聚合物发泡与挤出胀大过程数值模拟及实验研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
当今世界经济发展的三大工业支柱是材料、能源和信息,没有材料工业的发展就没有现代技术的发展。随着社会经济技术的发展,塑料已发展成为在国民经济中与钢铁、木材、水泥三大传统材料并驾齐驱的重要材料,并在科学技术领域里发挥着越来越重要的作用,成为仪器仪表、交通运输、无线电、电讯器材及日用品生产不可缺少的新型材料。塑料制品的成型加工方法很多,例如注塑、挤出、吹塑、压延等等。其中挤出成型具有效率高、投资少、制造简便、可以实现连续化生产、占地面积小和环境清洁等优点而成为塑料制品的主要成型方法之一。挤出成型工艺和模具设计开发过程中,传统的经验设计和常规的实验方法已经不能很好地满足生产指导的需要,而随着计算机软硬件技术的发展以及计算流体力学理论的发展,数值模拟技术显示出了巨大优势,为工艺设计和模具优化提供了理论基础。
     本文建立了挤出微孔发泡工艺中气泡在粘性不可压缩流体中非稳态等温长大的有限元模型,针对气泡长大过程进行数值模拟计算,获得了发泡过程中气泡压力和气泡尺寸的变化规律,并得到了聚合物熔体内发泡剂浓度场的分布规律。讨论了气泡长大的驱动力以及影响气泡长大的材料因素和工艺因素,预测了挤出微孔发泡过程中气泡长大规律,对挤出微孔发泡工艺具有一定的指导意义。在挤出微孔发泡工艺中,聚合物熔体离开口模后,气泡长大引起聚合物熔体膨胀,与此同时,聚合物熔体本身也存在挤出胀大现象,且聚合物熔体自身的挤出胀大对产品尺寸的影响不容忽视。针对聚合物挤出胀大过程,建立了不可压缩流体三维稳态等温流动的有限元模型,考虑了不同聚合物流变模型,对非牛顿流体挤出胀大过程进行了数值模拟,得到了聚合物熔体的速度分布规律,并获得了口模几何形状、材料参数以及工艺参数对挤出胀大率的影响规律。
     以聚合物流变学和流体动力学理论为基础,建立了挤出微孔发泡工艺中气泡在非牛顿聚合物熔体内等温长大过程的几何模型和数学模型。利用伽辽金加权余量法离散控制方程,并通过高斯积分变换获得数值计算的有限元方程。由于气泡长大过程时间短,长大速度快,发泡剂浓度梯度急剧增加,增加了数学求解的困难,数值结果振荡严重。针对以上情况,对控制方程进行无量纲化处理,有效提高了数值计算稳定性。
     基于有限元模拟技术,对挤出微孔发泡工艺中气泡长大过程进行数值模拟,研究了气泡在非牛顿聚合物熔体内的等温长大过程。分析了挤出微孔发泡工艺中气泡长大的动力来源,获得了气泡压力和气泡半径随时间的变化规律,研究了气液界面处发泡剂浓度梯度以及“细胞”内外壁处发泡剂浓度的变化规律。讨论了几何模型(气泡初始半径以及“细胞”外径尺寸)、材料参数(零剪切粘度、扩散系数、亨利常数以及表面张力系数)以及工艺参数(发泡温度和气泡压力)对气泡长大过程的影响。
     以流体力学有限元理论为基础,建立了粘性不可压缩流体挤出胀大的有限元模型。采用罚函数法将连续性方程代入动量方程,从而避免了对压力项直接求解,减少了同时计算的变量数,有效提高了计算效率。挤出胀大问题的求解困难在于聚合物胀大部分的自由表面位置是事先未知的,给数值求解额外增加了非线性。本文采用解耦合方法求解自由胀大表面位置,先假设一个自由表面的位置,利用流线方程更新自由表面节点坐标从而得到真实表面位置。考虑聚合物熔体的非牛顿特性,采用幂律本构流变模型,针对常见的正方形口模进行挤出胀大过程的数值模拟。引入的罚数是一个不确定量,通过系统地数值计算获得罚数的最佳取值。分析了聚合物熔体离开口模后的速度分布规律,探讨了非牛顿流体挤出胀大现象的产生机理。同时研究了体积流量对挤出胀大率的影响。讨论了相同体积流量和相同口模截面面积的情况下口模截面形状对挤出胀大率的影响。
     粘弹性是聚合物熔体的一种重要特性,在实际加工生产中,对塑料产品的形状及尺寸具有较大影响。本文采用PTT本构方程,充分考虑聚合物熔体的粘弹特性,建立了粘弹流体的挤出胀大有限元数学模型。通过引入参考粘度对动量方程进行了椭圆化处理,提高了方程求解的稳定性。采用Streamline Upwind/Petrov-Galerkin formulation(SUPG)方法构造非对称权函数,克服了本构方程对流项占优时导致的数值解的振荡。针对圆环截面及椭环截面口模的挤出胀大过程进行数值模拟。针对圆环口模,分析了聚合物熔体内外边界处第一法向应力差的分布规律。在口模外径尺寸相同的情况下,选取了不同的口模内外径比例,分析了相同体积流量下,口模尺寸对挤出胀大率的影响。讨论了体积流量对挤出胀大率的影响规律。针对椭环形口模,研究了与材料本身性质有关的零剪切粘度、松弛时间以及拉伸参数对挤出胀大率的影响,同时也考虑了体积流量对挤出胀大率的影响。
     采用能够精确控制工艺参数的间歇法发泡工艺中的快速降压法,以实验中常用的聚苯乙烯为基体,超临界CO_2为发泡剂进行了微孔发泡实验研究。通过饱和吸收/解吸实验获得了发泡剂扩散系数和亨利常数;采用毛细管流变仪测定了150℃下纯聚苯乙烯的粘度;利用WLF方程计算得到实验条件下PS/CO_2均相体系的粘度;采用专业图像分析软件Image-Pro Plus对发泡样品的SEM照片进行统计计算,获得泡孔密度和泡孔平均直径。根据间歇法发泡实验获得的结果,得到了相同温度下压力对发泡工艺过程的影响规律。通过饱和吸收/解吸实验结果,获得了压力对气体在聚合物里的溶解度的影响。同时采用实验获得的材料参数与工艺参数进行了相应的有限元数值模拟,对比了模拟结果与实验结果。
The material,energy and information are the mainstay industries in the world's economic development today.Modern technology can't develop well without the development of material industry.With the development of social economy and technology,the plastics has become as important as the three traditional materials i.e.the steel,wood and the cement in national economy, and plays a significant role in scientific and technological fields.The plastics prove to be indispensable new materials in the production of instruments and meters,transport and communication trade,wireless,communication telephone and articles of everyday use.There are many methods that can be used to form plastics,for