高性能碳纤维的性能及其应用

探讨高性能碳纤维的性能及其应用领域.介绍了碳纤维的分类、制备、性能特征、应用以及国内外产业发展状况,分析了国际碳纤维产业的情况和我国碳纤维产业的现状及发展趋势.碳纤维应用涉及航空航天、体育运动、一般制造业、土木建筑、能源开发等领域.随着科技的发展和碳纤维应用技术的不断完善,碳纤维产业的发展空间必将越来越广.     

碳纤维导电纸的制备及性能研究

采用长度为6mm的碳纤维和皮芯型复合纤维,通过湿法抄造、酚醛树脂浸渍、热压等工艺制得高含量碳纤维的导电纸。不同碳纤维含量的碳纤维原纸、浸渍纸和浸渍后热压纸的理化性能数据表明:皮芯型复合纤维能够有效提高碳纤维的疏解分散和成纸强度,碳纤维含量为70%的碳纤维纸具有较好的抄造性、透气度、强度、电阻率等综合性能。     

吉林化纤:突破我国碳纤维产业发展瓶颈

正工业化生产碳纤维按原料路线可分为聚丙烯腈(PAN)基碳纤维、沥青基碳纤维和粘胶基碳纤维三大类,其中由聚丙烯腈纤维原丝制得的高性能碳纤维,生产工艺较其他方法简单,产量约占全球碳纤维总产量的90%以上。     

2.5D碳纤维/环氧树脂复合材料的电磁波传输性能研究

采用自由空间法研究不同碳纤维体积分数、不同型号和产地碳纤维的2.5D碳纤维/环氧树脂复合材料的电磁波传输性能,测试2.5D碳纤维/环氧树脂复合材料散射参数S,计算其对电磁波的反射损耗、吸收损耗、透射率和反射率。结果表明:2.5D碳纤维/环氧树脂复合材料在电磁波传输过程中以吸收电磁波为主,最佳吸收波段为Ku波段(12.0~18.0 GHz);碳纤维种类对2.5D碳纤维/环氧树脂复合材料的吸波性能的影响较小;碳纤维束越粗,2.5D碳纤维/环氧树脂复合材料吸波性能越好。     

新产品、新技术

碳纤维纸 　　 碳纤维纸是使用100％碳纤维或活性碳纤维及碳纤维或活性碳纤维与其它纤维混合抄造的纸。碳纤维自身之间不具有象植物纤维一样的互相交织和结合的性质,必须使用粘合剂。 　　 1、碳纤维 　　 碳纤维根据制造原料的不同分为聚丙烯氰类(以下称PAN类)、沥青类、粘胶类3种。另外,根据其最终处理温度的不同,又可分为碳纤维和石墨纤维。 　　 碳纤维具有以下特征： 　　 (1)质轻,机械强度、弹性、抗拉伸和抗压缩都比较好; 　　 (2)几乎没有弹性(蠕变)疲劳; 　　 (3)耐冲击性低;     

短切碳纤维最佳分散工艺研究

以3种长度2 mm、3 mm、5 mm的聚丙烯腈碳纤维为研究对象,以表面活性剂、分散剂聚氧化乙烯(PEO)和聚丙烯酰胺(PAM)为分散助剂,探讨表面活性剂、碳纤维长度、碳纤维悬浮液质量分数与分散剂种类、配比及用量对碳纤维分散性能的影响。结果表明,碳纤维长度和碳纤维悬浮液质量分数是影响碳纤维分散的重要因素; 3 mm碳纤维在分散体系中质量分数0. 1111%、分散剂用量0. 0059%、分散剂配比PEO∶PAM=3∶1 (质量比)、表面活性剂用量0. 025%时,碳纤维在水中达到最佳分散状态,且沉降时间为9 min;分散剂可以帮助碳纤维更快地浸润到水中,加快分散速度。     

