单层织物湿态热防护性能测试与分析

为研究消防服用织物的湿态热防护性能,以4种适宜用作消防服装多层结构的面料为试样, 通过热辐射和热对流综合热防护性能实验（TPP实验）,测试织物在5种湿状态下热辐射和热对流综合热防护值TPP值和二级烧伤时间,比较不同层面料吸湿后热防护性能的变化。用SPSS软件研究分析了单层织物吸湿后含水率对二级烧伤时间和TPP值的影响。结果显示, 在高强度热流量短时间作用情况下,水分有助于提高单层织物的热防护性能。二级烧伤时间和TPP值均随面料含水率的增大而增大,含水率与二级烧伤时间和TPP值之间存在显著的线性正相关关系。并在TPP值、二级烧伤时间与含水率之间建立了一元线性回归方程。     

复合多层织物的热湿性能分析

随着科学技术的发展与进步，纺织品的功能性和舒适性也随之不断扩充和完善。文中介绍了最新的一些纺织材料热湿性能研究成果，并对不同结构的吸湿排汗复合双层织物进行了讨论，而且运用相关的热湿耦合模型全面分析了各种结构的织物在穿着情况下的热湿性能。发现当疏水性纤维材料置于织物内层时有明显的吸湿排汗效果。     

含水率对消防服用多层织物系统热蓄积的影响

为全面准确地评估湿态下消防服用多层织物系统的热防护性能,通过改进现有的热防护性能测试仪器,采用传统热防护性能实验与蓄积热实验2种方法,利用模拟人体皮肤传感器取代标准测试中的铜片热流传感器,基于Pennes热量传递方程,根据Henriques人体皮肤烧伤模型做出烧伤预测,并利用迭代法获得二度烧伤最少热暴露时间。分析了织物系统含水率对二度烧伤最少热暴露时间及热蓄积指数的影响。实验结果表明:2种实验方法测得的二度烧伤最少热暴露时间随含水率的增大明显降低,热蓄积指数也呈降低趋势;二度烧伤最少热暴露时间与含水率之间存在显著的线性负相关关系。     

曲奇饼干等温吸湿规律及模型研究

重点研究了曲奇饼干在水分活度为0.11～0.92,温度分别为25、35、45℃条件下的吸湿平衡含水率变化规律。并根据目前在食品吸湿规律研究中常用的6种模型时3个温度条件下对曲奇饼干的吸湿试验点进行了模拟比较。得到饼干在3种温度下的等温吸湿曲线,并进一步推导出GAB模型为符合该曲奇饼干吸湿规律的数学模型。     

烟叶在高温湿度环境中平衡含水率的数学模型

为研究加工过程烟叶的吸湿过程,采用动态法测定了在60,70和80℃3个温度点下,30%～90%范围内7个相对湿度点的烟叶增湿特性曲线,再根据增湿特性曲线得到烟叶的平衡含水率,并用GAB模型对平衡含水率曲线进行拟合。结果表明:GAB模型可以较好描述烟叶在高温湿度环境中的平衡含水率并确定了模型参数,预测值与实验值比较吻合,相关系数r2=0.980。     

织物组织结构对机织物吸湿速干性能的影响分析

为研究织物组织结构对机织物吸湿速干性能的影响,以75 D/72 F十字截面涤纶长丝与7.29 tex(80S)纯棉纱的复合纱为原料,设计并织造5种不同组织结构的机织物。采用热板法测试不同组织结构机织物的吸湿速干性能,对试验结果进行分析。结果表明:5种机织物的干燥速率大小为平纹透孔斜纹缎纹蜂巢,其干燥速率与织物组织结构和织物厚度有关。通过对5种机织物吸湿速干性能的分析,为纺织企业生产吸湿速干机织物提供参考。     

基于不同数学模型的魔芋水分吸湿等温线模拟

根据吸附原理,采用静态调整环境湿度法,测定了魔芋在20、30、40℃3个温度下,0%~98%水活度范围内的平衡含水率,绘出魔芋的吸湿等温线。结果显示,魔芋的吸湿等温线属于II型等温线;在一定的水活度下随着温度的升高魔芋的吸附能力下降。并以平均相对误差和决定系数为评价指标,用八种数学模型对实验数据进行拟合,结果表明Peleg模型对魔芋的吸湿等温线拟合效果最好。     

三种不同吸湿速干整理剂工艺的探讨

以分别用水分散性聚酯、环氧树脂、有机硅三元共聚物为主成分的三种不同组分的吸湿速干整理剂，对涤纶织物和涤棉织物的整理工艺进行了研究。实验结果表明：经以聚酯为主组分的吸湿速干整理HMW8870适用于整理涤纶织物；以有机硅三元共聚物为主成分的HMW8871适用于整理涤棉织物；以环氧树脂为主成份的吸湿速干整理剂PA的整理效果相对较差。     

