It has a vital role. This Paper introduces the method of interface modification of PVC base wood S composite foaming material at home and abroad, and points out the attention of selecting modification route. .

Fi Jinmu: Key Project of Science and Technology Research of the Ministry of Education (No. 224, 01138); Special Fund for Doctoral Programs in Higher Education (20020561002 2006-03-0331113 (1311 et al. 2 using benzoyl chloride; Mahlberg et al. 3 with acetic anhydride, horse) Acetic anhydride and succinic anhydride; Qin Tefu et al. 141 acylation of wood fiber with acetic anhydride. It was found that the acyl group reacted with the hydroxyl group on the surface of wood fiber to form an ester compound, which made the polarity of wood fiber. And the hydrophilicity is greatly reduced, and the compatibility with the matrix resin is improved. Liu Tao uses oleic acid amide and polyurethane prepolymer to treat the wood fiber respectively, which improves the comprehensive performance of the material to some extent.

Stearic acid can not only esterify with fiber, but also its long chain of hydrophobic water can protect the surface of the fiber and reduce its surface free energy. And 236丨101118 and other methods of surface treatment of fibers by gas-phase gluing, the comprehensive performance of surface-treated composites is far superior to untreated. It was found that 181: glacial acetic acid can be used to esterify the polar i-functional group (hydroxyl group) on the surface of wood powder, reduce the interface repellency and improve the adhesion, but the acetic acid will increase the surface free energy. W. linoleic acid can also be Used as a surface modifier to increase the tensile strength, elongation at break and ring breaking work of the composite, but to reduce the modulus.

1.2 The coupling reaction coupling agent is a kind of amphoteric structure. A part of the group can react with the surface group of the inorganic substance to form a strong chemical bond; the other part of the group can react with the organic substance or physically entangle Therefore, the two materials with very different properties are firmly combined to function as a bridge. At present, the coupling agents widely used in the interface modification of PVC and wood fiber mainly include isocyanate, silane, titanate, aluminate and acrylate, among which isocyanate coupling agent has the best effect, and the effect of silane coupling agent depends on it. Dispersibility.

: Poly(methylene polyphenylene polyisocyanate) (PMPnc) not only forms a urethane bond with the hydroxyl group on the surface of wood fiber, but also has a strong adhesion with PVC, so it is an ideal one. The combination agent is superior to the silane coupling agent and the titanate coupling agent, but has certain toxicity.

In the study of the properties of modified wood flour/PVC composites, Zhong Xin et al. used silane coupling agent to modify the surface of wood flour. The results showed that the composite properties obtained were better than untreated. Zhao Yiping "2 uses 1 Hu Shengfei et al. found that the surface treatment of wood powder with a monoalkoxy pyrophosphate-based titanate coupling agent can significantly improve the surface quality of the composite, reduce melt fracture and improve mechanical properties. Because in addition to the reaction of the monoalkoxy group with the hydroxyl group of the wood powder, the free water will hydrolyze part of the pyrophosphate ester to the phosphate ester, thus increasing the fluidity of the wood powder and the wettability with PVC, and improving the interfacial adhesion ability. And it plays a role in reducing the moisture of the wood powder and improves the overall performance of the material.

Aluminate is also a commonly used modifier, inexpensive, and has an advantage in large-scale industrial production, and the effect of lowering the viscosity of the system is particularly pronounced. Since the aluminate is solid, it must be diluted with paraffin when used. Therefore, the interface modification effect is slightly inferior to that of titanate and silane coupling agent. 5 Recently, Bhavesh L. Hah et al. used chitin and polyurethane PVC. The interfacial modification of the PVC/wood flour system by the interfacial modified glucose of plastic composite foaming material found that the amino functional group can react with the chlorine-containing PVC on the surface of the wood powder to improve the interfacial bonding performance and the bending of the material. Both strength and modulus have been greatly improved.

There is an optimum value for the use of the coupling agent.

Liao Bing et al. grafted the organic group CH2-CH2-CN onto the surface of wood fiber, which made the wood fiber oleophilic, improved the interfacial adhesion and the dispersibility of wood fiber, thus improving the composite material. Tensile strength and impact strength. In addition, POE and maleic anhydride graft copolymers can be cross-linked with hydroxyl groups in wood powder to improve interfacial adhesion properties.

1.4 Low-temperature plasma reaction The essence of this method is to modify the non-polar surface with a polar group containing oxygen to improve the surface energy of the non-polar surface and increase the wettability. Low temperature plasma interface modification can be described as three steps: generating excited state molecules; decomposing into free radicals or ions (consuming energy); and modifying the reaction. Treatment of wood flour with low temperature plasma produces various surface effects such as surface energy, changes in the number of functional groups, and cross-linking in the vicinity of the surface.

Radiation treatment is also a useful method of interface modification. Ultraviolet rays, gamma rays, and electron beam irradiation are used to oxidize the surface of the polymer to increase surface polarity and improve wettability and interfacial adhesion. In addition, etherification is also a common method.

