静电纺丝制备高比表面积纳米多孔纤维的研究进展

静电纺丝技术是当前制造纳米纤维最主要的基本方法,增加静电纺纳米纤维比表面积和孔隙率对提高其应用性能有巨大作用。通过静电纺纳米纤维多孔化制备技术来改变纤维结构和表面形态,能够大幅度提高纤维的比表面积。综述了近年来静电纺纳米多孔纤维的研究进展情况。     

Bending load capacity of carbon fiber reinforced concrete beams as a function of fiber performance index (FPI)

Over the past several decades, textile reinforced concrete (TRC) materials have been developed due to their superior mechanical properties, corrosion resistance, lightweight application, and high load-bearing capacity. In this study, the effect of three main factors on bending load capacity of carbon fiber reinforced concrete (CFRC) beams is investigated; the number of reinforcements (carbon-fiber rovings), penetration of the cement within the fibers, and the post-cracking factor. The second and third factors are defined as the fiber performance index (FPI) for evaluating bending load capacity of CFRC beams. The best FPI for a different number of reinforcements was estimated using empirical values of bending load capacity of CFRC beams. The results were indicative of the efficiency and accuracy of the proposed FPI for a wide range of roving numbers, namely 2–24 with 800 tex as the titer. The post-cracking factor was suggested as 2.67 for TRCs and CFRCs materials, which are reinforced by rovings. In order to improve the FPI, the roving was impregnated partially with epoxy, which increased the maximum load capacity and displacement of the beams up to 26.68 and 23.24%, respectively. In addition, the impacts of roving numbers, the first factor, on the failure mode, load-bearing capacity, ductility, and toughness of the CFRC beams were investigated.     

工艺条件对粘胶基活性碳纤维比表面积与收率的影响

以粘胶纤维为原料,用磷酸盐浸渍,水蒸气活化,制备了活性碳纤维,研究了磷酸盐附着率、炭化温度、活化温度与活化时间对粘胶基活性碳纤维的比表面积与得率的影响。结果表明:适宜的磷酸盐附着率、较高的炭化起始温度及较快的升温速度有利于得到较大比表面积和较高得率的活性碳纤维。     

膳食纤维生理功能及其对常量营养素吸收影响

膳食纤维对人体健康具有特殊生理功能,尤其是对慢性疾病预防作用;膳食纤维本身不能直接被机体所吸收利用,但对胃肠道功能及多种营养素吸收都有一定影响,常量营养素包括碳水化合物、蛋白质及脂类;膳食纤维对于蛋白质消化吸收影响不大,但可减少脂类和碳水化合物吸收及利用。     

涤纶增强混凝土的性能研究

采用涤纶工业丝和相应的废弃的涤纶工业丝作混凝土的增强纤维,分别选择纤维的长度为20、30 mm和纤维的掺量为0.5、1.0、1.5 kg/m3,按国标要求制作试样并进行标准养护后,对增强混凝土的抗裂性能、抗压性能、劈裂抗拉性能和弹性模量进行测试和分析,结果表明纤维增强混凝土的上述力学性能均有所改善,试样受力破坏后不碎裂;并且随着纤维长度和掺量的增加,抗压强度和劈裂抗拉强度提高;回收涤纶与新涤纶的情况大体类似,这给废弃涤纶的回收再利用和节约资源、保护环境提供了途径。不论是涤纶还是回收涤纶,长度为30 mm、掺量为1.5 kg/m3的试样表现出最优的力学性能。     

The influence of production parameters on sound absorption of activated carbon fiber felts

Intended to study the influence of different production parameters on sound absorption of activated carbon fiber felts, viscose-based activated carbon fiber felts acquired from different production parameters were prepared and taken to test the sound absorption coefficients in normal incidence by means of transfer function method, within an acoustic range of 250–6300 Hz in the impedance tube. Analysis was made to find the influence of carbonization temperature, carbonization rate, activation temperature, and activation time on sound absorption properties. Sound absorption coefficients at medium–low frequencies strikingly climbed with the increasing frequency, while fluctuating at high frequencies. Other production parameters remaining constant, sound absorption coefficients increased at medium–low frequencies with the rising carbonization temperature and the extended activation time, while subsequently decreased with the rising carbonization rate and carbonization temperature. At the same time, sound absorption coefficients decreased at high frequencies with the rising carbonization temperature and carbonization rate, while increased but later decreased with the rising activation temperature, and increased again with the added time in activation.     

