短切芳纶纤维增强酚醛泡沫性能的研究

为了改善酚醛泡沫的性能,选用短切芳纶纤维作为增强材料,考察了不同短切芳纶纤维用量对酚醛泡沫压缩强度、压缩弹性模量、泡孔结构以及热稳定性能的影响。结果表明,短切芳纶纤维可以有效地增强酚醛泡沫的压缩性能。随着短切芳纶纤维用量的增加,酚醛泡沫的压缩强度和压缩弹性模量呈现先增加后减小的变化趋势。当短切芳纶纤维用量为4份时,酚醛泡沫的压缩强度比未添加短切芳纶纤维的酚醛泡沫提高约38%。短切芳纶纤维用量影响酚醛泡沫的泡体直径及其分布。当短切芳纶纤维用量为8份时,短切芳纶纤维在酚醛泡沫中的分布很不均匀,酚醛泡沫脆断截面上泡体破损现象较为严重,集束分布的短切芳纶纤维对酚醛泡沫的结构和力学性能带来不利影响。添加短切芳纶纤维可以明显提高酚醛泡沫在高温条件下(400℃)的热稳定性。     

短切碳纤维增强硬质聚氨酯泡沫复合材料压缩强度与形貌研究

本文研究了短切碳纤维增强硬质聚氨酯泡沫复合材料的压缩强度和形貌.探讨了不同短切碳纤维含量对硬质聚氨酯泡沫力学性能的影响,利用光学显微镜和扫描电镜观察了不同短切碳纤维含量情况下,硬质聚氨酯泡沫复合材料泡孔形成情况及试样破坏的微观相貌.研究结果表明,当短切碳纤维含量为30％时,硬质聚氨酯泡沫复合材料的压缩强度最大,泡体泡孔均匀致密;当短切碳纤维含量超过30％后,开始出现了大量闭孔和塌泡,碳纤维与聚氨酯泡孔剥离,力学强度下降.     

APP对硬质聚氨酯-酰亚胺泡沫泡孔结构及力学性能的影响

采用聚酰亚胺(PI)预聚法,合成由聚磷酸铵(APP)阻燃的硬质聚氨酯-酰亚胺泡沫塑料。分析了APP添加量对泡孔结构、泡沫结构参数、力学性能的影响以及三者之间的关系,并通过幂次法则建立起压缩性能、冲击性能与泡沫密度之间的关系。结果表明:随着APP添加量的增加,硬质聚氨酯-酰亚胺泡沫塑料的泡孔孔径和冲击强度减小,而泡沫密度、压缩强度和压缩模量均增大;冲击强度、压缩强度、压缩模量与泡沫密度之间的密度指数分别为-1.688、1.062和0.934;冲击性能和压缩性能与泡孔结构和孔隙率有密切关系。     

阻燃型全生物基多元醇聚氨酯泡沫的制备及性能研究

利用环氧大豆油分别与乙醇和苯基磷酸发生开环反应，制备了两种不同的大豆油基多元醇(Polyol-E与Polyol-PPOA)，将二者按照不同的配比与异氰酸酯(PM200)反应制备了硬质聚氨酯泡沫材料。对混合多元醇制备的硬质聚氨酯泡沫材料的泡孔结构、密度、力学性能及阻燃性能进行了测试和分析。测试结果表明，随着Polyol-PPOA质量分数的增加，样品的泡孔数量先减少后增加，泡孔尺寸先增大后减小。密度随着Polyol-PPOA的用量增加先增加后减小。压缩强度呈现先降低后升高的趋势，Polyol-PPOA为70%(质量)时的压缩强度达到0.133 MPa，在800℃时的残炭率达到17.57%，极限氧指数也在这时达到最高，为23.10%。     

化学发泡剂对吸油聚氨酯泡沫性能的影响

采用全水发泡体系,通过一步法制备了吸油聚氨酯泡沫材料。探究了化学发泡剂──水的用量对聚氨酯泡沫材料的密度、泡孔结构、吸油性能、吸水性能、拉伸强度的影响。结果表明:随着水用量的增加,发泡反应逐渐增强,聚氨酯泡沫的密度逐渐减低,泡孔尺寸逐渐增大,开孔结构增多;提高水的用量可以提高聚氨酯泡沫对油品的吸收能力,但是也会降低泡沫的拉伸强度,因而进一步增加水的用量没有实际意义。     

