杉木液化产物用于胶粘剂制备的研究

研究用少量的苯酚液化木材及其产物用于胶粘剂制备的方法,在硫酸催化剂作用下,用苯酚液化杉木木粉,得到木材液化产物.在液化产物中加入适量的甲醛和氢氧化钠溶液制备热固性酚醛树脂.压板测试结果表明,由木材液化产物所得树脂的干状胶合强度令人满意,但经蒸汽循环试验后,湿状胶合强度尚达不到JAS标准的要求,在下阶段工作中,需进一步研究木材液化产物胶粘剂的改性以提高其胶合耐久性.     

木材加工用耐水性苯酚液化树皮-甲醛胶粘剂的研制

树皮是一种来源丰富可再生的天然高分子材料。本文采用高温苯酚液化的方法,在复合酸存在下将落叶松全树皮液化成为木材胶粘剂的原料。研究了树皮液化产物制备木材胶粘剂的合成工艺,特别是碱用量对苯酚液化落叶松全树皮一甲醛胶粘剂各主要性能的影响。结果表明,增加碱用量会缩短树皮胶的贮存期,但可降低胶中的游离甲醛;通过降低树皮胶合成时的终点黏度,并在合成末期用水稀释,可有效提高树皮胶的适用期,并可确保树皮胶具有很好的胶接强度和耐水性、较快的固化速率以及很低的游离甲醛释放量。     

Resol‐type phenolic resin from liquefied phenolated wood and its application to phenolic foam

A liquefied wood‐based resol resin was prepared with excellent yield by a reaction of liquefied wood and formaldehyde under alkaline conditions. The effects of various reaction parameters on the extent of the yield of the resol resin, unreacted phenol content, and viscosity were investigated. Milder resol resinification conditions were required as compared to those used in conventional methods. The liquefied wood‐based resol resin was successfully applied to produce phenolic foam using appropriate combinations of foaming agents. Diisopropyl ether with a relatively higher boiling temperature was suitable for the foaming of liquefied wood‐based resol resin. Hydrochloric acid and poly(ethylene ether) of sorbitan monopalmitate were used as a catalyst and a surfactant, respectively. The obtained foams showed satisfactory densities and compressive properties, comparable to those of foams obtained from conventional resol resin. Foams with low density were obtained by the blending of liquefied wood‐based resol resin and conventional resol resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 468–472, 2002; DOI 10.1002/app.10018     

Molecular weight distributions in novolac type phenol-formaldehyde polymerizations

In the acid-catalysed condensation polymerization of phenol and formaldehyde, the ortho and para positions of the phenol ring are known to exhibit different reactivities^1,2. Along with this on polymer molecules, the internal sites have lower reactivity due to molecular shielding. To model the novolac formation, five reactive sites have been proposed³ and their reactivities are assumed to be completely determined by the site involved. To find the molecular weight distribution (MWD) of the polymer from this information, a given polymer chain has been assumed to consist of these sites in the same relative ratio as in the reaction mass. A mass balance, on polymer molecules of given size, has been made and solved numerically as a function of time. The sensitivity analysis has been carried out to show that the MWD is little affected by the variation of reactivities of the internal sites. The reactivity of para external positions and the ratio of phenol and formaldehyde, however, play a major role in determining the MWD.     

Molecular weights and molecular weight distributions of irradiated cellulose fibers by gel permeation chromatography

Radiation degradation of cellulose fibers was investigated by gel permeation chromatography (GPC). Scoured cotton of Mexican variety (cellulose I), Polynosic rayon (cellulose II), and their microcrystalline celluloses obtained by hydrolysis of the original fibers were irradiated by Co-60 γ-rays under vacuum or humid conditions. The irradiated samples were then nitrated under nondegradative conditions. The molecular weights and molecular weight distributions were measured by GPC using tetrahydrofran as solvent. The relationship between molecular weight and elution count was obtained with cellulose trinitrate standards fractionated by preparative GPC. The degree of polymerization of the fibers decreased with increasing irradiation dose, but their microcystalline celluloses were only slightly degraded by irradiation, especially in microcrystalline cellulose from cellulose I. Degradation of the fibers irradiated under humid conditions was less than that irradiated under vacuum. It was found that the G-values for main-chain scission for the irradiated cellulose I, cellulose II, microcrystalline cellulose I, and microcrystalline cellulose II were 2.8, 2.9, less than 1, and 2.9, respectively, but the G-value for main-chain scission for the irradiated cellulose II was increased to 11.2 at irradiation doses above 3 Mrad. Consequently, it is inferred that cellulose molecules in the amorphous regions are degraded more readily, and the well-aligned molecules in crystalline regions are not as easily degraded by irradiation.     

