Photopolymerization of acryl composites for producing waveguides with high transparency within telecommunication spectral regions

The photopolymerization of hydrocarbon and fluorine-containing monomers and oligomers synthesized in this work for the creation of planar polymer waveguides has been studied. The kinetics of the copolymerization of hydrocarbon and fluorinated compounds hardly depends on the number and structure of fluorinated moieties. The overall kinetics of the photoinitiated polymerization of acryl oligomers with different chemical nature of their oligomer block, molecular masses, and local and macroscopic viscosities has been studied by IR spectroscopy. At high initiation rates, the oligomer block’s flexibility, which is governed by the number of groups with a low potential rotational barrier, e.g., carbonate groups, is the principal factor that influences the kinetics of polymerization. At low initiation rates, the viscosity of oligomers becomes an essential factor. The optimal conditions for molding optical articles from hydrocarbon and fluorinated acryl oligomer composites have been determined.     

LDPE高透明薄膜专用料156-050的开发

通过对乙烯聚合机理和聚乙烯分子结构的分析,指出了影响薄膜透明性、光泽度的各种因素,从而确定了生产低密度聚乙烯高透明薄膜专用料156-050的工艺方法和控制参数,反应温度控制在310-320℃。反应压力控制在242MPa。用156-050生产的薄膜,其性能指标都在优等品的范围。     

Biodegradable composites with improved barrier properties and transparency from the impregnation of PLA to bacterial cellulose membranes

Poly(lactic acid) (PLA) was impregnated in bacterial cellulose (BC) membranes. BC/PLA films were prepared by solvent casting and mechanical, optical and barrier properties, and biodegradation process were investigated. The transparency of processed films was higher than that of neat BC and increased with PLA content. Moreover, the incorporation of PLA to BC enhanced significantly the water vapor barrier properties of the BC membranes. The bionanocomposites contained a high percentage of cellulose due to the impregnation method that leads to the film with a BC content of 94%, which practically maintains the excellent mechanical properties of BC. However, when increasing the PLA content in the bionanocomposites the mechanical properties decreased slightly with respect to BC. Biodegradation under real soil conditions was determined indirectly through the study of the visual degradation and disintegration, demonstrating that the bionanocomposites were degraded faster than the neat PLA. The successful production of BC/PLA bionanocomposites suggested the possible application of them for active food packaging. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43669.     

高介电常数硅橡胶复合材料的制备研究

研究了以绝缘硅橡胶和导电硅橡胶为主体材料,采用不同配比进行混炼,制备的力学性能和电性能不同的硅橡胶复合材料。这些硅橡胶复合材料能满足不同电压等级要求的介电常数、介质损耗、击穿强度和力学性能等。测试结果表明,由于渗流效应,随着绝缘硅橡胶中导电硅橡胶的含量不断增加,所制备的硅橡胶复合材料的介电常数不断变大。同时,在渗流阈值附近,硅橡胶复合材料的介电常数有了极大的提高。当导电硅橡胶的含量为40%左右时,硅橡胶复合材料的介电常数达到了20.8,为纯绝缘硅橡胶体介电常数的8~10倍,同时材料的介电损耗仍保持较低值。这表明传导机理对材料的介电常数的提高起到了很重要的作用。     

萃取精馏生产高纯度环氧丙烷的工艺研究

丙烯环氧化反应获得的粗环氧丙烷(PO)中含有乙醛、甲醇、甲酸甲酯和水等杂质，由于这些杂质与PO相对挥发度接近于1，普通精馏难以提纯PO；同时，分离过程中PO易发生水解生成1,2-丙二醇(PG)，而PG又导致萃取剂萃取性能下降。据此，结合萃取精馏和液液萃取技术，同时考虑PO水解反应，开发了水洗回收PO和侧线采出共沸物脱除PG流程，在有效脱除杂质的同时，提高了PO的回收率和萃取剂的萃取效率，获得了高纯度PO产品。采用流程模拟软件Aspen Plus对上述流程进行了全流程模拟计算，借助NRTL热力学方法，分析了萃取精馏塔的溶剂比、理论塔板数、原料进料位置、溶剂进料温度等主要工艺参数对分离过程的影响。结果表明该工艺流程合理、可靠，经济性优于现有工艺，可指导工业过程设计和操作优化。     

Evaluation of the moulding process for production of short-fibre-reinforced C/C-SiC composites