聚丁烯异相成核发泡行为的研究

以偶氮二甲酰胺（AC）为发泡剂,采用热塑模压的方法制备了聚丁烯泡沫材料。分别以滑石粉和碳酸钙为异相成核剂,根据经典成核理论,探究了不同种类成核剂的添加量及粒子尺寸对泡沫材料的力学性能与泡孔结构的影响。结果表明,随着成核剂添加量的增加,滑石粉与碳酸钙作为成核剂制备的泡沫材料的平均泡孔直径减小至135 μm,泡孔密度增加至7×105个/cm3;成核剂粒径越小,制得的泡沫材料泡孔密度越大,平均泡孔直径越小,粒径为10 μm的碳酸钙作为成核剂时,添加量为6 %时,制备的泡沫材料的泡孔密度达到106个/cm3,平均泡孔直径为85 μm。     

硫化体系对再生胶发泡性能的影响

采用跳模法对再生胶进行发泡,考察了硫黄、促进剂CZ、TMTD对再生胶发泡特性及发泡体物理机械性能的影响,并用体视显微镜表征了泡孔结构。结果表明,随着硫黄用量的增加,再生胶发泡体的密度增大,发泡率、收缩率、泡孔体积分数及泡孔直径均减小,邵尔C硬度和压缩强度增大;随着CZ用量的增加,再生胶发泡体的密度和泡孔直径减小,发泡率和泡孔体积分数先减小后增大,收缩率先增大后减小,压缩强度和邵尔C硬度均先减小后增大;随着TMTD用量的增加,再生胶发泡体的密度增大,发泡率和泡孔体积分数均减小,收缩率和泡孔直径先增大后减小,压缩强度增大后略有下降。     

纳米SiO2对以HFC-365mfc为发泡剂的硬质聚氨酯泡沫的性能影响研究

针对以HFC-365mfc为发泡剂制备的环保型硬质聚氨酯泡沫,从压缩强度、泡孔尺寸、扫描电子显微镜照片等多个角度探讨3种不同类型(亲水型:A200,疏水型:R974、R972)的纳米二氧化硅(SiO2)粒子对泡沫性能的影响。结果表明,随着疏水型纳米SiO2加入量的增加,泡沫的压缩强度呈现先降低再升高而后又降低的现象,当加入量为3%(质量分数,下同)时,压缩强度达到最大值,其中,R974效果优于R972;加入A200出现压缩强度降低的现象;泡孔尺寸均呈现先减小后增大的趋势。     

含溴环氧树脂对聚氨酯硬泡性能的影响

采用聚醚多元醇、多亚甲基多苯基多异氰酸酯(PAPI)、泡沫稳定剂、催化剂、高效阻燃剂、发泡剂、含溴环氧树脂等原料通过一步法制备了聚氨酯硬质泡沫材料,研究了不同含溴环氧树脂添加比例的聚氨酯硬质泡沫材料的压缩强度和阻燃指数。结果表明,随着含溴环氧树脂添加量的增加,压缩强度出现先增加后减少的趋势。在含溴环氧树脂添加量占白料总质量10%时,压缩性能最佳;随着含溴环氧树脂添加量的增加,聚氨酯硬泡的极限氧指数呈上升趋势;高效阻燃剂用量可以使改性聚氨酯硬泡极限氧指数得到显著增加,达到30%以上。     

TDI型聚氨酯酰亚胺泡沫的合成及性能研究

采用一步法合成了TDI型聚氨酯酰亚胺泡沫材料,讨论了水作部分发泡剂对泡沫材料性能的影响,采用体示显微镜观察了泡孔结构及孔径大小,测试了试样拉伸强度、撕裂强度、DSC和热重性能。结果表明,随着水用量的增大,泡孔尺寸变大,泡沫密度减小,拉伸强度和撕裂强度均下降,热重性能变化较小,聚氨酯段Tg升高,聚酰亚胺段Tg降低。     

Effects of 4,4′‐diaminodiphenyl ether on the structures and properties of isocyanate‐based polyimide foams

