拉伸流场对聚合物填充体系的分散混合作用

聚合物加工过程中，分散混合一般是在一定应力场下的流场中实现的。常见的流场有剪切流场和拉伸流场，拉伸流场比剪切流场更有效，并且具有更宽的加工工艺窗口。通过对加工工艺的控制，对成型模具流道的合理设计，对加工装备结构尺寸的优化，可以实现高效分散的拉伸流场。     

纳米粉体在聚合物熔体中的分散理论

综述了纳米粉体在聚合物熔体中的分散理论,包括纳米粉体聚集体中聚集力的模型及影响因素、纳米粉体聚集体在流场中所受外力的模型及影响因素,介绍了纳米粉体聚集体分散的破裂机理和剥蚀机理,评述了各个模型及相关机理的优点和局限性,建议要将更多的影响因素如表面能等引入模型中,要考虑破裂分散与剥蚀分散之间的竞争关系,注重分散结构在加工过程中的演变过程,以强化分散模型的动力学特征。     

基于拉伸流动的聚合物复合材料分散混合研究进展

相对常用聚合物成型加工设备通过剪切力场来实现对聚合物及其填充体系的分散混合,拉伸流场具有更好的分散混合效果及较高的分散效率.通过对成型加工设备结构进行优化设计,以及成型设备进行合理改造来实现高效分散的拉伸流场,并对拉伸流场的产生方式进行论述.     

无机纳米粒子在聚合物熔体中分散机理及表征

讨论了聚合物基纳米复合材料的熔融共混制备过程及其特点。分析了无机纳米粒了在聚合物熔体中的分散机理和相关的理论模型．以及分散程度的定量表证。     

纳米粒子在聚合物熔体中分散方法的研究

由于纳米粒子的易团聚性及其与聚合物熔体间较差的亲和性,熔融共混法一般难以使其获得单粒子的分散状态.对反应型溶剂法,母料法、超声波法等可以有效地克服纳米粒子在熔体中团聚的辅助熔体分散方法及其最新进展进行了介绍.     

碳纳米管在聚合物基体中的分散方法

综述了碳纳米管（CNTs）在聚合物基体中的分散方法，包括直接分散法和表面修饰法，其中表面修饰又根据是否形成共价键分为两类，重点叙述了近几年成为研究热点的非共价键修饰法。直接分散法简单、快捷，保证了CNTs的结构完整性，但分散效果较差；表面修饰法通过共价键或非共价键的方式对CNTs的表面进行改性，克服了直接分散法的缺点，但共价键的形成会破坏CNTs的结构完整性，造成CNTs其他性能的下降，而非共价键修饰又存在结合不牢固的问题。因此，CNTs在聚合物基体中的分散方法仍是今后聚合物／CNTs复合材料应用中需要解决的一个重点问题。     

聚合物熔体中团聚体分散问题的研究进展

从团聚体结构和外界流场对团聚体的应力作用两个方面综述了各因素时团聚体分散过程的影响。讨论了不同的团聚体强度模型、“腐蚀”和“破碎”分散方式厦其影响因素，并对团聚体分散效果进行了理论分析。评价了相关模型的特点和局限性，所提出的理论模型厦模拟研究对混合设备中实际分散过程的深入研究具有指导意义。     

碳纳米管在聚合物复合材料中的分散及应用

综述了碳纳米管在聚合物中的常用分散方法,并介绍了碳纳米管分散表征方法以及聚合物复合材料的合成工艺。加入碳纳米管可以不同程度地改善聚合物基体的性能,但对碳纳米管在聚合物中定向分散以及其结合机理研究甚少。最后介绍了聚合物/碳纳米管复合材料应用领域。随着碳纳米管的合成、化学修饰、分散工艺的不断改善,碳纳米管的应用将逐步向用量小、产生效益高的领域发展。     

固体粉末在聚合物基体中分散混合的数值模拟研究

根据聚合物混合理论以及固体粉末团聚体在聚合物基体中的破碎理论,提出利用累积尺度分布函数直接表征固体粉末团聚体在聚合物中分散效果的表征方法,并建立了相应的数值模型。利用这种方法得到的模拟结果与理论分析一致,说明在数值模拟中利用累积尺度分布函数表征固体粉末团聚体在聚合物中的分散混合效果是正确可行的。     

聚合物分散技术在采油工艺中的应用分析

在当代的采油技术中,聚合物分散技术是一种十分常见且十分重要的工艺技术。通过聚合物分散采油技术,我们能有将聚合物干粉的颗粒按照既定的比例均匀的粉撒在水中,而后在水的作用下,聚合物能够获得充分的湿润随即分散溶解,实现采油。通过聚合物分散技术,我们能够根据实际情况的需要控制油田的产量并提高在高含水期油田的收集率。     

