共查询到18条相似文献,搜索用时 218 毫秒
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热熔挤出技术已成为一种制备药物固体分散体的新方法,螺杆转速作为挤出过程中的工艺参数对药物的混合具有重要影响。以吲哚美辛(INM)和聚乙二醇(PEG10000)为原料,设计了挤出机混合段螺杆构型,采用Polyflow进行数值模拟,基于加权平均剪切应力、累积最大剪切应力分布、累计停留时间分布和平均回流系数,分析螺杆转速对INM混合性能的影响。同时,以INM为原料药,采用热熔挤出技术制备了不同螺杆转速下的挤出样品,使用扫描电子显微镜(SEM)和溶出实验对样品进行表征。结果表明,在一定范围内,随着螺杆转速的增大,药物的分散混合和分布混合性能增强,但是,螺杆转速较大会导致药物分布混合性能降低,不利于药物的混合。 相似文献
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啮合同向双螺杆挤出机中组合螺杆性能的数值研究(Ⅱ)混合特性分析 总被引:7,自引:0,他引:7
采用有限元软件POLYFLOW,对组合式啮合同向双螺杆挤出机ZSK60中不同构型的组合螺杆进行了混合分析。通过计算螺杆转过不同角度时的拟稳态流场,采用粒子示踪分析(PTA)方法,对组合螺杆中聚合物熔体的动态混合过程进行了可视化模拟;在此基础上通过对大量粒子运动轨迹的统计处理,分别采用停留时间分布、分布混合指数、分离尺度等累积混合指数表征了组合螺杆的轴向混合性能、分布混合性能以及分散混合性能。此外还研究了不同工艺条件下组合螺杆的混合特性。并将部分数值模拟结果与前人实验研究进行了对比。 相似文献
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Narayanan Murugan Padmakumar Amrishkumar Golok Behari Nando Nikhil Kumar Singha 《应用聚合物科学杂志》2020,137(27):48900
EMA–NBR has been explored to be a potential thermoplastic elastomer blend having good thermal stability as well as oil resistance property. The present investigation reports the optimization of process parameters for the novel polymer blends based on poly(ethylene-co-methyl acrylate) (EMA) and poly(acrylonitrile-co-butadiene) rubber (NBR) with criteria based on the statistical design of experiment (Taguchi L9 orthogonal array). In this case, the polymer blends were prepared by changing the polymer blending conditions such as mixing temperature, mixing time and rotor speed as per Taguchi's L9 orthogonal array. Optimization of the process parameters was carried out based on the physicomechanical properties such as tensile strength, elongation at break, hardness, and tensile impact strength of the resulting EMA/NBR blend. Each processing parameter has been optimized from the experimental data, which are converted into signal-to-noise ratio. The standard statistical technique of analysis of variance result was used to evaluate the proportional role of the different control variables. It has been found that the mixing temperature play very significant role trailed by rotor speed and mixing time in controlling droplet matrix morphology of the EMA/NBR blends. Predominantly, these factors affect the size of the NBR domain and its distribution in the EMA matrix, which in turn have a notable contribution to the physicomechanical properties of the blends. By the optimization of processing conditions, the NBR matrix domain size greatly decreases, leading to significant improvement in physicomechanical properties of the EMA/NBR blends. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48900. 相似文献
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选用难溶性药物吲哚美辛(INM)为模型药物,泊洛沙姆188(F-68)为载体,从数值模拟和实验研究2方面研究采用双转子混合器制备F-68/INM固体分散体过程中,转子速比对INM熔化相变和混合过程的影响规律。结果表明,提高转子速比,INM在载体F-68中的分布、分散混合和熔化扩散作用均得到增强,INM的溶出进程加快。 相似文献
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利用POLYFLOW软件,对聚合物熔体在双转子连续混炼机混炼段的拟稳态流场进行数值模拟,采用粒子示踪分析方法对物料所经历的流场特性进行统计学分析。得到了平均剪切应力、停留时间分布、累积最大拉伸速率等参数,通过其分析了转子结构和工艺参数对双转子连续混炼机混合性能的影响。结果表明,转子转速的提高使得物料所经受的剪切和拉伸作用增强;喂料速率的提高,使比剪切速率减小,物料在混炼段的停留时间变短;螺棱交汇区长度减小,流场中的剪切作用增强,螺棱交汇区长度和螺棱包角对停留时间分布的影响不大。最后对数值模拟的结果进行试验验证,结果基本一致。 相似文献
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In the production of rotomolded parts, the distribution of particle sizes in the form of polymer powder is highly important to produce parts of good quality. In the case of polymer blends, the particle size distribution becomes even more important to assure that good mixing occurs before the polymer melts. In this work, the mixing of free flowing polymer powders in a horizontal rotating cylinder has been studied. Special attention is given to the initial moments of mixing and the transition from a standstill to a fully developed rolling regime. The parameters studied include Froude number (rotational speed), cylinder loading, relative powder composition and particle sizes. For the first time, mixing dynamics are quantified using two image analyzes: grey-level co-occurrence matrix (GLCM) and Threshold methods. Using the experimental data, a model is proposed to follow the mixing dynamics and to determine the equilibrium time. The results also indicate that the Froude number is not enough to characterize the flow regime and the filling ratio must be accounted for. 相似文献
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SiC加入量和粒度对耐火浇注料性能的影响 总被引:1,自引:0,他引:1
以特级矾土骨料、氧化铝微粉、二氧化硅微粉、刚玉细粉、SiC和纯铝酸钙水泥为主要原料,研究了SiC加入量和粒度对耐火浇注料性能的影响。研究发现,在浇注料基质内加入6%的150目SiC,可以改善耐火浇注料的抗热震稳定性。 相似文献
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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. 相似文献
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