【作者】 续通；

【导师】 毛志平；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2013， 博士

【摘要】 耐高温阻燃防护服由三层构成：外壳层、蒸汽阻挡层和隔热层。隔热层是防止外界热量渗透到穿着者皮肤上最重要的一层,是关系到阻燃防护服性能好坏的关键。目前隔热层材料的耐高温隔热性能尚不能满足穿用者的需要。如何制备出一种既具有优良耐火阻燃性能又具有较好机械性能的隔热层材料一直是学术界和工业界关注的焦点。尽管国内外研究开发出了多种耐高温有机纤维用于隔热层,但这些纤维耐明火能力差,不能赋予消防服和作战服足够出入火场的能力。而一些无机纤维,如陶瓷纤维和玻璃纤维等虽具有优良的耐明火性能,但其织造性能和柔韧性较差,也不适合作为耐高温防护服的隔热层材料。因此,有机/无机复合型隔热层材料的开发成为研究重点,通过有机和无机材料的复合可实现优势互补,兼顾材料的耐火阻燃性能和机械性能。本课题是国家863项目“有机纤维表面耐明火热隔绝柔性防护层的设计与实现”(项目号2007AA03Z336)的部分内容,旨在开发出既具有优良耐火阻燃性能又具有较好机械性能的隔热层材料。本文通过对蛭石、蒙脱土结构的分析,研究其成膜性及成膜条件,并分别制备蛭石、蒙脱土(montmorillonite, MMT);和改性聚多巴(poly(N-benzyloxy-carbony1-3,4-dihydroxyphenylal-anine), PNBD)-MMT复合膜包覆聚酰亚胺(polyimide, PI)复合材料,同时对复合材料的耐明火热隔绝性能进行研究。具体研究内容如下：(1)剥分蛭石包覆PI纤维复合材料的制备及性能研究；a、剥分蛭石的制备及表征：采用化学和物理相结合的方法对蛭石原矿进行膨胀和剥分处理,制备剥分蛭石。采用扫描电子显微镜(SEM)技术对每个处理阶段的蛭石进行表征,研究发现,经过有机插层和机械剥分处理后的蛭石,其解离程度增加,单个蛭石片晶的径厚比与蛭石原矿相比增大。选择粒径分布均一的剥分蛭石片晶制备纯无机蛭石膜,并对其结构进行分析表征,结果发现纯无机蛭石膜具有规整的层状结构。b、剥分蛭石包覆PI复合材料的制备及性能研究：将经过筛选的剥分蛭石片晶包覆在PI纤维表面制备出一种新型的有机／无机复合材料。采用SEM对具有不同蛭石增重率的复合材料表面状态进行分析表征,结果表明复合材料表面无机蛭石膜的覆盖程度随蛭石增重率的增加而增大,当蛭石增重率达到一定值时,剥分蛭石片晶也可以在纤维之间的空隙形成无机蛭石膜。对剥分蛭石包覆PI复合材料进行耐高温隔热性能测试发现,复合材料(蛭石增重率为90wt%)在600℃下加热480s后内外表面温差为220℃,而纯PI材料在相同条件下测试内外表面温差小于100℃,说明剥分蛭石对PI纤维材料的包覆提高了材料的隔热性能,且复合材料的隔热性能随蛭石增重率的增加而增强。此外,在600℃加热480s后纯PI材料的形变率为38%,而复合材料(蛭石增重率为90wt%)的形变率仅为15%,材料形变率的降低说明剥分蛭石的包覆提高了有机纤维材料在高温条件下的热稳定性。(2)MMT包覆PI纤维复合材料的制备及性能研究；a、纯无机MMT膜的制备：以不同浓度的乙醇水溶液作为分散介质,调节钠基MMT分散液的pH值,采用超声波细胞粉碎仪对MMT分散液进行处理,以此MMT分散液为原料制备纯无机MMT膜。通过对膜的微结构及柔韧性等的研究,确定最佳制膜工艺。b、MMT包覆PI复合材料的制备及性能研究：将钠基MMT片晶包覆在PI纤维表面制备复合材料并对其进行表征。采用SEM研究MMT片晶在PI纤维表面的排列状态,发现MMT片晶相互交叠包覆在PI纤维表面形成一层无机膜。分别采用热重分析(TG)、锥形量热仪、明火烧蚀、温差测定等对复合材料的热稳定性能、火灾危害性能、耐明火性能及隔热性等进行研究。结果表明,经MMT包覆后的PI材料其耐明火阻燃性能、隔热性能等都得到了极大提高,经过MMT包覆后的PI复合材料在800℃加热600s内外表面温差为400℃,而纯PI材料在相同条件下内外表面温差为100℃。对复合材料进行力学性能测试发现,经MMT包覆后的PI复合材料与纯PI材料相比,其机械强力有所提高。(3) PNBD-MMT复合膜包覆PI纤维复合材料的制备及性能研究；a、PNBD-MMT复合膜的制备：以阳离子交换容量为90mmol/100g的钠基MMT和实验室自制的PNBD(?)：分子量为6000g/mol)为原料采用Layer-by-Layer (LbL)自组装方法制备复合膜。对复合膜热稳定性和层间距的研究发现,复合膜的失重率随制备复合膜所用PNBD溶液浓度的增加而增大,同时,随着制备复合膜所用PNBD溶液浓度的增加,复合膜中MMT的001晶面间距亦增加。b、PNBD-MMT复合膜包覆PI纤维复合材料的制备及性能研究：以浓度分别为0.02wt%、0.04wt%和0.10wt%的PNBD溶液与重量百分比为0.02wt%的MMT分散液为不同组分,通过LbL方式在经过预处理的PI纤维材料表面进行组装制备复合材料。研究了复合膜包覆对PI纤维耐火阻燃性能的影响及复合膜与PI纤维的结合牢度。结果表明,纯无机MMT膜包覆PI复合材料经过20次标准水洗后,其表面无机膜的覆盖量明显减少；而PNBD-MMT复合膜包覆PI复合材料经过20次水洗后,其表面仍被大量复合膜包覆,且复合材料表面所包覆膜的残留量随PNBD浓度的增加而增加。对比两者的热稳定性和耐火阻燃性发现,PNBD-MMT复合膜包覆PI复合材料进行多次水洗后仍具有优良的热稳定性能和阻燃性能,而MMT包覆PI复合材料经过多次水洗后,其热稳定性能和阻燃性能明显下降。对水洗前后复合材料进行垂直燃烧测试,PNBD-MMT复合膜包覆PI复合材料经过20次标准水洗后损毁长度为7-14mm,与水洗前(7-9mm)相比略有增加,而MMT包覆PI复合材料从水洗前的8mm增大到水洗后的17mm,说明包覆在PI纤维表面的PNBD-MMT复合膜与有机纤维具有更好的结合牢度,从而可赋予有机材料持久的耐火阻燃性。强力测试表明,PNBD-MMT复合膜包覆PI材料的机械强力较纯PI材料有一定程度增强。综上所述,通过PNBD参与MMT包覆PI过程,大大提高了MMT与PI的结合牢度,所制得的复合材料,既具有持久的耐火阻燃性能,又具有很好的机械性能,完全满足作为耐高温阻燃防护服隔热层材料的要求,是隔热层材料研发的又一突破。更多还原

【Abstract】 High-temperature resistance flame-retardant protective suit is composed by three layers: out layer, vapor barrier layer and heat insulation layer. The heat insulation layer is the most important layer that prevents the penetration of external heat into wearer’s skin, and the key which is related to the characteristic of flame-retardant protective suit. Currently, heat insulation performance of the insulation layer can not meet the needs of users. It has always been an important issue for academia and industry that producing a kind of excellent flexible and fire retardant material to be used as insulation layer for flame-retardant suit. Although there has been a variety of high-temperature resistance organic fibers to be used as thermal insulation layer of fire-retardant uniform, the fire resistance of these fibers is too poor to achieve the need of the uniform. In