密炼机中橡胶混炼的流变理论及应用

介绍了密炼机中橡胶混炼的流变理论,即混炼的主要阶段胶料呈粘弹性流体,胶料的混炼工艺主要由胶料粘度决定,胶料达到最佳粘度时,混炼工艺最优。密炼机功率曲线反映了密炼室中胶料的混炼状态,通过功率曲线可以分析判断胶料的混炼工艺情况,根据密炼机中橡胶混炼的流变理论,开发了MLJ－300型密炼机微机智能控制系统,该系统可以对混炼工艺进行自动或半自动优化,根据胶料配方和 炼机性能可建立混炼 炼机性能可建立混炼胶质量预测数学模型,包括粘度和分散性预测数学模型,采用预测数学模型控制生产,可保证每批混炼胶质量达到要求,实现密炼机的高效优质生产。     

密炼机混炼过程功率曲线的作用*

密炼机橡胶混炼过程功率曲线,在根据密炼机混炼流变理论赋予其新的物理意义后,其主要作用有：根据功率曲线图形可判明该混炼是否符合规程的要求,并可发现某些异常现象;根据曲线图形可判明工艺的好坏,并可提供改进的途径;运用曲线图形研究混炼工艺,更直接、更快速、更准确;可预测混炼胶的粘度和分散度。     

海豚举办密炼机讲座

8月5～6日,天津海豚橡胶集团有限公司举办了为期两天的“密炼机橡胶混炼微机智能控制系统专题讲座。这次讲座是为经中国橡胶工业协会介绍,邀请华南理工大学张海教授专程来津作为专题报告而组织的。海豚集团领导对这次活动非常重视,李春来总经理亲自过问和关心支持,讲座由总工程师张天云主持,有关企业负责技术和动力设备的领导和骨干以及密炼机车间主任和操作能手共ZO多人参加。会上,张海教授根据自己4O多年的科研成果重点讲授了密炼机橡胶混炼理论的6个方面内容：1．密炼机橡胶混炼理论;2混炼过程功率曲线的物理意义;3．提高混炼…     

XHM－140／20型密炼机中胶料混炼工艺分析

应用密炼机中胶料混炼和流变理论，采用ＭＧＫＪ密炼机微机监控系统对混炼过程进行监测。对混炼过程功率曲线和有关参数进行统计分析，建议在整个混炼过程中控制好三点：加填料的ａ点，结束混炼的ｅ点和扫粉的ｄ点。建议在现有设备和新建设备上采用先进的ＭＧＫＪ密炼机微机监控系统。     

强化密炼机下辅机混炼的理论基础和工艺技术实践思考

一、密炼机下辅机的发展进程F.H Banbury发明本伯里密炼机至今,密炼机混炼已逐步成为现代混炼工艺中最主要而普通的方式。随着密炼机的进步,密炼机从最初的低速混炼发展到现在的中高速混炼,并且容量也不断增大,混炼技术从过去的一段混炼法发展到目前的多段混炼法,密炼机的混炼效率得到了很大的提     

橡胶混炼过程功率曲线新的物理意义

根据密炼机流变理论和橡胶混炼流变理论,赋予混炼过程功率曲线新的物理意义。指出从密炼机混炼过程功率曲线的变化可判断混炼过程是否最佳,打滑是否严重,胶料粘度是偏大还是偏小,加入油料时间是否适时等     

F370密炼机混炼室主要装配和磨损间隙的分析

阐述了F370密炼机混炼室主要部位的装配间隙和磨损后的允许间隙值,分析了产生磨损的原因,以及间隙的偏大偏小所引发的一系列问题,并提出了根据间隙磨损量的掌握,选择适当的时机进行密炼机的大修或采取局部的修理措施,恢复密炼机混炼室的装配精度。     

XHM-140／20型密炼机中胶料混炼工艺分析

应用密炼机中胶料混炼和流变理论，采用ＭＧＫＪ密炼机微机监控系统对混炼过程进行监测。对混炼过程功率曲线和有关参数进行统计分析，建议在融洽上混炼过程中控制好三点：加填料的ａ点，结束混炼的ｅ点和扫粉的ｄ点。建议在现有设备和新建设备上采用先进的ＭＧＫＪ密炼机微机监控系统。     

