热塑性聚氨酯/碳纳米管湿纺导电纳米复合纤维的应变响应行为研究

采用湿法纺丝工艺制备出了碳纳米管(CNTs,质量分数为10%)/热塑性聚氨酯(TPU)导电纳米复合纤维。该纤维具备良好的电导率(0.64 S/m),高的强度(9.81 MPa)和高的断裂伸长率(487%)。纤维的电阻-应变响应范围为0~325%,其相对电阻(Δ_(R/R0))在该范围内分3个阶段呈指数增长。纤维的电阻-应变循环响应结果出现了肩峰和初始下降的现象,其灵敏度随应变的增大而增大,并且具备优异的耐久性。因此,TPU/CNTs导电纳米复合纤维在柔性应变传感器的应用方面具有很大的潜力。     

高弹性MXene/TPU纳米纤维纱线的制备及其应变传感性能

采用静电纺丝技术制备了热塑性聚氨酯弹性体(TPU)纳米纤维膜,并通过"Biscrolling"的方法制备高弹性过渡金属碳化物/氮化物(Ti_3C_2T_x MXene)改性TPU纳米纤维纱线。通过SEM、电阻测试、传感性能测试等对复合纳米纤维纱线进行结构和性能表征。结果显示,随着MXene负载量的增加,复合纱线的强度先增加后降低,断裂伸长率可达459%以上,展现出优异的弹性和弹性回复性;MXene片可在纳米纤维纱线表面及内部形成连续导电薄膜,赋予复合纱线较好的导电性[电阻(76±16)?/cm]。纱线的应变传感性能测试表明,MXene/TPU纳米纤维纱线的传感系数可高达477.86,线性度高达0.995,高于绝大多数文献报道的纱线传感器,并且在监测人体的各种运动状态上展现出较好的应变传感性能。     

高弹性MXene/TPU纳米纤维纱线的制备及其应变传感性能

采用静电纺丝技术制备了热塑性聚氨酯弹性体(TPU)纳米纤维膜,并通过“Biscrolling”的方法制备高弹性过渡金属碳化物/氮化物（Ti3C2Tx MXene）改性TPU纳米纤维纱线。通过SEM、电阻测试、传感性能测试等对复合纳米纤维纱线进行结构和性能表征。结果显示,随着MXene负载量增加,复合纱线的强度先增加后降低,断裂伸长率可高达459%以上,展现出优异的弹性和弹性回复性;MXene片可在纳米纤维纱线表面及内部形成连续导电薄膜,赋予复合纱线较好的导电性（电阻76 Ω/cm）。纱线的应变传感性能测定实验表明,MXene/TPU纳米纤维纱线的传感系数可高达477.86,线性度高达0.995,高于绝大多数文献报道的纱线传感器,并且可以监测人体的各种运动状态,展现出较好的应变传感性能,在智能可穿戴领域展现出广泛的应用前景。     

石墨烯基聚氨酯复合膜的电及热性能研究

以热塑性聚氨酯为基材,商业石墨烯为导电填料,采用共混法制备柔性复合膜。系统地研究了复合膜的电性能、热性能及红外光热响应和电热响应性能。实验结果表明,复合膜电性能和热性能与热塑性聚氨酯初始质量分数、石墨烯质量分数等密切相关。当TPU初始质量分数为20%且复合膜中石墨烯质量分数为5%时,复合膜的电阻率约为2. 7×10-3Ω·cm,导热系数为0. 298 W/(m·K)。随着复合膜中石墨烯含量增加,复合膜的导电性逐渐增加,但导热系数先增加而后下降。复合膜具有较强的红外光热响应特性,含有石墨烯0. 3%的复合膜在红外光热处理60 s后,膜温升至123. 4℃,明显高于纯聚氨酯膜温度的75. 6℃,但是膜温的变化与石墨烯含量间关系不大。TPU初始质量分数为20%且石墨烯含量分别为3%、4%、5%的复合膜,在0. 3 A电流作用下,50 s内薄膜温度分别可达114、90、68℃,说明复合膜具有较快的电热响应特性。     