spite of the excellent high-temperature resistance performance of ceramic fiber and glass fiber, the limited weaving property and flexibility of the fibers make them not suitable to be used as insulation layer of flame-retardant protective suit. Therefore, the exploitation of organic/inorganic composite materials has become the important issue. The composites of organic and inorganic material could achieve the complementary advantages, and both mechanical behavior and fire retardant property of the material.This study was part of the State863Project "Design and realization of flexibility and high temperature resistance protective coating of organic fiber"(Project NO.2001AA03Z336), aimed at developing a kind of material with wonderful mechanical behavior and flame retardant. This study focused on analyzing the structure and film-forming property of vermiculite and montmorillonite (MMT), and preparing the exfoliated vermiculite coated polyimide(PI) composite, MMT coated PI composite and PNBD(poly(N-benzyloxycarbonyl-3,4-dihydroxyphenylalanine))- MMT coated PI composite. Then the fire resistance and thermal insulation property of those composites was discussed. The main work of the study were as follows:(1) Study the preparation of exploited vermiculite, exploited vermiculite coated PI composite, and discuss the fire retardant properties of the composites.A. Preparation and characteristic of exploited vermiculite. First, chemical and physical method was used to prepare exfoliated vermiculite. Scanning electron microscope (SEM) was used to analyze vermiculite samples, the results showed that the layered structure of vermiculite was almost cleavage and the aspect ratio of lamellae became larger after intercalation and exfoliated treatment. Finally, exfoliated vermiculite lamellae with uniform size was selected to prepare inorganic vermiculite film. The structure of the film was layered. This could indicate the film-forming property of exploited vermiculite.B. Study the preparation and thermal insulation property of exfoliated vermiculite coated PI composite. Exfoliated vermiculite lamellae with uniform size were used to coat on PI fiber material to prepare a new type of organic/inorganic composite material. The composite material was characterized by SEM, the result shown that with the increasing weight of vermiculite, more lamellae were covered on PI fibers. When the weight gain of vermiculite reached a certain value, the inorganic clay coating could also form between fibers. The exploited vermiculite coated PI composite was tested at600℃for480s to evaluate the heat-insulation performance of the composites, the results indicated that the temperature difference between the inner and outer surfaces of composites (weight gain,90wt.%) was220℃, and that of uncoated PI was less than100℃under the same condition. It suggested that the vermiculite coating could enhance heat-insulating property of PI, and the insulation performance of the composite material was stronger with the increase of vermiculite weight addition. In addition, the deformation rate for uncoated PI fiber material was38%after heated at600℃for480s, and that of the composites (weight gain,90wt.%) was only15%under the same condition. This could also indicate that the vermiculite coating could enhance the thermal stability of the composites.