燃料电池用PAN/Lyocell复合碳纤维纸的制备与性能研究

本研究以Lyocell纤维为增强纤维、PAN短切碳纤维为主体纤维,制备燃料电池气体扩散层用复合碳纤维纸（简称碳纤维纸）,探究了磨浆强度对Lyocell纤维浆料和纤维特性的影响,分析了Lyocell纤维的添加对碳纤维的分散性与碳纤维纸的强度性能、透气性能、导电性能的影响。结果表明,Lyocell纤维的添加有效提升了碳纤维的分散性能,提高了碳纤维纸前驱体（CPP）的匀度指数和强度性能,改善了碳纤维纸的强度性能、透气度和导电性能,当碳纤维与Lyocell纤维质量比为7∶3时,碳纤维纸的性能最佳,拉伸强度为14.3 MPa,抗弯强度为5.9 MPa,透气度为248 mm/s,平面电阻率为5.48 mΩ·cm。     

改性碳纤维浆料的制备与性能研究

针对环氧树脂基碳纤维浆料的分子粒径较大、稳定性不足的问题,采用丙烯酸和丙烯酸丁酯为单体,制备改性碳纤维浆料。测试分析了市场在用的碳纤维浆料和制得的改性碳纤维浆料的性能。结果表明:制得的改性碳纤维浆料粒径更小、稳定性更好、黏度较低。认为:采用丙烯酸和丙烯酸丁酯制备的改性碳纤维浆料性能更好,能满足碳纤维上浆的需求。     

碳纤维表面改性研究进展

碳纤维表面活性官能团较少,很难与极性聚合物相容。通过对碳纤维进行表面处理,可接枝官能团、短支链、长链结构和聚合物等,从而改变碳纤维表面的比表面积和表面极性,改善其与基体的相容性,拓展碳纤维的应用范围。本文综述了近年来国内外碳纤维改性工作的进展,比较了化学接枝法、电化学法、涂层法、表面氧化法和等离子法等改性方法对碳纤维增强复合材料界面强度的改性效果,发现利用化学接枝法可较显著地提高碳纤维的表面粗糙度。     

碳纤维增强树脂基复合材料的回收及其再利用研究进展

为有效回收碳纤维树脂基复合材料,避免资源浪费和环境污染,综述了热固性和热塑性树脂基碳纤维复合材料的不同回收方法及其进展,包括物理机械法、热回收法、溶剂解离法、熔融注塑和切片再塑法等,梳理了溶剂解离法的回收思路,介绍了针对碳纤维复合材料回收的可降解热固性树脂及回收方法,阐述了碳纤维增强热塑性树脂的回收机制。总结了目前碳纤维增强热固性树脂回收方法的回收效率低,设备要求高,再生碳纤维性能下降等特点,认为碳纤维增强热塑性树脂具备快速成型、成本低、能够多次回收利用的特点,适于碳纤维复合材料在民用领域大量应用的发展趋势。     

虾、蟹壳利用的研究进展

虾、蟹壳是虾、蟹加工过程中产生的主要废弃物,含有较大量的蛋白质、灰分和甲壳素,以及少量的脂肪、游离氨基酸和虾青素等。近年来,随着我国养殖、捕捞技术的进步以及伏季休渔制度的实施,虾、蟹产量逐年上升。因此,有效利用虾、蟹壳副产物,开发基于虾、蟹壳废弃物的利用途径和产品类型,以提高产品附加值,减少环境污染,对于虾、蟹产业的健康发展具有重要意义。目前,采用酸碱法制备甲壳素是虾、蟹壳利用的主要方法,该方法易于操作,但能耗高且污染严重,近年来研究人员对传统的酸碱法制备甲壳素的工艺进行了优化,并积极探索酶法和发酵法等新型提取工艺。此外,虾、蟹壳中其他可利用成分(蛋白质、脂肪、钙质和虾青素)的提取和利用也获得了许多研究成果。本文主要综述了虾、蟹壳的组成成分,虾、蟹壳整体利用途径以及虾、蟹壳中甲壳素、蛋白质、脂肪、钙质、虾青素等成分的提取和利用途径的研究进展,以期为虾、蟹壳的高效、低成本、无污染和高附加值利用提供借鉴。     

纸质文献保存和修复方法专利技术综述

通过对纸质文献保存和修复领域专利技术文献的收集、分析、标引和梳理,分析了该领域专利技术分布及专利申请情况,分别探析了脱酸、修补、加固、装裱4种技术的专利技术演进路线,最后对该领域专利技术进行了总结。     