HPNGO/TPU复合纳米纤维的制备及其结构与性能研究

以N,N-二甲基甲酰胺(DMF)为溶剂、超支化聚酰胺修饰的氧化石墨烯(HPNGO)和热塑性聚氨酯(TPU)为原料,采用静电纺丝法制备了HPNGO/TPU复合纳米纤维。通过扫描电子显微镜、傅里叶变换红外光谱仪和动态力学分析仪研究了不同添加量的HPNGO对HPNGO/TPU复合纳米纤维的形貌、结构及性能的影响。结果表明:HPNGO/TPU复合纳米纤维直径与HPNGO的添加量成反比关系,纤维拉伸强度和初始模量与HPNGO的添加量成正比关系;当添加HPNGO质量分数(相对TPU)为3%时,HPNGO/TPU复合纳米纤维直径最小,平均直径为0.17μm,拉伸强度和初始模量最大,分别为3.884,0.193 MPa,断裂伸长率最小为170.2%;HPNGO的加入对TPU的分子结构无影响,二者之间为物理复合。     

纺丝液混合方式对电纺CA/TPU复合过滤膜性能的影响

以醋酸纤维素(CA)和热塑性聚氨酯(TPU)为原料,制备了CA/TPU口罩芯层材料,探究CA和TPU纺丝液以混合纺丝、同芯纺丝和偏芯纺丝的方式混合对制备材料的微观形貌、力学性能、润湿性能、孔径和过滤性能的影响.结果表明,3种纤维膜相比较,混合纺丝制备的纤维膜纤维粗细均匀度,力学性能,平均孔径,过滤性能均优于同芯纺丝和偏...     

AgNPs/TPU导电纤维的制备及性能研究

以热塑性聚氨酯(TPU)为弹性纤维基体，三氟乙酸银(C₂AgF₃O₂)为导电银纳米粒子(AgNPs)前驱体，水合肼为还原剂，采用湿法纺丝工艺、原位还原技术及热处理制备AgNPs/TPU导电纤维，研究了水合肼浓度、还原时间、C₂AgF₃O₂含量、热处理对纤维导电性能的影响，并对其微观形貌、化学组成、力学性能、拉伸电阻敏感性进行表征。结果表明：在C₂AgF₃O₂/TPU质量比为1.5：1.0,水合肼质量分数为15%,还原时间为20 min, 120℃热处理30 min的条件下得到的AgNPs/TPU导电纤维具有最佳的导电性能，电导率可达108.9 S/cm; AgNPs/TPU导电纤维微观上呈中空多孔结构，纤维表面被AgNPs均匀覆盖；AgNPs/TPU导电纤维的力学性能相比纯TPU纤维有所降低，断裂伸长率为484%,断裂强度为0.15 cN/dtex;该纤维可在0～70%的应变范围内表现出较为...     

热塑性聚氨酯纳米复合材料的性能研究进展

热塑性聚氨酯（TPU）兼具弹性与刚性,同时也具有较好的生物相容性。通过结合碳纳米纤维、金属纳米颗粒等材料,TPU具有更好的力学特性与热学性质,并且也能获得电学性能、光学性能。文章介绍TPU纳米复合材料的一般结构、特性与制备方法。综述TPU纳米复合材料性能的最新研究进展,主要针对掺杂不同材料对TPU纳米复合材料力学性能与热学性能影响的进行介绍。指出为了进一步提高TPU纳米复合材料的应用价值,可以改进TPU与纳米材料之间的连接或附着方式,也可以引入新的纳米材料。     

静电纺聚氨酯纳米纤维膜的制备及其性能研究

静电纺丝技术是制备纳米纤维膜的一种比较简单而且常用的技术。对静电纺丝技术制备聚氨酯(TPU)纳米纤维膜的最佳纺丝条件进行探索。此外,对制备的TPU纳米纤维膜进行了力学性能和介电性能的表征。结果表明,在纺丝液质量分数为12%、电压20 V、接收距离15 cm、THF与DMF的体积比为5∶1的条件下,制备的TPU纳米纤维膜表面无珠粒、纤维直径均匀,纺丝效果最佳。与纯TPU薄膜进行性能对比,TPU纳米纤维膜的断裂伸长率和拉伸强度远低于纯TPU薄膜,前者的介电常数比后者略低,但是前者的弹性模量低于后者。制备的TPU纳米纤维膜可以应用于气体过滤领域。     

