超声辐射对PVA/CB导电复合材料气敏性能的影响

以聚乙烯醇(PVA)为基体,填充各种类型炭黑导电粒子,制备了导电复合薄膜。研究了超声作用下导电复合薄膜在不同溶剂蒸气中的气敏性能。考察了PVA与炭黑的比例、炭黑种类、超声时间、超声功率等条件对导电薄膜响应性能与响应稳定性的影响,并对这种导电复合薄膜产生气敏响应性的机理作了分析。结果表明,以PVA/乙炔炭黑组成的导电复合薄膜具有较强气敏响应性。当将其置于丙酮、正丁醇、乙醇、水极性溶剂中,电阻急剧提高102~103倍,表现为正蒸气系数效应(PVC);随炭黑含量提高,复合材料薄膜室温电阻下降,对溶剂蒸气的响应强度提高;超声时间、功率对导电粒子分散行为及复合材料的气敏性有影响,随超声时间延长及功率增大,接枝改性效果明显,导电薄膜的响应性及重复稳定性提高。     

新型聚合物基气敏传感器用导电材料研究进展

按复合材料型传感器、杂合材料型传感器和传感器阵列分类,综述了新型炭黑(CB)填充聚合物气敏传感器用导电材料的研究进展,描述了这种传感材料的气敏响应性能,讨论了影响材料气敏性能的一些因素,并对材料的响应机理作了初步探讨。     

PVA/石榴皮粉复合薄膜的制备及性能研究

以聚乙烯醇(PVA)为基材、石榴皮粉为填充材料,采用溶液共混的方法制备了不同石榴皮粉含量的PVA/石榴皮粉复合薄膜。通过扫描电子显微镜(SEM)、红外光谱、紫外可见光谱、力学性能测试、水蒸气透过率测试、热重差热分析等手段考察了石榴皮粉含量对PVA复合薄膜性能的影响。结果表明:石榴皮粉与PVA相容性良好,与纯PVA薄膜相比,PVA/石榴皮粉复合薄膜的热稳定性显著增强,并表现出优异的紫外光阻隔性能,同时,随着石榴皮粉含量的增加,复合薄膜的水蒸气透过率提高,脆性增大。     

CB/PLA与CB/RF/PLA导电高分子复合材料气敏性能对比

通过熔融共混法制备了炭黑(CB聚乳酸(PLA和CB/苎麻纤维(RFPLA导电高分子复合材料(CPCs。扫描电镜(SEM观察发现导电填料在CB/PLA中分散良好。通过预混合的方法,可以先使CB和PLA良好接触,随后的熔融加工过程中,CB/RF/PLA中CB粒子分布在RF附近,这种纤维搭接的CPCs逾渗值比CB/PLA更低。气敏测试对比研究发现,含RF的导电复合材料在不良溶剂中响应度高,重复性好;在良溶剂中,响应时间长,气敏稳定性好。为制备逾渗值低,气敏性能优良的可降解CPCs提供了新思路。     

PVP与PVA对原位聚合导电聚苯胺薄膜的影响

分别以水溶性高分子聚乙烯吡咯烷酮(PVP)和聚乙烯醇(PVA)为稳定剂,采用苯胺的分散聚合体系,在玻璃基片上原位沉积了表面光滑均匀、亚微米厚度的导电聚苯胺薄膜,改善了导电聚苯胺的加工性能。研究了薄膜的形貌、厚度及电导率。结果表明:聚苯胺薄膜表面光滑,黏附一些胶体粒子,以PVP为稳定剂制备的聚苯胺薄膜表观质量好于以PVA为稳定剂得到的聚苯胺薄膜,表面更加光洁致密;不同稳定剂影响聚苯胺薄膜厚度及性能,在其他实验条件相同的情况下,以PVA为稳定剂制备的聚苯胺薄膜厚度及电导率均高于以PVP为稳定剂制备的聚苯胺薄膜厚度和电导率。     

CB-g-WPU/WPU复合材料的制备与气敏响应性能

通过对导电填料炭黑（CB）进行官能化，在CB表面引入羧基官能团，利用CB表面的羧基等活性官能团与端异氰酸酯基聚氨酯预聚物反应得炭黑接枝水性聚氨酯（CB-g-WPU），采用乳液共混法制备得CB—g-WPU／WPU气敏导电复合材料，并对CB—g-WPU／WPU复合材料的气敏响应行为进行了研究。X射线光电能谱（XPS）、傅立叶变换红外光谱（FTIR）、热重分析（TGA）等分析结果表明聚氨酯接枝到了炭黑表面；SEM分析表明，炭黑经过接枝改性后均匀分散在基体WPU中。该法制备的CB—g-WPU／WPU复合材料逾渗值低、气敏响应度大、响应范围广，是一种综合性能优异的气敏导电复合材料。     

