废旧棉纤维纸基地膜的制备及强度性能研究

以废旧棉纤维为主要原料,加入一定量废纸,并添加助剂制备一种新型的易降解纸基地膜。研究了棉纤维打浆度、各种助剂和废纸用量对地膜性能的影响。结果表明:制备该新型纸基地膜的最佳工艺条件为85%棉纤维打浆度60°SR,废纸浆5%,水溶性PVA纤维10%,阳离子淀粉1.3%,阳离子壳聚糖0.1%,阳离子聚丙烯酰胺0.7%,羟丙基瓜尔胶0.2%,聚酰胺环氧树脂的0.6%;该条件下制得的新型纸质地膜材料强度性能良好,抗张指数为42.7N·m~2/g,撕裂指数为67.1mN·m~2/g,湿强保留率达49.4%,符合地膜材料的应用要求。     

分散剂对石墨水悬浮液分散性能的影响

通过测定分散体系的吸光度,探讨不同浓度的各种分散剂对石墨水悬浮液分散性能的影响,其中添加含有阴离子型、非离子型和高分子表面活性剂的三种复配分散剂(SGDF1、SGDF2、SGDF3)的石墨水悬浮液分散效果较好。进一步研究在复配分散剂存在下,pH值、静置时间对石墨水悬浮液性能的影响。结果表明,当pH值大于7后,石墨水悬浮液的分散能力维持在较高水平,pH值为9时,Zeta电位绝对值最高,吸光度最大,分散体系稳定性最好。添加分散剂的石墨较未添加分散剂的石墨聚集程度明显减弱,分散性能变好。其中添加SGDF3的石墨水悬浮液的石墨的聚集程度最小,分散稳定最佳。     

具有高分散稳定性的磷酸锆悬浮液的液固相变循环性能

由于纳米颗粒有聚集和沉降的倾向,纳米悬浮液作为一种相变材料,其液固相变循环稳定性与其冷冻/熔化性能一样重要,然而相关研究却很少。本研究将具有高分散稳定性的磷酸锆(ZrP)碟片悬浮液作为一种新型相变材料,并将其冷冻/熔化性能和循环稳定性与水和石墨烯纳米悬浮液进行比较。实验结果表明:所有样品的过冷度随着冷冻/熔化循环次数的增加而减少;在相同次数的冷冻/熔化循环中,ZrP和石墨烯纳米悬浮液的过冷度比水低,且粒子浓度较大的纳米悬浮液过冷度较小。分析表明,ZrP和石墨烯纳米片和冰晶均可诱导纳米悬浮液中的成核。与石墨烯纳米悬浮液相比,ZrP纳米悬浮液的过冷度在粒子质量浓度为0.1%时较大,但在质量浓度为1.0%时较小。比较两种纳米悬浮液经过冷冻/熔化循环后的分散稳定性,结果表明,与石墨烯纳米悬浮液相比,ZrP纳米悬浮液具有更好的液固相变循环稳定性,因而能更有效减小过冷度。     

热压温度对芳纶1414纤维/1313浆粕复合纸微区结合特征的影响

针对国产间位芳纶纸力学性能不足的问题,采用芳纶1414(聚对苯二甲酰对苯二胺)短切纤维与芳纶1313(聚间苯二甲酰间苯二胺)浆粕复合,制备芳纶1414纤维/1313浆粕复合纸,研究不同温度下芳纶1414纤维/1313浆粕复合原纸的热压性能,分析纸张的强度性能;采用SEM、压汞仪和FTIR研究芳纶1414纤维/1313浆粕复合纸的内部结构变化。阐述热压温度对芳纶1414纤维/1313浆粕复合纸热压过程中短切纤维与浆粕之间的相互作用以及微区结合特征的影响。结果表明:芳纶1414纤维/1313浆粕复合纸在热压温度为280℃、热压时间为6min、热压压力为15 MPa条件下,短切纤维与浆粕之间黏结状态良好,自制芳纶1414纤维/1313浆粕复合纸孔隙率为23.21%,其抗张指数最大值为212.2N·m·g~(-1),为Nomex T410纸强度的两倍。FTIR结果表明,随着热压温度的升高,纸张中未形成新的化学键,芳纶分子间氢键缔合程度明显增大,是芳纶1414纤维/1313浆粕复合纸强度提高的主要原因。     

航空发动机用聚酰亚胺树脂基复合材料衬套研究进展

综述了航空发动机用聚酰亚胺树脂基复合材料衬套的特性及其研究进展与应用现状,重点介绍了石墨填充复合材料衬套、纤维编织增强复合材料衬套及短切纤维增强复合材料衬套的制备技术、性能特点与应用发展,指出低成本、连续化生产、耐高温及长使用寿命是未来航空发动机聚酰亚胺树脂基复合材料衬套及其材料体系的主要发展方向。     

