纺织品中发热纤维功能性测试研究

收集市面上5种厚度和面密度相近的保暖内衣,其中4种标称含有发热纤维。分析它们的吸湿发热性、保暖性、透气性、透湿性、起毛起球性和抗紫外线性等方面的差异,研究发热纤维的功能性。结果表明:织物的功能性与织物的厚度、面密度及纤维组分有关,含有发热纤维的织物其吸湿发热性、保暖性、透气性优于以聚酯纤维为主要成分的保暖内衣;提升腈纶的吸湿性可增加织物的吸湿发热性能及透湿率,依克丝(EKS)纤维在提高织物保暖性方面有一定的作用。     

吸湿发热聚丙烯腈纤维的性能研究

采用傅立叶变换红外光谱、扫描电子显微镜、X射线衍射仪和热重分析仪对交联改性制备的吸湿发热聚丙烯腈(PAN)纤维的吸放湿性能进行表征,与普通PAN纤维及进口吸湿发热PAN纤维进行对比。结果表明:交联改性制备的吸湿发热PAN纤维红外光谱出现了较强的羟基峰和羧酸盐的伸缩振动峰,相比普通PAN纤维,表面沟槽加深、粗糙度增加,在100℃内失重率达17.17%,热分解温度提高近70℃,结晶度大幅下降,力学性能降低;交联改性PAN纤维的吸放湿性能较普通PAN纤维大幅度提高,并高于进口吸湿发热PAN纤维,其平衡回潮率约30%,吸湿积分热达155 J/g。     

新型保暖纤维的研究与应用

作为功能性纤维材料的研究热点之一,保暖纤维的开发与应用备受关注.本文简要介绍了保暖纤维的实现途径与方法,着重介绍了异形纤维、气凝胶纤维、吸湿发热纤维、光能发热纤维、相变调温纤维等新型保暖纤维的研究与应用,并对保暖纤维今后的发展进行了展望.     

荷兰开发吸湿排汗控温纤维

荷兰Advansa公司新近开发了一种新型的调温吸湿排汗纤维,目前在北美洲市场有售。该纤维采用杜邦公司P1T纤维与Lenying公司的Lyocell纤维混纺而成。P1T纤维可低温染色、色牢度好、悬垂性好,而Lyocell纤维柔软、美观,其快速吸收水分并传递至外部的特性是调温吸湿排汗纤维具有吸湿排汗功能的主要原因。目前该纤维制成的产品有运动服、袜子、休闲服等。该纤维制成的面料吸湿速度比其他功能面料高48％,排湿速度高53％。     

竹原纤维热湿性能研究

通过测试竹原纤维的耐热性能、吸放湿性能和吸湿溶胀性能,并与苎麻纤维、竹浆纤维的性能进行了分析比较,认为竹原纤维和苎麻纤维吸湿后都会发生较大的溶胀,耐热性都较好,但竹原纤维吸湿更好、放湿更快,略优于苎麻纤维;竹浆纤维因其加工方法不同,除吸湿能力优于竹原纤维外,其放湿速度慢、吸湿溶胀率小、耐热性能也比竹原纤维差。     

荷兰开发吸湿排汗控温纤维

生意社10月19日讯荷兰Advansa公司新近开发了一种新型的凋温吸湿排汗纤维，目前在北美洲市场有售。该纤维采用杜邦公司PTT纤维与Lenying公司的Lyocell纤维混纺而成。PTT纤维可低温染色、色牢度好、悬垂性好，而Lyocell纤维柔软、美观，其快速吸收水分并传递至外部的特性是调温吸湿排汗纤维具有吸湿排汗功能的主要原因。目前该纤维制成的产品有运动服、袜子、休闲服等。该纤维制成的面料吸湿速度比其他功能面料高48％，     

服装纺织用吸湿发热粘胶纤维的制备与性能分析

将具备吸湿发热功能的添加剂掺入到粘胶中进行共混纺丝,以此制备吸湿发热粘胶纤维,并对吸湿发热粘胶纤维的制备与性能作了检测。结果表明,吸湿发热粘胶纤维的横截面呈不规则的锯齿状,且沟槽较多,深度较大,锯齿状十分突出。由于吸湿发热粘胶纤维的结晶度相对较低,故取向度有所增大,断裂强度显著下降,而拉伸断裂伸长率则稍有增大,回潮率提高较多,摩擦系数明显上升。在相同条件下,同质量吸湿发热粘胶纤维在同体积中,温度上升幅度显著高于普通粘胶纤维,具有较好的吸湿发热功能。     

异形涤纶导湿性能研究

对异形涤纶的导温性能进行研究 ,设计了 7种异形孔并纺制纤维试样 ,分别测试它们的吸湿排汗能力、带液率、干燥速率。讨论同孔形不同尺寸的孔及不同孔形对异形纤维导湿性能的影响。结果发现 ,同孔形不同孔尺寸的异形纤维异形度随叶片长宽比的增加而增加 (控制在 7以下 ) ,纤维的吸湿功能与异形度有关 ,还与凹槽的深度、形状有关 ,H孔型的吸湿排汗功能最好     