叶幕类型对摩尔多瓦葡萄酒品质的影响

以棚架和篱架两种栽培方式的摩尔多瓦葡萄果实为试材,成熟后采收进行酿酒试验,测定水平叶幕和直立叶幕对葡萄酒品 质的影响。 结果表明,棚架葡萄酒与篱架葡萄酒可滴定酸含量无显著差异（P＞0.05）,但棚架葡萄酒的pH值比篱架葡萄酒高0.02,葡萄 酒色度提高44.12%,总酚、抗坏血酸含量分别提高18.65%、14.64%,抗氧化能力（铁还原能力和DPPH自由基清除能力）分别提高43.76%、 17.39%。同时,棚架葡萄酒香气物质种类比篱架葡萄酒多7种,酯类、醇类物质含量分别是篱架的3.06倍、1.36倍,其中,正己醇、辛酸乙 酯、苯乙醇含量是篱架葡萄酒的2.08倍、2.26倍、1.93倍,乙酸异丁酯、丙醇、乙酸异戊酯含量也分别高69.80%、41.87%、60.57%。 由此表 明,棚架水平叶幕可提高葡萄酒次生代谢物质含量,增加葡萄酒色调饱和度,增强葡萄酒稳定性,提升葡萄酒风味,改善葡萄酒品质。     

Effect of common and new gums on the quality,physical, and textural properties of bakery products: A review

Hydrocolloids (gums) have a good functional characteristic such as emulsifying, gelling, solubility, and textural improvement. In the bakery products, hydrocolloids were used to improving dough performance, bread and cake characteristics, sensorial quality, and extension the products shelf life. Several studies reported the potential use of hydrocolloids in breads, biscuits, cakes, and pasta formulation. The present review summarized the effect of the most common and new hydrocolloids (xanthan, guar, Arabic, carrageenan, karaya, alginate, acacia, methylcellulose, carboxy methyl cellulose, hydroxyl propyl methyl cellulose, locust bean, balangu seed, wild sage seed, basil seed, and cress seed gums) on the rheological, physicochemical, textural, and quality characteristics of bakery products. Gums addition improved volume and porosity of the breads and cakes. Gums influence on the gelatinization and retrogradation of starch and decreased the retrogradation of starch. In the bakery products, hydrocolloids were used to improving mixing and increasing the shelf life of the products through moisture preservation and avoidance of syneresis in some frozen foods. This study summarized the influence of the most common and new hydrocolloids on the rheological, physicochemical, textural, and quality characteristics of bakery products. Addition of seeds gum to the breads, biscuits, cakes, and pasta formula led to an increase in the viscosity of the batter. Also, the firmness of bakery products showed that they became softer with increasing gum levels.     

纺纱牵伸胶辊胶圈应用技术概要

阐述棉纺牵伸胶辊、胶圈的应用技术和牵伸原理,重点探讨了胶辊、胶圈的牵伸工艺特性及其合理配置、胶辊制作、周期管理、质量管理、使用管理、产品缺陷与其机械波分析、纺纱环境和挡车工操作水平对纺纱性能的影响,提出胶辊、胶圈有关机件的质量要求等。     

3种功能性甜味剂对大米蒸煮品质和消化特性的影响

为提高米饭蒸煮品质、延缓米饭回生和改善米饭消化性能,比较不同质量分数低聚果糖、山梨糖醇和麦芽糖醇3 种低能量甜味剂对大米浸泡吸水率、直链淀粉比例、硬度、微观结构、晶体结构、热特性及消化特性等指标的影响。结果表明,3 种甜味剂处理均能够提高大米的吸水率,降低米饭的硬度。此外,低聚果糖、山梨糖醇和麦芽糖醇处理均能降低米饭的体外消化水解率。其中,1.6%低聚果糖处理的大米在浸泡25 min时吸水率提高了11.18%,直链淀粉比例、糊化焓值和放置24 h后硬度分别降低了7.36%、22.91%和21.79%,且与其他处理相比,显著降低了糊化焓值和结晶度,并表现出较好的微观结构和抗回生性。该研究为大米精深加工与方便米饭产品开发提供依据。     

酿酒工艺与产品风格质量的关系

文章根据酿酒就是培养微生物获取代谢产物-酒精与香味物质的原理,从"酿酒工艺不同,微生物种类不同,代谢产物不同,主香成分不同,香型不同,产品风格质量不同"几个方面,论述了酿酒工艺与产品风格质量之间的关系.提出了酿酒工艺是培养微生物的手段,获取其代谢产物酒精与香味物质才是酿酒目的的观点.指出:只有在坚持传统酿酒工艺的基础上不断改进传统酿酒工艺,才能使"手段"(酿酒工艺)更科学,更先进,更合理,更完善,更高明,才能获取更多代谢产物(酒精和香味物质),达到优质高产的"目的".     