Microscopic analysis of the wood bond line using liquefied wood as adhesive

The bonding of beech (Fagus sylvatica L.) with liquefied wood (LW) causes deterioration of the wood surface, resulting in a high percentage of wood failure at a relatively low bond shear strength. Light microscopy, scanning electron microscopy, FT-IR micro-spectroscopy and elemental carbon, nitrogen and sulphur (CNS) analysis techniques were used to investigate the formation of such bonds. It was assumed that the degradation of lignin, hemicelluloses and parts of the cellulose occurred in the cells of the wood surface where the LW had been applied. At the elevated temperatures occurring during the bonding process, the deteriorated cells were carbonised to some extent. The weak boundary layer of the bond was determined to be a layer of delignified cells located between the zone of partly carbonised cells on the one side and the cells of the undamaged wood of the adherend on the other side. The bonds which formed during the bonding of wood with LW were found to be very untypical compared to bonds formed by synthetic wood adhesives. No adhesive film was formed, the adhesive-adherend interface was not clear and the cells of the adherend subsurface were damaged.     

液化石油气杂质含量的气相色谱法测定

通过恒温水浴完全气化样品,建立了用毛细管气相色谱法测定液化石油气中二甲醚、甲醇及甲缩醛含量的方法。采用PLOT/Q(30 m×0.53 mm×40μm)毛细管柱、热导池检测器,以面积校正归一化法计算杂质含量。结果表明:该方法操作简单,实用性强,重复性好,可以用于液化石油气中杂质含量的快速分析。     

采用液化天然气冷量的空分系统新流程

从多个角度分析了空分装置中应用液化天然气(LNG)冷量的优势,针对不同的场合提出了2种引进LNG冷量的液体空分流程新方案。方案1适用于投资建设新设备的场合,方案2适用于现有流程的改造生产液体的场合,2种方案有一个共同点即使用LNG冷量冷却循环氮气制冷。采用Aspen P lus软件对2个方案进行了模拟计算,结果表明:引进LNG冷量之后,所需循环氮气量明显减少,系统最高运行压力降低由传统流程的4.2—5.0 MPa降低到2.1—2.6 MPa,液态产品的单位能耗从约0.5 kW.h/kg降低到0.327—0.338 kW.h/kg,节能效果明显。LNG气化过程中换热压力的提高对冷量回收影响较小,而采用液泵加压节省能耗,将气化过程安排在升压过程之后有利于能源的合理利用。     

液化石油气制芳烃技术开发及工业应用

采用组合固定床反应-再生系统和改性HZSM-5分子筛催化剂,开发出利用液化石油气制芳烃工艺(GTA)。该工艺可将液化石油气转化为苯、甲苯和二甲苯等轻质芳烃,而且流程简单,操作稳定,所产混合芳烃不含非芳烃组分,简化了抽提流程,节省了投资,并降低了能耗。4.0万t/a的工业化装置运行结果表明:利用GTA技术能将醚化后的C4组分转化为质量分数56.76%的芳烃,同时还能得到质量分数为23.74%的民用液化气。     

Determination of molecular weight averages and molecular weight distribution by g.p.c. of N-trifluoroacetylated polyamides

To determine their molecular weight averages and molecular weight distribution, N-trifluoroacetylated (TFA) polyamides are studied using gel permeation chromatography in tetrahydrofuran at 25°C. Several calibration methods (calibration with polydisperse standards, universal calibration) are tested; among these, direct calibration of M_w of polydisperse samples vs. peak maximum of the corresponding g.p.c. chromatogram leads to the best results. Calculated molecular weight averages of nylon 6-TFA and Trogamid^R-TFA are compared with data from light scattering, viscometry and osmometry.     

应用吸收稳定系统的加氢裂化装置生产液化气的探讨

通过对比中石化股份有限公司天津分公司180万t／a加氢裂化装置和某厂120万t／a加氢裂化装置工艺流程,发现180万t／a加氢裂化装置的吸收稳定系统生产的液化气产品性质好,收率高;并且能够有效地解决“干气不干”的问题。     

Molecular weight determinations of polyamides by N-trifluoroacetylation

By N-trifluoroacetylation (TFA) polyamides become soluble in ordinary organic solvents such as acetone, butanone, methylene chloride, chloroform and tetrahydrofuran. In these solvents light scattering and osmotic measurements (membrane and vapour-phase osmometry) were carried out to determine the weight and number average degrees of polymerization. Comparison with the results on non-TFA-polyamides in various solvents clearly shows that no polymer degradation takes place. The [η]-P relationships of Trogamid^R-TFA and nylon-6-TFA in tetrahydrofuran at 25°C were determined and corrected for polydispersity.     