基于模糊相似优先比的织物吸湿速干性评价

通过制织23种吸湿速干机织物,测取芯吸高度、扩散面积、干燥速率等吸湿速干性能指标,运用模糊相似优先比的方法,对织物的吸湿速干性能通过优先比秩位排序,综合评价织物性能的优劣。结果表明,模糊相似优先比在织物比较方面具有实用意义。     

羊毛角蛋白溶液对涤纶织物的整理

用自制羊毛角蛋白溶液对涤纶织物进行整理,对不同用量羊毛角蛋白溶液整理的织物和未整理的织物的吸湿速干性能作了对比性的测试和分析,X射线光电子能谱和拉曼光谱分析结果表明,羊毛角蛋白溶液作为整理剂对涤纶有很好的吸附交联,能在织物上交联形成二硫键,对涤纶针织物的性能有很大改善,用10％角蛋白溶液整理就可达到针织物吸湿速干技术要求.     

Effect of particle size on droplet infiltration into hydrophobic porous media as a model of water repellent soil

The wettability of soil is of great importance for plants and soil biota, and in determining the risk for preferential flow, surface runoff, flooding,and soil erosion. The molarity of ethanol droplet (MED) test is widely used for quantifying the severity of water repellency in soils that show reduced wettability and is assumed to be independent of soil particle size. The minimum ethanol concentration at which droplet penetration occurs within a short time (≤ 10 s) provides an estimate of the initial advancing contact angle at which spontaneous wetting is expected. In this study, we test the assumption of particle size independence using a simple model of soil, represented by layers of small (~0.2-2 mm) diameter beads that predict the effect of changing bead radius in the top layer on capillary driven imbibition. Experimental results using a three-layer bead system show broad agreement with the model and demonstrate a dependence of the MED test on particle size. The results show that the critical initial advancing contact angle for penetration can be considerably less than 90° and varies with particle size, demonstrating that a key assumption currently used in the MED testing of soil is not necessarily valid.     

The Effect of Functional Finishes and Laundering on Textile Materials Part II: Characterization of Liquid Flow

The effect of finishes and laundering on the liquid flow in cotton and polyester-fiber fabrics is investigated. The liquid flow can be categorized into vertical wicking and demand wettability. Since the liquid flow in fibrous materials is affected by the pore size, based on the Washburn equation, the effect of fabric pore size and pore-size distribution was also studied.

The presence of the three different finishes (durable-press, stain-repellent, and antistatic) and laundering changed the vertical-wicking and demand-wettability phenomena owing to changes in the surface energy of fibers and/or changes in pore characteristics. However, the results from vertical wicking and demand wettability did not always agree. The vertical-wicking test was more sensitive to finishing treatments and responded in a more predictable way. In general, changes in liquid flow in finished fabrics can be predicted from the surface energy of the fiber in the fabrics and the pore size and pore-size distribution in the fabrics, as expressed by the Washburn equation. To assess the relationship between liquid flow in fabrics and the surface properties of fibers quantitatively, however, it is necessary to have specific information on the number of pores in a fabric, in addition to the data on the pore-size distribution.     

Effect of Packaging Materials on Temperature Fluctuations in Frozen Foods: Mathematical Model and Experimental Studies

An analytical solution of the conduction heat transfer equation was developed for prediction of temperature in frozen foods exposed to periodic environmental temperature fluctuations. The prediction model includes the effect of surface heat transfer resistances. Theoretical predictions were compared with experimental values recorded from frozen ice cream at different storage regimes. Slab-shaped metal containers were used in the experiment. Surface heat transfer resistances were simulated with single layers of commercial packaging cardboard sheets and restricted air movement over the containers. A satisfactory agreement was obtained between predicted values and experimental data. Packaging materials coupled with a layer of stagnant air are effective barriers against thermal fluctuations.     

筒仓中粮食卸料动压力的数值模型

筒仓中粮食卸料时拱不断形成并不断坍塌。以这些不稳定拱(瞬态拱)为依据,建立一个预测筒仓中粮食卸料动压力的数值模型。将粮食分成许多薄层,结拱层上方的粮食视为多层弹簧振子系统,建立该系统的振动方程,从而解出结拱层的加速度,再对结拱层运用动量定理,推导出粮食卸料时对仓壁的动压力。计算结果表明:粮食卸料时粮食对筒仓壁产生的动压力大于Janssen方程计算的储藏静压力,粮食卸料时超压因子随粮食深度的增加而增加,对于直径10 m的筒仓(ρ=800 kg/m3,φ=25.0,°μ=0.4,Q=1.0 kt/h,ν=0.4,Ev=30.0 MPa),粮食深度从2.0 m增加到24.0 m时,超压因子从约1.33增加到1.87;粮食卸料时超压因子随粮食流量的增大而增大,随粮食体积弹性模量的增大而增大,随粮食和仓壁摩擦系数的增大而增大,随粮食内摩擦角的增大而减小;储藏静压力和卸料动压力都随粮食和仓壁摩擦系数的增大而减小,都随粮食内摩擦角的增大而减小。     