Experimental profiles of lateral mixing of feed particles in a three‐dimensional fluidized bed

Solids mixing data of high quality is one of the most crucial steps for quantitative studies, but it is a difficult task to obtain in a fluidized bed especially with a 3D configuration. Therefore a novel sampling technique is developed with bed collapse method, for measuring lateral mixing of feed particles in a 3D fluidized bed. The sampling tool is designed using a “bottom‐to‐top sampling” idea. Its development, configuration and measurement repetition are discussed in detail. The effects of mixing time, fluidizing gas velocity, and particle size of bed material on the tracer distribution are investigated. A quantitative comparison of lateral dispersion coefficient shows that our results agree fairly well with measurements and predictions of correlations for lab‐scale fluidized systems in previous studies. The presented 2D profiles of the lateral mixing can be used to validate fundamental solids mixing models or verifying convenient measurement techniques. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Rheokinetic study on homogeneous polymer reactions in melt state under strong flow field

A branch reaction of high density polyethylene initiated by Dicumyl peroxide in an internal batch mixer was used to investigate the rheokinetics on homogeneous polymer reactions in melt state under strong flow environment. The effect of shear strength on the reaction process was focused. A real conversion of reaction was put forward from the rheological measurement, i.e., the torque of mixer. A comparison of the reaction conversion from experiment and the chemical kinetic model gave a flow dependent combination rate parameter. A rheokinetic equation was therefore obtained which is in a good accordance with the theoretical prediction by Fredrickson and Leibler [4]. The rheokinetic equation was further verified by a simplified nonisothermal two-dimensional numerical simulation which incorporates macro-convection effect.     

Estimation of the melt rheology of polymer waste from melt flow index

The need for recycling of polymeric waste has been well recogmized as a result of the escalating prices of the petrochemical feedstocks and the growing awareness to curtail solid waste that causes environmental pollution. During processing, the molecular weight of the polymer is reduced due to thermal and shear degradation. Since the melt rheology of the processed material is sensitive to the changes in molecular structure, knowledge of the complete flow curve depicting the variation of melt viscosity with shear rate at processing temperatures is a useful tool for assessing the reprocessibility of waste material and for specifying the conditions of reprocessing. In the present paper, an effective method is proposed to generate the melt flow curves of polymer waste from knowledge of its melt flow index. The method makes use of a master curve that can be obtained by plotting the available viscosity data in terms of modified functions based on the melt flow index. The master curves characteristic of the particular generic resin type are presented for low-density polyethylene, polypropylene and polystyrene.     

复色多相聚合物／油／水分散体系的分散过程

研究了上粘度与配伍、水相粘度、水相表面张力和两相体积比对复色多相聚合物／油／水 影响规律。结果表明：聚合物／油／水分散体系的分散过程主要是由两相粘度决定的,油相粘度大于１．５０Ｐａ·ｓ时,易使粒子分散成为丝状或条形,油相粘度在１．５０Ｐａ·ｓ以下,则得到球形成椭球形粒子;水相粘度过大、油相／水相体系比增大,均将使油相粒子细分散化,两相体积比的临界值随水相粘度的增大而减小;水相表面张力对多相分散体系     

图象处理技术在混合效果分析中的应用

运用混合理论和计算机图象处理技术开发一个实用的混合效果评定软件,该软件主要包括图象处理和图象分析。图象处理可以改善图象的主观观察效果;图象分析可对混合效果量化。以普通螺杆、球窝型动态混合器、条槽型动态混合器分别进行混合实验,以目标数、图象重心、目标复杂度及方差为准则,评定其混合效果。结果表明球窝混合器的混合效果最好。     

Measuring of coalescence in polymer melt blends flowing through converging channels

Droplets of polymer blends flowing through convergent channels undergo collisions and coalescence because of the appropriate wineglass‐shaped flow paths with essential flow constriction at the entrance zone. Therefore, an attempt has been undertaken to use capillary flow for studying coalescence phenomena in polymer blends. When the initial drop diameters in a barrel (before extrusion), d_b, and in the extrudate, d_e, are measured, coalescence efficiency can be easily calculated as E_c = d/d, provided that no breakup of elongated domains occurs. Compared with methods employing simple shear flow, it has several advantages. For example, the convergent flow pattern combining both shear and extensional flows is directly related to industrial processing operations like extrusion, injection molding, blowing, etc. The method imposes minor limitations on processing parameters and materials used. Applicability of the technique proposed was verified by systematic studies of coalescence in PMMA/PS binary melts blends during capillary extrusion and by comparing these results to theoretical predictions and experimental data from literature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011