Internal stress levels in xerographic papers

The stress relaxation method for determining internal stress levels in polymers has been used to estimate internal stress levels in certain fine papers typical of those used in xerographic processing. The effects of stress relief, obtained by wetting and redrying a sheet without restraint, strain rate, initial stress and sheet anisotropy on the results were examined.     

Roll fusing of toner particles on rough papers in the xerographic process

This paper deals with squashing of toner particles in a variety of paper topographies in the roll fusing of toner images in xerographic machines. The model developed can be used for predicting the mean spreading ratio of toner particles related to fix level with given rheological properties and fusing temperature and pressure. The deformation of toner particles is solved with respect to the asperity pressure encountered in the contact between the roll and the paper surfaces. Various contact situations are considered, among them: toners on smooth papers, on tops of paper asperities, and at valleys of a paper surface. In addition to rheological properties and fusing conditions, toner spreadings also depend on toner size, paper roughness, and the rubber modulus of the fuser roll. Based on an integration algorithm, statistical averages of toner spreadings can be computed in terms of distribution functions of toner and paper asperity height. Comparisons of theoretical predictions with measurements show good agreement over a broad range of data.     

注塑制品内应力计算的非线性黏弹性本构方程

在聚合物黏弹性理论的基础上,构建了新的注塑制品内应力计算的四元件串联力学模型,并推导了其瞬态黏弹性响应的非线性本构方程,给出了聚合物材料参数弹性模量和黏壶系数的计算公式,并对PS平板注塑制件脱模前的内应力进行了模拟计算。计算结果与固体高聚物的结构和力学性能的相关研究结论相一致,所建计算模型合理可靠。     

密炼机转子参数的优化设计

根据密炼机设计的步骤，建立两种不同结构密炼机同步转子数学模型，提出优化方向。按照数学模型，采用约束坐标轮换法设计优化程序，根据经验以实际数据优化计算密炼机的转子参数。结果表明，所提出的模型和优化方法可以计算出符合要求的密炼机转子参数。     

Numerical simulation of the fountain flow problem for viscoelastic fluids

Fountain flow for isothermal viscoelastic fluids is simulated by a numerical method based on a combination of a finite element method and a finite volume method. For the treatment of moving free surfaces, a fringe element generation method is used. Circulating flow and elongation in the transverse direction at the melt front are simulated well. Numerical results also suggest that circulation in fountain flow and viscoelastic retardation may give rise to symmetric V-shaped patterns of birefringence between the center-plane and wall. Such information on molecular orientation in fountain flow is important for physical properties of thick molded products.     

Determination of parameters in convected Maxwell model from linear viscoelastic parameters

Owing to its simplicity and general ability to correctly portray a number of important flow phenomena, the two-parameter Maxwell model has been employed in a number of important engineering studies. The relation of this equation to linear viscoelasticity and to some molecular theories is considered. A new rule is developed which shows how the shear-dependent relaxation time and viscosity of the Maxwell model can be determined from linear viscoelastic parameters. It is thus shown that the two-parameter Maxwell model may be more general than earlier anticipated.     

Propagation of stress waves in viscoelastic media

A new method for the determination of the characteristic parameters of the stress wave propagation, such as attenuation coefficient, wave velocity, Young's modulus and the viscosity coefficient, at various frequencies in viscoelastic rods is presented. The method is based on the propagation of an arbitrary pulse in such a rod and the determination of the characteristic wave propagation parameters of each term of the Fourier series expansion of the propagating pulse. Since each term corresponds to a definite frequency, the characteristic properties of the wave propagation over a wide frequency range can be determined, by means of one test only. The analysis is based on the assumption that the viscoelastic material obeys a Kelvin-Voigt model. The stress pulse was created by means of a steel ball, projected by an air-gun, and was recorded by a transient recorder with digital memory. Two typical viscoelastic materials were tested, namely a poly(methyl methacrylate) (plexiglas) and a polycarbonate of bisphenol A (lexan). The characteristic wave propagation parameters were determined in a frequency range between 3 and 35 kHz and the results obtained agreed satisfactorily with corresponding results of previous investigators.     

