, the change was not so obvious as to draw any further conclusion concerning the influence of NW and NS treatments on the surface energy of wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(4): 1–4 [译自: 北京林业大学学报]     

Effect of ACQ-D treatment on the surface free energy of Chinese fir (<Emphasis Type="Italic">Cunninghamia lanceolata</Emphasis>)

In this study, the contact angles of three different reference liquids （including distilled water, diiodomethane, and formamide） and PF resin on the surfaces of Chinese fir （Cunningharnia lanceolata） samples untreated or treated with different concentrations of ACQ-D （ammoniacal copper quat Type D） solutions were measured. Then, the surface free energy was calculated by two approaches： acid-base approach and geometric mean approach. ACQ-D treatment caused higher contact angles and lower surface free energies at a retention level corresponding to the commodity treated wood products. When wood was treated with much higher concentrations of ACQ-D, the total surface free energy of wood would be higher than the untreated control. Acid-base/polar components related with the hydrogen bonding state in wood were considered to be responsible for the observed changes according to the applied approaches. The hydrophobic properties and also higher contact angles of PF resin drop on wood surfaces after ACQ-D treatment at a reasonable retention level confirms the changes on surface free energy.     

Improvement of wood properties by urea-formaldehyde resin and nano-SiO2

In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO₂, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were impregnated with the modifiers and heated to prepare UF-SiO₂-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance and hardness. Nano-SiO₂ showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO₂-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO₂ compound improved general properties of poplar wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(2): 123–128 [译自: 北京林业大学学报]     

Preliminary study on the characteristics of tactility of wood by physiological index HRV

We used heart rate variability (HRV), an electrophysiological index, to investigate the changes of the sympathetic and parasympathetic nervous systems of people when they were in contact with wood and other materials, in a time-domain, a frequency-domain, and by means of nonlinear dynamics. Our aim was to discover the relations among thermal parameters of different kinds of material, human physiological feedbacks, and psychological perceptions. It shows that the activity of the sympathetic nervous system when in contact with wood increased no more than when in contact with metal and ceramic materials, while the activity of the parasympathetic nervous system weakened less than when in contact with these materials. The time taken by the sympathetic and parasympathetic nervous systems to revert to their normal state after contact with cloth and wood was shorter than that after contact with metal and ceramic. A subjective survey, by SD method, showed that the tactility of wood was favorable and people preferred wood to other kinds of material. Correlation analysis’ results showed that there was a close correlation among the HRV indices, human psychological emotion ratings, and thermal parameters of the different kinds of materials. The experiment proves that the effect of wood on our autonomous nervous system is slightly better than that of other materials except for cloth. Wood does not damage people’s health. __________ Translated from Journal of Northeast Forestry University, 2005, 33(2): 29–31 [译自: 东北林业大学学报, 2005, 33(2): 29–31]     

Dynamic viscoelastic behavior of wood under drying conditions

In this study heartwood from a Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantation was treated using a high-temperature drying (HTD) method at 115°C, a low-temperature drying (LTD) method at 65°C, and freeze vacuum drying (FVD), respectively. The dynamic viscoelastic properties of dried wood specimens were investigated. The measurements were carried out at a temperature range of −120 to 250°C at four different frequencies (1, 2, 5, and 10 Hz) using dynamic mechanical analysis (DMA). We have drawn the following conclusions: 1) the storage modulus E′ and loss modulus E″ are the highest for HTD wood and the lowest for FVD wood; 2) three relaxation processes were detected in HTD and LTD wood, attributed to the micro-Brownian motion of cell wall polymers in the non-crystalline region, the oscillations of the torso of cell wall polymers, and the motions of the methyl groups of cell wall polymers in the non-crystalline region in a decreasing order of temperatures at which they occurred; and 3) in FVD wood, four relaxation processes were observed. A newly added relaxation is attributed to the micro-Brownian motions of lignin molecules. This study suggests that both the HTD and the LTD methods restrict the micro-Brownian motion of lignin molecules somewhat by the cross-linking of chains due to their heating history. __________ Translated from Journal of Beijing Forestry University, 2008, 30(3): 96–100 [译自: 北京林业大学学报]     

