助交联剂对过氧化物硫化EPDM/白炭黑胶料力学性能的影响

分别采用三官能团丙烯酸酯、三羟甲基丙烷三甲基丙烯酸酯、N,N'-间苯基双马来酰亚胺、三烯丙基异氰尿酸酯作为过氧化物硫化EPDM的助交联剂,研究了助交联剂的品种和用量对EPDM/白炭黑胶料的硫化特性、力学性能、压缩永久变形性能和动态力学性能的影响.结果表明,添加助交联剂的胶料比空白试样的硫化最大转矩、定伸应力和硬度均有明...     

助交联剂TAC和TAIC对EPDM过氧化物硫化的影响

研究了三烯丙基氰脲酸酯（ＴＡＣ）和三烯丙基异氰脲酸酯（ＴＡＩＣ）对ＥＰＤＭ过氧化物硫化特性参数的影响,并以平衡溶胀和傅立叶转换红外光谱（ＦＴ－ＩＲ）分析对二的硫化反应机理进行了探讨。试验结果表明,助交联剂ＴＡＣ和ＴＡＩＣ提高了ＥＰＤＭ的交联程度和硫化速度;平衡溶胀及ＦＴ－ＩＲ分析表明,助交联剂ＴＡＣ和ＴＡＩＣ与ＥＰＤＭ可能发生接枝和共交联反应,形成活性剂桥键,从而提高了体系的交联密度。     

用TMPTA加速EPDM的交联反应过程

采用三羟甲基丙烷三丙烯酸酯（ＴＭＰＴＡ）作共交联剂,研究其对ＥＰＤＭ的过氧化物硫化行为、力学性能及老化性能的影响。结果表明,ＴＭＰＴＡ可降低混炼胶料的粘度,缩短正硫化时间,提高交联效率,改善力学性能,提高耐老化性能等。     

EPDM耐高温潜油电缆胶料的研制

介绍了QYEQ型EPDM耐高温潜油电缆胶料的研制。用正交试验法确定的耐高温潜油电缆胶料配方为 :EPDM　 10 0 ;氧化锌　 5 ;防老剂　 2 ;硫化剂DCP　 4;煅烧陶土　 5 0 ;四氧化三铅　 5 ;石蜡　 4;滑石粉　 10 ;半补强炭黑　 1;偶联剂A 172　 2。用该配方胶料制备的QYEQ型耐高温潜油电缆性能达到GB/T 1675 0— 1997和IEEE10 18— 1997标准。     

助交联剂PDM和硫黄用量对CM/EPDM并用胶性能的影响

试验研究在过氧化物硫化体系下助交联剂N,N'-间亚苯基双马来酰亚胺(PDM)和硫黄用量对氯化聚乙烯橡胶(CM)/EPDM并用胶性能的影响.结果表明:在硫化剂DCP/助交联剂PDM硫化体系下,当硫化剂DCP用量为3份、助交联剂PDM用量为1.5～2份时,CM/EPDM并用胶的综合性能较好;在硫化剂DCP/硫黄硫化体系下,...     

耐高温潜油电缆EPDM绝缘层胶料配方的研究

介绍耐高温潜油电缆EPDM绝缘层胶料配方的研究。结果表明，采用主体材料为牌号JSR EP33的EPDM(第三单体亚乙基降冰片烯质量分数为0．4～0．6．丙烯质量分数为0．4～0．5)、硫化体系为硫化剂DCP／甲基丙烯酸锌并用体系、防护体系为防老剂NAPM／RD／石蜡并用体系、增塑剂为SUNPAR2280的配合，绝缘层胶料的性能较好；采用两次高温硫化工艺制备的成品电缆长期使用温度为180℃，冲击使用温度为190℃．最高使用温度为200℃。     

废轮胎胶粉在EPDM胶料中的应用

介绍了废轮胎胶粉在EPDM胶料中的应用。试验结果表明，采用过氧化物/硫黄并用硫化体系，胶粉(60目)用量达到30份，EPDM硫化胶的性能仍然较好；胶粉改性剂选用热固性酚醛树脂较好；胶粉粒径越小，EPDM硫化胶的性能越好。     

过氧化物交联剂对PP/EPDM/SEBS三元体系性能的影响

采用过氧化物交联剂动态硫化聚丙烯(PP)/三元乙丙橡胶(EPDM)/苯乙烯-乙烯-丁烯-苯乙烯(SEBS)三元体系,并研究了交联剂对三元体系性能的影响.结果表明,随着过氧化物交联剂用量增加,体系的拉伸强度和熔体流动速率增加,断裂伸长率和撕裂强度降低,压缩永久形变呈现先降低然后略有增加的变化趋势,当交联剂用量为8份时达到最小值(70℃和125℃分别为21.9％和28.6％),比未添加SEBS时分别降低12％和23.1％,说明复配SEBS对弹性改善效果明显;体系表观黏度随着剪切速率的增加而降低,呈现剪切变稀现象,动态硫化后的表观黏度比未硫化时有明显降低.所得材料中检测不到卤素和重金属,符合无卤化和绿色环保要求.     