短切石英纤维/聚酰亚胺复合材料的制备与性能

采用湿法混合工艺制备了短切石英纤维增强的PMR 型聚酰亚胺复合材料模塑粉, 使用热模压一次成型技术制备了聚酰亚胺树脂基复合材料, 对复合材料的性能进行了系统研究。研究结果表明: 短切石英纤维增强的复合材料具有优异的热性能和良好的力学性能, 纤维含量对复合材料玻璃化转变温度和热失重温度影响不大,对材料的力学性能影响显著。复合材料具有优异的介电性能, 在1 kHz～18 GHz 宽频范围内具有稳定的介电常数和介电损耗。      

一种新型短切碳纤维增强纸基摩擦材料研究

以短切碳纤维为增强纤维,采用湿法工艺研制成功一种新型无石棉纸基摩擦材料,采用TG-DTA热分析方法、定速摩擦试验和惯量摩擦研究了摩擦材料耐热性能、摩擦性能和磨损性能.试验结果表明,新研制的炭纤维增强纸基摩擦材料的起始分解温度和失重速率等耐热性能指标优良,动摩擦系数高达0.136～0.149,且摩擦系数稳定,磨损率低,是一种理想的新型无石棉纸基摩擦材料.     

纳米Al2O3在水相体系中的分散稳定性研究

主要研究了pH值、分散剂（SDBS、CTAB、GA）种类和分散剂的浓度对纳米Al2O3在水相体系中进行分散时的影响。实验结果表明：pH值在8左右，SDBS、GA作为分散剂时，纳米Al2O3悬浮液的Zeta电位绝对值较大，粒径较小；在pH值为2～3，CTAB作为分散剂时，Al2O3纳米悬浮液的Zeta电位绝对值较大，粒径较小。比较3种分散剂的分散效果，其中在pH为8左右，SDBS作为分散荆时，纳米氧化铝悬浮液的Zeta电位绝对值最大，粒径最小。在此基础上又讨论了最佳分散剂SDBS的浓度对纳米氧化铝悬浮液的影响，当SDBS分散剂的浓度为0.055％左右时，纳米Al2O3在水相体系中稳定分散性较好。     

导电短纤维分散性对其吸波性能的影响

通过电磁场仿真和实验,研究了导电短纤维的分散性对其吸波性能的影响。仿真结果表明,对于单根纤维,电磁波电场平行纤维极化时的电磁损耗明显大于垂直纤维极化时的损耗;对于多根平行纤维,随着纤维间距变小、团聚程度增加,其电磁损耗明显降低。采用模压成型工艺分别制备了短切碳纤维具有不同分散状态的树脂基复合材料层板,并进行了反射率测试。实验结果表明,短切碳纤维分散均匀性差层板试样,其吸波性能较差;而利用特殊工艺获得的短切碳纤维均匀分散的层板具有优异的吸波性能。     

碳纳米管/纤维素纤维复合纸及其电磁屏蔽性能研究

研究了以碳纳米管(CNTs)作为导电剂纤维素纤维为基体的复合纸的制备工艺和电磁屏蔽性能。通过使用球磨、超声、剪切和磁力搅拌等多种分散工艺制得CNTs/纤维素纤维复合纸,研究了不同分散工艺对复合纸性能的影响,并确定最佳制备工艺。采用扫描电镜(SEM)、透射电镜(TEM)和X-射线衍射(XRD)对CNTs检测检测。采用四探针电阻仪、矢量网络分析仪对CNTs/纤维素纤维复合纸进行性能检测。研究结果表明,球磨与剪切复合工艺制得的CNTs/纤维素纤维复合纸电导率达到47.35S/m,电磁屏蔽效能最高,为18~22.5dB,具有较好的性能。     