牛皮胶原纤维热降解活化能的研究

初步研究了牛皮胶原纤维的热降解动力学 ,采用Flynn -wall-Ozawa和 ˇSatava -ˇSest偄ｋ 2种方法处理了不同升温速率下 ,未鞣制皮胶原纤维、铬鞣皮胶原纤维和戊二醛鞣制皮胶原纤维的热重数据。结果表明 :未经鞣制皮胶原纤维的热降解活化能为 1 3 0～ 1 60kJ/mol,经铬鞣后 ,皮胶原纤维的热降解活化能增加至 2 2 5～2 5 5kJ/mol,经戊二醛鞣制皮胶原纤维的热降解活化能与未鞣制皮胶原纤维相比变化不大 ,为 1 2 0～ 1 63kJ/mol。     

Effects of body surface area estimates on predicted energy requirements and heat stress

The 0.09 x W(0.67) equation (where W = weight in kilograms) used to estimate body surface area (SA) in cattle energy requirements models was developed using measurements of sheep that weighed between 24 and 38 kg. The SA estimates it produced were compared with those of the equation 0.14 x W(0.57), based on Holstein cattle weighing 41 to 617 kg. The estimate of SA produced by the first equation was 23% greater for a 650-kg cow than that obtained by the second equation. The impact of SA estimates on thermal comfort range and development of cold and heat stress effects was calculated, using a thermal balance model, for a 600-kg cow producing 35 kg/d. Predicted metabolic heat production increment at -10 degrees C ambient temperature with 0.5 m/s wind velocity was 0.44 Mcal/d and 1.21 Mcal/d by the first and second equation, respectively. Predicted lower critical temperature (LCT) was -8.7 degrees C by the first equation and -0.6 degrees C by the second equation, an 8 degrees C difference. The LCT difference between SA estimates increased from 4.6 to 9.4 degrees C, with milk production rising from 10 to 45 kg/d. By the first equation, skin nonevaporative heat loss started to decrease at 15 degrees C and became close to nil at and ambient temperature of 35 degrees C, whereas by the second equation, respective values were 10 degrees C and 39 degrees C, a 5 degrees C shift in the estimated temperature at which thermal stress would start developing. The larger SA and skin water loss predicted by the first equation reduced by 50% the respiratory heat loss involved in maintenance of thermal balance at higher temperatures for a 600-kg cow. The second equation seems preferable for Holstein SA estimation since it is based on Holstein cattle data. It provides more adequate estimates of energy requirement in the cold and of heat stress relief needs for Holstein cattle.     

盐离子浓度对氧自由基吸收能力(ORAC)检测准确性的影响

氧自由基吸收能力(ORAC)检测是在抗氧化和应激氧化领域中被广泛使用的抗氧化评价方法。现有ORAC检测方法中,基本未考虑抗氧化物质在分离纯化过程中引入的盐对检测结果的影响。通过在抗氧化标品Trolox中分别添加不同种类及不同浓度盐离子(NH4Cl、CH3COONa、CH3COONH4和NaCl),分析盐离子对ORAC实验结果准确性的影响。结果表明,样品中盐离子的存在使测得的ORAC值都有不同程度的提高,其中CH3COONa的影响最为明显;原因可能是盐的存在影响荧光素的电离,从而改变荧光素的氧化速率。可在标准曲线样品中加入与待测样品同等浓度的盐来消除样品中盐引起的测定误差。     

石英陶瓷比磨削能正交试验研究

磨削是陶瓷材料最常用的加工方法,选择合理的工艺参数,降低加工成本是陶瓷磨削加工研究的重要内容。通过大量的正交试验,研究陶瓷材料在低速下的磨削性能,优化陶瓷磨削参数,对于丰富陶瓷磨削理论,指导实际生产具有重要的现实意义。     

硬脂酸多孔玉米淀粉酯的性质与结构研究

对以多孔玉米淀粉为原料经干法酯化制备的硬脂酸多孔玉米淀粉酯进行性质测定。与多孔玉米淀粉进行比较,考察了吸油率和比表面积,并对产品做了结构分析。结果显示:酯化后的淀粉无论在吸油率还是比表面积上都比未经酯化处理的多孔淀粉都有所增大。     

Influence of chemical treatment on tensile strength,water absorption,surface morphology,and thermal analysis of areca sheath fibers

Proper surface modification is highly essential to improve compatibility of natural fibers with polymer matrix to develop eco-friendly materials. In the present work, an attempt has been made to study the effect of various chemical treatments such as alkaline, acrylic acid, permanganate, sodium chlorite, and benzoylation on areca sheath fiber. After surface modifications, its density, water absorption property, mechanical property, thermal gravimetry analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and surface morphology have been thoroughly investigated. It has been observed that benzoyl chloride-treated fiber gives better performance in comparison to other treatments.     

