粉体对泡沫灭火剂发泡能力和热稳定性影响研究

研究了纳米二氧化硅、硅微粉、石墨、纳米级铜粉对于蛋白泡沫的发泡能力及热稳定性的影响,并且测试了形成的复合泡沫的热稳定性,结果表明：将耐烧粉体直接添加进灭火泡沫中有望增强其抗烧能力和灭火性能。在常温下纳米二氧化硅以及纳米级铜粉能与蛋白泡沫较好的结合为复合泡沫,添加测试粉体后复合泡沫的热稳定性均有明显增强,其中添加纳米二氧化硅和纳米级铜粉的复合泡沫整体性能良好,无泡沫排液和聚并现象,可以起到良好的隔热作用。     

Preparation and properties of rigid polyimide foams derived from dianhydride and isocyanate

A series of rigid polyimide (PI) foams were synthesized via the reaction of a first solution with a second solution. The first solution was isocyanate‐terminated polyimide prepolymers; the second solution contained deionized water and surfactant. The effect of different water contents and isocyanate index on the structures and properties of rigid PI foams were investigated. The apparent density, hardness, compressive strength, and the 5% weight loss temperatures (T_5%) decreased with the increase of water content. With the increase of isocyanate index, the apparent density and the T_5% values decreased, whereas the glass transition temperatures (T_g) increased and the hardness, compressive strength first increased and then decreased. The rigid PI foams composed of closed‐cells were confirmed by scanning electron microscopy. The maximum compressive strength of rigid PI foams prepared was up to 1.31 MPa. Moreover, excellent thermal stability was presented with the T_5% values were all above 360°C and the residual weights of the foams (R_w) were more than 50% at 800°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

聚乙二醇对聚酰亚胺泡沫的结构及热性能的影响

采用聚(酯-铵)盐(PEAS)前体粉末发泡法制备聚酰亚胺泡沫,分别考察了分子量为400,1000和2000的聚乙二醇(PEG)对PEAS前体及聚酰亚胺泡沫的影响。结果表明,PEG的加入使聚酰亚胺泡沫的平均孔径由0.35 mm增加到0.50 mm以上,不同分子量的PEG没有导致聚酰亚胺泡沫的平均孔径产生显著的差别。红外光谱表明,PEG的加入对聚酰亚胺泡沫及其前体的化学结构没有明显改变。由PEG/PEAS前体制备的聚酰亚胺泡沫在350℃仍保持较好的热稳定性。     

Improved thermal stability and flame resistance of flexible polyimide foams by vermiculite reinforcement

In this work, a series of flexible polyimide composite foams with dianhydride and isocyanate as the starting materials were prepared by pre‐dispersing vermiculite in isocyanate. The experimental results revealed that the cellular diameter of foams obviously decreased with the addition of vermiculite. The open cell content decreased with the increase of vermiculite, and foams containing vermiculite possessed higher apparent densities of about 10 kg/m³ when compared with the neat polyimide foams. The compressive strength was dramatically enhanced by vermiculite incorporation, and reached maximum when the filler content was 2%, indicating dramatically reinforcing effect of vermiculite. With the addition of vermiculite, the thermal stability and flame resistance of polyimide foams were improved. The limiting oxygen index of polyimide foams showed an increase from 31 to 33.5% with increase of vermiculite from 0 to 8% and the peak heat release rate decreased, indicating high flame retardant properties. Vermiculites possess excellent heat insulation and high temperature stability. When conditioned at high temperature, the filler would block the heat transfer during the bulk foam. Therefore, it is feasible to further increase the mechanical and thermal properties of polyimide foams by vermiculite filling. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44828.     

高温热处理对聚酰亚胺薄膜性能的影响

研究了高温热处理对聚酰亚胺(PI)薄膜拉伸性能和热性能的影响。在薄膜完全环化后,随着热处理温度的升高,薄膜的拉伸强度、弹性模量先增大后基本保持不变,断裂伸长率先保持不变后明显降低,热膨胀系数也显著降低,而薄膜的玻璃化转变温度略有增大。高温热处理工艺可制备高强度和低热膨胀系数的高性能PI薄膜。     

Effect of ceramic matrix compositions on pore structure and properties of lightweight foamed ceramics