改性水滑石/聚乙烯醇复合膜的制备及性能

采用焙烧复原法将山梨酸(SA)插入水滑石(LDH)层间合成了纳米插层材料SA-LDH,将其与聚乙烯醇(PVA)共混,通过溶液流延法制备得到复合薄膜SA-LDH/PVA。采用傅里叶变换红外光谱(FT-IR)、X-射线衍射(XRD)、热重-差热分析(TG-DSC)和扫描电镜(SEM)对其结构、热稳定性以及形貌进行表征,并测试了复合薄膜的力学性能、溶胀率、溶解率和抑菌性能。结果表明:复合薄膜SA-LDH/PVA中SA-LDH含量为5 wt%时得到的LDH晶型最为完整,对应的SA-LDH片层在PVA薄膜中分散比较均匀;添加3 wt%SA-LDH可提高PVA膜的热稳定性;SA-LDH添加量为5 wt%和7 wt%时,提高了复合膜的抗拉性能和断裂伸长率;SA-LDH的添加提高了PVA膜的耐水性能;SA-LDH的添加量分别为5 wt%和6 wt%时,SA-LDH/PVA复合薄膜对金黄色葡萄球菌和大肠杆菌的抑菌效果最佳。制备的改性水滑石/聚乙烯醇复合抑菌膜,为食品包装领域提供一种广谱的抑菌材料。     

取向微孔结构的PVA/CB导电复合材料对流动有机蒸汽的响应行为

通过定向冷冻干燥法,制备了取向微孔结构的导电聚乙烯醇/炭黑(PVA/CB)复合材料。研究分析了该导电复合材料的微观结构、逾渗行为及其对有机蒸汽的响应行为。结果表明:大量的CB聚集体不均匀地分布在该PVA/CB复合材料的微孔壁上,并且孔壁之间的CB搭接成较完善的导电通路,通过计算可得出该导电复合材料的逾渗阈值为16.9%;该PVA/CB复合材料在流动的四氢呋喃(THF)、丙酮、丁酮和苯蒸汽中的最大响应率分别为204、183、95、44,其响应率的不同是由于这4种有机蒸汽对PVA基体具有不同的溶胀效果。     

聚酰亚胺/聚苯胺/炭黑抗静电复合薄膜的制备与表征

采用原位复合的方法制备抗静电聚酰亚胺(PI)复合薄膜,以导电炭黑（CB）和聚苯胺（PANI）作为导电改性剂,研究了不同配比下CB与PANI对复合薄膜电性能的影响,通过扫描电子显微镜观察其形貌,同时对材料的热稳定性和力学性能进行分析。结果表明,混合填料填充的复合薄膜粒子间的分散性优于单独加入CB或PANI体系;当PANI和CB比为1∶2时表面电阻达到抗静电的要求且热稳定性最好。     

表面活性剂对聚乙烯醇基薄膜透光性及机理的影响

针对聚乙烯醇（PVA）与表面活性剂能组成复配体系,制备了聚乙烯醇基亲水性薄膜材料,研究了表面活性剂的掺量对聚乙烯醇基薄膜的微观结构、孔隙度、透光性能、PVA结晶度及晶粒尺寸的影响。采用紫外分光光度计考察了各薄膜的透光性;采用扫描电子显微镜观察了聚乙烯醇/表面活性剂的横截面微观结构;采用X射线衍射仪考察了不同表面活性剂的添加量对复合薄膜的晶相组成及PVA晶粒尺寸的影响,结果表明当表面活性剂添加量在6%~10%（质量分数,下同）时,阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）明显地降低聚乙烯醇的结晶度,而阴离子表面活性剂十二烷基苯磺酸钠（SDBS）则没有此效果;CTAB的加入使聚乙烯醇/CTAB体系中PVA晶粒尺寸增大,SDBS的加入使聚乙烯醇/SDBS体系中PVA晶粒尺寸减小。最后对聚乙烯醇与表面活性剂相互作用机理示意图进行了预测。     

炭黑/水性聚氨酯复合材料的制备与气敏性能研究

在环境友好的水性聚氨酯（WPU）基体乳化前加入导电填料炭黑（CB），制备了CB／WPU气敏复合材料，并研究了其气敏响应和吸收行为。研究表明，CB／WPU复合材料对有机溶剂蒸气的吸收量与气敏响应度之间没有定量关系，气敏响应时间要比吸收平衡时间小得多，当吸收尚未达到平衡时，复合材料的电阻早已达到最大值。气敏响应度的大小与有机溶剂的溶度参数尤其极性分量有关，基体和溶剂的总溶度参数相差越小，气敏响应度越大。     

High performance carbon nanotube based composite film from layer-by-layer deposition

So far, preparation of strong carbon nanotube (CNT)/polymer composites still faces big challenges mainly due to the limited controls of CNT dispersion and alignment in polymers. Here, a new “layer-by-layer deposition” method is put forward to prepare CNT/polyvinyl alcohol (PVA) composite films. This is based on intermittent deposition of aligned CNT and PVA layers on a paper tape substrate. The in situ deposition allows PVA to infiltrate into the CNT film efficiently, and, as a result, the mechanical property of CNT/PVA composite film has been improved remarkably. For example, the composite film possesses a tensile strength of 1.7 GPa, which is almost one order of magnitude and 20 times higher than those of the pure CNT and PVA films, respectively. The high performance of the composite film could be ascribed to the role of PVA infiltration, which leads to not only the formation of strong interfacial bonding between CNTs and PVA matrix but also the reduction of film thickness. The novel process offers a new research direction for preparing CNT-based composites and future performance maximization.     

