中空玻璃密封胶固化后产生气泡的原因分析

本文通过现场制样和试验摸拟的方法分析气泡产生的原因，总结出气泡产生主要在于密封胶中添加了含氢硅油、表干时间过快导致固化反应放出的小分子副产物在固化胶中释放不出来、密封胶已过适用期形成像气泡的“胶疙瘩”、换桶时桶中及胶表层混入的空气没有排放干净、双组份打胶机有漏气的地方、施胶不规范以及手工混胶不可避免会引起机械气泡等原因，同时强化密封胶“适用期”的概含。旨在于使中空玻璃生产厂家在使用密封胶过程中固化胶内有气泡产生时及早排查出原因并采取相应的纠正和预防措施。     

聚醚型聚氨酯密封胶适用期的主要影响因素

聚氨酯密封胶,根据固化方式的不同,分单组分和双组分型。就双组分型而言,按工程的不同,要求密封胶具有不同的适用期。聚氨酯密封胶的制造及应用虽然有文献记载,但对影响适用期诸因素的研究报导尚少。本文的目的,在于探索影响适用期的因素,从而为正确选择材料、设计配方及固化方法提供依据。     

加热和湿气双重固化聚氨酯胶的制备和性能研究

通过控制配方中NCO值,配合环氧树脂、改性胺助剂,制备了能在加热和湿气条件下双重固化的聚氨酯胶,并探讨了NCO值、环氧树脂用量、固化温度和时间、改性胺用量对聚氨酯胶性能的影响。研究结果表明:加热和湿气双重固化的密封胶,解决了普通聚氨酯胶在高温烘烤过程中固化起气泡的问题。     

中空玻璃密封胶气泡的危害及控制

固化后的中空玻璃密封胶如果表面或内部存在大量的气泡或胶疙瘩（假气泡）,小但会影响中空玻璃的外观,而且会显著降低中空玻璃的黏结强度、位移能力和密封性能,形成不良密封或引起黏结失效,成为结构装配的安全隐患。本文通过检测数据展现气泡或“胶疙瘩”所产生的危害,并针对各种因素造成的气泡提出了预防措施和解决对策。     

汽车涂装中门折边PVC密封胶气泡原因分析与改善

汽车涂装使用的PVC胶通常分为焊缝密封胶和防石击底涂胶,主要用于车身门盖折边、钣金搭接区域、裸露的切边、车身底盘等部位,作用是增加车身的密封性、耐久性及装饰性,同时达到减震降噪的目的,提高车身的抗腐蚀能力。防石击底涂胶由于位置、材料黏度较低等特性,质量问题较少,但焊缝密封胶经常出现涂胶气泡等问题。结合某生产现场新车型投产时中门盖折边胶气泡原因分析与改善过程,讨论了PVC焊缝密封胶的材料特性、涂胶烘干过程、输胶系统、焊装折边胶等因素对密封胶气泡的影响,并制定了有效的控制措施,降低气泡发生的频次。     

SE-7单组分环氧胶粘剂研制

一、概述作为精细化学品的胶粘剂,品种日益增多,以功能分有结构胶、非(半)结构胶、密封胶等。环氧胶粘剂属高性能结构胶,在结构胶方面占支配地位,有单组份环氧胶、室温固化胶和胶膜等品种。单组份环氧胶是将基料、添加剂及固化剂等各组份调配包装而成,又称一液型环氧胶。其特性是有一定的贮存期(对单组份环氧胶而言即适用期),放置数月不固化,可随时使用,无需临时称量搅拌配制,在使用过程中无     

木质素基聚氨酯密封胶的制备与表征

木质素是一种含有羟基的三维网状天然高分子,因其存在醇羟基和酚羟基,被广泛用于聚氨酯领域。采用木质素与聚醚二元醇,制备了木质素基聚氨酯密封胶。对合成的木质素基聚氨酯预聚体进行了FT-IR和TG分析,并探讨了木质素与聚醚二元醇的羟基比对预聚体性能的影响以及Ca CO3和潜固化剂对木质素基聚氨酯密封胶性能的影响。结果表明:木质素基聚氨酯密封胶预聚体中木质素与二元醇羟基物质的量比为2∶1时,拉伸强度可达2.38MPa、断裂伸长率为576%。聚氨酯密封胶中引入木质素使得聚氨酯密封胶在热分解初期热失重量较高,但后期热分解的剩余物保留率高。在木质素基聚氨酯密封胶加入不超过50%碳酸钙时,随着碳酸钙添加量的增加断裂伸长率降低,拉伸强度则随着碳酸钙添加量的增加而增加。噁唑烷类潜固化剂能够有效降低单组分湿固化聚氨酯密封胶在固化时胶层中的气泡。     

