化学改性转化木材为塑性和热固性材料

综述了利用经典的纤维素酯化和醚化改性反应对木材进行化学改性, 使其转化为可溶或可熔的新型热塑性或热固性高分子材料的方法及这些新材料的应用。     

聚氯乙烯／热塑性弹性体共混增韧的研究进展

聚氯乙烯（PVC）是一种性能优良,价格低廉的通用树脂,但其脆性大、热稳定性差、加工性能不佳等,需要进行改性。通过用热塑性弹性体（TPE）对PVC进行共混增韧改性,可得到高性能的PVC复合材料。共混改性为PVC增韧改性的最简单易行的有效方法。本文概述了聚氯乙烯／热塑性弹性体共混体系的种类和制备方法,同时对影响热塑性弹性体...     

热塑性聚酰亚胺及其改性材料的制备与性能

聚酰亚胺具有优异的耐高温性能,但其熔融、加工性能较差,限制了其广泛应用。通过在聚酰亚胺分子结构中引入柔性基团、设计分子结构的异构化等方法,可制备热塑性聚酰亚胺,使得其加工性能得到改善,并可通过挤出、注塑等成型加工。本文在对热塑性聚酰亚胺单体及其树脂的合成方法进行综述的基础上,讨论了热塑性聚酰亚胺改性尼龙、聚醚醚酮、环氧树脂等材料的制备方法和性能特点,并对聚酰亚胺改性工程塑料的未来发展方向进行展望。     

可固化环氧封端聚芳醚酮加工过程的模型化研究

以可固化环氧热塑性材料———环氧封端聚芳醚酮（Ｅ ＰＥＫ）为研究对象，采用模型化的方法，对其进行了物理性能 化学结构 加工技术一体的综合研究．建立了描述Ｅ ＰＥＫ反应加工过程的系列模型．以此为基础，借助计算机确定了加工参数．用纤维增强复合材料验证了所建立的加工模型和所确定的加工参数的可靠性．结果表明，采用作者所建立的方法，仅需很少的实验，就可完成对加工过程各影响因素的预测分析和加工参数的优化     

一些热塑改性热固性树脂体系结构对反应诱导相分离时间/温度依赖性的影响

利用光学显微镜、DSC等手段研究了一些上临界共溶温度(UCST)类型的热塑性改性热固性树脂体系反应诱导相分离时间/温度依赖性随组分化学结构的变化规律.结果表明,分相活化能Ea(ps)受热塑性树脂的主链结构、热固性单体、交联剂结构、化学计量比等因素的影响.利用相互作用能密度解释了实验所研究的UCST体系的相分离活化能Ea(ps)随组分结构的变化规律.     

不同热塑性树脂改性热固性树脂体系反应诱导相分离过程的时间/温度依赖性

对几种不同热塑性树脂改性热固性树脂体系反应诱导相分离过程,包括UCST(最高互溶温度)、LCST(最低互溶温度)体系和含有复杂多步反应体系,在耐高温高分辨热台显微镜、流变仪和小角激光光散射仪上进行了研究.发现体系的反应诱导相分离时间/温度关系遵循Arrhenius方程.其相分离活化能对体系反应速率、粘弹性变化、体系中热塑性树脂的含量和分子量不敏感,也不受相分离检测手段的影响,而依赖于树脂化学环境相容性和交联反应的温度依赖性.对这一共性的物理本质进行了讨论.     

Reinforced Modification of PEEK and its Applications

聚醚醚酮（PEEK）作为一种特种热塑性工程塑料,在许多工程领域有着广泛的应用。采用不同手段改性聚醚醚酮,改善其热学性能、力学性能、摩擦学性能和加工性能等,有利于降低生产成本和进一步拓展其应用范围。本文从化学改性和纤维增强、无机填充、表面改性、与有机共混等物理改性两个方面综述了近年来国内外聚醚醚酮改性研究进展情况,以及对其在工业领域、电子电器领域、航空领域、汽车领域和医学领域中的应用作了简单的概括,最后展望了聚醚醚酮改性研究开发问题及解决方法。     

聚乙烯醇的热降解及热塑加工改性研究进展

聚乙烯醇(PVA)是一种含有大量羟基的水溶性高分子材料,由于其优良的成膜性、水溶性、气体阻隔性、机械性能和生物降解性,已被广泛应用于纤维,薄膜,粘结剂等领域。但PVA的熔融温度和分解温度接近,使得熔融的同时发生分解反应,难于热塑加工。因此对PVA进行改性以提高热塑加工性能成为该材料研究的重要方向之一。常用的改性方法包括化学改性,物理改性和与其它高分子材料复合改性。本文综述了近年来在PVA的热降解行为以及实现PVA热塑加工的改性技术方面的研究进展。     