Experimental investigation on the role of PVA in eliminating inhibition phenomenon of carbon black during the synthesis of polystyrene/carbon black composite particles

In this study, the role of polyvinyl alcohol (PVA) in eliminating the inhibition phenomenon of modified light‐weight carbon black (CB) during the synthesis of polystyrene/modified light‐weight carbon black (PS/MLCB) composite particles was examined. It was interesting to note that the polymerization time was largely shortened in the presence of a certain PVA. And the effect of PVA dosage on the polymerization time and the macromorphology of obtained PS/MLCB composite particles were systematically investigated, as well as the correlation between PVA dosage, polymerization time, and MLCB content. In addition, the potential mechanism about the role of PVA in eliminating the inhibition phenomenon of MLCB during the suspension polymerization of styrene was also proposed and analyzed in detail. The PS/MLCB composites particles were studied in terms of surface morphology, thermal stability, and molecular weight. Scanning electron microscopy images of the resulting PS/MLCB composite particles demonstrated that CB was well dispersed in the PS matrix. And the thermal stability of obtained PS/MLCB composite particles was significantly enhanced with the incorporation of MLCB, and increased with the increasing content of MLCB. This synthesis technique brought about a promising future in the large‐scale production of black expandable polystyrene. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Surface modification of carbon black to facilitate suspension polymerization of styrene and carbon black

To carry out suspension polymerization of styrene in the presence of carbon black, an effective method was introduced to modify carbon black using nitric acid for oxygen treatment. The surface modification of carbon black with oxidation was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy (SEM), which demonstrated that the chemical structure of carbon black has clearly changed. Compared with pristine carbon black (CB), SEM illustrates that the aggregation phenomenon of modified carbon black (MCB) was clearly weakened. After modification, the aggregation and inhibition effects of MCB on the polymerization of polystyrene/modified CB (PS/MCB) composite particles are obviously weakened. The lipophilicity of CB after modification was also increased during the synthesis of PS/MCB. The oxidized CB was successfully dispersed by polystyrene using in situ suspension polymerization. The dispersion and dosage of MCB in PS/MCB composite particles was greatly improved over that of CB in PS/CB composite particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46387.     

炭黑/环氧树脂复合材料导电行为的研究

分别采用不同的混合分散方法制备炭黑/环氧树脂(CB/EP)复合材料(CB牌号为F101、XE2,EP牌号为E-54、E-51和E-44),研究了制备工艺、CB用量和CB结构等对复合材料导电性能的影响。结果表明:不同方法制得的复合材料体积电阻率的大小依次为机械混炼法离心混合法超声分散法;CB/EP复合材料的导电性能随CB用量增加而显著提高,并且F101/E-54、XE2/E-54复合材料体系均表现出明显的导电渗流行为;CB结构对复合材料的导电性能影响较大,F101/E-54、XE2/E-54复合材料体系的导电渗流阈值分别为3.85%、0.47%。     

炭黑/环氧树脂复合材料阻温特性研究

分别以低结构炭黑(F101)和高结构导电炭黑(XE2)作为导电填料,不同牌号(E-54,E-51和E-44)的环氧树脂(EP)作为基体树脂,采用超声分散溶液混合法制备了炭黑/环氧树脂(CB/EP)复合材料.研究了CB结构、CB含量和EP基体等对复合材料正温度因数(PTC)效应的影响.结果表明:F101/EP复合材料具有...     

Using a conductive sphere as a probe to characterize the sensitivity of soft piezoresistive films

Flexible piezoresistive films, such as, carbon black/polydimethylsiloxane (C-PDMS) composites, are often used as skin analogs and integrated into complex array sensors for tactile sensing. The uniformity of the sensor characteristics heavily depends on the homogeneity of the composite. Therefore, the ability to locally characterize a film that will be integrated into a complex force sensor could be critical. Here, a method to characterize the local sensitivity of flexible piezoresistive films is presented. Using a conductive sphere, which was chosen over a flat probe to eliminate misalignment issues, the surface of a thin film composite is indented to characterize the change in resistivity in terms of average strain. Experiments were performed with 15 and 18 wt% carbon black C-PDMS films of varying thickness. The contact radius of the probe with the piezoresistive film was estimated using the Johnson-Roberts-Kendall contact theory. Theoretical contact area estimates were found to agree with contact radius measurements carried out using optically transparent PDMS films observed through an optical microscope. Results show that C-PDMS with 15 wt% carbon black exhibit a higher rate if change of resistivity and gauge factor than films of same thickness with 18 wt% carbon black. On the other hand, thicker films exhibit higher gauge factors for the two tested carbon black contents. Tests carried out at multiple locations yielded consistent sensitivity values, making these types of composites suitable for array type force sensors.