炭纤维层压导电复合材料及其活性炭纤维纸功能化的研究与应用

2019-02-24 21:09:11

The ACF ACFP 导电 炭纤维









中文题名炭纤维层压导电复合材料及其活性炭纤维纸功能化的研究与应用

 





副题名 





外文题名 





论文作者杨小平   





导师沈曾民教授   





学科专业材料学  复合材料   





研究领域\研究方向 





学位级别博士 





学位授予单位北京化工大学   





学位授予日期2001   





论文页码总数146页   





关键词导电纸  纸  导电复合材料  层压导电复合材料  面发热材料  炭纤维导电纸   





馆藏号BSLW

/2001

/TB332

/76 





【中文摘要】

    炭纤维层压导电复合材料(或称炭纤维面发热材料)及其活性炭纤维纸的研究属于炭纤维功能复合材料的分支,对其制备、结构与性能的研究有助于炭纤维功能复合材料的开发与应用。本文首先研究了一种新的炭纤维导电复合材料的成型方法,即采用湿法成纸的制备工艺,将短切炭纤维分散在木质纤维素浆粕或化学纤维浆中,使炭纤维在水溶液体系中,通过炭纤维与木质纤维素浆粕或化学纤维浆的化学键结合以及物理机械搅拌混合,以最大程度的保持炭纤维的长度及分散均匀性,形成三维导电网络的炭纤维导电纸。本文以一系列炭纤维面发热材料的专利技术为基础,详细研究了炭纤维导电复合纸、树脂基层压面发热板和柔性橡胶基层压面发热板等导电复合材料的制备、结构与性能。
   本文研究了炭纤维导电纸的电性能、压敏特性、结构特征和与树脂层压复合成面发热板时的工艺与电性能关系。结果表明:炭纤维/木质纤维素复合导电纸属于“渗滤”体系,其体积电阻率随炭纤维含量的变化有一个“阈值”,其值为0.376vol%,超过该“阈值”后,导电纸的体积电阻率随炭纤维含量的增加而下降趋势平缓。炭纤维导电纸的体积电阻率与炭纤维体积分数存在以下关系:ρ=ρ〓(Φ+0.62)〓。采用圆网造纸工艺制备的炭纤维导电纸在沿成纸的X方向上具有择优取向的特征,随炭纤维含量的增加,沿X方向择优取向排布趋向变成X和Y方向上交叉分布且具有相同几率。炭纤维导电纸具有压敏特性,存在“电阻蠕变(滞后)”现象,并随炭纤维含量有所不同,在炭纤维含量低于“阈值”时,导电纸的压敏特性明显,而炭纤维含量高于“阈值”后,导电纸的压敏特性对其电阻的影响较小。在相同的压力下,导电纸的X方向的ρ〓与Y方向的ρ〓值不同,其体积电阻率的差异随炭纤维含量的增加而趋于相近。炭纤维导电纸的结构模型为三维导电网络结构,导电机理为压敏导电机理模型。炭纤维导电纸的层压导电复合材料的导电机理是“导电网络+热膨胀”机理,可以用热压敏导电机理模型来描述。通过引入耐热不燃的矿物纤维和木浆纤维的混合体系的基材,与炭纤维成纸可达到阻燃的目的。其耐热阻燃导电纸的电阻率与炭纤维含量的关系、压敏特性与纯木浆基材的导电纸的特性一致。
   通过对溴化环氧树脂浸渍玻璃布(FR-4半固化片)和炭纤维导电纸层压复合面状发热板的电学性能研究,结果表明:溴化环氧树脂固化过程的压力、温度及树脂固化对其电性能产生影响,对于不同规格的导电纸,其电阻下降率不同。面状发热板的电阻在升温和降温过程中存在不同程度的偏离,呈现PTC或NTC效应,数次热循环后,可以使室温电阻保持恒定。发热板的电阻随通电时间的延长而逐渐下降并趋于稳定,通断电次数对其电阻影响不大,在长期通电使用下能保持其功率稳定性,发热板的功率密度与表面温度呈现良好的线性关系。溴化环氧树脂的的引入,提高了炭纤维面发热材料的耐热性能,可达到阻燃的效果(达V-0级)。炭纤维面状发热板具有远红外辐射特性,其波长在8-15μm范围内,法向发射率为85%,单面电热辐射转换效率为66%,对人体具有理疗作用。
   本文还研究了橡胶/炭纤维层压复合导电面状发热板的硫化过程对其电阻的影响以及所制备的面状发热板的电学性能,结果表明:硫化过程对面发热板的电阻有直接影响,不同规格的导电纸的层压面发热板的电阻下降率不同。发热板具有较好的热循环稳定性,数次热循环后,室温电阻可保持恒定;其伏安特性、功率密度-表面温度均呈现良好的线性关系,在长期通电使用下,能保持其功率稳定性。
   基于上述的研究结果,将树脂基炭纤维层压导电复合板应用在毛纺行业的毛纺面料后整理电压工序。使用性能表明:采用以炭纤维面状发热材料为加热元件的电压板,具有远红外辐射传热和长期使用电性能稳定等特点,可使毛纺面料产品的质量提高。另外,橡胶/炭纤维复合导电面状发热板具有温度均匀、面状发热、绝缘强度高、耐酸碱、防滑、使用寿命长等特点。可广泛应用于仔猪用保温箱、孵化箱,育苗及园艺用加热器、建筑施工保温、居室地板采暖、工业流体防冻及保温、医疗保健等领域。
   最后,本文在炭纤维导电复合材料研究的基础上,进一步研究了采用湿法造纸工艺制备活性炭纤维纸(ACFP),探讨了分散剂、活性炭纤维与纸浆纤维配比对活性炭纤维纸的透气度、抗张强度、比表面积和微孔体积的影响。结果表明:分散剂可增加ACFP的抗张强度而对透气度影响较小,随活性炭纤维含量的增加,ACFP的透气度增加而抗张强度下降,ACFP具有与活性炭纤维类似的孔径大小和孔径分布,二者的氮气吸附等温线均为I型等温线,吸附机理均为微孔填充,ACFP的形态结构为无序随机排列。适当的阳极氧化处理能使ACF获得较佳的表面结构,如比表面积增大,微孔孔容增大;同时增加ACF的表面含氧官能团数目,使ACF苯吸附性能有较大的提高;ACF的阳极氧化表面处理机理研究表明:首先,阳极氧化表面处理使ACF表面的无定形碳氧化刻蚀,增加了ACF的微孔数目和比表面积;然后,随着氧化刻蚀的不断进行,ACF被过度刻蚀,部分微孔将发生扩孔,甚至有部分微孔之间的隔断被打通,形成中孔或大孔,结果使得ACF的比表面积下降。与此同时,ACF经过阳极氧化表面处理后成纸提高了ACFP的抗张强度。