吸湿排汗纤维开发与性能研究

对影响吸湿排汗纤维截面形状的主要纺丝工艺参数进行了探讨;比较了纤维截面形状的变化对织物吸湿快 干能力的影响。结果表明在一定范围内,纤维截面形状的变化对织物吸湿快干能力无明显影响;通过对吸湿排汗纤维进行 亲水整理,织物的吸湿快干能力得到显著提高并具有持久性。     

织物组织结构对吸湿快干机织物性能的影响

以质量比50/50的云母纤维/竹浆纤维混纺纱为原料,设计开发了具有吸湿快干功能的平纹组织、小提花组织和透孔组织3种单层机织物,对这3种组织织物的基本性能和热、湿舒适性能进行了测试,分析了织物组织结构对机织物吸湿快干性能的影响。测试结果得出:这3种织物均具有吸湿快干的性能,其中透孔组织为吸湿快干性能最佳的织物组织。     

生物质及生物质组分的慢速热解热效应研究

利用绝热加速量热仪(ARC)进行多种生物质及生物质组分的慢速热解,检测热解过程的吸放热情况,结果显示在缓慢升温过程中,纤维素的放热峰在256.2~279.2℃之间,放热量约为673.9J/g,质量分数为51.8%固体炭产物;而木聚糖在219.8~253.7℃之间有一尖锐的放热峰,放出热量约为873.3J/g,得到质量分数为68.7%的残余固体;木质素的热流曲线却在133.3~292.2℃有吸热趋势,吸收热量为340.1J/g,得到质量分数为80.4%的固体炭。各生物质的热流曲线中均有两个相连的放热峰出现,分别来源于半纤维素和纤维素。各生物质热流曲线特征值各异,但起始放热温度在190℃前后,第1个峰值温度在220℃左右,第2个放热峰峰值集中在255℃前后。     

Polyacrylonitrile/acrylamide‐based carbon fibers prepared using a solvent‐free coagulation process: Fiber properties and its structure evolution during stabilization and carbonization

Polyacrylonitrile (PAN)/acrylamide (AM) fibers were fabricated via dry‐jet wet spinning process using a solvent‐free coagulation bath. The effects of AM loading as comonomer on the mechanical and thermal properties of PAN‐based carbon fiber have been studied. The thermal stability and mechanical stability of the fibers were characterized using differential scanning calorimetry (DSC) and tensile testing. Fibers fabricated from PAN with 5 wt% AM had the highest Young Modulus at 5.54 GPa. It also showed better exothermic trend process with broader exothermic peak and lower initiation stabilization temperature compared with homopolymer PAN. The elemental composition and chemical structure evolution of the fibers during the heat treatment processes were evaluated by elemental analyzer and Fourier Transform Infrared Spectroscopy. Crystal structure evolution of the fibers during the heat treatment process was elucidated by X‐ray diffraction (XRD) analysis. The elemental analyzer, XRD and FTIR results revealed that pyrolysis process used had successfully transformed PAN/AM fibers produced from solvent free coagulation bath into carbon fibers that were comparable with the conventional coagulation bath. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Thermal stability of the interface between discharged non-graphitizable carbon and electrolyte for lithium-ion batteries

The thermal stability of a non-graphitizable carbon electrode was studied quantitatively by differential scanning calorimetry (DSC). Charged non-graphitizable carbon electrode powder gave exothermic peaks at around 300 °C and the heat values varied depending on the ratio of the electrode powder to coexisting electrolyte solution. Based on the similarities in the exothermic behaviors of charged graphite and non-graphitizable carbon electrodes, the exothermic reactions at around 300 °C should be assigned to the reductive decomposition of a surface film by charged non-graphitizable carbon. On the other hand, non-graphitizable carbon electrode powder showed exothermic reactions at around 290 °C even at a discharged state, while almost no exothermic heat was seen for a discharged graphite electrode powder at temperatures above 250 °C. The heat values decreased as Li-ions in the non-graphitizable carbon electrode were extracted. Based on the present results and a consideration of the slow diffusion and irreversible trapping of Li-ions in non-graphitizable carbon, Li-ions remaining in non-graphitizable carbon could induce exothermic reactions at around 290 °C, even at a discharged state.     

The effect of kevlar fiber reinforcement on the curing,thermal, and dynamic‐mechanical properties of an epoxy/anhydride system

Curing, thermal, and dynamic‐mechanical relaxational behavior of an epoxy/‐anhydride resin and a Kevlar‐fiber/epoxy composite were compared. Reinforcement by Kevlar fibers had a catalytic effect on the curing reaction. Reinforced formulations produced higher extents of reaction than neat formulations at the same curing time. Curing kinetics was also studied by means of DSC heating scans. When the Kevlar content increased, the heat flow curves and the exothermic peak temperature shifted significantly to lower temperatures. The glass transition temperature of the matrix also decreased as the Kevlar content increased. Postcuring reduced the differences between the neat and reinforced formulations. Loss tangent and storage modulus versus frequency master curves were obtained from isothermal dynamic‐mechanical measurements. The effect of fiber addition on the main dynamic‐mechanical relaxation was analyzed with a simple mechanical model.     