A series of thermal insulation, acoustic absorption isocyanate‐based lightweight polyimide (PI) foams with 4,4′‐diaminodiphenyl ether (ODA) units were prepared from polyaryl polymethylene isocyanate (PAPI) and the esterification solution derived from pyromellitic dianhydride (PMDA) and ODA. The structures and properties of the PI foams prepared with different molar ratio of ODA/PMDA were investigated in detail. The results show that the ODA units have great influence on the foam properties. With the increase of the ODA units, the density decreases firstly and then increases. When the molar ratio of ODA/PMDA is 3/10, the foam reaches the minimum density (13.7 kg/m³). Moreover, with increasing the ODA units, the acoustic absorption properties increase firstly and then decrease owing to the variation of the average cell diameter of the PI foams. All PI foams show excellent thermal stability, and the 5% and 10% weight loss temperature are in the range of 250–270 °C and 295–310 °C, respectively. In addition, the PI foams present low thermal conductivity and thermal diffusivity. Furthermore, the mechanical property was also evaluated and the compressive strength of the PI foams is in the range of 33.0–45.7 kPa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46029.     

石墨和碳纤维改性聚酰亚胺复合材料的导热性能

以石墨、碳纤维(CF)、聚酰亚胺(PI)三元复合材料为研究对象,考察了CF体积含量对PI三元复合材料导热性能的影响,并采用了拟二元体系模型探讨了石墨和CF填充PI复合材料的协同效应。结果表明,CF的加入可以提高复合材料的力学性能：拉伸强度呈现先升高后降低的趋势,当CF含量为11.8 %（体积分数,下同）时,拉伸强度可达66.37 MPa;弯曲强度随着CF体积含量的增而增加,当CF含量为24.6 %时,弯曲强度可达103.3 MPa。复合材料热导率呈非线性增长,表明石墨和CF间存在协同效应;当CF含量为34.1 %时,环境扫描电子显微镜分析表明,CF与石墨能很好地搭接,增大了传热面积,复合材料热导率可达0.512 W/(m·K),约是其计算值的2倍。     

Improved tribological properties of polyimide composites by micro–nano reinforcement

The hydroxylate carbon nanotubes (CNTs) were grafted by chemical method on the surface of the oxidized carbon fibers (CF) to improve the mechanical and tribological properties of polyimide (PI). The microstructure and fracture surface of the polyimide composites indicated that CF–CNTs hybrid as a multiscale reinforcement can distribute into the PI matrix homogeneously. Tribo-tests further showed that CF–CNTs hybrid had a better effect on hardness increment, impact strength enhancement, friction reduction, and wear resistance. Compared to the neat PI, the friction coefficient and wear rate of CF–CNTs/PI composite deceased by 23.2 and 55.9%, respectively. In particular, the loading capacity and high speed resistance of CF–CNTs/PI composite were greatly improved. The corresponding wear mechanisms were also discussed by observing the worn surface of the PI composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47900.     

Effect of Dibutyltin Dilaurate and Triethanolamine Catalysts on Structure and Properties of Polyimide Foams

A series of rigid polyimide (PI) foams were prepared by the prepolymer method with pyromellitic dianhydride and polyaryl polymethylene isocyanate as the starting materials and dibutyltin dilaurate (DBTDL), and triethanolamine (TEOA) as catalysts. The effect of the two kinds of catalysts on the structure and properties such as molecular structure, cell morphology, density, mechanical properties, thermal properties, and flame retardancy of the resulting foams were characterized in detail. The experimental results showed that the PI foams prepared in this work possessed low density, good mechanical properties, outstanding thermal stability, and excellent flame retardancy. The thermal stability and flame retardancy were improved obviously with the increase of DBTDL content. While with the increase of the content of TEOA, the mechanical strength and apparent density of PI foams increased significantly. Therefore, different structure and performance of PI foams can be prepared by adjusting the content of these two catalysts. J. VINYL ADDIT. TECHNOL., 25:385–395, 2019. © 2019 Society of Plastics Engineers     