(2) Study the preparation of MMT coated PI composite, discuss the fire retardant and heat insulation property of the composites.A. Preparation of MMT film. Different kinds of MMT dispersion were prepared with different pH value and different dispersing medium, in order to prepare MMT films. The optimum process which was used to prepare MMT film was determined by investigating the structure and flexibility of those MMT films.B. Study the preparation and characteristic of MMT coated PI composite. MMT-PI composites were prepared by coating MMT on the surface of PI material. The arrangement of MMT lamellae on the surface of PI fiber was analyzed by SEM, the result indicated the MMT lamellae coated on the surface of PI fiber by forming a kind of inorganic film. TG, cone calorimeter, open flame ablation, temperature difference of internal and external surface test were used to investigate the thermal stability property, fire hazard performance, resistance to open flame performance and thermal insulation property of the composites. The results showed that those characteristics of the composites were more excellent than pure PI. For example, the thermal insulation property of MMT-PI composite and PI material was tested at800℃for600s, the temperature difference between outer surface and inner surface of MMT-PI was400℃, and that of PI material was just100℃under the same condition. In addition, mechanical property of the composites was tested and the result indicated that, compared with pure PI, the mechanical strength of MMT-PI was improved.(3) Study the preparation of PNBD-MMT composite film, and discuss the fastness between PNBD-MMT film and PI fiber, and the fire resistance of the composites.A. Preparation PNBD-MMT composite film. Na-MMT (CEC=90mmol/100g) and homemade PNBD (6000g/mol) were used to prepare composite film by LbL self-assembly method on the surfaces of glass slides. The test result of thermal stability property and interlayer distance of composite film indicated that the weight loss of the composite films and d001of MMT lamellae in the composite films were increased with the increase of PNBD solution concentration.B. Study preparation and characteristic of PNBD-MMT coated PI composite material. PNBD solution (concentration,0.02wt%,0.04wt%,0.10wt%) and MMT dispersion (0.02wt%) were used to coat on PI fiber by LbL method to prepare composite materials. The flame resistance of PNBD-MMT coated PI and fastness between PNBD-MMT composite film and PI fibers was investigated. The result indicated that there was more PNBD-MMT coating on the surface of PI than MMT coating after20times standard washing. The thermal stability and flame resistance of PNBD-MMT coated PI composite was still excellent after20times standard washing. However, those properties of MMT-PI was decreased after20times standard washing. For example, the result of vertical burning test showed that, the burning length of PNBD-MMT coated PI were about7-9mm and7-14mm before and after20times standard washing, and that of MMT-PI were8mm and17mm. Those result indicated that the combination fastness between PNBD-MMT composite film and PI fiber was stronger than that of MMT film, so as to endue durable fire retardant property to the composites. The mechanical strength testing of PNBD-MMT composite film coated PI showed that the mechanical strength of the composites was stronger than that of pure PI.In summary, the combination fastness between MMT lamellae and PI fiber was improved greatly by PNBD. So as to endue durable fire retardant property and mechanical properties to the PNBD-MMT coated PI composite material. The composites could meet the need of thermal insulation layer of high-temperature resistance and flame-retardant protective suit. So it was another breakthrough of the thermal-insulation materials research and development.更多还原