Foamed ceramics were prepared with polishing slag and shale as raw materials. According to the phase diagram of CaO-MgO-Al₂O₃-SiO₂, a reasonable composition system was designed to obtain foamed ceramics with good property. The related properties of foamed ceramics were characterized by X-ray fluorescence, X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, field emission scanning electron microscopy, energy disperse spectroscopy, etc. The results indicate that, when the amount of polishing slag and shale are 30% and 60% respectively, foamed ceramic with bulk density of 0.225 g·cm⁻³ has good compressive strength and thermal conductivity, which are 1.95 MPa and 0.065 W/m·K, respectively. The element compositions of the matrix materials affect the melt viscosity, resulting in glass phase separation and the crystallization. The main phases of the foamed ceramics are anorthite CaSi₂Al₂O₈, spinel MgAl₂O₄ and spinel Mg(Al, Fe)₂O₄. The internal relationship among melt, pores, and crystal precipitates was discussed.     

短切碳纤维增强聚酰亚胺泡沫的制备及性能

针对现有软质聚酰亚胺泡沫强度低的缺点,通过一步法制备了短切碳纤维增强聚酰亚胺泡沫,研究了短切碳纤维的添加量对聚酰亚胺泡沫的化学结构、微观形貌、压缩强度及热导率的影响。结果表明,短切碳纤维在发泡过程中起到成核剂的作用,随着其添加量的增加,泡沫的泡孔平均尺寸先减小后增加;当短切碳纤维质量分数为20%时,泡孔的最小平均尺寸为507μm;泡沫密度随着短切碳纤维用量的变化没有明显的改变;泡沫的压缩强度随着短切碳纤维的用量先增大后逐渐减小,压缩强度最大为54.52 kPa;短切碳纤维的加入对聚酰亚胺泡沫材料的化学结构和热稳定性没有明显的影响,但是材料的热导率随着短切碳纤维含量的增加有一定的增加。     

明胶溶液浓度对其发泡性能的影响

明胶具有发泡性能,该性能在食品、医药、洗涤、化妆品等行业具有很好的潜在应用价值。明胶浓度对其体系的发泡性能和发泡稳定性产生的影响,将直接影响到其产品的质量和性能。因此,本文采用搅拌法,在60℃水浴条件下,采用100mL明胶溶液,研究了明胶溶液浓度对其发泡性能和泡沫稳定性的影响。实验结果表明:在相同的温度和转速条件下,随着明胶溶液浓度的增加,其发泡量逐渐减少,而泡沫稳定性则越来越好。A型明胶溶液浓度为1%时发泡量最大,最大值为71mL;在浓度为9%时泡沫半衰期为86min,表现出较好的泡沫稳定性。B型明胶溶液浓度为1%时发泡量最大值为52mL;溶液浓度为9%时泡沫半衰期为3min。A型明胶和B型明胶两者相比,A型明胶具有更好的发泡性能及泡沫稳定性。     

聚酰亚胺的合成及其膜的制备

先在四氢呋喃/甲醇(质量比为4:1)混合溶剂体系中合成聚酰胺酸(PAA),后在真空烘箱中(200℃/h)形成聚酰亚胺(PI)膜,并通过IR和TG/DTG对产物进行了表征,结果表明能得到耐高温的Pl膜。     

锌粉和有机硅对聚氨酯涂层耐蚀性和热性能的影响

通过浸泡腐蚀和高温烘烤,以涂层的冲击强度为依据,研究了不同锌粉含量的聚氨酯涂层在10%(质量分数,下同)HCl、10%NaOH和20%NaCl溶液中的耐腐蚀性以及不同有机硅添加量的涂层在120℃下的耐热性.通过热重分析(TG-DSC),比较了改性前后聚氨酯涂料的热稳定性,测试了涂层的综合性能.结果表明,含锌量为83%的...     

