黄麻纤维织物增强乙烯酯复合材料的制备与力学性能

织物增强聚合物(TRP)因其具有优异的机械性能而被广泛应用于汽车、建筑等领域。传统TRP材料通常以玻璃纤维、碳纤维作为增强体,由于成本高及不可降解等问题限制了发展和应用。本研究采用可生物降解的天然黄麻纤维为增强体,以乙烯酯为基体树脂,采用模压工艺制备双层黄麻织物增强乙烯酯树脂复合材料。考察经纱和纬纱的取向对复合材料密度、孔隙率及力学性能的影响。通过调整黄麻织物的纱线角度(0°,30°,45°,60°和90°),研究经纬纱角度对复合材料性能的影响,采用的模压成型工艺是80℃、7 MPa条件下压制2.5 h。为了考察模压温度的影响,将纱线角度为60°的试样在40℃的低温条件下(其余条件不变)压制成型。结果表明:与纯乙烯酯相比,黄麻纤维具有一定的增强作用,复合材料的弯曲强度和冲击强度分别提高24.77%和39.83%,拉伸性能降低30.52%。扫描电子显微镜结果显示,复合材料力学强度的提高与纱线间的孔隙分布有关。在研究范围内,经纬纱定向对复合材料的冲击强度影响比较显著。低温(40℃)条件下,制备的定向角为60°时的黄麻纤维增强乙烯基酯复合材料的各项力学性能达到最佳。     

细纱松捻纱产生的机械原因

与细纱机工艺设计偏差所导致的松捻纱不同,机械零部件的使用及保养不当所产生的“松捻”纱,因其出现的随机性,更令设备管理者和操作者难于把握,而给紧随其后的加工工序造成不便及纱疵.因而详细分析“松捻”纱产生的原因,加强设备管理及保养,及时发现和消除“松捻”纱是细纱设备管理者与检修人员应具备的重要素质.     

Preparation and characterization of melt-spun PVC filament yarns

Polyvinyl chloride (PVC) fibers were melt-spun to prepare mono and multifilament yarns. To find optimum spinning and drawing conditions, various parameters such as spinning temperature, spinneret diameter, drawing temperature, and drawing ratio were examined. From the observation of the spinnability under various conditions, we found that the optimum conditions were as following: the extrusion temperature and die temperature were 175–180°C and 185–190°C, and the drawing temperature and drawing ratio were 85–95°C and 3.4, respectively. Under these conditions, the spinneret diameter could be reduced to the minimum value, 0.5 mm. Spun PVC filament yarns were subjected to the different yarn texturing process of stuffing box and pin false-twist method. The PVC yarn fabric was prepared by the knitting of textured yarns. Finally, the anion-emission and antibiotic properties of the knitted PVC fabrics were precisely evaluated.     

Study on the liquid flow behaviour of cotton wick

The present paper reports the interaction effect of yarn twist, yarn count and number of plies on wicking behaviour of plied cotton yarn. A three-variable factorial design technique proposed by Box & Behnken was used to investigate the combined interaction effect of the above variables. Both the vertical as well as horizontal wicking experiments were carried out with liquids of varying surface tensions, like distilled water, saline water and petrol. Each wick samples were subjected to nine different types of wicking related tests. The yarn count and number of plies in the cotton wick was found to play major role in wicking related properties, whereas the effect of twist in plied cotton wick was not that prominent when the twist per unit length of single and plied yarns were the same and in opposite direction. The rate of vertical wicking for saline water was found to be significantly lower than that of distilled water. The rate of horizontal wicking for distilled water was less than that of vertical wicking of distilled water. Use two or three parallel strands instead of one resulted in marked increase of vertical wicking.     

Quality Improvement of Upland Cotton (Gossypium hirsutum L.)

Abstract

Quality of cotton can be defined through seed or fiber properties, but is most often associated with fiber properties that influence processing into yarn and textile products. Global competition in the production and consumption of cotton fiber combined with technological evolution of yarn manufacturing has spurred renewed efforts to enhance cotton fiber quality. Cotton fiber quality can be improved through genetics, crop management, and postharvest processing. Knowledge of the effects of fiber properties on processing and their inheritance, relationships, and environmental influences is necessary to formulate improvement strategies. Breeding to improve fiber quality has traditionally focused on enhancing measures of the longest fibers or fiber strength for ring yarn manufacturing systems. With the technological evolution of yarn manufacturing from solely ring-based spinning to predominately rotor and potentially in the near future air-jet spinning, needs for fiber profiles have been revised for these spinning systems. Successful rotor spinning requires high fiber strength for all yarn counts, along with fiber fineness for fine count yarns. The even more productive air-jet spinning requires a minimum, but uniform fiber length, fiber fineness, and to a lesser extent strong fiber. In contrast, ring spinning requires a minimum fiber length, fiber strength, and to a lesser extent fiber fineness. Breeders do not conduct direct selection for yarn properties because of impracti-calities, thus they select for fiber properties that influence processing, so-called indirect selection. The inherent environmentally induced variability in fiber properties presents challenges to enhance them through breeding or biotechnological approaches. Because variability in fiber properties is problematic to fiber processing, future-breeding and biotechnological approaches should simultaneously focus on enhancing fiber properties and reducing variation. This paper will review strategies to enhance fiber profiles through genetic approaches while ameliorating their variation.     