密炼机混炼过程的数学模型的研究

本文应用正交实验法进行密炼机的实验设计，并把数理统计、回归分析方法与混炼过程相结合，意在探讨建立一种客观的、统一的和实用的密炼机混炼过程的数学模型。从实验的选择、数据的处理、多元线性方程的求解等方面建立了一整套的建模方法。     

混炼参数:橡胶炼胶机的工具条

<正>自从Fernley H.Banbury在1916年推出密炼机后,橡胶胶料通常用同样的方法混炼。密炼机比标准双辊开炼机有许多优点:密炼机更高效、更清洁、更安全。多年来,通过一系列机械改进,密炼机混炼的质量和产量有了很大提高。这些改进措施包括新的转子设计、改进密炼机室内设计、改进转子冷却系统和排料等。除了机械上的改进外,其他一些因素也影响混炼效率、混炼时间和胶料性能。混炼时使用的     

XHM-140/20密炼机终炼工艺条件的改进

对ＸＨＭ１４０／２０密炼机终炼工艺条件进行改进：在密炼机中加硫黄／促进剂和粘合剂Ａ,通过时间控制排胶温度。试验结果表明,采取这些措施不仅缩短混炼时间,提高混炼效率,改善工作环境和降低劳动强度,而且还可改善硫黄和粘合剂Ａ的分散,缩短粘合剂Ａ混入时间,改善混炼胶质量     

密炼机混炼胶粘度预测数学模型的建立*

依据密炼机流变学理论,运用回归分析方法,从单台密炼机的角度,研究了混炼胶的粘度μ与排胶功率Ｐ、转速Ｎ和填充因数γ之间的关系,即μ＝２ＰπＮ２Ａ;建立了单台机粘度预测模型,即μ＝ＰＮ２×１０００×（－１３８７２９＋１５１４４４／γ－２０６８１１／γ２）。此模型预测值与实测值之差的绝对值的平均值为１４１０５个门尼,且预测结果与按每种胶料所建模型的预测值非常接近     

Analysis of agglomerate dispersion mechanisms of multiwalled carbon nanotubes during melt mixing in polycarbonate

Dispersion of primary nanotube agglomerates in polymer melts is one of the difficult tasks when applying melt mixing for nanocomposite preparation. Hence, there is a need for a better understanding of the ongoing processes. Filler agglomerates generally undergo dispersion by rupture and erosion mechanisms, which usually occur simultaneously. To analyse these mechanisms and their corresponding dispersion kinetics 1 wt% multiwalled carbon nanotubes (MWNT) were incorporated into polycarbonate using a microcompounder. Different mixing speeds at constant melt temperature were applied thereby changing the applied stress. The states of MWNT agglomerate dispersion at different mixing times were assessed by quantifying the agglomerate area ratio and particle size distribution using image analysis of optical transmission micrographs. A model is proposed to estimate the fractions of rupture and erosion mechanisms during agglomerate dispersion. At low mixing speeds, the dispersion was found to be governed by both mechanisms, whereas rupture dominance increases with increasing mixing speed. Further, the relationship between electrical resistivity and dispersion was studied indicating a critical behaviour. A dependency on the amount of dispersed nanotubes was found only in a certain range of state of dispersion.     

Study on dispersion and intercalation of organoclay in PP and PP‐g‐MA matrices

Understanding the complex mechanism of dispersion and intercalation of the clay tactoids can allow us to control the final morphology, homogeneity, and the macroscopic properties of clay nanocomposites. The objective of this work is a multiscale study of the dispersion state of PP/organoclay and PP‐g‐MA/organoclay composite. The microscopic investigation, WAXS diffractograms, rheological analysis, and mechanical properties were used to characterize the dispersion of organoclay in PP and PP‐g‐MA matrices during melt blending in two different shear rates. The morphological results show a system of aggregating intercalated clay particles which disperse by increasing mixing time with a strain‐controlled process and a very quick intercalation process in early mixing times for PP‐g‐MA/organoclay nanocomposite, while PP/organoclay samples only form microcomposites. The relative network modulus of these intercalated particles as a function of mixing time was obtained; and the tensile modulus of nanocomposite samples were compared with Halpin‐Tsai model prediction. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