螺旋转子的结构参数对管内换热影响的数值研究

管内插入物是一种强化管内换热的有效方法,内插可以旋转的结构在强化换热的同时还具有良好的除垢效果。数值研究了内插螺旋转子的管内流动与换热,发现与光管相比,换热强化30%,而阻力则为光管的6～7倍。数值计算结果表明,叶片与管壁间隙、转子螺旋节距的增加以及转轴半径的减小,可引起转子转速不同程度的减小,从而导致管内Nusselt数和阻力系数的减小。适当增加转子螺旋节距,减小转轴半径及叶片与管壁间隙,可使其强化换热性能更优。     

Postfilling analysis of viscoelastic polymers with internal structure parameter

A new constitutive model with internal structure parameter is presented in this study for simulating orientation and deformation of polymer chain in the postfilling stages of injection molding process. Implementation of such a model is based on a hybrid finite-element/finite-difference numerical solution of the generalized Hele-Shaw flow. The simulation of a compressible viscoelastic fluid under nonisothermal conditions has not yet been discussed in most previous works. In addition to the distribution of pressure, temperature, density, and velocity, theoretical predictions also include shear and normal stresses, which can be used for subsequent calculation of residual stresses. An amorphous material, namely a commercial-grade polystyrene (PS), was used in the present work. Good agreement is obtained between the simulation and experimental pressure trace from this study.     

Dynamics of viscoelastic spherical shells during internal explosive loading

The dynamics of a thick-walled closed spherical shell was investigated theoretically and experimentally for determining the dynamic viscoelastic characteristics of steel St. 3. A liquid explosive charge placed in a capsule discharge in the center of a flask was used for uniform loading. The value of the logarithmic decrement was obtained from the results of measuring the meridional deformation by means of a strain-gauge complex.Arzamas. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 91–95, July–August, 1992.     

Numerical simulation of viscoelastic two-phase flows using openFOAM

In this work a new solver is developed for the OpenFOAM^® CFD toolbox, which handles viscoelastic two-phase flows. A derivative of the volume-of-fluid (VoF) methodology is used to describe the interface. Established constitutive equations derived from kinetic theory, such as Oldroyd-B, Giesekus, FENE-P and FENE-CR, from network theory of concentrated solutions and melts, such as linear and exponential Phan-Thien–Tanner (PTT), and from reptation theory, such as Pom–Pom and XPP models, as well as multi-mode formulations are implemented in OpenFOAM. Validation of the numerical technique is performed by comparing detailed simulation predictions to data from several experimental studies, numerical studies and analytical models found in the literature. Two well-known viscoelastic free-surface effects, namely the Weissenberg and the Die Swell effect, are simulated. Furthermore, transient and steady-state droplet flow in shear and elongational flows is examined.     

Methods for determination of breakage distribution parameters

The distribution of primary breakage products in laboratory mills can be estimated by batch grinding for short times. Three methods are given for manipulating the data, the second and third methods correcting for secondary breakage. Method III is the most accurate, but since it uses the specific rates of breakage of the various sizes in the correction procedure it is necessary to have experimental or theoretical estimates of these values. A general computer program is given for the computations.     

Numerical simulation of three-dimensional viscoelastic flow within dies

In recent years, the development of CAE (Computer Aided Engineering) in polymer processing has been remarkable, and it is expected to be more realistic in viscoelastic numerical simulation, particularly in three-dimensional complex geometry. Because of the problems of computational memory capacity, CPU time, and the numerical convergence of viscoelastic flow simulation, three-dimensional viscoelastic simulation applicable to industrial flow behaviors has not yet been attempted. In this paper, we developed the numerical simulation of three-dimensional viscoelastic flow within dies using a decoupled method, streamwise integration, and penalty function methods to decrease memory, and the TME (“Transformation of Equation of Motion to the Elliptic Equation,” S. Tanoue, T. Kajiwara, and K. Funatsu, The Eleventh Annual Meeting, the Polymer Processing Society Seoul, Korea, Extended Abstracts p.439) method, which raises the stability of convergence. We confirmed the reliability of this simulation technique to compare simulation results with experimental data of the stress field at a downstream wall shear rate of 5.41s^?1 within a 60° angle tapered contraction die. We compared the predictions of a viscoelastic model (Phan-Thien and Tanner model) with a pure viscosity model (Carreau model) at a downstream wall shear rate of 120s^?1 and discovered a remarkable effect of viscoelasticity in the shear stress and first normal stress difference in particular in the tapered region.     

Application of dimer acid–based polyamide for xerographic toners for textiles printing

Xerographic printing of textiles was explored. A number of fabrics were printed using commercially available and synthesized polymers as toner vehicles. The polymers were characterized using standard methods (DSC, DMA, tensile tests). The performance of the prints was evaluated using textiles‐specific tests (crockfastness, flexural rigidity). It was found that the initial modulus is a reasonable predictor of the performance of the printed fabrics. However, the requirements on toner vehicles for good textile performance (low initial modulus, flexibility) contradict the requirements for production of toner powders by grinding (brittle behavior). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2399–2407, 2001     

Genetic algorithm for the determination of linear viscoelastic relaxation spectrum from experimental data