Physicomechanical and thermal properties of moldings made from liquefied wood‐based novolak PF resins under various hot‐pressing conditions

The wood powder of Cryptomeria japonica (Japanese cedar) was liquefied in phenol, with H₂SO₄ and HCl as a catalyst. The liquefied wood was used to prepare the liquefied wood‐based novolak phenol formaldehyde (PF) resins by reacting with formalin. Furthermore, novolak PF resins were mixed with wood flour, hexamethylenetetramine, zinc stearate as filler, curing agent, and lubricating agent, respectively, and hot‐pressed under 180 or 200°C for 5 or 10 min to manufacture moldings. The results showed that physicomechanical properties of moldings were influenced by the hot‐pressing condition. The molding made with hot‐pressing temperature of 200°C for 10 min had a higher curing degree, dimensional stability, and internal bonding strength. The thermal analysis indicated that using a hot‐pressing temperature of 180°C was not sufficient for the liquefied wood‐based novolak PF resins to completely cure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

液氯液化尾气合成氯化氢生产氯乙烯

对液化尾氯的应用进行了可行性探索,通过对液化尾氯的生产数据分析,并从理论计算上求证,证明氯气液化尾氯合成氯化氢直供电石法PVC生产是安全可行的。     

煤炭地下气化制液化天然气技术经济性分析

为了核算煤炭地下气化制液化天然气(UCG-LNG)技术的经济可行性,在试验数据的基础上,以年产液化天然气2亿m3的UCG-LNG项目为例,计算了项目的总投资额,以及工程费用和天然气生产成本的构成及各项占比,并分析了项目的敏感性。结果表明,项目总投资约18.7亿元,总投资的88.3%为工程费用,而在工程费用中,空分设备、煤气净化设备以及天然气液化设备的总费用占比高达69.5%;在天然气销售价格为3.21元/m3时,整个项目的税前内部收益率(IRR)为10.90%,投资回收期为9.85 a(含3 a建设期),经济上可行,敏感性分析得出天然气销售价格对项目IRR的影响最大。     

On-Line measurement of parison geometry during blow molding: Parison swelling for three high-density polyethylenes with different molecular weights and molecular weight distributions

An image analysis technique has been developed to measure diameter and thickness distribution of a parison during the extrusion stage in blow molding. The system operates on-line during extrusion on any commercial blow-molding machine. The system has been developed to help development of new blow-molding resins by increasing our understanding of the connection between polymer structure and parison shape. The system can also be used for die design during optimization of a production process. The combined use of experimental design and multivariate projection techniques makes this an efficient tool for the practical processing engineer. Experiments done on three high-density polyethylene blow-molding resins show the importance of measuring the time dependence of the diameter and thickness distribution under different extrusion conditions for a given polymer. Our results show that many of the swell and sag related properties we see cannot be directly inferred from standard laboratory swell-experiments.     

Molecular weight distributions of tars produced by flash pyrolysis of coals

The molecular weight distributions of tars produced during flash pyrolysis of coal have been determined by a combination of gel permeation chromatography and vapour phase osmometry. Small particles (62–88 μm) of two high-volatile and one low-volatile bituminous coal, and a lignite have been pyrolysed at heating rates of ≈1000 K s^?1 at temperatures from 600 to 1300 K in a heated wire mesh apparatus. The molecular weight distributions range from ≈100 to 4000 and peak in the range from 250 to 750 in all cases. The evidence gathered on a softening bituminous coal clearly indicates a selective evaporation of light fractions of the metaplast.     

Molecular weight distributions and size fractionations of H-coal liquids

This Paper deals with a comparative study on the use of gel permeation chromatography (g.p.c.) and vapour pressure osmometry (v.p.o.) to obtain molecular weight data for the hexane-soluble fractions of three H-coal liquids. The use of two types of column packing materials, polyvinylacetate and styrene-divinylbenzene copolymer gels, is described. A successful, preparative use of the polyvinylacetate gel to fractionate the hexane-soluble fraction of H-coal liquid, atmospheric still overhead (ASO), has been established. Molecular weight data obtained by v.p.o. for the benzene-soluble fraction and the pyridine-soluble fraction of the three H-coal liquids are reported. Solvent extraction has been utilized also to find the amount of oil, asphaltenes and asphaltols in the three H-coal liquids.     

Molecular weight distribution of phenol-formaldehyde resols by high performance gel permeation chromatography

Resol resins are particularly difficult to characterize with respect to molecular weight because of the large amounts of caustic soda (10–20% w/w) which they contain. A method is described for solubilizing these materials using trichloroacetic acid, such that molecular weight distribution can be measured using a normal gel permeation chromatography system with μ-Styragel columns and tetrahydrofuran as solvent.     

Molecular weights and molecular weight distribution in phase equilibria of the polystyrene-poly(methyl methacrylate)-toluene system

The composite gel permeation chromatography (GPC) chromatogram of a mixture of polystyrene and poly(methyl methacrylate) has been successfully resolved into its component chromatograms by using a newly developed technique. This technique has made possible the calculation of M _w and M _n values of these polymers in the conjugate phases of the ternary systems with toluene as the solvent. Calculated M _w and M _n values of the two polymers indicated that the larger polystyrene molecules tend to stay in the top polystyrene-rich phase while its smaller molecules tend to stay in the bottom phase to interact with the other polymer. The reverse is true with the poly(methyl methacrylate) molecules. This tendency strongly suggests that interactions among the two polymers were accomplished mainly by their smaller molecules.