Preservation of beech and spruce wood by allyl alcohol-based copolymers

Allyl alcohol (AA), acrylonitrile (AN), methyl methacrylate (MMA), monomers and monomer mixtures AA+AN, AA+MMA were used to conserve and consolidate Beech and Spruce. After impregnation, copolymerisation and polymerisation were accomplished by gamma irradiation. The fine structure of wood+polymer(copolymer) composites was investigated by Scanning Electron Microscopy (SEM). It was observed that copolymer obtained from AA+MMA monomer mixture showed the optimum compatibility. The compressional strength and Brinell Hardness Numbers determined for untreated and treated wood samples indicated that the mechanical strength of wood+copolymer composites was increased. It was found that the mechanical strength of the wood samples containing the AA+MMA copolymer was higher than the others. In the presence of P(AA/MMA), at highest conversion, the compressive strength perpendicular to the fibres in Beech and Spruce increased approximately 100 times. The water uptake capacity of wood+copolymer composites was observed to decrease by more than 50% relative to the original samples, and biodegradation did not take place.     

聚合物改性水玻璃均相杂化液对速生杨木的改性

将丙烯酰胺单体在钠水玻璃溶液中聚合制成水玻璃-聚丙烯酰胺均相杂化液,通过浸渍法使杂化液与速生杨木材复合,制成无机/有机木材复合材。SEM、FT-IR表征了速生杨木与杂化前驱液复合前后的结构和形貌变化,研究了复合木材的热稳定性及力学性能的变化,结果表明,用该均相杂化液改性的复合木材WPG为31.6%时,其氧指数为50.3%;并且与素材的力学性能相比,复合木材的抗弯曲强度较素材提高了11.2%,弹性模量提高了18.2%,其径面、弦面和端面的硬度分别提高了15.6%、17.3%和26.2%。     

Physicochemical and Quality Properties of Dried Courgette Slices: Impact of Vacuum Impregnation and Drying Methods

The aim of this study was to determine the effects that the type of impregnating solution and drying method (freeze drying (FD) and vacuum drying (VD) at 45 °C and convective drying (CD) at 50, 60, and 70 °C) had on the physicochemical and quality properties of courgettes. Courgette slices were vacuum-impregnated (6 kPa) in freshly squeezed onion, kale, and onion and kale (50:50) juices with 3% NaCl solution (N). The application of vacuum impregnation (VI) with impregnating solutions from freshly squeezed onions and kale had a beneficial effect on the bioactive values of courgette. The highest contents of quercetin (41.84 μg/g d.m.) and carotenoids (276.04 μg/g d.m.) were found in courgette impregnated with onion juice after freeze drying. The highest values of lutein and zeaxanthin (216.42 μg/g d.m.) were recorded for courgette impregnated with kale juice and convective dried. By analysing the kinetics of convective drying, the best matching of the logistic model was found. Increasing the drying process temperature from 50 to 70 °C reduced the drying time from 15% to 36%, depending on the type of impregnating solution used. Water activity < 0.6 was recorded for courgette dried by freezing, vacuum, and convection at 60 and 70 °C. Conclusions: The vacuum impregnation process and the impregnation solutions from freshly squeezed vegetables can be used to develop new snacks with high levels of bioactive compounds. The FD method is the most appropriate considering both the bioactive compounds content and the obtained colour and water activity.     

尼龙66与甲基丙烯酸甲酯接枝共聚合的研究——DMA/硫酸铜引发体系

烯类单体与聚酰胺(尼龙)纤维接枝共聚合已有报道.Varma等人研究了Ce4+引发丙烯腈、丙烯酰胺分别与尼龙纤维的接枝共聚反应。Lenka发表了用P2O48-引发甲基丙烯酸甲酯(MMA)与尼龙6纤维接枝共聚合的研究结果.Nayak等人报道了用乙酰丙酮锰为引发剂使MMA与尼龙6接枝共聚合.本文以二甲基苯胺(DMA)/硫酸铜为引发体系,用MMA接枝尼龙66纤维丝,研究了Cu2+浓度等因素对该接枝共聚反应的影响.     