沸石分子筛对消除聚氨酯胶粘剂固化气泡作用的研究

研究了13X沸石分子筛对双组分聚氨酯胶粘剂固化性能的影响。结果表明,13X分子筛含量为3%～5%时,不仅可延长聚氨酯胶粘剂的适用期,而且还可消除聚氨酯胶粘剂固化后产生的气泡。     

轮胎气泡产生的原因分析及解决措施

探讨轮胎气泡产生的原因分析并提出相应的解决措施。轮胎气泡产生的原因是:原材料的水分和油分含量超标;胎面部件挤出前胶料返炼时堆积胶过多、割刀次数不够;胎面接头过大、不平整,帘布筒成型时形成褶子,胎面与帘布层间压合不实;水胎、胶囊泄漏等。采取相应的原材料质量控制和工艺控制措施后,轮胎出现气泡的问题得到有效解决。     

全钢载重子午线轮胎气泡的产生原因及解决措施

分析了全钢载重子午线轮胎各种气泡的产生原因，并提出了解决措施。如三角胶端点不能太厚．三角胶挤出时需控制好温度和速度；宜选用两辊或型辊挤出法制备内衬层和密封胶层的复合件；成型风压需控制在0．6MPa以上；成型胎坯的停放时间应稍长。     

低模量单组份聚氨酯密封胶的研制

以聚醚多元醇、TDI、MDI、增塑剂为原料合成聚氨酯预聚体,添加滑石粉、触变剂、潜固化剂等助剂研制出一种无泡、低模量、高弹性的单组份聚氨酯密封胶,探讨了聚醚多元醇、潜固化剂、气相二氧化硅对密封胶性能的影响。结果表明,该密封胶配方的适宜配比为n(TDI)/n(MDI)=2～2.5、n(-NCO)/n(-OH)=1.7～1.9、潜固化剂含量1.2%～1.5%、气相二氧化硅含量1.5%～2.5%。     

单组分湿固化型聚氨酯密封胶催化剂的研究

单组分湿固化型聚氨酯密封胶是一种发展前景很好的密封胶 ,而催化剂是影响其性能的重要因素之一。本文讨论了该类密封胶所用催化剂的种类及其催化效果以及催化剂对材料发泡性的影响     

Countercurrent cooling of blown film

Presently used methods for the external cooling of blown film involve the use of an air ring located at the base of the bubble that blows air upward along the surface of the bubble. The air is heated as it rises, while the film is cooling and moving in the same direction. This is an example of cocurrent heat exchange, and the result is the accumulation of heated air around the upper portion of the bubble, which interferes with the cooling in this region. While rapid initial cooling is required to maintain bubble stability, we have explored the possibility of using countercurrent cooling for the upper region of the bubble. A standard air ring is mounted at the base of the bubble, and a circular shroud surrounds the bubble above this air ring. All the heated air is collected in an upper chamber surrounding the shroud and is exhausted by means of a secondary blower. The proposed scheme was found to increase heat transfer in the upper regions of the bubble and to permit the ducting of all heated air away from the film line.     

Migration of a single gas bubble in water during the formation of stable gas-hydrate crust on its surface

A theoretical model of gas-hydrate formation during the migration of the methane bubble in water under thermobaric conditions of hydrate stability has been considered. Numeric solutions were obtained and analyzed for two limiting cases when the rate of formation of the hydrate crust on bubble surface is constrained by the intensity of heat removal, which is released during hydrate-formation process by the surrounding water or the diffusive resistance of gas hydrate crust against the transfer of hydrate-forming components. A comparative analysis of the numeric results with the experimental data showed that the diffusive transfer of hydrate-forming components through the crust most adequately described the process of hydrate-particle growth that was observed in experiments during the ascent of methane particles in seawater. The conditions of the best agreement between the theoretical and experimental data on changing of radius of gas-hydrate particle allowed numeric estimates to be obtained for values of the reduced coefficient of gas and water diffusion through the hydrate crust.     