化学改性转化木材为热塑性和热固性材料

综述了利用经典的纤维素酯化和醚化改性反应对木材进行化学改性，使其转化为可溶可熔的新型热性或热固性高分子材料的方法及这些新材料的应用。     

静电纺丝法在制备改性醋酸纤维素中的应用

纤维素是一种天然存在于有机物或植物中储量巨大的可再生资源。醋酸纤维素是在催化剂的作用下,将纤维素的羟基酯化而得到的一种热塑性树脂。由于其具有稳定,易于加工,不易燃烧,生物可降解性等特点,常用来替代天然纤维素作为静电纺丝的原料。静电纺丝技术作为目前制备纳米纤维材料的一种简单有效的方法,近些年来一直备受关注。本文系统介绍了以醋酸纤维素为静电纺丝的基体材料, 通过添加纳米粒子、聚合物溶液、表面改性、同轴电纺等物理改性方法以及再生纤维处理和硝化反应等化学改性方法制备改性醋酸纤维素纤维, 讨论了改性后的新材料结构和性能等多方面的变化。综述了近几年来国内外关于以静电纺丝法制备改性醋酸纤维素纤维的研究进展以及其在生物医药、组织工程支架、过滤膜以及功能性织物等方面的应用前景。     

The Reaction Mechanism of the Transetherification and Crosslinking of Melamine Resins

Melamine formaldehyde resins (MFR) are well known resins in the wood board and paper coating market. Etherified MFR's are applied as crosslinkers in the automotive coating industry. In Europe the growth of the market and the research activities are relatively small. On the other side in comparison to other polymers outstanding properties are possible to realize. So the development of new melamine ether resins (MER) was started. MER is a partly methylolated and fully etherified resin with a highly stable “thermoplastic” processing range. The MER's themselves are transparent granulates with enough stability for storage and transport. The crosslinking reaction can be started either by thermal or acidic catalytic activation, without losses of formaldehyde. Transetherifications with oligomeric diols can lead to more elastic and higher molecular melamine polyether resin (MPER) structures. The reaction mechanism and the crosslinking kinetics of the partly methylolated melamine ethers of methanol in comparison to the fully methylolated hexamethylol melamine ether will be discussed in this paper.     

Effect of the Propionylation Method on the Deformability under Thermal Pressure of Block-Shaped Wood

Converting wood waste into thermoplastic materials is an attractive means of increasing its utilization because complex three-dimensional molded products can easily be obtained by press molding wood with thermoplasticity. Chemical modification, especially esterification, is a promising method for imparting thermoplasticity to wood. In this study, we produced multiple propionylated wood specimens using several propionylation methods and elucidated the factors affecting the deformability of the wood. Regardless of the method, all of the propionylated wood samples showed deformability in the tangential direction. However, in the longitudinal direction, not only the degree of propionylation but also the propionylation method had a significant influence on the deformability. The flow in the tangential direction occurred under a relatively low pressure, whereas the flow in the longitudinal direction occurred under higher pressure. The chemical composition and motility of each sample were evaluated using solid-state NMR measurements. With some propionylation methods, decomposition of the cellulose main chain occurred during the reaction, which had a dominant effect on the deformability of the wood in the longitudinal direction. These results indicate that the deformability of wood can be controlled by the appropriate selection of a propionylation method and its treatment conditions.     

6. Prospects for future applications of cellulose acetate

The prospects for future applications of cellulose acetate (CA) and cellulose esters (CE) were assessed via an analysis of literature data. An examination of more than 50,000 citations in the published literature with relevance to CA and CE has shown that, while the R&D effort continues without discernible slow-down, the emphasis has shifted in favor of D at the expense of R in recent years; more publications now originate in Southeast Asian countries; and most current journal articles deal with specialty products, such as membranes, controlled release agents, and biopolymers. The prospects for future applications are viewed as being related to the ability to add new performance features to CA, particularly thermal processability, water-dispersibility, and the ability to interact with other polymers on the molecular level. This can be achieved by such secondary modifications as the introduction of plasticizing (mixed) ester substituents, carboxyl groups, and the use of (monofunctional) oligomers in block copolymers, respectively. In addition, the adoption of acetylation technology to lower grade pulps and even wood and wood fibers may result in new business opportunities in thermoplastic and soluble wood esters, or in acetylated solid wood products with superior dimensional, biological and light-stability characteristics.     

Discrimination of Thermoplastic Polyesters by MALDI-TOF MS and Py-GC/MS

The aim of this work is to discriminate thermoplastic polyester-polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT), which cannot be easily identified by many methods. Both matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were applied to identify these polyesters owing to their analytical ability to determining polymers' chemical structure. The three thermoplastic polyesters can be easily distinguished by MALDI-TOF MS according to their different repeated units. Py-GC/MS was used to analyze their specific pyrolyzates. The three polyesters can be identified through their characteristic pyrolysis products as well.     