【外文摘要】

 ABSTRACT
   Carbon fiber (CF) electrically conductive composites consisting of electrically conductive paper, facial-heating materials laminated FR-4 brominated epoxy resin and flexible facial-heating materials laminated rubber have been studied in order to develop and apply carbon fiber functional composites. The relationships between the CF volume fraction and the resistance ratio of electrically conductive paper, which were made by short carbon fiber mixing with natural lignocellulose through general wetting-making paper method, were investigated. A sharp drop in resistance ratio was observed in the case after a critical concentration of fiber reached, which was called percolation threshold (about 0.376vo1%) mainly depended on carbon fiber geometry and structure. The relationship for the resistance ratio of electrically conductive paper and the volume fraction of carbon fiber presents as follow: ρ=ρ〓 (Φ+0.62) 〓. The pressure-sensitive characteristics of the electrically conductive paper filled with carbon fiber have been also studied. The results suggested that the electrical conductivity of the composites depends on the pressure critically. In the range of the experimental pressure, the resistance ratio reduces constantly with the increase of the pressure, which is called"Negative Pressure Coefficient of resistive (NPCR) "effect. The press-sensitivity of the electrical resistance and the behavior of electrical resistance wriggle shown under the same pressure at different time are associated with the reformulation and the destruction of the conductive network under a certain strain. A three dimension conductive network structural model for the electrically conductive composites was presented on the basis of the research of its electrical properties and pressure-sensitive characteristics and the observation of its microstructure. It can well be applied to the thermal history experiment of the paper and the facial heating-board laminated with resin. A conductive mechanism model called "conductive network combined with thermal expansion model"was also pointed out.
   The electrical properties of carbon fiber facial heating-sheet made by carbon fiber conductive paper laminated with FR-4 brominated epoxy prepreg glass cloth have been studied in this paper. The results showed that the curing of FR-4 prepreg influenced the changes of electrical properties. Different kinds of conductive paper samples had different decrease ratios. The resistance and temperature (R-T) relationship of facial heating sheet during the heating and cooling recycling process presented some difference between the heating curve and the cooling curve. The samples exhibited PTC or NTC effect, but the room temperature resistance kept stable after several times of heat treatment. Resistance of facial heating sheet decreased slightly and kept stable after use for several hours. This kind of facial heating sheet had constant power under long use. Power density and surface temperature curve showed linear behavior. The electrical properties、the character of far infrared radiation and the power properties for carbon fiber facial heating voltage-board for wool textile finishing were studied further. It can be widely used as a new kind of carbon fiber facial heating voltage-board based on the application at some wool textile factories.
   The electrical properties of laminated rubber/carbon fiber paper facial heating-sheet were investigated. The results show that the vulcanization process had direct effect on the resistance of conductive paper and facial-heating board, and the sheets in different sizes had different resistance decay rates during vulcanization. Heating-sheets possessed good heat circle stability, and the room temperature resistance kept constant after several heat circles. The linear relationships of voltage-current and power density-surface temperature relationships existed. It also can keep constant power for long time use on the basis of the formation of interconnecting continuous conducting networks in electrically conductive carbon fiber paper. It can be widely used as a new kind of low temperature facial heating material for livestock and other uses.
   Activated carbon fiber paper (ACFP) was made through wetting-making-paper technology. The effect of dispersing agent and the ratio of activated carbon fiber to cellulose fiber on permeability, tensile strength, BET surface area and microporosity of ACFP was investigated. The results show that dispersing agent can increase the tensile strength of ACFP and has little influence on the permeability of ACFP. The permeability of ACFP increases and the tensile strength of ACFP decreases while increasing the percent of ACF in ACFP. ACFP has similar pore size and pore size distribution to ACF. Both of them have the similar nitrogen adsorption isotherm plot, i. e. I type isotherm plot. The adsorption mechanism of ACF and ACFP is micropore filling. The structure of ACFP is randomly arranged.
   Secondly, surface treatment of ACF by anode oxidation using 〓 electrolyte has beeen carried out. The results indicated that the concentration of electrolyte is much more important than the other factors and the better condition of anode oxidation treatment is as follows: the concentration of electrolyte 3% (wt%) , the electric current intensity 1. 6A, oxidation time 150s. The structure between as-received ACF and oxidized ACF was characterized by AFM, XPS, XRD, SEM, BETSSA and PSD methods. The different structure of ACF and oxidized ACF indicated that OACF has higher adsorption capacity than ACF and the mechanical properties of ACFP by surface treatment were improved. In the course of anode oxidation, amorphous carbon atoms were etched under the suitable conditions at first, then, crystallitic carbon atoms would be etched as the surface treatment conditions becoming more rigorous.