导电聚硫密封剂研究

随着电子行业的飞速发展,电子设备对电磁环境的要求也更加苛刻,电子设备箱的密封需要使用具备导电功能的密封剂。本文研究了导电炭黑对聚硫密封剂导电性能和力学性能的影响,确定了导电炭黑在聚硫密封剂中的最佳用量,还研究了热空气老化对导电聚硫密封剂性能的影响。结果表明,研究的导电聚硫密封剂可以在高温环境中使用。     

环氧树脂对聚硫密封胶耐高温性能的影响

环氧树脂是聚硫密封胶常用的增粘剂,在聚硫密封胶中加入环氧树脂可以起到明显的增粘作用。试验发现,环氧树脂对聚硫密封胶的多项性能都有不同程度的影响。通过力学性能测试等手段,研究了环氧树脂对聚硫密封胶耐高温空气和耐高温燃油性能的影响,分析了环氧树脂提高聚硫密封胶耐高温性能的原理。     

Buoyancy-driven motion of bubbles in square channels

The motion of air bubbles in square capillaries moving under the influence of gravity is studied over a range of Reynolds numbers. The steady shapes and velocities of the bubbles as a function of the bubble size are determined experimentally at moderate Bond and capillary numbers. Bubbles are nearly spherical at lower bubble volumes and become prolate losing their fore and aft symmetry at larger bubble volumes. At higher Weber numbers, a reentrant cavity develops at the rear of bubble. The critical Weber number at which this shape transition occurs lies between 0.89 and 1.38. At small Weber numbers, the terminal velocity of bubbles increases monotonically with bubble volume and eventually reaches a plateau value, which is independent of the bubble size. At higher Weber numbers, a maxima develops in the velocity-volume curve at moderate bubble sizes which grows in magnitude as the Weber number increases. Even at small bubble volumes with nearly spherical shape, the terminal velocity of the bubbles is less than the Hadamard-Rybczynski velocity due to the wall drag. The speed and the maximum bubble width for air bubbles rising in a square channel is higher than that of an air bubble rising in a circular channel with the same hydraulic diameter. The experimental data compares well with predicted trends in the viscous and inertial limits for long bubbles.     

Experimental Study of the Aging and Self-Healing of the Glass/Ceramic Sealant Used in SOFCs

High operating temperatures of solid oxide fuel cells (SOFCs) require that the sealant must function at a high temperature between 600°C and 900°C and in the oxidizing and reducing environments of fuel and air. This paper describes tests to investigate the temporal evolution of the volume fraction of ceramic phases, the evolution of micro-damage, and the self-healing behavior of the glass–ceramic sealant used in SOFCs. It was found that after the initial sintering process, further crystallization of the glass–ceramic sealant does not stop, but slows down and reduces the residual glass content while boosting the ceramic crystalline content. Under a long-term operating environment, distinct fibrous and needle-like crystals in the amorphous phase disappeared, and smeared/diffused phase boundaries between the glass phase and ceramic phase were observed. Meanwhile, the micro-damage was induced by the cooling down process from the operating temperature to room temperature, which can potentially degrade the mechanical properties of the glass/ceramic sealant. The glass/ceramic sealant exhibited self-healing upon reheating to the SOFC operating temperature, which can restore the mechanical performance of the glass/ceramic sealant.     

Experimental studies on the instabilities of viscous fingering in a Hele-Shaw cell

When air is injected into silicone oil contained in a horizontal Hele-Shaw cell, a single air bubble forms and grows showing various interesting phenomena. In this study the effects of the bubble front velocity, air injection velocity at a nozzle, fluid properties and cell depth on the stability of the growing bubble were investigated experimentally. By using the modified capillary number involving the aspect ratio, we obtained the onset conditions of the unstable bubble. Also, the bubble width was analyzed both quantitatively and qualitatively. Before the bubble experiences splitting, the bubble front velocity is almost proportional to the air injection velocity. Therefore the latter velocity may be used in a practical sense.