微波等离子体处理西南桤木表面的ESR和XPS分析

采用电子顺磁共振波谱 (ESR)和X射线光电子能谱 (XPS)技术 ,分析了微波等离子体处理前后西南桤木木材表面的性质。ESR图谱分析表明 :经过微波等离子体处理后 ,木材表面可迅速有效地产生大量的自由基 ;XPS图谱分析表明 :微波等离子体处理使木材表面O C原子比增加 ,C1 含量降低 ,而C2 、C3含量增加 ,并有C4 的出现。这些结果表明经微波等离子体处理后木材表面产生了大量的含氧官能团或过氧化物     

Improvement in compatibility and mechanical properties of modified wood fiber/polypropylene composites

To improve the interfacial compatibility between wood fibers and polypropylene and the toughness of wood-fiber/polypropylene composites, maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-ethylene-butadiene-styrene copolymers (SEBS-g-MAH) were used as modifiers. Mechanical properties of wood-fiber/polypropylene (WF/PP) composites were improved when PP-g-MAH or SEBS-g-MAH was added. When either of these copolymers was added, the composites had better interfacial compatibility than the unmodified composite. This was verified by scanning electron microscope (SEM) observations and dynamic mechanical analysis (DMA). The mechanical properties of the composites were significantly improved because of the good interfacial bonding between wood fibers and polypropylene when PP-g-MAH and SEBS-g-MAH were added. __________ Translated from Journal of Beijing Forestry University, 2007, 29(2): 133–137 [译自: 北京林业大学学报]     

微波等离子体处理对杉木表面性能的影响

为了解微波等离子体处理对杉木表面性能的影响,使用接触角测定评估表面润湿性,使用扫描电子显微镜观测表面处理前后的差异。结果表明,杉木表面轻微波等离子体处理后,接触角下降为零,即使处理条件十分微弱、处理效果仍然十分明显,这表明微波等离子体处理可显著提高木材表面的润湿性,微波等离子体处理使杉木表面形成粗化面,即表面明显有等离子体蚀刻过的痕迹并留下凹凸不平的坑洼,粗化面的形成可能是导致杉木表面接触角下降,     

Wettability and adherence of acrylic paints on long and short rotation teaks

ABSTRACT

The quality of finished wood products depends on the quality of its coating layer. An important indicator for evaluating the quality is Adherence of the paint on the wood surface. The purpose of this research was to analyze the effect of wood surface roughness and the viscosity of acrylic paints (pure acrylic and acrylic copolymer) to the wettability and Adherence for long and short rotation teaks. Wood surface with various degrees of roughness was prepared by sanding with abrasive papers of P120, P240, and P360 grits. Different viscosity of the acrylic paints was prepared composition between paint and water (w/w) of 100:0, 90:10, 80:20, and 70:30. The wettability of the acrylic paints on teak wood surfaces was measured using a sessile drop contact angle method with the S/G model. Adherence of the coating layer was measured using a crosscut test. The results showed that the increase in the roughness (Ra) and the decrease in the viscosity of the paints resulted in the increase in the wettability which leads to better Adherence of acrylic paints on the surface of teak woods. The pure acrylic paint generated better wettability and Adherence compared to the acrylic copolymer.     

Influence of steam heating on the properties of pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis>) and eucalypt (<Emphasis Type="Italic">Eucalyptus globulus</Emphasis>) wood

Heat treatment of Pinus pinaster and Eucalyptus globulus woods, two important species in Portugal, was performed in the absence of air by steaming, inside an autoclave, for 2–12 h at 190–210°C. Mass losses increased with treatment time and temperature reaching 7.3% for pine and 14.5% for eucalypt wood. The wood behaviour with moisture was improved. The equilibrium moisture content decreased by 46% for pine and 61% for eucalypt, the dimensional stability increased (maximum anti-shrinking efficiency in the radial direction of 57 and 90% for pine and eucalypt, respectively) and the surface wettability was lowered. In relation to mechanical properties, the modulus of elasticity was little affected (maximum decrease of 5% for pine and 15% for eucalypt) but the bending strength was reduced (by 40% at 8% mass loss for pine and 50% at 9% mass loss for eucalypt wood). The variation of properties was related to treatment intensity and mass loss but significant improvements could already be obtained for a 3–4% mass loss without impairing the mechanical resistance. The response of eucalypt was higher than that of pinewood. Heat treatment of eucalypt wood shows an interesting potential to improve the wood quality for solid timber products.     