instant,injection,extrusion,blow molding,rolling etc.,among which the extrusion is one of the most widely-used methods as it has several merits such as high efficiency,less investment,applicability in manufacturing and continuous production,less space occupation and environmental cleaning etc.Conventional empirical design and routine experiments can not direct production well any more,while computer aided engineering has great advantages in providing the theoretical foundation for technological design and die optimization,due to the development of computer hardware and software technology,as well as the theories of computational fluid dynamics theory.
     A finite element model was established to analyze the growth of bubble in viscous incompressible fluid.The growth process of bubble in extrusion foaming technology was simulated,presenting the regularity of bubble pressure and bubble radius as well as that of the foaming agent concentration distribution. The driving force of bubble growth and effects of materials and technological factors on bubble growth were discussed,predicting the regularity of bubble growth.The bubble growth leads to an expansion process after the polymer flows out of the die in extrusion foaming process.Meanwhile,extrudate swell is a common phenomenon for polymer itself and its effect on product size can't be ignored.Aiming at the extrudate swell phenomenon in extrusion foaming process,a finite element model of three-dimensional incompressible fluid isothermal steady flow was also created.Considering different rheological models,the extrudate swell of non-Newtonian fluid,as well as the influences of die geometry,material parameters and technological parameters on extrudate swell ratio were discussed.
     Based on the theories of polymer rheology and fluid dynamics,this thesis established the geometrical and mathematical models for bubble growth in isothermal non-Newtonian polymer melt,and obtained the finite elemental model by Gaussian integral transformation.Due to the rapidity of bubble growth, the concentration of foaming agent increases drastically which leads to solving difficulty and oscillation of results.As a reslut,controlling equations were nondimensionalized to improve their numerical stability currently.
     Based on the finite element method,the bubble growth in extrusion foaming process was simulated,investigating the bubble growth in isothermal non-Newtonian polymer melt.The driving force of bubble growth was studied and variation tendency of bubble pressure and bubble radius were analyzed. Concentration gradient of foaming agent on the gas-liquid interface and that on both inside and outside wall of the "cell" were obtained.The effects of geometry model(initial bubble radius and outer radius of the "cell"),material parameters (zero-shear viscosity,confusion coefficient,Henry's constant and surface tension coefficient) and technological parameters(foaming temperature and initial pressure) on bubble growth were discussed in details.