近20年全国烤烟产区种植规模消长变化分析

利用2001至2020年期间全国烤烟生产数据,对全国不同烤烟产区种植规模消长及其地位变化进行了分析,并对产区分类方式和种植规模转移等相关问题进行了比较论证。结果表明,近20年,全国有22个省份每年都种植烤烟,生产规模经历了“三起三落”的较大波动,但总体呈“上升－下降”趋势。全国种植面积从2001年的94.3万hm²开始,逐年振荡上升,至2013年达到141.0万hm²的最高峰,然后连年下滑,到2020年降到了88.7万hm²。按照各省烤烟种植规模大小及其占比的上升或下降变化趋势相似性,将全国各烤烟产区分为4类。与2001年相比,2020年云南、四川和湖南种植面积占比分别增加了12.1、5.4和2.5百分点,而贵州、河南、山东、陕西、黑龙江、重庆、吉林和广东种植面积占比分别减少了5.8、4.9、2.2、1.7、1.5、1.4、0.7和0.7百分点,全国烤烟种植规模消长变化及转移主要在这11个省份之间发生,其他省份的变化及其影响甚小。本文提出的依据面积及其占比变化趋势相似性进行产区分类方法及对不同产区种植规模消长变化分析,可为了解和研究我国烤烟种植规模布局调整和未来发展规划决策提供参考。     

Differences in the amount and structure of extractable skin and seed tannins amongst red grape varieties

Background and Aims:  Red wine is a very rich source of flavanols, consisting of catechins and oligomeric and polymeric proanthocyanidins (PAs). The aim of this study was to investigate the composition of the fraction of flavanols, which is extractable from the grape into the wine.
Methods and Results:  Using HPLC-DAD-MS analysis carried out before and after thioacidolysis of wine-like extracts obtained from skins and seeds, the flavanol composition of 20 samples derived from Cabernet Sauvignon, Carmenere, Marzemino, Merlot, Pinot Noir, Syrah and Teroldego was determined.
Conclusions:  It was confirmed that grape extracts are mainly rich in monomers and small oligomers (mean degree of polymerization <8). Grape seed extracts contained three monomers (catechin, epicatechin and epicatechin gallate) and procyanidin oligomers. Grape skin extracts contained four monomers (catechin, epicatechin, gallocatechin and epigallocatechin), procyanidins and prodelphinidins oligomers. Upper and extension units of PAs were constituted mainly of epicatechin units, with the co-presence of catechin and epicatechin gallate in the seed PAs, and of gallocatechin in the case of skin PAs. The terminal units of the grape PAs were a mixture of five compounds, the same found also as monomers. Catechin gallate, gallocatechin gallate and epigallocatechin gallate, which are found in other flavanol-rich, plant-derived foods and beverages, were not present in grape extracts.
Significance of the Study:  The grape variety determines both the amount and the structure of wine flavanols, leading to differences in the composition, which are likely to play an important role in the nutritional and sensorial properties of the wines.     

Fruit and Vegetable Waste: Bioactive Compounds,Their Extraction,and Possible Utilization

Fruits and vegetables are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, as well as processed, due to their nutrients and health‐promoting compounds. With the growing population and changing diet habits, the production and processing of horticultural crops, especially fruits and vegetables, have increased very significantly to fulfill the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. For example, the United Nations Food and Agriculture Organization (FAO) has estimated that losses and waste in fruits and vegetables are the highest among all types of foods, and may reach up to 60%. The processing operations of fruits and vegetables produce significant wastes of by‐products, which constitute about 25% to 30% of a whole commodity group. The waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils, among others. These phytochemicals can be utilized in different industries including the food industry, for the development of functional or enriched foods, the health industry for medicines and pharmaceuticals, and the textile industry, among others. The use of waste for the production of various crucial bioactive components is an important step toward sustainable development. This review describes the types and nature of the waste that originates from fruits and vegetables, the bioactive components in the waste, their extraction techniques, and the potential utilization of the obtained bioactive compounds.