密炼机中胶料的混炼工艺与填充因数研究

对不同硬度的三元乙丙橡胶、丁腈橡胶、天然橡胶和氯丁橡胶胶料在密炼机中的混炼工艺与填充因数进行研究。结果表明:胶料的分散过程分为生胶塑炼、添粉/吃粉、分散后结团、形成团聚体、软化、配合剂分散和细分散、配合剂分布以及形成复合结构8个阶段;影响混炼填充因数的因素主要为胶料粘度和硬度;胶料的粘度和硬度越高,混炼填充因数越小;混炼工艺确定后,以胶料最佳分散为目标,可确定适合的混炼填充因数。     

Natural convective heat transfer from open vertical tubes

Natural convection heat transfer in vertical tubes is described by a one-dimensional dispersion model similar to that used previously for fluid mixing in the presence of an unstable density gradient. Temperature profiles have been measured in air in 2 m high insulated vertical tubes (21.3, 24.5, 27.7 cm internal diameter), closed at the bottom and open at the top, and heated at the bottom with a known heat flux. The effective mixing lengths for eddy heat transport are of the same order as the tube diameters.     

Experimental study of the rheological,mechanical, and dielectric properties of MgO/LDPE nanocomposites

The properties of the polymer nanocomposites (PNCs), consisting low density polyethylene (LDPE) and magnesium oxide nanoparticles (MgO‐NPs), were systematically discussed in this paper. The shear mixing time and MgO concentration were considered as the two factors affecting the dispersion state, which was found to be effective to change the crystallinity and the mechanical performance of MgO/LDPE PNCs. A reduction in the dynamic shear viscosity was observed when the concentration of MgO‐NPs at a relative low level, which was also dominant by the dispersion states of MgO‐NPs. Evident enhancement of the static yield stress was revealed only by introducing a minute amount of MgO‐NPs (0.25 wt %). Meanwhile, the elastic and loss modulus were also found to be dependent on the dispersion state of MgO‐NPs. A positive increase in dielectric permittivity was identified by uniaxial stretching the MgO/LDPE PNCs strips owing to the orientation enhancement of internal microstructure. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43038.     

CFD modeling of flow,macro-mixing and axial dispersion in a bubble column

The flow pattern in a bubble column depends upon the column diameter, height, sparger design, superficial gas velocity and the nature of gas–liquid system. In this paper, the effect of some of these parameters have been simulated using Computational Fluid Dynamics (CFD). The relationship of these parameters with the interphase force terms has been discussed. A complete energy balance has been established. Using this methodology, the flow patterns reported by Hills (1974), Menzel et al. (1990), Yao et al. (1991) and Yu and Kim (1991) have been simulated. Excellent agreement has been shown between the CFD predictions and the experimental observations. The above model has been extended to homogenization of an inert tracer. In order to confirm this model, mixing experiments were carried out in a 200 mm i.d. bubble column. A radioactive tracer technique was used for the measurement of mixing time. Tc-99m (^99m Tc), in the form of sodium pertechnate salt, was used as the liquid phase tracer. Good agreement has been shown between the predicted and the experimental values of mixing time. The model was further extended for the estimation of axial dispersion coefficient (D_L). Excellent agreement between the simulated and the experimental values of the axial dispersion coefficient confirms the predictive capability of the CFD simulations for the mixing process.     

Dispersion,temperature and torque models for an internal mixer

Models based on kinetic, thermodynamic and rheological equations have been developed to compute dispersion extent, batch temperature and relative batch viscosity at discrete intervals during a mix cycle in an internal mixer. The calculated relative bulk viscosity can be linked empirically to a measured variable such as rotor torque or power consumption. Solution of the models over successive time intervals allows the computation of complete dispersion, temperature, and torque/power profiles for a mix cycle. The mix models exhibit good fits to experimental torque and temperature curves for mixing natural rubber with carbon black over a wide range of carbon black loadings (0 to 50 phr) for rotor speeds ranging from 40 to 70 RPM in two lab‐scale internal mixers. The models are shown to be suitable for moderately reinforcing (ASTM N660) as well as highly reinforcing (ASTM N121) grades of carbon black. Rate constants for filler dispersion, incorporation and erosion can be extracted from the models and can be interpolated to generate dispersion, temperature and torque curves at new conditions of carbon black loading and rotor speed. The mix models could thus be used for process‐control purposes and for specifying drop targets based on batch properties in addition to the time‐temperature‐energy criteria typically used today. Polym. Eng. Sci. 44:1247–1257, 2004. © 2004 Society of Plastics Engineers.