Pressure dependence of liquid epoxy resin impregnation through polyester non-woven fabric in vacuum

The mechanism for liquid epoxy resin impregnation through polyester nonwoven fabric, sandwiched between two circular glass plates in atmospheric pressure, has been studied by the Kozeny-Carman equation improved by the introduction of the theoretical calculated capillary force and the gas leakage parameter for the void formation in the impregnating area. Impregnating velocity increases with reduced gas pressure. Experimental data on the vacuum impregnation were analyzed by the improved Kozeny-Carman equation by using wettability under measurements of the ascending heights due to liquid epoxy resin impregnation in a vacuum. The gas leakage quantity, obtained from the gas leakage parameter, is related to the gas pressure at the starting point of the impregnation. Voids for most of the impregnation stage disappear with passing impregnating time, 120 minutes as well as breaking the vacuum in the chamber.     

有机/无机杂化复合木材的制备与性能

将硅溶胶/聚丙烯酸酯,有机/无机杂化液浸注于I-69杨木材中,制成有机/无机杂化木材。FT-IR红外光谱、扫描电子显微镜分析了复合木材的微观结构和组成,结果表明,经有机/无机杂化改性后的复合木材,既保持了木材本来的性质,又具有机/无机复合物的某些特性,其力学强度和尺寸稳定性较素材显著提高。     

Electrical properties and X-ray diffraction of wood and wood plastic composite (WPC)

Wood plastic composite (WPC) of kadom, simul, mango and debdaro were prepared with two monomers, methylmethacrylate (MMA) and butylmethacrylate (BMA) using high energy ionizing radiation. X-ray diffraction and scanning electron microscope (SEM) studies reveal that significant grafting occurred with wood fiber. Electric properties like resistivity and dielectric constant of both wood and WPC were measured under different moisture contents and relative humidities. The resistivities of wood decreased dramatically with increase of moisture content, but those of WPC decreased very slowly with moisture content. The dielectric constant of wood increased significantly with moisture content but no significant difference was observed in the case of WPC within the range of moisture contents studied. The dielectric constants of untreated wood also increased with their densities.     

Graft copolymerization of 2-hydroxyethyl methacrylate and methyl methacrylate onto hide powder

Graft copolymerization of 2-hydroxyethyl methacrylate(HEMA) and mixtures of HEMA with methyl methacrylate (MMA) onto hide powder was attempted using ceric ammonium nitrate as initiator, with a view to optimize the conditions for graft copolymerization. Percent grafting and grafting efficiency were calculated for various variables such as monomer concentration, initator concentration and mole ratio of HEMA to MMA. R_p, R_g and R_h (rates of polymerization, grafting and homopolymerization respectively) were also evaluated. It was observed that R_p increased linearly with increasing concentration of MMA except at very low concentrations of the monomer. An explanation is given for the effect of variables on extent of grafting and grafting efficiency.     

IFSS, TG, FT-IR spectra of impregnated sugar palm (Arenga pinnata) fibres and mechanical properties of their composites

This study aimed to investigate the effect of resin impregnation on the interfacial shear strength (IFSS), thermogravimetric (TG) and fourier transform infrared (FT-IR) of sugar palm (Arenga pinnata) fibres. In addition, the effect of resin impregnation on the mechanical properties of sugar palm fibre reinforced unsaturated polyester (UP) composites was also studied. The fibres were impregnated with UP via vacuum resin impregnation process at a pressure of 600 mmHg for 5 min. Composites of 10, 20, 30, 40 and 50 % fibre loadings were fabricated and tested for tensile and flexural properties. It was observed that the impregnation process caused the fibres to be enclosed by UP resin and this gave a strong influence to the increase of its interfacial bonding by the increase of its IFSS from single fibre pull-out test. It was also observed with TG and FT-IR spectra that the impregnated fibre had lower moisture uptake than the control and there was no significant increase in thermal stability of the impregnated fibre. The sequence of fibre decomposition started from the evaporation of moisture, hemicelluloses, cellulose, lignin and finally ash content and the presence of these components were proven by FT-IR spectra. For the composite specimens, due to the high interfacial bonding of the impregnated fibre and the matrix, the impregnated composites showed consistently higher tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus and toughness than the control samples. It was also observed that 30 % fibre loading gave optimum properties.     

Kinetic studies on void formation during liquid epoxy resin impregnation through polyester non-woven fabric

Under the condition that liquid epoxy resin impregnation was through polyester non-woven fabric sheets, sandwiched between two circular glass plates, the increase in gas pressure caused by decrease in the volume of non-impregnating area was not as much as expected according to Boyle's law. Hence, the quantity of the gas consumed by dissolution and diffusion into the liquid resin and the polyester fibers, as well as by the void formation in the impregnating area of liquid resin, was calculated. According to the results, the quantities of gas decreased by dissolution and diffusion from the non-impregnating area into the impregnating liquid resin and into the polyester fiber are found to be so small that the deviation from Boyle's law mostly depends on the gas consumption due to the void formation in the impregnating area. Observing the impregnating region with a microscope, many voids were found in the area between the non-impregnating area and the completely impregnated area. The number and size of voids are theoretically estimated by assuming the non-uniformity of the fiber distribution in the polyester non-woven fabric.     