聚丙烯纤维对混凝土抗冲击和抗折性能的影响

研究了不同长度的聚丙烯纤维对混凝土的抗折和抗冲击性能的影响。试验结果表明:在混凝土中分别掺入纤维体积率为0.5%的六种不同长度的聚丙烯纤维,均能提高混凝土的破坏冲击次数和冲击延性指数;当纤维长度为35 mm时,纤维混凝土的破坏冲击次数较素混凝土提高近2倍;在混凝土中掺入聚丙烯纤维,混凝土的抗折强度降低,而混凝土的中心挠度显著提高,较素混凝土最多增加达1 mm,能有效改善混凝土的韧性。     

芳纶纤维表面改性对黏附功与成纸强度性能的影响

利用不同质量比浓度的乙醇、丙酮、丙酸、二甲基亚砜、二甲基乙酰胺等化学试剂对芳纶纤维表面进行处理和踟性,并进行纤维成纸性能研究。研究了改性对芳纶纤维强度、纤维表面黏附功及其纸张性能的影响。结果表明：当隐性剂的表面能接近纤维的表面能时,对提升纸张强度影响最为显著;纸张强度性能是纤维表面黏附功和纤维本身强度共同作用的结果。在乙醇质量比浓度为11．10％时,改性纤维强度、纤维表面黏附功、纸张抗张强度分别可达到1365．05N／g,116．33mJ／m2和43．27N·m／g,分别提高5．44％,9．90％和5．53％。     

利用固定化酶改善酸法大豆浓缩蛋白持水性和吸油性的研究

利用固定化谷氨酰胺转胺酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并对改性SPC进行红外光谱分析。通过单因素和正交实验研究了MTG改性对SPC持水性和吸油性的影响。结果表明,当固定化MTG添加量1U/g,pH6.0,50℃下反应2h时,改性后大豆浓缩蛋白的持水性和吸油性分别比对照提高了24.8%和64.5%;与大豆分离蛋白相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则低8.0%。     

利用计算机快速测定葡萄叶面积的方法研究

试验通过数码照相获取葡萄叶片图像,利用图形处理软件CorelDRAW11.0获得叶缘的矢量化图形,然后利用AUTOCAD2002,可快速测量出叶面积和周长.测量结果与叶面积仪法之间达到极显著相关.使用CorelDRAW对叶片边缘进行自动矢量化可以极大提高计算机测量效率.用该方法测量酿酒葡萄品种赤霞珠、品丽珠,蛇龙珠和梅鹿辄的叶片面积和周长数值,方差分析和多重检验表明,面积、周长及其比值(R)3个参数可以较好的区分4个品种.计算机图形处理技术测定葡萄叶面积的方法可以对现有葡萄叶形结构参数进行优化,也为其他植物叶面积的测量提供一种新的思路.     

涂层的BET表面积对喷墨打印纸打印性能的影响

采用六种颜料配制高光泽彩喷纸涂料，研究了其涂料涂层微孔BET表面积与孔隙体积、平均孔径的关系，以及BET表面积与打印质量指标，即油墨点面积、油墨点圆度和油墨密度的关系。结果表明，BET表面积增大，孔隙体积增大，BET表面积与平均孔径无关；BET表面积增大，油墨点面积减小，但BET表面积与油墨点圆度及油墨密度无关。     

温度变化对薄荷油增溶量的影响

本文从定量方面对薄荷油的胶束增溶体系进行了研究，做了有关温度变化对增溶量的影响，并绘制了不同条件下的三元相图。     

速溶豆粉微结构的研究

速溶豆粉微结构研究是理解豆粉速溶性的基础；SEM观察表明，速溶豆粉颗粒是中空凹凸不平的球体．壁厚度在5000～20000nnl之间，具有多微孔的内外表面，微孔随机连通，直径50～300nm；XPS测定表明，速溶豆粉颗粒表面由蛋白质、18碳脂肪酸钠和皂甙构成，3种物质重量比约32：41：27；N2吸附法测定表明，对孔径大于70nm的大孔、大于3nm的微孔和小于3nm的超微孔来说，速溶豆粉的比表面积和孔隙体积都超过普通豆粉10倍。