聚氨酯/石墨烯复合纤维的制备及其发泡性能研究

以热塑性聚氨酯(TPU)、单层纳米石墨烯(GR)通过溶液与熔融共混并用的方法制备TPU/GR共混物,利用不同牵引速度纺丝制得不同直径的TPU/GR复合纤维,对其进行超临界二氧化碳微孔发泡,制得发泡TPU/GR复合纤维,探究了GR在TPU中的分散性,纤维尺寸和GR含量对发泡TPU/GR复合纤维泡孔结构及力学性能的影响。结果表明:GR在TPU体系中具有良好的分散形态及较高的二氧化碳气体阻隔性能;当发泡TPU/GR复合纤维直径为200μm时,随着GR含量的增加,纤维的发泡面积逐渐变大,泡孔直径呈现先减少后增加的趋势;对于直径为500μm的发泡TPU/GR复合纤维,随着GR含量的增加,纤维的泡孔直径逐渐变小,泡孔密度逐渐增加,即当加入质量分数为5%的GR,纤维泡孔直径由原来未加GR时的3. 78μm降低至1. 97μm,泡孔密度由原来的未加GR时4. 93×10~9cells/cm~3增加至2. 42×10~(10)cells/cm~3。     

基于硝化纳米纤维素/琼脂的高灵敏度湿度传感器

湿敏材料是决定湿度传感器性能的关键,本研究将具有特殊化学结构的纤维素和琼脂这两种生物质材料有机结合起来,制备具有不同湿度敏感性的硝化纳米纤维素/琼脂（nitrocellulose nanocrystals/Agar,NCNCs/Agar）复合敏感膜材料,基于石英晶体微天平（quartz crystal microbalance,QCM）制备出具有高灵敏度的湿度传感器。结果表明,NCNCs/Agar复合敏感膜修饰的QCM湿度传感器的灵敏度和频率响应值较单一材料敏感膜修饰的QCM均有较明显的提高。经过优化测试,得到NCNCs与琼脂的最佳质量比为1∶25,涂覆2.049μg敏感材料的QCM传感器（QCM-b）性能最优异。在相对湿度（RH）11%~84%下,QCM-b具有良好的线性（R²=0.9933）,灵敏度为32.54Hz/%RH。在RH 11%~97%下,QCM-b响应值可达到-5820Hz,具有优异的对数拟合系数（R²=0.9994）,恢复时间短（5s）,并且具有良好的重现性和长期稳定性,显示出在湿度探测领域的良好应用前景。     

Synthesis and humidity sensitive properties of pyrrole‐based polyelectrolytes

Pyrrole (Py)‐based polyelectrolytes (Py‐PE): P(Py‐COOLi), P(Py‐COONa), and P(Py‐COOK) was synthesized, characterized, and used to prepare thin film resistive humidity sensors. Their humidity sensitive properties have been investigated, and sensing mechanism was presented. The Py‐PE contains PPy as backbone and the side chain bearing carboxylic salt group, which made its sensor exhibited a very wide humidity sensing range of 0–97% relative humidity (RH), high conductivity even at very low humidity, and both ionic and electronic conduction contributed to its conductivity. Among all the Py‐PE, P(Py‐COOK) showed high sensitivity, with the impedance changing of about three orders of magnitude (10³–10⁶ Ω) from 97 to 0% RH, whereas P(Py‐COONa) showed quick response for both absorption (12.5 s) and desorption (15.2 s). Py‐PE prepared is promising for preparation of thin film resistive humidity sensors capable of detecting low humidity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