For the production of C/C-SiC brake discs via the liquid silicon infiltration method (LSI), the hot pressing process is the state of art technique for the moulding of the CFRP composites. This technique consists of several manual steps which increase production cost. The overall cost can be reduced by implementing injection moulding process.In this paper the influence of the moulding process (hot pressing, injection moulding) on the properties of semi-finished and final products during the production of short-fibre-reinforced C/C-SiC composites by means of the LSI process are examined. The starting polymer is chemically characterised. Carbon-fibre-reinforced plastic (CFRP) composites are fabricated by hot pressing, as well as injection moulding process. The CFRP composites are converted into porous C/C composites by pyrolysis. Liquid silicon is infiltrated to form dense C/C-SiC composites, which are further investigated during the course of this paper. Significant differences in properties of the composites are discussed.     

Pineapple agroindustrial residues for the production of high value bacterial cellulose with different morphologies

Bacterial cellulose (BC) with different morphologies was biosynthesized by Gluconacetobacter medellinensis strain under static and dynamic culture conditions using sugar cane juice and pineapple residues as sources of carbon and other nutrients. Hestrin and Schramm's standard culture medium was used as reference. The fermentation condition and resulting yield, physico‐chemical properties, and morphology relationships of obtained cellulose were analyzed. Pineapple agroindustrial residues can be envisaged as an inexpensive and sustainable alternative resource for the production of different BC morphologies. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41237.     

高导电碳系填充聚乙烯复合材料的研究进展

系统介绍了碳系分散体(碳黑、石墨、碳纤维、碳纳米管等)作为填料填充聚乙烯形成聚乙烯基导电复合材料的研究进展.并根据国内外高导电碳系填充聚乙烯复合材料研究成果的对比分析,对其今后发展提出建议.     

The production of carbon nanotube/epoxy composites with a very high dielectric constant and low dielectric loss by microwave curing

Multiwalled carbon nanotube (MWCNT)/epoxy (EP) composites were developed using microwave curing (m-MWCNT/EP). They have a very high dielectric constant and low dielectric loss. For comparison, composites based on the same components were also prepared by thermal curing (t-MWCNT/EP). Results show that the two types of composites have greatly different dielectric properties. With the same content of MWCNTs, m-MWCNT/EP composites show a much higher dielectric constant and lower dielectric loss than t-MWCNT/EP composites. Specifically, the dielectric constant and loss at 100 Hz of m-MWCNT/EP composite with 0.04 vol% MWCNTs are about 2.5 and 0.05 times the corresponding value of t-MWCNT/EP composites, respectively, because of their different structures. Compared with t-MWCNT/EP composites, the nanotubes in m-MWCNT/EP composites not only have a better dispersion in the matrix, but also align in a direction. An equivalent circuit model was set up to evaluate the influence of dispersion and spatial distribution of MWCNTs on the dielectric properties. It shows that it is possible to control the dispersion and spatial distribution of carbon nanotubes using a different curing technique to obtain high performance composites with unexpected dielectric properties, especially those with very high dielectric constant and low dielectric loss.     

Thermokinetic effect of the aging of epoxy matrix prepregs for high performance composites

The reactivity and processability of prepregs for high performance composites have been investigated as a function of time and storing conditions. The study has been focused on the stability of epoxy matrix carbon fiber prepregs, affected by exposure to controlled environmental conditions before their use in composite manufacturing. Effects of the aging on glass transition temperature, reactivity and processability have been investigated by calorimetry. Dynamic, isothermal and cure simulating tests have been performed to this aim. Results on toughened TGDDMDDS epoxy matrix prepregs are reported. A theoretical kinetic model proposed for the unaged system has been adapted for aged prepregs, by properly evaluating the variations of kinetic parameters with the aging time.     

Enzymatic activation of wood fibres as a means for the production of wood composites

The incubation of wood fibres with a phenoloxidase (laccase) results in the oxidation of the lignin crust on the fibre surface which finally is released from the fibre surface into the incubation medium. During this reaction, the lignin is highly oxidized, as can be seen from its high carboxyl content. When fibres treated with the enzyme are pressed together under conditions usually employed during the process of making fibre boards, boards are obtained which meet the required standards for German medium density fibre board (MDF). The enzymatically activated fibres in the wood composites made by this process are bound together in a way which is closer to the situation in the naturally grown wood than any other process used today in the present production of wood composites.     