聚酰亚胺/多壁碳纳米管泡沫材料的制备及性能研究

将不同质量分数的多壁碳纳米管（MWCNT）与PI通过原位聚合制备了聚酰亚胺（PI）/MWCNT泡沫复合材料,并利用扫描电子显微镜、热失重等仪器对材料性能进行了测试。结果表明,随着MWCNT质量分数的增加,泡孔直径增大,泡沫密度降低,当MWCNT含量超过0.4 %（质量分数,下同）易发生团聚作用,限制了泡沫结构的形成,导致泡沫的形状不规则;在添加0.2 %的MWCNT时,压缩强度、压缩模量、硬度获得了最好的增强效果,并发现增强效果随MWCNT质量分数的增加增强效果呈现先增大后降低的趋势;样品的热稳定性在添加0.05 %质量分数的MWCNT时达到最佳水平。     

天然鳞片石墨/环氧树脂复合材料的制备及导热性能研究

以天然鳞片石墨为导热填料,E44型环氧树脂为基体,采用超声分散法制备天然鳞片石墨/环氧树脂复合导热材料.系统考察了天然鳞片石墨用量、石墨粒度和炭黑添加量等因素对复合材料导热性能的影响.结果表明:随着天然鳞片石墨用量增加,复合材料的导热系数增大,抗压强度先增加后减小;复合材料的导热系数随天然石墨粒径的增大而增大,抗压强度先减小后增加;在石墨/环氧树脂复合导热材料中添加不同用量的炭黑时,随着炭黑添加量的增加,复合材料的抗压强度增大,导热系数先增大后减小.制备天然鳞片石墨/环氧树脂复合导热材料的最佳配方为天然鳞片石墨用量45％,粒径≤270 μm,炭黑用量2％.     

Effect of organoclay on the morphology,mechanical, and thermal properties of polyimide/organoclay nanocomposite foams

A series of polyimide (PI)/organoclay nanocomposite foams containing different contents of organoclay were prepared by the monomer in situ intercalative polymerization. The effect of organoclay on the chemical structure, morphology, mechanical, and thermal properties of the nanocomposite foams was studied. Fourier transform infrared spectra showed that the hydrogen bonds between organoclay and the polymer matrix were formed. X‐ray diffraction and transmission electron microscope results indicated that the organoclay were well dispersed in the PI matrix. The compressive strength and tensile strength of the nanocomposite foams enhanced significantly, especially for the nanocomposite foam containing 4 wt% organoclay, increasing by 15% and 9%, respectively, compared with these of the neat PI foam, and the presence of the organoclay in the PI foam improved apparently the cellular structure of the nanocomposite foams. Besides, thermogravimetric analysis revealed that the addition of organoclay improved the thermal stability of the nanocomposite foams strongly, and dynamic mechanical analysis indicated that the incorporation of organoclay significantly influenced the storage modulus of the nanocomposite foams. POLYM. COMPOS., 35:2311–2317, 2014. © 2014 Society of Plastics Engineers     

PP/POE/CaCO3复合材料的性能研究

采用熔融共混工艺制备了聚丙烯/聚烯烃弹性体/碳酸钙(PP/POE/CaCO3)复合材料,研究了POE及CaCO3用量对复合材料力学性能、流变性能及热性能的影响。结果表明:随着POE含量的增加,复合材料的冲击强度显著增大,当POE含量为12%时,冲击强度较纯PP增加233%;同时拉伸强度随POE含量的增加缓慢下降。随着CaCO3含量增加,冲击强度先增加后缓慢下降。     

Graphene induced carbonization of polyimide films to prepared flexible carbon films with improving-thermal conductivity

Carbon films prepared by polyimide (PI) films treated under 1500°C exhibit favorable thermal conductivity. However, the bonds of carbon films will fracture and recombine which will cause shrinking and forming defects. The flexibility of the carbon films will be greatly reduced, and then affect the application of the carbon films in the field of thermal conduction. When the films prepared by the graphene oxide/polyimide (GO/PI) composite films and the reduced graphene oxide/polyimide (rGO/PI) composite films, respectively, rGO and GO can fill the defects, then increasing the flexibility of the carbon films and inducing the carbonation process. Because of the high thermal conductivity and the six-membered ring structure of rGO and GO, the carbonization temperature will decrease and save costs. When the composite films treated under 1500°C, the thermal conductivity increases with the content of rGO and GO. There are connections between PI and graphene. As the amount of rGO and GO increases, the strong interactions between the rGO or GO and PI lead to contact that enhances its thermal conductivity. However, the rGO and GO have different effects on the films flexibility and thermal conductivity and the differences will be described in the article.     

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