2. Physical interaction The physical interaction between the fiber and the resin matrix is ​​improved by changing the structure and surface energy of the fiber.

2.1 The treatment of wood powder with acid, jun and organic solvents contains low molecular impurities such as lignin, hemicellulose and pectin, which have a negative impact on the strength of the fiber and the properties of the composite. Rinsing of certain solutions not only increases the roughness of the interface, but also removes some of the substances that may cause weak boundary layers, such as oxides on the interface, low molecular impurities and contaminants, and also splits the fiber bundle into smaller fibers. Increase the aspect ratio and interface area. Therefore, low molecular impurities are removed as much as possible using an acid, base or organic solvent prior to interfacial modification of the polymer.

The NaOH solution can dissolve low molecular impurities in the wood powder, reduce the microfiber rotation angle, and improve the molecular orientation and breaking strength of the fiber without changing the chemical structure of the host cellulose. At the same time, the NaOH solution opens up part of the hydroxyl groups of the wood fiber, which reduces the crystallinity of the cellulose, makes the surface fluffy and has a large number of voids, making the silane coupling agent easier to react with the hydroxyl groups in the wood powder, reducing the wood fiber. Hydrophilicity, which improves the interfacial adhesion NaOH solution only improves the dispersibility of wood fiber, while silane coupling agent improves the dispersibility of wood fiber and improves the adhesion between wood fiber and polymer matrix. . In addition, the role of the acid and the organic solvent is mainly to remove part of the pectin which is insoluble in alkali.

The concentration of NaOH solution has a great influence on the treatment effect: as the concentration of NaOH increases, the impact strength, tensile strength and elongation at break of the material increase, but when the concentration is greater than 15%, the NaOH solution may be destroyed. The structure of the wood fiber crystallizes, resulting in a decrease in tensile strength and modulus of elasticity of the material.

2.2 The addition of a non-reactive compatibilizer compatibilizer is generally a block copolymer, a graft copolymer or a functional group copolymer containing a reaction with a blending component. According to a similarly compatible principle, one end containing a polar group is compatible with the xylem moiety, and one end containing a non-polar group is compatible with the resin matrix. The addition of compatibilizer can reduce the interfacial tension, increase the thickness of the interface layer, prevent the dispersed phase from agglomerating, stabilize the phase morphology structure, and increase the compatibility of the interface. Some compatibilizers can also be entangled with the surface of the polymer blend to increase adhesion. The study found that the use of CPE to fill PVC-based wood-plastic composite materials can not only make PVC-CPE-plant fiber evenly blended, but also improve the flame retardancy, processability and impact strength of composite materials. . Zhao Yiping used stearic acid coated wood powder to improve the PVC/wood powder system and achieved good results.

In addition, sputtering surface discharge and corona discharge method can be used to change the surface energy of cellulose, generate free radicals and functional groups on the surface, increase surface roughness, and improve adhesion. Physical processing methods, namely stretching, calendering and heat treatment, are also commonly used in the interface modification method, and the compatibility of the matrix is ​​improved by changing the spatial structure and surface properties of the fiber without changing the chemical composition of the surface of the wood fiber. The gas explosion method is a new physical modification method, which can change the microstructure of the fiber, that is, the cell wall is broken; the hemicellulose and lignin are removed, thereby increasing the cellulose content in the wood powder and increasing the interface area. Ethanolamine copper improves the properties of wood-plastic composites by increasing the thermal conductivity of wood powder. 127. These methods are mainly targeted to change some of the main parameters of the fiber, such as surface tension, hygroscopicity, swelling, adsorption and high polymerization. Compatibility of things.

3. Comparison of different treatment methods Generally speaking, the chemical modification effect is obviously better than the physical effect, but the two methods do not conflict, and the chemical modification and physical effects can complement each other under certain conditions.

In terms of improving the tensile strength effect, the titanate effect is better in the low-component wood powder filling system (less than 30 phr), and the silane coupling agent is better in the high-component filling system. Aluminate is less effective but cheaper. Stearic acid (Hst) coating alone is the least effective. For the improvement of impact strength, the effects of the four methods are not obvious.

The study found that butyl acrylate prepolymer can also improve the mechanical properties of PVC-based wood-plastic composites, but the effect is slightly inferior to silane coupling agents. In terms of processability, when the amount of wood flour added is 10 phr, the butyl acrylate can significantly improve the fluidity of the composite material, thereby improving the processability of the material, compared with the decane and aluminate coupling agent.

Some scholars have compared the effects of three surface modifiers of titanate, oleic acid amide and polyurethane prepolymer on the properties of PVC/wood powder system. It is found that all three can improve the interfacial adhesion and improve the mechanical properties of the system. Rheological properties, especially 4 phr polyurethane prepolymer and 6 phr oleic acid amide can better improve the mechanical properties of the system, 4 phr ~ 6 phr polyurethane prepolymer can minimize the viscosity of the system, but the excess of modifier will also be due to dispersion Decreased and weakened mechanical properties.