Effect of chemical structure and preparation process on the aggregation structure and properties of polyimide film

In this article, polyimide (PI) films were fabricated via the three‐step method including the reactions of condensation polymerization, chemical imidization, and thermal imidization. In comparison with the conventional two‐step method to produce PI films, there was an additional step in the present method, i.e., chemical imidization. The aim of chemical imidization was to get PI intermediates with different pre‐imidization degree (pre‐ID). And PI component in PI intermediates acted as in‐situ rigid‐rod segments and induced orientation in the films of PI intermediates. Then the orientations of molecular chains were preserved in the following thermal imidization, and caused the difference in aggregation structure and property of the final PI films. The test results indicated that the orderly degree of molecular chains and mechanical properties of PI films increased with pre‐ID increasing. Furthermore, this tendency was much more obvious for more rigid backbone structure. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of electromagnetic interference shielding polyimide foam

This article focused on the preparation and characterization of ultralight and high‐temperature resistant polyimide foam (PIF) for electromagnetic interference shielding. PIF was first prepared based on a one‐pot process by the primary reactions of derivatives of pyromellitic dianhydride and polyaryl polymethylene isocyanate. Then, PIFs with silver (0) coating were then prepared by spraying silver (0) on the surfaces of PIF through physical spraying method. The surface density of silver coating was 0.18 kg/m², and the densities of silver‐coated PIFs were less than 23 kg/m³. The scanning electron microscopy coupled with an energy‐dispersive X‐ray spectrometer (EDX) measurement were carried out to investigate the morphological and chemical properties of uncoated and coated PIFs. For coated PIFs, the EDX spectrums indicated increasing higher silver proportions from interior to exterior surface, together with increasing higher carbon proportions from exterior surface to interior. Thermogravimetry/Fourier transform infrared instrument that combined thermogravimetric analysis with pyrolysis product analysis by Fourier transform infrared spectroscopy were applied to investigate the thermal stability and pyrolysis products of uncoated and coated PIFs. The results indicated that the thermal properties of silver‐coated PIFs were improved obviously with the 5% weight loss temperature higher than 400°C and the residual weight retentions at 800°C ～ 80%. In the frequency range 200–7000 MHz, the EMI shielding efficiency with one surface and two surfaces coated with silver were in the range of 36.4–60.7 dB and 61.6–95.6 dB, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

聚酰亚胺薄膜及纤维的探索研究

利用均苯四甲酸二酐(PMDA)、4,4'-二氨基二苯醚(4,4'-ODA)和自制三单体在强极性非质子有机溶剂N,N-二甲基乙酰胺(DMAc)中进行共缩聚反应,制得高粘度的聚酰胺酸(PAA)溶液,经涂膜、热亚胺化,得到坚韧透明的聚酰亚胺(PI)薄膜,其具有较好的拉伸断裂强度和合适的伸长率;同时将得到的PAA溶液进行湿法纺丝,制成PAA纤维,采用热亚胺化和高温拉伸的方法制得PI纤维,其断裂强度能达到3.67cN/dtex。     

Research on rapid preparation and performance of polymethacrylimide foams

A high‐performance polymethacrylimide (PMI) foam was prepared from the reactive monomers of acrylonitrile (AN) and methacrylic acid (MAA) via ultrasonic combined with thermal initiation radical bulk copolymerization and free heat foaming. The reaction progress of cyano and carboxyl groups were tracked by Fourier transform infrared (FTIR) spectroscopy and X‐ray Photoelectron Spectroscopy, and the results indicated that the imide groups were formed and cyano groups gradually decreased during foaming and thermal treatment. The cell morphologies of the PMI foams were characterized by scanning electron microscopy, and the results showed the PMI foams were consisted of the honeycomb structure. The thermostability of the prepared PMI foam was evaluated by thermogravimetric analysis (TGA), and the results revealed that the PMI foam possessed excellent thermal stability and char forming capability. The mechanical properties of PMI foams were measured by tensile, flexural, and compressive strength, and the responding values for the PMI foams with the density of 32.30 kg m^?3 were 0.71, 0.86, and 1.49 MPa, respectively, which demonstrated the obtained PMI foams presented superior mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44959.     

起泡剂的起泡性能及使用浓度优选研究

起泡剂的起始发泡体积和泡沫稳定性是决定起泡剂起泡性能的两个重要因素,也是实际应用当中筛选起泡剂的重要指标.采用Ross-Miles法对13种不同类型起泡剂在常温下的起泡性能进行了评价.结果表明：不同类型起泡剂的起始发泡体积和泡沫稳定性具有显著的不同.不同起泡剂的起始发泡体积随浓度的增加而增大.当起泡剂浓度增加到0.5％时,起始发泡体积趋于稳定,由此确定起泡剂的最佳使用浓度为0.5％.     