Effect of ACQ-D Treatment on the Surface Free Energy of Chinese Fir (Cunninghamia lanceolata)

In this study, the contact angles of three different reference liquids (including distilled water, diiodomethane, and formamide) and PF resin on the surfaces of Chinese fir (Cunninghamia lanceolata) samples untreated or treated with different con- centrations of ACQ-D (ammoniacal copper quat Type D) solutions were measured. Then, the surface free energy was calculated by two approaches: acid-base approach and geometric mean approach. ACQ-D treatment caused higher contact angles and lower surface free energies at a retention level corresponding to the commodity treated wood products. When wood was treated with much higher concentrations of ACQ-D, the total surface free energy of wood would be higher than the untreated control. Acid-base/polar compo- nents related with the hydrogen bonding state in wood were considered to be responsible for the observed changes according to the applied approaches. The hydrophobic properties and also higher contact angles of PF resin drop on wood surfaces after ACQ-D treatment at a reasonable retention level confirms the changes on surface free energy.     

Nonisothermal moisture movement in wood

In order to analyze the effect of temperature gradient on moisture movement during highly intensive drying, such as microwave-vacuum drying, the profile of the temperature and moisture content in sealed wood whose opposite faces were subjected to temperature gradient for a short time was measured. The ratio of the moisture content (MC) gradient to the temperature gradient (dM/dT) was calculated and the factors influencing moisture movement under nonisothermal conditions were discussed. The results indicate that moisture moved in wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperatures for a short period. The moisture content on the cold surface was higher than that on the warm surface. The moisture content gradient opposite to the temperature gradient was established, and the dM/dT was below 0.9%/°C. The temperature in the sample and the distance from the hot surface of the sample was strongly linearly correlated. With an increase in temperature, initial moisture content and experimental time, the dM/dT was significantly increased. __________ Translated from Journal of Beijing Forestry University, 2005, 27(2): 96–100 [译自: 北京林业大学学报, 2005, 27(2): 96–100]     

Regeneration and reuse of exhausted solutions of electroless nickel plating wood veneer

The regeneration of exhausted solutions of electroless nickel plating wood veneer was realized using soluble calcium salt to precipitate and remove phosphite and then using fluoride to remove residual calcium ions from the solution. The effect of the pH value of the solution, treatment temperature and the molar ratio of calcium ions to phosphite ions on the removal efficiency of phosphite was investigated. Wood veneer was electroless plated using regenerated solutions. A coating with better electrical conductivity and electromagnetic shielding was obtained. __________ Translated from Journal of Northeast Forestry University, 2005, 33(3): 47–48 [译自: 东北林业大学学报, 2005, 33(3): 47–48]     

Wettability of Poplar Wood Impregnated by Phenol-formaldehyde Resin

In this study,plantation poplar wood was first impregnated by low molecular weight phenol-formaldehyde(PF) resin solution by vacuum-pressure process.And then the wettability of sanded and non-sanded radial and tangential sections from un-impregnated and impregnated poplar wood was tested respectively by the measurement of contact angles using different liquids.Finally,the surface free energy of different samples was estimated by the plot extrapolation method.The results showed that the wettability of woo...     