无铅铜基钙钛矿Cs2CuBr4的湿度传感性能

铅卤钙钛矿因其优异的光电性能引起了人们的极大关注,但由于其内在的不稳定性以及铅的毒性问题,限制了其实际应用。本文制得一种性能较稳定的无铅铜基钙钛矿Cs₂CuBr₄,利用其对湿度较为敏感的特性,创制了基于Cs₂CuBr₄敏感膜的石英晶体微天平（quartz crystal microbalance, QCM）湿度传感器。结果表明,当钙钛矿溶液的浓度小于0.4μg/μL时,敏感膜在11%~84%相对湿度下具有良好的湿度传感性能。其中最优浓度为0.3μg/μL（QCM-3）、薄膜质量398.95ng时,传感器具有高灵敏度（37.65Hz/% RH）,优异的对数线性关系（R²=0.9948）和快速的响应/恢复时间（5s/1s）。由此可见,无铅铜基钙钛矿Cs₂CuBr₄在湿度传感领域具有良好的应用前景。     

Hyperbranched polycarboxylates and their nanocomposites with ZnO: Investigations on the humidity‐sensitive properties

Hyperbranched polycarboxylates (HBPC) with different alkali metal cations (Li⁺, Na⁺, and K⁺) were prepared and characterized by ¹H‐NMR and thermal gravimetric analysis. Thin film humidity sensors based on HBPC and its composite with ZnO nanorods were fabricated. The morphologies of films of HBPC and the nanocomposite were investigated by atomic force microscopy, which revealed uniform distribution of ZnO nanorods in HBPC. The humidity‐sensitive characteristics of HBPC and the nanocomposite were investigated at room temperature. It was found that the type of cations significantly affected the humidity‐sensing behaviors of HBPC. In addition, the nanocomposite exhibited better humidity‐sensitive properties than HBPC alone. Its impedance decreased for about three orders of magnitude over the range 19–97% RH, showing high sensitivity. Moreover, the nanocomposite exhibited fast response (～ 9 and 10 s for response and recovery time between 97% RH and 33% RH, respectively) and small hysteresis (～ 1.4% RH). The improved humidity‐sensing behaviors of the nanocomposite over HPBC alone is explained by taking into account the hyperbranched structure of the polymer and the special interactions of the polymer and ZnO with water molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Humidity‐sensitive properties of new polyelectrolytes based on the copolymers containing phosphonium salt and phosphine function

A simple strategy was developed based on a new reactive function‐ and a salt‐containing new monomer, 4‐vinylbenzyl dimethyl 2‐(dimethylphosphino)ethyl phosphonium chloride (VDEPC), to obtain stable humidity‐sensitive membranes. The major ingredient of a humid membrane is crosslinked polyelectrolytes obtained from copolymers of VDEPC/2‐ethylhexyl acrylate (2‐EHA) = 1/0, 4/1, and 2/1. Isothermal humidity absorption experiments were performed for the estimation of humidity‐sensing materials. The crosslinked copolymers prepared from the reaction of VDEPC/2‐EHA = 4/1 with 1,4‐dichlorobutane showed an average impedance of 595, 39.1, and 3.9 KΩ at 30, 60, and 90% RH, respectively. Their hysteresis, temperature dependence, frequency dependence, and response time were measured. The reliability including water resistance and a long‐term stability were estimated for the application of the common humidity sensor. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1062–1070, 2003     

Effect of solvent quality and humidity on the porous formation and oil absorbency of SAN electrospun nanofibers

In this study, nanofibrous mat with high oil sorption capability was prepared via one‐step electrospinning process without any further post‐treatments. For this purpose, the fabrication of styrene/acrylonitrile copolymer nanofibers was carried out using various dimethylformamide (DMF)/tetrahydrofuran and DMF/ethanol (DMF/EtOH) binary mixture ratios in an electrospining atmosphere with various relative humidity (RH) levels. Scanning electron microscope micrographs showed that DMF/tetrahydrofuran and DMF/EtOH ratio and RH value could considerably affect the diameter, surface, and interior morphology of the resultant nanofibers. The nanofiber morphology was dependent upon the polymer/solvent(s)/water ternary phase diagram behavior. In overall, the partial hydrophilicity of styrene/acrylonitrile copolymer resulted in electrospun nanofibers with wrinkled surface. In addition, the incorporation of nonsolvent in the spinning solution and using high RH atmosphere forced the polymeric solution jet to intensively phase separate and, therefore, produce the nanofibers with highly interior porous structure during drying process. The maximal capacity and rate of oil sorption (170 g/g) was observed for the nanofibrous mat prepared using EtOH/DMF (2/3: vol/vol) and RH value of 60% showing the highest internal porosity. The results showed that the oil sorption capability and mechanical strength of the fibrous mat are strongly dependent on nanofibers diameter and porous structure, which can be controlled through adjusting the RH and spinning solvent quality. The electrospun mat with highest Young's modulus (7.68 MPa) was prepared using EtOH/DMF (2/3) binary mixture and RH value of 45%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45586.     