Development of reinforced hydrogels — I. Radiation induced graft copolymerization of methylmethacrylate on non-woven polypropylene fabric

Polypropylene (PP) fibers were grafted with methylmethacrylate. Effects of direct and pre-irradiation method and monomer concentration on the degree of grafting were investigated. The grafted PP fibers were characterized by swelling measurements, IR spectroscopy and by its mechanical and thermal properties. It was found that the direct method was more efficient than the indirect or pre-irradiation method and the monomer concentration for highest degree of grafting was 40% of MMA. Mechanical properties (tensile strength) and thermal stability decrease with grafting yield. Those changes were related to degradation of tie molecules between crystals and formation of rigid branches of PMMA on PP amorphous phase.     

助剂对Ru/C催化剂的表面性质及氨合成催化性能的影响

以碱金属、碱土金属硝酸盐作为助剂前体，活性炭为载体制备了系列负载型钌催化剂，采用物理吸附、化学吸附和XRD等表征手段，考察了助剂对Ru/C催化剂的比表面、孔分布和钌分散度的影响，并在430 ℃、10.0 MPa和10 000 h－1条件下进行氨合成活性评价。结果表明，单助剂Ru/C催化剂，碱金属助剂的促进作用与其相应氢氧化物碱性变化规律一致，碱土金属助剂的促进作用与其相应氧化物碱性变化规律一致。在同类化合物中，铯和钡均是最有效的助剂，钡比铯具有更强的促进作用。以硝酸钡和硝酸铯制备双助剂Ru/C催化剂，先钡后铯分步浸渍制备钌催化剂的活性不仅明显高于钡、铯共浸渍钌催化剂，而且也高于先铯后钡分步浸渍钌催化剂。     

Temperature dependence of liquid epoxy resin impregnation through polyester non-woven fabric

The temperature dependence of liquid epoxy resin impregnation under atmospheric pressure was measured under the condition that the impregnation was through polyester non-woven fabric sheets, sandwiched between two circular glass plates. It was expected that impregnation would take place to a small extent, because the pressure in the sheet increases to more than atmospheric pressure in the course of impregnation from the perimeter of the circular sheet toward its center, but the liquid resin impregnates to a great extent and impregnating velocity increases with a rise in temperature. This phenomenon can be analyzed by the Kozeny-Carman equation improved by the introduction of the theoretically calculated capillary force in the modeled fiber bed structure and a parameter to postulate gas solubility and diffusion into the liquid resin. An increase in the impregnating velocity with the temperature rise is caused by decrease in the resin viscosity, by increase of the capillary force pressure and by decrease in the gas pressure corrected by a parameter.     

Grafting of methyl methacrylate onto natural rubber in supercritical carbon dioxide

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber (NR) was carried out by supercritical carbon dioxide (scCO₂) swelling polymerization with benzoyl peroxide (BPO) as an initiator. Fourier transform–infrared spectroscopy (FT–IR) was used to confirm the formation of graft copolymers with the characteristic bands of symmetric C?O and C? O? C stretching vibrations at 1728 cm^?1 and 1147 cm^?1, respectively. The effects of the rubber‐to‐monomer ratio, amount of initiator, reaction time, and pressure on the monomer grafting level (GL) and grafting efficiency (GE) were investigated, and the optimum conditions for the preparation of NR‐g‐MMA were found to be 70:30 of the rubber‐to‐monomer ratio, 1.2% of the initiator content, and the reaction pressure of 23 MPa for 6 h. The thermal behavior of the NR and the different NR/MMA molar ratio grafted copolymer samples was studied by differential scanning calorimetry (DSC). The observed glass transition temperature (T_g) was consistent with the GL. The tensile strength, modulus of elasticity, elongation at break, hardness, and oil resistance of graft copolymers were determined and compared with the values of NR and that of polymerization products prepared in traditional toluene solution. The results showed that the tensile strength, modulus of elasticity, hardness and oil resistance were greatly improved after modification in scCO₂. Copyright © 2007 John Wiley & Sons, Ltd.     