双基发射药和混合硝酸酯发射药的热分解特性

采用C80微热量仪分析了等容条件下初始药量对双基发射药和混合硝酸酯发射药热分解性能的影响.结果表明,随着初始药量的增大,双基发射药的反应放热峰向低温方向移动,混合硝酸酯发射药的反应放热峰位置基本不变;双基发射药单位质量发热量和反应活化能均呈逐渐降低趋势,而混合硝酸酯发射药单位质量发热量和反应活化能保持在一较小范围内基本不变.这种差异由混合硝酸酯发射药中二缩三乙二醇二硝酸酯(TEGDN)分解产生的过量甲醛引起.     

Scale-up concept for modular microstructured reactors based on mixing, heat transfer, and reactor safety

Microstructured reactors are characterized by rapid mixing processes and excellent temperature control of chemical reactions. These properties allow the safe operation of hazardous chemistry in intensified processes. Problems occur during scale-up of these processes, where heat transfer becomes the limiting effect. With high flow rates and transitional or even turbulent flow regimes in small channels, rapid mixing and excellent heat transfer can be maintained up to high production rates. For exothermic reactions, limits for parametric sensitivity and safe operation are shown from literature and combined with convective heat transfer for consistent scale-up. Good knowledge of reaction kinetics, thermodynamics and heat transfer is essential to determine runaway regions for exothermic reactions. From these correlations, consistent channel design and continuous-flow reactor setup is shown.     

流动与非流动测热方式对酶催化反应放热测量的影响

采用微量热仪(Micro DSCⅢ)对鸡肝酯酶催化α-乙酸萘酯水解反应进行了流动与非流动测热方式的对比研究。研究显示,流动测热的流速对反应热测量结果有较大影响,当30μL浓度为120mmol/L的α-乙酸萘酯底物以0.22 mL/min的流速流经0.5 g固定化鸡肝酯酶时,催化反应放出的热量为0.033 J,持续放热时间为495 s;而流速为0.18 mL/min与0.35 mL/min时,测得的放热量分别为0.030 J与0.025 J,持续放热时间分别为625 s与365 s。用与流动测热相同酶活单位的鸡肝酯酶液酶进行非流动测热,所得到目的反应热的量为0.035 J,持续放热时间为800 s。与非流动方式测热相比,流动测热方式的测量灵敏度较高,检测出目的放热量所需时间较短,但不能充分检测出生化反应热总热量。     

Recuperative coupling of exothermic and endothermic reactions

Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the size of the reactors. One type of reactor suitable for such a type of coupling is the heat exchanger reactor. In this work, a one-dimensional pseudo-homogeneous plug flow model is used to analyze and compare the performance of co-current and counter-current heat exchanger reactors. A parametric analysis is carried out to address the vital issues, such as the exit conversion of the endothermic reaction, the temperature peak (hot spot) of the exothermic reaction and the reactor volumetric productivity. The measures to reduce the hot spot by different catalyst profiling techniques are also addressed. Some features of the dynamic behavior exhibited by these reactors, which are important from design, operational and control point of view, are presented.     

活性炭对恩诺沙星吸附的热力学与动力学研究

从热力学和动力学角度,研究了活性炭对水溶液中恩诺沙星的吸附行为。热力学研究表明：活性炭对恩诺沙星的吸附符合Freundlieh等温吸附方程。测得△H=-16．02kJ·mol^-1,说明活性炭对恩诺沙星的吸附过程为放热过程,且IAHI〈20kJ·mol^-1,表明吸附过程为物理吸附。同时测得吉布斯自由能AG〈0,受温度影响不大,表明吸附质从溶液到吸附剂表面的吸附过程是自发过程。动力学研究表明：活性炭对恩诺沙星的吸附更好地符合伪二级动力学描述,测得其表观活化能眈为105．72kJ·mol^-1。     

活性炭对呋喃西林吸附的热力学与动力学研究

文章从热力学和动力学角度,研究了活性炭对水溶液中呋喃西林的吸附行为。热力学研究表明:活性炭对呋喃西林的吸附符合Freundlich等温吸附方程。ΔH=-8.76kJ?moL-1,且|ΔH|40kJ?moL-1,说明该吸附为放热过程且为物理吸附。同时测得吉布斯自由能ΔG0,受温度影响不大,表明吸附质从溶液到吸附剂表面的吸附过程是自发过程。动力学研究表明:活性炭对呋喃西林的吸附更好地符合伪二级动力学描述,测得其表观活化能Ea为9.68kJ?moL-1。