Structure and characterization of Chinese fir (Cunninghamia lanceolata) wood/MMT intercalation nanocomposite (WMNC)

With water-soluble phenol-formaldehyde resin as an intermediate, Chinese fir (Cunninghamia lanceolata) wood/montmorillonite nanocomposite (WMNC) was prepared through vacuum impregnation and characterized with XRD, SEM, FTIR and TG-DTA analyses. The XRD analysis indicated that the wood crystallinity of WMNC decreased, the MMT exfoliated and some nano silicate layers entered into the non-crystallized microfibrillar region of the wood cell wall. Wood structure is anisotropic and its impregnation is anisotropic. Due to the nonuniformity of the MMT organic modification, PF intercalation and wood impregnation, the MMT configuration and distribution in wood were diverse. The SEM graphs of WMNC showed that some silicate grains were blocked in the wood cell lumen, some silicate layers adhered to the inner surface of the wood cell wall, and some exfoliated MMT layers even penetrated the wood cell wall. The obtained hydroxyl of WMNC increased and its ether linking decreased. It was considered that MMT and wood interacted not only with hydroxyl bonds, but also involved some chemical linking. Compared with untreated wood and the PF-impreg, the pyrolysis process of WMNC changed; its starting decomposing temperature decreased and its pyrolysis weight loss at high temperatures greatly decreased. The WMNC indicated certain nanoeffects of the composition of the inorganic MMT nanolamellae. __________ Translated from Journal of Beijing Forestry University, 2007, 29(1): 131–135 [译自: 北京林业大学学报]     

采用H2O2溶液对落叶松表面进行活化处理的研究

为提高用水性高分子异氰酸酯胶粘剂(API)胶接的落叶松木材的胶接性能,采用H2O2溶液对落叶松表面进行活化处理.试验结果表明采用H2O2溶液处理落叶松木材表面可以提高其胶接强度,用H2O2溶液处理过的落叶松表面比未处理过的落叶松素材的常态压缩剪切强度提高15%.文中还讨论了采用H2O2溶液对落叶松表面进行活化处理可以提高其胶接强度的主要机理.通过傅立叶红外吸收光谱(FTIR)证明用H2O2溶液处理落叶松木材表面可以提高其常态压缩剪切强度的机理主要是氧化作用,即用H2O2溶液处理落叶松木材表面后,其表面或获得活性基团羰基.通过对其表面接触角的测定可以看出,H2O2溶液处理过的落叶松表面润湿性增加,这对胶接有利.     

Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]     

3种水性漆在杨木表面的润湿性对比研究

选取丙烯酸酯、聚氨酯、丙烯酸-聚氨酯共聚物3种水性漆为滴液,用接触角测试仪对3种水性漆在杨木表面的接触角进行测试,对比分析其对杨木表面润湿性的影响。结果表明:未进行超纯水稀释的水性漆中,丙烯酸酯、共聚物水性漆在杨木径切面的润湿性优于弦切面,聚氨酯水性漆则反之;共聚物水性漆相比于其他两种漆润湿性更好,聚氨酯次之,丙烯酸酯水性漆的润湿性则相对较差。相比未进行超纯水稀释的水性漆,经稀释处理的3种水性漆在杨木表面的接触角均有不同程度的下降。接触角下降率分析表明:丙烯酸酯水性漆相比其他两种漆在杨木表面的润湿性更好,此外共聚物水性漆在杨木弦切面润湿性优于径切面,而其他两种水性漆则相反。     

Niche of insect borers within Pinus massoniana infected by pine wood nematode

In November 2003 and June 2004, the insect borers and their spatial distribution within Pinus massoniana were investigated in Zhoushan City, in East China’s Zhejiang Province, where pine wood nematode (Bursaphelenchus xylophilus) are typically found. The niche width, proportional similarity of niche and the niche overlap of dominant species of dying trees were computed. Results show that five insect species infect and damage Pinus massoniana, which had been infected by pine wood nematodes, among which four are wood boring beetles and one termite. Species within host trees vary from winter to summer and all the species have their own niche width, proportional similarity of niche and the niche overlap. They can achieve competitive equilibrium and coexistence according to their biological characteristics and life habits. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 108–111 [译自: 北京林业大学学报, 2005, 27(6): 108–111]