Drying Foodstuffs with Superheated Steam

Abstract

A thin-layer superheated steam drier was constructed with the objective of determining the drying characteristics, drying rates, and the effect of superheated steam on product quality in thin-layers. Results from superheated steam drying experiments with sugar-beet pulp, potatoes, Asian noodles, and spent grains indicate that drying times and rates increase with increasing steam temperature. For sugar-beet pulp it was also found that these changes were more significant than increases seen by hot-air drying under the same conditions and that drying rates were not affected by velocity for hot air but were increased for superheated steam. When quality aspects were examined, superheated steam dried Asian noodles saw both beneficial changes to recovery, adhesiveness, and gumminess while parameters of maximum cutting stress, resistance to compression, and surface firmness saw deleterious effects. Spent grains saw high levels of starch gelatinization and retention of fibre content.

     

Drying Foodstuffs with Superheated Steam

A thin-layer superheated steam drier was constructed with the objective of determining the drying characteristics, drying rates, and the effect of superheated steam on product quality in thin-layers. Results from superheated steam drying experiments with sugar-beet pulp, potatoes, Asian noodles, and spent grains indicate that drying times and rates increase with increasing steam temperature. For sugar-beet pulp it was also found that these changes were more significant than increases seen by hot-air drying under the same conditions and that drying rates were not affected by velocity for hot air but were increased for superheated steam. When quality aspects were examined, superheated steam dried Asian noodles saw both beneficial changes to recovery, adhesiveness, and gumminess while parameters of maximum cutting stress, resistance to compression, and surface firmness saw deleterious effects. Spent grains saw high levels of starch gelatinization and retention of fibre content.     

Superheated Steam Vacuum Drying of Rubberwood

The effect of superheated steam vacuum drying (SSVD) on the drying time and mechanical properties of rubberwood was studied. Rubberwood boards with dimensions of 1000 mm × 76.2 mm × 25.4 mm were dried at 86.7–89.3 kPa vacuum pressure (14.6–12.0 kPa absolute) and temperatures of 60, 70, and 80°C. Superheated steam at 110°C was injected intermittently to relieve stress buildup in wood and eliminate cracking. The prong test was used to evaluate the initial acceptability of the dried wood and the mechanical properties of wood were measured. From this study, the total drying time was reduced from 168 h to less than 20 h (MC reduction from 0.80 to 0.06 db). In addition, compared to the reference values shown in the parentheses, the shear parallel-to-grain, the compression parallel-to-grain, the compression perpendicular-to-grain, the modulus of rupture (MOR), the modulus of elasticity (MOE), and the hardness for the optimum drying temperature of 70°C were 28.87 (11.0) MPa, 59.09 (32.0) MPa, 21.09 (5.0) MPa, 101.97 (66.0) MPa, 9838.5 (9240.0) MPa, and 6475 (4350) N, respectively. Thus, the vacuum-dried wood showed a 32% increase in hardness, a 12% increase in compression parallel-to-grain, and an 88% increase in shear parallel-to-grain.     

Modeling Superheated Steam Vacuum Drying of Wood

Abstract

A two-dimensional mathematical model developed for vacuum-contact drying of wood was adapted to simulate superheated steam vacuum drying. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady-state mass conservation of dry air. A drying test conducted on sugar maple sapwood in a laboratory vacuum kiln was used to infer the convective mass and heat transfer coefficients through a curve fitting technique. The average air velocity was 2.5 m s^?1 and the dry-bulb temperature varied between 60 and 66°C. The ambient pressure varied from 15 to 11 kPa. Simulation results indicate that heat and mass transfer coefficients are moisture content dependent. The simulated drying curve based on transfer coefficients calculated from boundary layer theory poorly fits experimental results. The functional relation for the relative permeability of wood to air is a key parameter in predicting the pressure evolution in wood in the course of drying. In the case of small vacuum kilns, radiant heat can contribute substantially to the total heat transfer to the evaporative surface at the early stages of drying. As for conventional drying, the air velocity could be reduced at the latter stage of drying with little or no change to the drying rate.     