短切聚酰亚胺纤维增强可瓷化三元乙丙橡胶复合材料的制备与性能

以三元乙丙橡胶(EPDM)为基体,高岭土(Kaolin)和滑石粉(Talc)为功能填料,Al(OH)_3为阻燃剂,短切聚酰亚胺纤维(PI Fiber)为增强材料,制备了不同PI纤维含量的可瓷化PI Fiber-Kaolin-Talc-Al(OH)3/EPDM(PKTA/EPDM)复合材料。研究了短切PI纤维对复合材料拉伸性能、热稳定性和微观形貌的影响,分析了短切PI纤维增强复合材料的陶瓷化机制。研究表明,短切PI纤维含量增加会导致可瓷化PKTA/EPDM复合材料拉伸性能下降,当纤维含量与EPDM质量比低于10∶100时,复合材料力学性能良好。可瓷化PKTA/EPDM复合材料在800~1 100℃热解后均发生陶瓷化反应。当PI纤维与EPDM质量比为4∶100~8∶100时,可以有效保持复合材料高温热解后的形状尺寸稳定,并且热解产物弯曲强度在6~18 MPa之间。热分析结果表明,加入PI纤维可以提高可瓷化PKTA/EPDM复合材料的热稳定性。结合热分析和断面SEM分析表明,PI纤维热解、炭化后贯穿在EPDM裂解后的炭层中形成纤维增强炭层结构。这种纤维增强结构在复合材料热解过程中有助于获得尺寸稳定、形状完整的陶瓷产物。     

石墨烯包覆玻璃纤维复合材料的制备及其电学性能研究

以牛血清白蛋白(BSA)改性玻璃纤维表面, 利用静电吸附原理制备氧化石墨包覆的玻璃纤维复合材料, 采用氢碘酸还原氧化石墨得到石墨烯包覆玻璃纤维导电材料。利用X射线衍射(XRD)和傅立叶变换红外光谱仪(FT-IR)等表征样品的物相结构和基团类型, 扫描电镜(SEM)表征石墨烯包覆玻璃纤维的形貌特征。当氧化石墨分散液pH低于6时, 随着pH减小, 包覆效果变得更明显。通过粒径/Zeta电位仪表征氧化石墨和BSA在不同pH下的Zeta电位, 结果表明BSA等电点约为5.3, 氧化石墨的等电点小于3。得到的石墨烯包覆玻璃纤维导电材料的电导率达到4.5 S/m, 制备的导电玻璃纤维具有一定的柔性, 在弯曲后仍能保持原有的导电性能; 导电玻璃纤维在高于100℃热处理后, 由于石墨烯在高温下可以继续还原, 其电导率得到一定的提高, 表明制备的导电玻璃纤维可以在较高温度下使用。     

Modelling of inter-laminar toughening from chopped Kevlar fibers

Inter-laminar toughening from sparsely distributed chopped fibers is analyzed in this paper. A detailed micromechanical model describing the special toughening effects of those chopped Kevlar fibers lying within the delamination plane has been developed. To determine bridging forces of the Kevlar fibers lying in the matrix near a delamination-crack face, a simplified model based on coupling of matrix spalling (matrix fracture following by separation of fiber away from the matrix) and fiber pull-out is proposed. The model is then used to study toughening of carbon-fiber/epoxy composite laminates with chopped Kevlar fibers. The model shows that the energy dissipation in the pull-out process of chopped Kevlar fibers is much more than that in the matrix spalling process. The numerical results indicate that interfacial properties, interactions among Kevlar fibers and percentage of Kevlar fibers involved in crack bridging play important roles in delamination toughening. The modelling results are in good agreement with the experimental results available in the literature.     

短切碳纤维/乙烯基酯树脂片状模塑料拉伸性能的有限元模拟

采用Python语言对ABAQUS软件进行二次开发,生成了短切碳纤维在乙烯基酯树脂中随机分布的二维平面应变模型,建立代表性体积单元（RVE）,通过Hypermesh对模型进行网格划分,为保证RVE应力场的均匀协调性,在周期性边界条件下,对短切碳纤维/乙烯基树脂进行拉伸性能数值模拟计算分析,并结合实验研究了短切碳纤维长度对片状模塑料拉伸性能的影响。结果验证了对短切碳纤维/乙烯基树脂片状模塑料拉伸模量随纤维长度的增大出现先增大后变缓的趋势,表明利用Python-ABAQUS建立二维平面应变RVE模型的合理性。本研究为短切碳纤维/乙烯基树脂片状模塑料在汽车轻量化行业的应用提供了理论及实验依据。      

A Comparative Investigation of the Tribological Behavior of Short Fiber Reinforced Polyimide Composites Under Dry Sliding and Water-Lubricated Condition

The friction and wear behavior of high performance polyimide (PI) and its composites reinforced with short cut fibers such as carbon fiber, glass fiber and quartz fiber was comparatively evaluated under dry sliding and water-lubricated condition, aiming at selecting matching materials for the pumps of pure water power transmission. The wear mechanisms of the composites under the two different sliding conditions were also comparatively discussed, based on scanning electron microscopic examination of the worn composite and steel counterpart surfaces. As the results, the PI composites reinforced with carbon fiber have the best mechanical and tribological properties compared with glass fiber and quartz fiber. PI composites sliding against stainless steel register lower friction coefficients and wear rates under water-lubricated condition than under dry sliding though the transfer of PI and its composites was considerably hindered in this case. PI and its composites are characterized by plastic deformation, micro cracking, and spalling under both dry-and water-lubricated sliding. Such plastic deformation, micro cracking, and spalling is significantly abated under water-lubricated condition. The glass and quart2 fibers were easily abraded and broken when sliding against steel in water environment, the broken fibers transferred to the mating metal surface and increase the surface roughness of mating stainless steel. This is probably the cause of the increased wear rate of glass fiber and quartz fiber PI composites in this case.     