Chitosan coating surface properties as affected by plasticizer, surfactant and polymer concentrations in relation to the surface properties of tomato and carrot

The objectives of this work were to determine the effects of the concentrations of glycerol and sorbitol (as hydrophilic plasticizers), Tween 80 (as surfactant) and chitosan on the wettability of Cuban chitosan-based edible coatings in view of their application on tomato and carrot and to develop a model allowing the optimization of coating composition.The values of the polar and dispersive components of the superficial tension of the foods were determined to be 3.04 and 25.67 mN/m, respectively, for tomato, and 0.34 and 26.13 mN/m, respectively, for carrot, the sum of the two components being the superficial tensions of tomato and carrot (28.71 and 26.48 mN/m, respectively). The skins of both foods are therefore low-energy surfaces, meaning that the Zisman method for the determination of wettability could be applied.The best experimental values of wettability were obtained for the following coating composition: 1.5% (w/v) of chitosan and 0.1% (w/w) of Tween 80.The increase in the concentration of chitosan and glycerol or sorbitol as plasticizers decreased the values of wettability and adhesion coefficients.The results of wettability were adjusted to a polynomial model that describes the dependence of the adhesion coefficient (W_a), cohesion coefficient (W_c) and spreading coefficient (W_s) on chitosan and Tween 80 concentrations. The optima calculated by the model equations were in excellent agreement (relative error below 3%) with the experimental values.     

Influence of carrier agents on the physicochemical properties of blackberry powder produced by spray drying

The aim of this work was to study the effect of different carrier agents (maltodextrin, gum arabic or a blend of both carrier agents) on the physicochemical properties of blackberry powder produced by spray drying. Moisture content, anthocyanin retention, antioxidant activity, colour parameters, bulk and absolute density, porosity, wettability, sorption isotherms, particle size and morphology of blackberry powders were evaluated. The use of maltodextrin resulted in less hygroscopic powders with lower moisture content and better reconstitution properties. Powders produced with maltodextrin or a blend of maltodextrin and gum arabic presented the best anthocyanin retention and the highest antioxidant activity. Experimental data of water adsorption were well fitted to GAB model. All the samples exhibited a large number of irregular particles with spherical shapes. However, particles produced with gum arabic were smaller and showed more dented surfaces, which probably contributed to the increase in wettability values and lower pigments retention.     

兔毛纤维的吸湿性能

对兔毛纤维的润湿性能和吸湿性能进行研究,测定兔毛纤维的接触角和在标准状态下的吸放湿特征曲线,并与羊绒纤维进行比较,根据特征曲线推导出兔毛纤维在标准状态下达到吸、放湿平衡过程中回潮率对于时间的回归方程以及吸、放湿速率方程。结果显示:未经洗涤的兔毛纤维具有良好的润湿性能,与羊绒纤维相当,但其吸湿能力稍低于羊绒纤维,初始吸湿速度与羊绒相近,放湿速度低于羊绒,达到吸、放湿平衡所用时间要长于羊绒纤维。     

A RESEARCH NOTE UNIAXIAL COMPRESSION OF DOUBLE LAYERS OF SOLID FOODS 1

The compressive force deformation relationships of various foods, that included breads, cheeses and sausages, were described by a two parameter power model. To predict the behavior of double layered arrays of some foods, their model parameters were incorporated into an equation that describes the relationships between the force and the total deformation of the array for a given cross-sectional area and any initial thickness of each of the two layers. Construction of the force-deformation relationships of the double layered array was done by numerical solution of this equation for various levels of deformation. The force deformation relationships predicted in this way were found to be in good agreement with experimental relationships. This was irrespective of whether the force deformation curve of the components had a concave upward or downward shape.     

针织物染色上染率动力学模型

College of Information Science and Engineering;Huaqiao University;Quanzhou;Fujian 362021;China     

振动破碎粉末食品拱的研究

本文研究了在竖向振动条件下带有漏斗的容器中粉末食品的动力学特性。容器中粉末食品被分为n层,设想每两相邻层被一个弹簧和一个阻尼器联接,容器的底部受竖向振动,粘性的粉末系统被简化成振子-弹簧-阻尼器系统。选各粉末层的位移为广义坐标,建立了系统的动力学方程,给出了模型参数的确定方法,推导出在竖向振动条件下的破拱判据,给出了模型计算的数值结果,数值结果与GeTong等的实验数据一致。结果表明:系统具有一个共振频率,容器的底部以这个频率竖向振动时,各粉末层的加速度达到各自的最大值;当容器的底部以共振频率竖向振动时,各粉末层的加速度是不相同的,当拱所在的那一粉末层有最大的振动加速度时,拱最可能被破碎。