Dimethylaniline (DMA)–Cu2+ ion system-induced graft polymerization of methyl methacrylate on viscose

Graft polymerization of methyl methacrylate on viscose fibers induced by the DMA–Cu²⁺ ion system was investigated under different conditions. Variables studied include concentration of DMA, Cu²⁺ ion, and MMA, reaction time, and temperature. There are optimal concentrations of DMA and Cu²⁺; below or above these concentrations lower grafting occured. Within 4 hr reaction time, the grafting reaction showed an initial fast rate followed by a slower one at 80°C. At 70°C, on the other hand, the graft yield increased in proportion to the increase in reaction time. Increasing the monomer concentration did not have a significant effect on the graft yield during the first 45 min of reaction. Beyond this, the effect of monomer concentration was marked.     

Radiation-induced grafting polymerization of MMA onto polybutadiene rubber latex

The grafting of methyl methacrylate (MMA) onto polybutadiene rubber latex by the direct radiation method was carried out. The effects of monomer concentration, absorbed dose and dose rate of gamma rays on the grafting yield were investigated. The graft copolymers were characterized by transmission electron microscopy (TEM), FTIR spectroscopy, and differential scanning calorimetry. TEM photographs revealed that the core–shell structures of latex particles are formed at low MMA content, and with the increasing of MMA content, the semi-IPN-like structure with core–shell could be developed due to the high gel fraction of polybutadiene (PBD) seed particles. In addition, infrared analysis confirmed that MMA could be grafted onto PBD molecular chains effectively under appropriate irradiation conditions. The interfacial adhesion between PBD rubber (core) and PMMA (shell) phases could be enhanced with the increase of MMA concentration.     

Synthesis and Characterization of Bagasse Poly(methyl methacrylate) Graft Copolymer

Summary: Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using ceric ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA.     

Diffusion rate of polyethylene glycol into cell walls of red pine following vacuum impregnation

Rates of penetration of polyethylene glycol (PEG) molecular weight (MW) 1,000, 2,000, and 4,000 from 30% aqueous solutions into hydrated cell walls of red pine samples following vacuum impregnation were estimated by examining retained swelling of the samples after different post-treatment conditioning times. To model PEG diffusion into wood cell walls, a hollow cylinder diffusion model was developed and diffusion coefficients were estimated and compared to those determined with a plane membrane diffusion model. The models gave similar results. The diffusion coefficient of PEG MW 1,000 at room temperature was estimated to be in the order of 10⁻¹³ m²/s, while the penetration rates of both PEG 2,000 and 4,000 were about an order lower. These findings indicate that treatments of wood by PEG can be significantly shorter than present practices of soaking green samples in solution if the samples are vacuum/pressure impregnated with PEG solution.     

Graft copolymerization onto jute fiber: Ceric ion-initiated graft copolymerization of methyl methacrylate

Graft copolymerization of methyl methacrylate (MMA) was carried out on both defatted and bleached jute fibers using ceric ammonium sulfate (CAS) as the initiator. In order to obtain the optimum condition for grafting, the effects of initiator concentrations, temperature, time of reaction, lignin content of jute, and the monomer concentration were studied. The maximum percent grafting and grafting efficiency were found to be 132% and 0.71, respectively. Kinetic studies showed that at 0.03M CAS, the reaction appeared to obey the second-order process. The activation energies were found to be 7.74 and 5.12 kcal/mole for defatted (lignin content, 15.7%) and chlorite-bleached jute (lignin content 10%), respectively. The activation energies of graft copolymerization of MMA onto jute fiber are compared with the energies of activation of graft copolymerization of acrylonitrile (AN).     

Grafting onto Wool. XXVI. Graft Copolymerization of Vinyl Monomers by Use of Cr(acac)3-TBHP as Initiator

Methyl methacrylate (MMA), methyl acrylate (MA), and ethyl acrylate (EA) have been graft copolymerized onto wool fiber in aqueous medium using the chromium acetylacetonate-tertiary-butyl hydroperoxide (Cr(acac)₃-TBHP) system as initiator. The percentage of grafting has been determined as a function of the concentrations of monomer, chelate, and TBHP, and the time and temperature under optimum conditions. MMA produced a maximum grafting of 119.8%, MA produced a maximum grafting of 56%, while EA afforded maximum grafting to the extent of 41.9%. Different vinyl monomers were found to follow the following reactivity order toward grafting onto wool fiber in the presence of the Cr(acac)₃-TBHP system: MMA > MA > EA.