Comparison of artificial neural network and linear regression models for prediction of ring spun yarn properties. I. Prediction of yarn tensile properties

In this study artificial neural network (ANN) models have been designed to predict the ring cotton yarn properties from the fiber properties measured on HVI (high volume instrument) system and the performance of ANN models have been compared with our previous statistical models based on regression analysis. Yarn count, twist and roving properties were selected as input variables as they give significant influence on yarn properties. In experimental part, a total of 180 cotton ring spun yarns were produced using 15 different blends. The four yarn counts and three twist multipliers were chosen within the range of Ne 20–35 and α _e 3.8–4.6 respectively. After measuring yarn tenacity and breaking elongation, evaluations of data were performed by using ANN. Afterwards, sensitivity analysis results and coefficient of multiple determination (R²) values of ANN and regression models were compared. Our results show that ANN is more powerful tool than the regression models.     

Empirical modelling of tensile strength of woven fabrics

Aesthetic properties of fabrics have been considered as the most important fabric attribute for years. However, recently there has been a paradigm shift in the domain of textile material applications and consequently more emphasis is now being given on the mechanical and functional properties of fabrics rather than its aesthetic appeal. Moreover, in certain woven fabrics used for technical applications, strength is a decisive quality parameter. In this work, tensile strength of plain woven fabrics has been predicted by using two empirical modelling methods namely artificial neural network (ANN) and linear regression. Warp yarn strength, warp yarn elongation, ends per inch (EPI), picks per inch (PPI) and weft count (Ne) were used as input parameters. Both the models were able to predict the fabric strength with reasonably good precision although ANN model demonstrated higher prediction accuracy and generalization ability than the regression model. The warp yarn strength and EPI were found to be the two most significant factors influencing fabric strength in warp direction.     

Investigating the effect of various blend ratios of prepared masterbatch containing Ag/TiO2 nanocomposite on the properties of bioactive continuous filament yarns

In this research, possibility of producing and processing antibacterial organic/inorganic nanocomposite polypropylene filament yarns for permanent antimicrobial efficiency has been investigated. First PP powder and inorganic nanocomposite filler were mixed in a twin screw extruder and modified masterbatch was produced. Continuous filament yarn was made by a pilot plant melt spinning machine from the blend of PP granule and various blending contents of the prepared masterbatch. Pure PP and all other combined samples showed acceptable spinnability at the spinning temperature of 240 °C and take-up speed of 2000 m/min. After producing as-spun filament yarns, samples were drawn, textured and finally weft knitted. Physical and structural properties of as-spun and drawn yarns with constant and variable draw ratios were investigated and also tensile and crimp properties of textured yarns were evaluated. Moreover, the DSC, SEM, FTIR techniques have been used for characterization of samples. Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity reduction of modified drawn yarns has reached to 5 %. The observed improvement in the tensile properties of modified as-spun yarns compared to the pure PP was significant. Drawing process improved generally the tensile properties of as-spun yarns. Tensile properties of modified textured and drawn yarns were higher than the pure PP. An optimum of antibacterial activity has been observed in the sample containing 0.75 wt% of nano-filler. It is interesting that the optimum of tensile properties has been also obtained for the sample with maximum bioactivity.     

中洛管道冬季运行现场试验

为制订切实可行的安全经济运行方案,确保中洛输油管道冬季运行的安全性,对中洛输油管道输送的混合原油的密度、凝点和粘度进行了测试和记录,并对不同配比的油段进行现场跟踪、测取和分析.基于现场测试结果,采用优化运行软件对混合原油的流变参数进行了计算.     

利用喷嘴减少苎麻纱毛羽的探讨

本文从喷嘴在纺纱中的几个实例出发，根据它们产品毛羽少的共性，在苎麻纺纱实验中采用了喷嘴与环锭纺的方法，以期减少苎麻环锭纱的毛羽。