Changes in lignin and cellulose by irradiation

The effect of high-energy radiation on wood and cellulose was investigated. By irradiation of beech wood, changes in lignin, in carbohydrates and in wood structure take place. Furthermore, new lignin carbohydrate complexes are formed. A way is shown to prevent undesirable reactions. Irradiated pulp possesses a lower degree of polymerization and a higher accessibility for chemical reactions. Processing irradiated pulp to viscose fibres will be more efficient.     

水热裂解开采稠油技术研究的进展

从水热裂解反应、催化作用下的水热裂解反应、反应机理及水热裂解开采稠油现场应用实验等四个方面综述了国内外水热裂解开采稠油技术的研究进展。并对此技术的研究成果及未来发展进行了探讨，认为水热裂解开采稠油技术具有很高的潜在价值，是未来经济高效开采稠油的新途径。当前水热裂解开采稠油技术的主要研究方向是深入研究高温水的特性及其作用；对更多稠油中可能参与水热裂解反应的不同组分，选用合适的模型化合物进行模拟实验或其它方法，建立这些组分的反应热力学和动力学模型库；然后，根据具体稠油中所含的组分，设计水热裂解反应的路线，选择合适的催化剂，促使反应向稠油改质降粘的方向进行。其中，最关键的还是针对不同稠油研制成本低、活性和选择性高、反应条件宽的催化剂，并筛选或研制协同效果好的助剂，进而研究催化剂及其助剂在油层中与稠油作用的机理，设计合理的现场实施技术和工艺。     

Blends of a new thermoplastic in a thermoset epoxy matrix

Properties of thermoplastic modified epoxy network have been studied. The particularity of this work is the use of new thermoplastic epoxies whose structure is close to the final matrix. Blends of thermoset epoxy (Diglycidyl Ether of Bisphenol A/4-4′ methylenebis [3-chloro 2,6-diethylaniline]) with a thermoplastic content from 5 to 40%w have been realised. Initial miscibility in the thermoset precursors shows an UCST behaviour with a maximal value near 130°C for a thermoplastic content of 10%. Due to the presence of tertiary amine and pendant hydroxyl groups on the thermoplastic backbone, epoxy amine reactions are faster than for the neat system but the thermoplastic seems not to have reacted with the thermoset network. The final blends are transparent but toughening increase is rather low.     

Thermoplasticization of wood. I. Benzylation of wood

A study of converting wood into thermoplastic materials was undertaken to develop a new technique in effective utilization of wood wastes. Thermoplasticizatoin of wood carried out by means benzylation. Various reaction parameters, such as alkalinity of reaction media, reaction temperature, and time were taken into account to produce benzylated wood with different degrees of substitution (based on weight gain) FTIR, DSC, DMTA, SEM and x-ray crystallography were used to characterize the chemical and mechanical properties of benzylated wood. Experimental data showed that preswelling and reaction temperature had critical effects on benzylation reaction. Lignin in wood appeared to inhibit benzylation but extractives had little effect. Different species showed some variation in reaction rates. The thermoplasticized wood exhibited good melting properties and were readily molded into bulk materials or extruded into films and sheets. A wide range of glass transition temperatures from 66 to 280°C for the benezylatedwoods was achieved, and they were larely dependent on the weight gain. The molded and extruded products exhibited acceptable mechanical strength for structural engineering applications. The property and structure relationship for the thermoplasticized wood were discussed     

Thermoplasticization of wood. II. Cyanoethylation

Cyanoethylation was attempted to convert wood into thermoplastic material as a means to utilize low quality wood species as well as wood waste materials. Cyanoethylation reaction was conducted with control of the alkalinity of the reaction media, reaction temperature and time, and wood-to-acrylonitrile ratio. Cyanoethylated wood was purified and its nitrogen content and weight gain were determined. Fourier transform infrared (FTIR) spectroscopy was used to monitor the absorption peak of cyano group. Thermoproperties of cyanoethylated wood were analyzed by means of a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). Reaction mechanisms and chemistry influencing the thermoproperties of cyanoethylated wood were discussed.     

Carboxymethyl Xylan - Control of Properties by Synthesis

The hemicellulose xylan is a polysaccharide that occurs in nature in enormous amount in various one year- and perennial plants having different structures and molecular masses. Versatile ways to generate bio-based functional polymers result from the chemical modification of this biopolymer. In our research, xylans from various resources like birch-, beech-, and eucalyptus wood and from oat husk, rye bran, and corn cob were used to investigate the important method of carboxymethylation in detail. Different activation procedures were elaborated to synthesize carboxymethyl xylan. One step reactions lead to products with a degree of substitution (DS) from 0.13 to 1.22 in dependence on the molar ratio of anhydroxylose unit (AXU) to reagent. Two step syntheses yielded DS values up to 1.65. Carboxymethyl xylans are water soluble at a DS of 0.3. The solutions have different clearness depending on the provenience. NMR spectroscopy and HPL chromatography were applied to characterize the carboxymethyl xylans in detail.