Conventional procedures employed in the modeling of viscoelastic properties of polymer rely on the determination of the polymer's discrete relaxation spectrum from experimentally obtained data. In the past decades, several analytical regression techniques have been proposed to determine an explicit equation which describes the measured spectra. With a diverse approach, the procedure herein introduced constitutes a simulation‐based computational optimization technique based on non‐deterministic search method arisen from the field of evolutionary computation. Instead of comparing numerical results, this purpose of this paper is to highlight some subtle differences between both strategies and focus on what properties of the exploited technique emerge as new possibilities for the field. In oder to illustrate this, essayed cases show how the employed technique can outperform conventional approaches in terms of fitting quality. Moreover, in some instances, it produces equivalent results with much fewer fitting parameters, which is convenient for computational simulation applications. The problem formulation and the rationale of the highlighted method are herein discussed and constitute the main intended contribution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

两转两吸转化工艺流程的选择及工艺参数的确定

重点分析在硫铁矿制酸中几种不同工艺条件下转化工序的设计参数,从分析结果可以看出:两转两吸"3 1"流程二段进口温度一般宜选为 440℃,以提高一次转化率,并使总转化率尽可能达到 99.7%.一般ψ(SO:)＜8.5% 的气体只要"3 1"流程即可,只有当所要求的四段出口转化率接近四段平衡转化率时,二次转化才用 2 个转化段.如果不考虑废热利用,换热流程用ⅣⅠ-ⅢⅡ较好.如考虑废热利用,可采用ⅢⅠ-ⅣⅡ或ⅢⅡ-ⅣⅠ流程.对于二氧化硫浓度低、而氧含量又高的冶炼烟气制酸装置,用"2 1"、ⅢⅠ-Ⅱ换热流程较为实用.     

Linear viscoelastic and morphological description of multiphase systems affected by processing parameters

Influence of processing methods, in terms of comparing compression and injection moldings, on the rheological behavior of polycarbonate (PC)/acrylonitrile‐butadiene‐styrene (ABS) blends and PC/ABS/glass fibers composites is presented. Blend compositions and fiber content are considered as material variables. For blends, the effect of the processing route on the viscoelastic functions is evident only for low shearing frequencies. Injection molding created morphology with cocontinuous character, while compression molded blends have “relaxed” structure, where dispersed phase domains are several times larger than in injection molded ones. The glass fiber reinforcement led to the significant differences in viscoelastic properties of composites processed by injection and compression molding. Injected composites have both moduli always higher than compression molded. Also, fiber lengths are reduced more for compressing molding. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Relations between viscoelastic parameters of hydrophobic fiber and dyeing with disperse dyes

Experimental evidence is presented to show that the kinetics of dyeing of hydrophobic fibers with disperse dyes can be represented by an equation of the same form as the well-known equation giving creep in fibers. A mechanism is proposed whereby one can regard the dye uptake in the fiber at a constant temperature as a viscoelastic phenomenon in the dye-polymer system. A comparison of these two equations enables the dyeing constants to be interpreted in terms of the viscoelastic parameters of the system. It is also possible to find the upper bounds for the dyeing rate and a condition for rapid dyeing on the same basis.     

Residual stress and viscoelastic deformation of film insert molded automotive parts

Complex automotive parts were produced by film insert molding and the ejected parts were annealed to investigate the viscoelastic deformation. Warpage of the part was predicted by numerical simulation of mold filling, packing, and cooling stages with non‐isothermal three‐dimensional flow analysis. The flow analysis results were transported to a finite element stress analysis program and the stress analysis was performed by using time‐temperature superposition principle to investigate viscoelastic deformation. Predicted residual stresses, viscoelastic deformation, and warpage showed good agreement with experimental results. Thermal shrinkage of the inserted film and relaxation of the residual stress affected the viscoelastic deformation of the part significantly during annealing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

数值模拟黏弹流体通过椭圆环模具的挤出胀大

The numerical simulation of extrudate swell is significant in extrusion processing.Precise prediction of extrudate swell is propitious to the control of melt flow and the quality of final products.A mathematical model of three-dimensional(3D)viscoelastic flow through elliptical ring die for polymer extrusion was investigated.The penalty function formulation of viscoelastic incompressible fluid was introduced to the finite element model to analyze 3D extrusion problem.The discrete elastic viscous split stress(DEVSS)and streamline-upwind PetrovGalerkin(SUPG)technology were used to obtain stable simulation results.Free surface was updated by updating the streamlines which needs less memory space.According to numerical simulation results,the effect of zero-shear viscosity and elongation parameter on extrudate swell was slight,but with the increase of volumetric flow rate and relax time the extrudate swell ratio increased markedly.Finally,the numerical simulation of extrudate swell flow for low-density polyethylene(LDPE)melts was investigated and the results agreed well with others’work.These conclusions provided quantitative basis for the forecasting extrudate swell ratio and the controlling of extrusion productivity shape.