纳米碳酸钙在水中的分散

筛选出了适合于在水中分散的纳米碳酸钙,分别考察了分散机转速、分散剂种类、分散剂用量、分散时间和悬浮液浓度等因素对纳米CaCO3在水中分散的影响,优化出了纳米CaCO3在水中分散的工艺条件,即：转速为7500r／min,分散剂为PK-100,分散时间为1．5h,分散剂用量为纳米CaCO3质量的3％,悬浮液浓度为15％．结果表明,优化条件下所制得的悬浮液黏度较低,纳米CaCO3平均粒径较小,分散均匀,且贮存稳定性良好．添加了该纳米CaCO3浆液的复合建筑涂料的耐沾污性、耐洗刷性、触变性、耐水性、耐碱性和耐老化性等得到了显著改善．     

Cu-水纳米流体的分散行为及导热性能研究

通过测定Cu-水纳米悬浮液的Zeta电位和吸光度,采用Hotdisk热物性分析仪测量了其导热系数,探讨了不同pH值和分散剂浓度对Cu-水纳米悬浮液分散稳定性和导热性能的影响.结果表明,pH值和分散剂加入量是影响Cu-水纳米悬浮液分散稳定和导热系数的重要因素.最优化的pH值和分散剂加入量能显著提高水溶液中Cu表面Zeta电位绝对值,增大了颗粒间静电排斥力,悬浮液分散稳定性较好,导热系数较高.从分散稳定和导热系数提高两个方面来考虑,pH=9.5左右被选为最优化值,在0.1%Cu-H2O纳米流体中,0.07%SDBS被选为最优化浓度.另外,Cu-水纳米流体的导热系数随纳米粒子质量分数的增大而增大,呈非线性关系,且比现有理论(Hamilton-Crosser模型)预测值大.     

Cement-based composites containing functionalized carbon fibers

Carbon fibers can be used to improve both mechanical properties and electrical conductivity of cement, allowing the preparation of a strengthened and toughened cement that can be used for self-monitoring applications. To guarantee both a good dispersion in water and a strong interaction with cement, surface functionalization of carbon fiber surface by reaction with acid was preferred to the use of a dispersing agent. The best oxidation conditions were chosen by using a Taguchi approach, and the samples contained the treated fibers were subjected to both mechanical and electrical tests, to determine flexural strength, toughness, compressive strength and electrical conductivity. It was shown that a not-too-strong oxidation by piranha solution was very effective to obtain well-dispersed fibers and a cement-composite with improved mechanical properties (in particular toughness) and electrical conductivity.     

表面改性离子交换化学镀制备表面覆镍聚酰亚胺纤维

以高强度的聚酰亚胺（PI）纤维为基纤,采用表面改性离子交换和化学镀相结合的方法,成功制备了高强度、高导电性和热稳定性好的聚酰亚胺-Ni （PI-Ni）复合导电纤维,采用SEM观察纤维的微观形貌,通过XRD和EDS表征了镀层组成及相态结构,测试了纤维的力学性能、导电性、界面黏结性能及热性能。结果表明,PI-Ni纤维表面平整光滑,完整致密,镀层为非晶态Ni-P合金。PI-Ni束丝拉伸强度约为1.2 GPa,电阻率为1.76×10^-4 Ω·cm,5%热失重温度为611℃,耐热性能优异,是一种高性能的有机导电纤维。     

Influence of the nature of polyaniline-based hole-injecting layer on polymer light emitting diode performances

We have studied the use of water and solvent-based polyaniline (PANI) dispersions as a transparent hole-injecting layer in polymer light emitting diodes (PLEDs). We have investigated the effects of the pH, the conductivity, the work function and the nature of the solvent and the dopant on the hole-injection properties. The water-dispersed PANI at a low pH (pH 1.8) showed an efficiency similar to that of PEDOT-based devices due to its high HOMO level and high conductivity. For the solvent-based PANI dispersions, the influence of the nature of the solvent and the dopant on the crystallinity, the conductivity of the PANIs and on the performances of the light emitting devices is discussed.