共聚聚酰亚胺纤维的制备及其性能研究

采用4,4’-二氨基二苯醚和1,6-己二胺(HDA)为二胺单体,与均苯四甲酸酐(PMDA)在二甲基乙酰胺(DMAc)中共聚得到聚酰胺酸(PAA)纺丝原液,通过干法纺丝工艺路线纺制PAA初生纤维,利用热酰亚胺化制备了共聚型聚酰亚胺(PI)纤维;通过红外光谱分析、动态力学分析、热重分析、X射线衍射等手段分析了PI纤维的力学性能及热性能。结果表明:红外光谱分析发现HDA的长亚甲基链引入到PI的链中;当HDA质量分数为20%时,PI纤维的断裂强度和模量分别为5.1 cN/dtex和76 cN/dtex;动态力学和热重分析发现,纤维的玻璃化转变温度为315～380℃,热稳定性在400℃以上;纤维经热处理后聚集态结构存在一定的有序性。     

纤维对水基泡沫液稳定性影响的研究

探讨了蔗渣浆、阔叶木浆和针叶木浆漂白后的纤维原料对水基泡沫液的发泡能力和稳定性的影响,并采用光学显微镜与Image J软件结合的方法,着重研究了水基泡沫液中气泡大小及其分布情况。结果表明,较宽的纤维长度分布有利于水基泡沫液的发泡性能;纤维长、多分散性数值大的水基泡沫液的稳定性好,气泡直径较小且大小均匀;3种浆料中,蔗渣浆纤维的水基泡沫液稳定性最差,其次是阔叶木浆纤维的水基泡沫液,针叶木浆纤维的水基泡沫液稳定性最好。     

含噁唑环支链的苯氧型共聚聚酰亚胺的合成与表征

以3,5-二硝基苯甲酰氯和邻氨基苯酚为原料合成了含苯并噁唑基团的二胺,然后将其与二氨基二苯醚(ODA)和二苯醚四甲酸二酐(ODPA)进行常温共聚合成聚酰胺酸,最后采用两步法合成了含苯并噁唑支链的可溶性聚酰亚胺(PI)。采用红外光谱(FT-IR)、差示扫描量热法(DSC)和热重分析(TGA)等测试手段分析了该PI的结构、热性能和在各溶剂中的溶解性能。实验结果表明,经300℃热处理1h后,聚酰胺酸转化为酰亚胺化比较完全;引入苯并噁唑支链基团可以提高PI的耐热性,其玻璃化转变温度(Tg)在300℃左右,初始热分解温度为552.5℃;该PI在强极性溶剂中溶解性能良好,但不溶于一般的极性溶剂中,说明其在提高加工性能的同时仍能保持耐一般溶剂的性能。     

静电纺聚酰亚胺纳米纤维的制备及其应用

综述了静电纺聚酰亚胺纳米纤维不同制备方法及各自优缺点,对静电纺聚酰亚胺纳米纤维的改性,提高其力学性能、热稳定性及其它特性,以及聚酰亚胺纳米纤维的潜在应用领域。综述表明,寻找适合的溶剂是实现一步法静电纺高性能聚酰亚胺纳米纤维的关键,通过改性调控可提高其热稳定性和力学性能。     

Preparation and characteristics of composite films with functionalized graphene/polyimide

Polyimide (PI) has the inherent defect of poor intrinsic thermal conductivity and cannot meet the increasing demand for rapid heat dissipation in the thermal management introduction. To improve the thermal conductivity of PI, in this study, thick sheet graphene-ionic liquid (TSG-IL) functionalized graphene has been prepared by a one-step ultrasonic-chemical method. Under the action of mechanical force, IL is successfully modified on the surface of TSG, and TSG is peeled to some extent. TSG-IL/PI has been prepared the typical method of solution casting followed by thermal imidization. The structure, morphology, thermal conductivity, and mechanical properties of the composites are evaluated by Fourier-transform infrared spectroscopy, x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and Hot Disk thermal conductivity tests. When the amount of TSG-IL is 0.3 wt%, the thermal conductivity of TSG-IL/PI (0.18 W·m⁻¹·k⁻¹) than pure PI and TSG (ultrasonication)/PI increased by 50.0% and 28.6%, respectively. Moreover, it can maintain good mechanical properties, and its tensile strength (121.5 MPa) is 6.5% and 3.5% higher than that of pure PI and TSG (ultrasonication)/PI, respectively. The potential for application in the preparation of composites with high-thermal conductivity is promising.