High performance and moisture stable humidity sensors based on polyvinylidene fluoride nanofibers by improving electric conductivity

Polyvinylidene fluoride (PVDF)‐based nanofiber was successfully produced for a high performance and stable humidity sensor via a solution‐blowing spinning method. The performances of the manufactured sensors, including the impedance change with relative humidity (RH), moisture stability, and response and recovery times, were investigated. To improve charge carrier transfer, which is the main mechanism of humidity sensing, especially under low RH conditions, lithium chloride was used and displayed the best linearity in the impedance change with RH. Fast response and recovery times of 1.7 and 16.1 s were, respectively, achieved with zinc oxide nanoparticles. Furthermore, the sensors showed excellent moisture stability, owing to the hydrophobicity of PVDF, and this was demonstrated via repeatability testing and scanning electron microscopy. The humidity sensing mechanism was discussed using complex impedance spectra. POLYM. ENG. SCI., 59:304–310, 2019. © 2018 Society of Plastics Engineers     

Mn‐Loaded Mesoporous Silica Nanocomposite: A Highly Efficient Humidity Sensor

We report a relative humidity sensor based on manganese‐nanoparticle‐loaded mesoporous silica SBA‐15 using a facile hydrothermal route. The as‐developed nanocomposite material (Mn/SBA‐15) possesses a high surface area and a high pore volume. The obtained samples were characterized by using low‐angle X‐ray Diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), N₂ adsorption–desorption, high‐resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and energy‐dispersive X‐ray (EDX) spectroscopy techniques. The Mn/SBA‐15 exhibited, improved humidity response and recovery time as compared to pure SBA‐15 in the 11%–92% RH range. Optimal results were obtained for the 5 wt% Mn‐loaded SBA‐15 sample, which displayed excellent linearity, low hysteresis, and high humidity response. A change in ~5 orders of magnitude in resistance was observed over 11%–92% RH range. The investigation of humidity sensing properties of Mn/SBA‐15 nanocomposite shows that this material has good prospects as humidity sensor.     

A Novel Highly Sensitive Humidity Sensor Based on ZnO/SBA‐15 Hybrid Nanocomposite

This work deals with the study of hydrothermally synthesized zinc oxide (ZnO) loaded mesoporous SBA‐15 hybrid nanocomposite for relative humidity sensing (RH) at room temperature. The sensor exhibits an excellent ~5 orders impedance change along with excellent linearity, quick response time (17 s), rapid recovery time (18 s), negligible hysteresis (1.2%), good repeatability, and stability (1.8%) in 11%–98% RH range. In addition, complex impedance spectra of the sensor at different RHs were analyzed to understand the humidity sensing mechanism. Our study can open a new way for realizing ZnO/SBA‐15 hybrid nanocomposite for fabrication of high‐performance RH sensors.     

A comparative quality study and energy saving on intermittent heat pump drying of Malaysian edible bird’s nest

This paper aims to study the influence of temperature and relative humidity (RH) during intermittent heat pump drying at 28.6–40.6°C, 16.2–26.7% RH, α?=?0.2–1.0, and the comparison was made against fan drying (27°C, 39.7% RH, α?=?1.00). It was observed that the effects of temperature and RH on drying rate were significant when moisture content was high. Experimental results showed that intermittent heat pump drying at 28.6°C, 26.7% RH, α?=?0.2 of edible bird’s nest greatly reduced effective drying time by 84.2% and color change compared to fan drying, and retained the good energy efficiency.