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51.
52.
D. Thoenes 《Chemical engineering science》1980,35(9):1840-1853
Modelling of chemical reactors is reviewed with an emphasis on process development and scale-up. A distinction is made between modelling of chemical kinetics, of rate processes in volume elements and of whole reactors. Examples are mainly taken from papers presented at the Sixth International Symposium on Chemical Reaction Engineering. Special attention is given to the modelling of single phase reactors, fixed beds, trickle beds, fluid beds, and gas bubble reactors. 相似文献
53.
介绍了可提高塑料混合时冷却效率的双工质塑料冷混机,并简要叙述了立式,卧式和立式搅龙双工质冷混机却装置冷却物料的工序。 相似文献
54.
55.
张卓 《现代塑料加工应用》1994,6(6):47-48
介绍了在原有吹制LDPE地膜设备上(挤出机长径比为20:1)吹制LDPE、LLDPE和HDPE共混微膜和超薄微膜,采用高速混合法的混料工艺达到了良好的预热效果,弥补了挤出机长径比小的不足。 相似文献
56.
The effects of mixing temperature and mixing time on the reaction of 3‐octanoylthio‐1‐propyltriethoxysilane (NXT silane) during mixing with precipitated silica and natural rubber (NR) were investigated. Results showed that the reaction between NXT silane and precipitated silica can proceed at temperatures above 130°C. Because of the blocking group of NXT silane, the silane–NR coupling reactivity is low, so that the reaction of NXT silane with NR occurs only during the curing period. There is no reaction between NXT silane and NR during mixing, which showed that the mixing time of silica‐filled NR compound containing NXT silane must be longer than 10 min at 150°C to obtain the desired silane coupling efficiency. With increasing mill temperature, the coupling efficiency increases. A high mixing temperature promotes improvement of silane–silica coupling efficiency, although the tensile strength, 100% modulus, 300% modulus, and hardness of NR vulcanizates decrease. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2295–2301, 2004 相似文献
57.
Statistical properties of interparticle/void distance (ID) for various particle/void and dispersion types are studied in relation with toughening of plastics using computer‐generated three‐dimensional models. Particle/void size groups adopted were either of constant diameter or of log‐normal distribution. Particles/voids were dispersed at uniform‐random or flocculated with multiple clusters. It was found that IDs are (a) of approximately Gaussian distribution for particles/voids of either a constant diameter or a log‐normal distribution, when they are dispersed at uniform‐random, but (b) not of Gaussian distribution for particle/void sizes of bimodal log‐normal distribution, nor for flocculated log‐normal distribution of particles/voids dispersed with multiple clusters. It was also found that the degree of ID uniformity for a single group of log‐normally sized particles/voids is not sensitive to standard deviation of particle/void size. Mixing effect on ID properties using two groups of log‐normally distributed particles/voids with similar mean particle/void diameters was simulated. It was found that, when a significant amount (36 vol %) of particles/voids of a small mean and standard deviation of ID was mixed with a group of particles/voids of a large mean and standard deviation of ID, mean and standard deviation of ID for the mixture were not substantially lower than those of the group of particles/voids of the large mean and standard deviation of ID. It was also found that the degree of ID uniformity for the mixture of the two groups was lower than those of individual groups, indicating that the mixing has deleterious effect on toughening. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4256–4262, 2006 相似文献
58.
Global hydrodynamic characteristics, liquid mixing and gas‐liquid mass transfer for a 63 L split‐rectangular airlift reactor were studied. Correlations for gas holdup and overall liquid circulation velocity were derived for the air‐water system as a function of the specific power input; these were compared to data and correlations for reactor volumes between 4.7 L and 4600 L. A partial recirculation of small bubbles in the riser was observed when Ugr > 0.03 m/s, which was attributed to the use of a single‐orifice nozzle as the gas phase distributor. The dimensionless mixing time and the overall axial dispersion coefficient were nearly constant for the range of gas flow rates studied. However, values of KL/dB were greater than those reported in previous studies and this is caused by the partial recirculation of the gas phase in the riser. While scale effects remain slight, the use of a gas distributor favouring this partial recirculation seems adequate for mass transfer in split‐rectangular airlift reactors. 相似文献
59.
Two series of siloxane-urethane copolymers were prepared from polydimethylsiloxane (PDMS) with a molecular weight of 1000 or 1800 which was used as a soft segment, 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (1,4-BD). Differential scanning calorimetry (DSC) demonstrated that the position (Tgs) and breadth (ΔB) of soft-segment glass transition of copolymers remained constant as the hard-segment content increased. Heat capacities at soft-segment glass transition of the copolymer (ΔCp) were 0.195∼0.411 J/g○C and heat capacities of pure PDMS (ΔCp0) were 0.571∼0.647 J/g○C, leading to the various ΔCp/ΔCp0 ratios. The ΔCp/ΔCp0 ratios decreased as the increasing of hard-segment content, showing poor phase separation. The FTIR spectrum confirmed the occurrence of hydrogen bonding in ether end-group of pure PDMS. The ether group of the soft segment led to interfacial mixing between soft and hard segments. The tan δ of the soft segment determined by dynamic mechanical testing (DMA) also identified the mixing of soft and hard segments. The mechanical properties of the copolymer were directly related to either the soft and hard segment contents or the chain lengths of soft and hard segments. The hard segment that reinforced the soft segment and interfacial thickness between soft and hard segment dominated the mechanical properties. 相似文献
60.
分析螺槽中熔体的流动状态 ,运用加权平均总应变来评价螺杆挤压机的混合能力 ,进而提出提高混合能力的途径。对于单螺纹螺杆 ,稍长的计量段 ,稍浅的计量段螺槽及较高的螺杆转速 ,有利于混合作用 ;开发新型螺杆 ,如犁钉分流混合螺杆 ;研制高效混合型螺杆挤压机 ,如球窝型高效混合型螺杆挤压机 相似文献