Use of Novoselitskii Kaolin for the production of high alumina fireclay

Conclusions The possibility of using Novoselitskii kaolin instead of Latnensk clay for the production of high alumina fireclay was studied.The addition of sulfite waste liquor favors an increase in the plasticity of the bodies and in the productivity of the extrusion press, a reduction in the optimum moisture content of the bodies, and strengthening of the briquet. Preliminary clacination at 700°C is a radical method of making a briquet for firing in a rotary kiln. Drying the briquet before feeding it to the kiln gives good results.Deceased.Translated from Ogneupory, No. 8, pp. 38–41, August, 1969.     

高纯碳酸锶生产新工艺

研究了以菱锶矿为原料，通过煅烧、浸取、除杂、重结晶、碳化等步骤制取高纯碳酸锶的工艺。并对影响该工艺的主要因素进行了讨论。该工艺不使用盐酸等酸浸工序，具有产品纯度高、不含氯离子、工艺简单、原料利用率高、“三废”排放少等特点。     

以高碳粉煤灰代替粘土生产水泥

本文对高碳粉煤灰代替粘土生产水泥进行了试验研究,提出了生产操作的主要技术方法和水泥配料方案.研究结果表明,立窑采用这种煅烧技术,可以配制煅烧62.OMPa以上的优质水泥熟料,减少配煤20%以上,具有十分显著的经济价值和社会意义.     

以尿素为氮源的高氮复合肥生产技术

笔者根据多年的实践经验 ,阐述以尿素为氮源 ,生产高氮〔w(N)≥ 2 0 %〕复肥的现实意义及生产技术要点 ,具体介绍 2个高氮复肥 (2 30 7)、(2 0 10 15 )的配方实例及操作要点     

One-step synthesis of few-layered-graphene/alumina powders for strong and tough composites with high electrical conductivity

The chemical vapor deposition of carbon onto a commercial α-Al₂O₃ powder bed produces a pristine film of few-layered-graphene (FLG) uniformly covering the α-Al₂O₃ grains. This obviates both the manipulation of nanocarbons, lengthy mixing steps and the risk of damaging any pre-existing graphene platelets. The powders are consolidated to 99 % by SPS, producing samples where a FLG film is located along the grain boundaries of the submicron α-Al₂O₃. Compared to the pure α-Al₂O₃, the composites are moderately stronger and similarly tough and hard due to crack-deflection and crack-bridging and they are electrically conducting with a percolation threshold below 0.74 vol.% of carbon. The high conductivity values reflect the high quality of the thin FLG film and its continuous nature over very long distances. The samples are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy.     

高效干燥设备在无机盐生产中的应用

目前中国无机盐行业采用炕式烘干、箱式干燥、隧道窑干燥等传统干燥工艺及设备，能耗高，劳动强度大，环境污染严重，产品易被污染，质量不稳定。选用高效、密闭、连续的带式串闪蒸、桨叶式串闪蒸、双螺旋串盘式等二级干燥工艺及设备、链式层干机、组合式干燥机、旋转列管式干燥机及喷雾干燥工艺和设备等新型干燥设备，改造传统工艺及设备，提升无机盐生产中干燥装置水平，以达到节能降耗，提升产品质量水平之目的。     

以高镁卤水为原料生产高活性氧化镁新工艺研究

以运城盐湖高镁卤水为原料,通过除杂反应、沉淀反应、煅烧反应制备高活性氧化镁。研究了原料浓度与配比、反应温度、反应时间对沉淀反应的影响以及煅烧温度对氧化镁相对密度的影响。结果表明,沉淀反应中反应温度70℃,反应时间60 min,镁和铵的摩尔比为1∶1.2以及煅烧反应温度为600~700℃时,可得到吸碘值在140~180 mg/g的高活性氧化镁,产品质量达到并超过了进口产品的标准。     

Optimization of pretreatment of Jatropha oil with high free fatty acids for biodiesel production

A central composite rotatable design and response surface methodology were used in order to investigate the individual and combined effects of the ethanol-to-oil ratio, H₂SO₄ concentration, temperature and time of reaction on the reduction of free fatty acid (FFA) in jatropha oil. A quadratic polynomial model relating the reaction variables with FFA reduction was developed, presenting a good coefficient of determination (R²= 0.893). For reducing FFA to less than 1%, the optimal combination was found to be 0.62 v·v^-1 ethanol-to-oil ratio (14.9 v·v^-1 ethanol-to-FFA ratio), 1.7% v·v^-1 H₂SO₄ concentration, and 79 min reaction time at a reaction temperature of 54°C. These results are of great relevance to maximize methyl esters formation by transesterification using an alkaline catalyst.