Modeling Superheated Steam Vacuum Drying of Wood

A two-dimensional mathematical model developed for vacuum-contact drying of wood was adapted to simulate superheated steam vacuum drying. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady-state mass conservation of dry air. A drying test conducted on sugar maple sapwood in a laboratory vacuum kiln was used to infer the convective mass and heat transfer coefficients through a curve fitting technique. The average air velocity was 2.5 m s^-1 and the dry-bulb temperature varied between 60 and 66°C. The ambient pressure varied from 15 to 11 kPa. Simulation results indicate that heat and mass transfer coefficients are moisture content dependent. The simulated drying curve based on transfer coefficients calculated from boundary layer theory poorly fits experimental results. The functional relation for the relative permeability of wood to air is a key parameter in predicting the pressure evolution in wood in the course of drying. In the case of small vacuum kilns, radiant heat can contribute substantially to the total heat transfer to the evaporative surface at the early stages of drying. As for conventional drying, the air velocity could be reduced at the latter stage of drying with little or no change to the drying rate.     

过热蒸汽改善水敏性稠油油藏开发效果研究

本文通过室内单管模型对某水敏感性稠油油藏的现场油砂进行了不同流体岩心流动实验,对比了岩心在相同温度条件下的热水、饱和蒸汽、过热蒸汽三种不同流体下的渗透率恢复率。通过X衍射分析,研究了岩心中粘土矿物与过热蒸汽作用下的变化规律。实验结果表明:过热蒸汽具有永久改善水敏性储层渗透率的特点,对水敏性储层渗透率恢复明显高于热水、普通蒸汽。在室内研究的基础上,进行了注过热蒸汽吞吐开发矿场试验,对比前期普通蒸汽开发效果,注过热蒸汽吞吐可提高日产量4~6倍,效果显著。     

Drying Western Red Cedar with Superheated Steam

This exploratory study evaluated the possibility of drying 50-mm-thick western red cedar with superheated steam. Since there are no industrial facilities in Canada drying western red cedar with superheated steam, the study was designed to explore the potential of this technology in terms of lumber quality, moisture content distribution, and drying time. The experiments showed that the 50-mm-thick product can be dried in less than three days without jeopardizing lumber quality (in comparison with the two weeks that is currently required in conventional kilns), and the percentage of pieces that remained wet after drying was within the 10% to 15% range that is typically tolerated in industry.     

Simulation of Superheated Steam Drying from Coupling Models

Modeling of the transfer between a porous medium and its surroundings is commonly made using transfer coefficients that are theoretically well known only under boundary layer hypothesis. The resolution of Navier–Stokes equations in the surroundings of the product in order to get information about the boundary conditions avoids the classical use of these transfer coefficients. In this article, a modeling and a simulation of superheated steam drying of a rectangular piece of porous medium is proposed using a coupling method between a porous medium code and a CFD software. In some cases of superheated steam drying, even if a thermal boundary layer exists, a mass boundary layer cannot be defined. Moreover, boiling occurs during the process. An analysis of the interfacial transfer coupled with the analysis of the temperature, moisture content, and pressure profiles inside the porous medium is proposed.     

过热蒸汽干燥技术的研究进展

过热蒸汽干燥技术具有安全、节能、环保等诸多优点,越来越受到广泛关注。对过热蒸汽干燥技术进行了简介,分析了其优缺点。总结了过热蒸汽干燥的理论研究进展,并对过热蒸汽干燥技术在食品、木材、纸张、污泥和和褐煤等物料的应用现状进行了综合评述。总而言之,过热蒸汽干燥技术是一种先进的干燥技术,具有广阔的应用前景。     

Simulation of Superheated Steam Drying from Coupling Models

Modeling of the transfer between a porous medium and its surroundings is commonly made using transfer coefficients that are theoretically well known only under boundary layer hypothesis. The resolution of Navier-Stokes equations in the surroundings of the product in order to get information about the boundary conditions avoids the classical use of these transfer coefficients. In this article, a modeling and a simulation of superheated steam drying of a rectangular piece of porous medium is proposed using a coupling method between a porous medium code and a CFD software. In some cases of superheated steam drying, even if a thermal boundary layer exists, a mass boundary layer cannot be defined. Moreover, boiling occurs during the process. An analysis of the interfacial transfer coupled with the analysis of the temperature, moisture content, and pressure profiles inside the porous medium is proposed.