The PVC-based wood-plastic composite foaming material interface modified branch copolymer (reactive compatibilizer) method and chemical modification method have found that the use of compatibilizer has the lowest cost and the most promising future. However, there are some disadvantages in the use of compatibilizers: only suitable for low water content composite systems; raw materials are limited to wood flour or short fibers; the proportion of wood flour in the system can not be too high m. 4 Conclusion The bond strength obtained by interface modification Not the higher the better, because the PVC is not tough, the composite material mainly absorbs and dissipates the impact energy through the fiber. If the better the bond, the higher the interlaminar shear strength, the crack that grows under stress easily spreads to the interface to exhibit brittle fracture; if the bond is weak, the interface is detached and broken before the crack grows, and the moisture is easy. Penetration into the voids in the interface leads to a significant decrease in strength; the choice of the modification pathway depends not only on the fiber type, morphology, and surface characteristics of the resin matrix, but also on the subsequent molding process, the industrialization of the manufacturing, and the degree of scale. Specific problems must be analyzed in detail. Only global considerations can be made to select the appropriate modification method for the composite material to obtain the ideal product. The various modification methods are not isolated, and can be used alone or in combination with multiple components. Modifiers, ie, the use of composite modifiers, are more effective than using a single modifier. This is because in the wood-plastic composite process, there is not only a chemical bond between the wood powder and the plastic, but also a physical bond embedded in each other. The single modification route cannot completely solve and improve the interface interaction of the composite material. However, it must be noted that there should be synergistic effects between the components, otherwise it will be counterproductive, not only will not achieve the modification effect, but also may increase the difficulty of processing. Cowen: Wang Zhiling Wang Zheng. Advances in research on interface compatibilization of wood/plastic composites. Wood Industry 200519 (3): 12-15. Qin Tefu, Yan Peng. Research on the principle of non-polarization of wood surface. Timber Industry 199913 (4): 17-20, 23. Liu Tao, Hong Fenghong Wu Dezhen. The effect of wood powder surface treatment on the performance of PVC/wood powder composites is Qin Zhiguo Wen Hanjiang. Overview of the research on the properties of thermoplastic wood-plastic composites. Wang Hao of Suzhou University. Research on improving the compatibility of wood-plastic composites. Shanghai Plastics 2004-127 (3): 32-36. Wang Shan. Plastic formula design question and answer. Beijing: China Light Industry Press, 2003343-346. Zhong Xin Xue Ping Ding Wei. Study on the properties of modified wood flour/PVC composites. Chinese plastic Zhao Yiping. Study on the performance of PVC wood powder filling system. Tianjin: Tianjin University of Science and Technology 2001° Hu Shengfei Yan Haijun, Hu Lixin. Single-screw one-step extrusion of PVC-based wood/plastic composite material Liu handsome. Plastic filled modification. Beijing: China Light Industry Press 199859 Li Kaifu. The effect of coupling agent on the interfacial compatibility of wood-plastic composites. Forestry Industry-200532 (3): 24-26. Zhu Deqin Liu Xirong, Sheng Yu and so on. Research and development of polymer-based wood-plastic composites. Fujian: Fujian Normal University, 12005. Gao Jie, Tang Liegui. Cellulose science. Beijing: Science Press 1999126-148. Proceedings of the Symposium on Equipment Development Strategy 2001: 310-313. Wang Xinbo Yan Ming. PVC plasticized wood powder and its water absorption. The PVC is opened. Polymer surface science. Beijing: China Petrochemical Press Teng Guomin Zhang Yong Wan Chaoyu and so on. Interfacial modification method for wood-plastic composites. Chemical Ding Yi Zhong Xin Xue Ping. The effect of wood fiber modification on the mechanical properties of PVC/wood fiber. Journal of Beijing University of Chemical Technology 200431 (1): 76-7882. Chen Zhixiu. Application of modifier CPE in PVC wood-plastic composites. PVC Li Jun. Development of Rigid PVC/Wood Powder Composites P. Beijing: Beijing University of Chemical Technology

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Paper dyeing process, the object is to dye the role of paper fibers. Mechanism of different Dyes with different pulp, wood is known as basic dyes great affinity, suitable for dyeing pulp lignin content; pulp surface with a strong negative charge, then the Direct Dyes hardly adsorbed ions , with it to reduce the surface charge, the dye near the fiber surface is fixed. Such non-electrostatic adsorption caused, bauxite is commonly used in papermaking dye retention agent, because the majority of paper dyes are anionic, cationic aluminum compound and anionic dye-forming cation may be precipitated and adsorbed on the fiber surface which is to retain this mechanism occurs at pH 4.0-5.2, then the charge density of the aluminum ions is high, the charge is stronger.
Dyes commonly used in the paper coating colored paper, the dye and the paper fibers by covalent bond, ionic bond between, with the key, and molecular hydrogen binding forces, which depends on the color fastness of adhesion strength, exactly in what based combination, depending on the structure of the dye molecule.

Paper

Paper Dyes, Paper Dyes Applications, Paper Dyes Industries

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