     Finite elemental model of extrudate swell in viscous incompressible fluid was obtained based on the theory of finite element theory in fluid mechanics. In order to avoid solving pressure directly,continuity equations were substituted into momentum equation by penalty finite element method,and this reduced the number of variables calculated simultaneously,leading to the improvement of the computational efficiency.The difficulty in the solving of extrudate swell lay in the fact that the free surface is unknown,which introduces non-linearity in the solving process.Presently,a contour of the free surface is assumed,and the streamline equations were adopted to update the free surface to obtain the real free surface.Taking non-Newtonian viscosity behavior into consideration,numerical simulation was conducted for square shaped die with power law constitutive model.Optimal penalty number was fixed by a serial of numerical calculations.The velocity field distribution of polymer melt out of the die was analyzed and the mechanism of extrudate swell of non-Newtonian polymer was discussed furthermore.The effect of volumetric flow rate on extrudate swell ratio was considered.In addition,the effect of die shape on extrudate swell ratio was discussed with the same volumetric flow rate and cross sectional area.
     Viscoelasticity is a key property for polymer melt and its effect on geometry and dimension of product in production and processing can't be neglected.Considering the characteristic of viscoelasticity for polymer melt, PTT constitutive equation was adopted in this dissertation.A finite element mathematical model was developed to simulate extrudate swell of viscoelastic fluid.Reference viscosity was introduced to improve the ellipticity of the momentum equation and the solving stability.Asymmetric weight function was constructed by Streamline Upwind/Petrov-Galerkin formulation method,in order to overcome unstability in solving caused by dominant convective term in constitutive equation.Extrudate swell in annular and elliptical ring dies were simulated respectively.For annular die,the distribution of first normal-stress difference on both inner and outer boundaries of polymer melt was obtained,and the effect of die dimension and volumetric flow rate on extrudate swell ratio was analyzed.For elliptical ring die,the effects of zero-shear viscosity,relax time, extensograph parameter and volumetric flow rate on extrudate swell ratio were studied.
     Microcellular foaming experiment with batch method was carried out using polystyrene as matrix and CO_2 as foaming agent.Confusion coefficient and Henry's constant were obtained by saturated absorption/desorption experiments.Viscosity of pure polystyrene was measured by capillary rheometer at the temperature of 150℃.The viscosity of PS/CO_2 homogeneous system was calculated with WLF equation.With the professional image analysis software Image-Pro Plus,cell density and cell diameter was calculated statistically according to SEM photograph of foaming plastic sample.The experimental results with batch method revealed the effect of pressure on foaming processing at the same temperature.While the infulence of pressure on the solubility of the gases in polymer was demonstrated by the results of saturated absorption/desorption experiments.Simulation was carried out with the parameters obtained by experiment,and the results of simulation and experiment were compared.
引文
[1]周达飞,唐颂超.高分子材料成型加工[M].北京:中国轻工业出版社,2005.
    [2]Z.塔德莫尔,C.G.高戈斯.聚合物加工原理[M].任冬云译.北京:化学工业出版社,2009.
    [3]王贵恒.高分子材料加工原理[M].北京:化学工业出版社,1982.
    [4]Klempner D,Frisch K C.Handbook of polymeric foams and foam technology [M].Munich:Hanser Publishers,1991.
    [5]张玉龙,李长德.泡沫塑料入门[M].杭州:浙江科学技术出版社,2000.
    [6]Kamran Kazemi Beydokhti,Amir H.Behravesh,and Taher Azdast.An experimental study on mechanical and microstructural properties of microcellular foams of ABS composites[J].Iranian Polymer Journal,2006,15(7):555-567.
    [7]开尔文 T.奥卡莫特.微孔塑料成型技术[M].张玉霞译.北京:化学工业出版社,2004.
    [8]Martini-Vvedensky J E,Shu N P,Waldman F A.Microcellular closed cell foams and their mothed of manufacture[P].U.S.Patent 4,473,665,1984.
    [9]Martini J E,Waldman F A.Suh N P.The production and analysis of microcellular thermoplastic foams[C].ANTEC 82,1982,28:674-676.
    [10]Malanda L M,Park C B,Balatinecz J J.Structures and mechanical properties of microcellular foamed polyvinyl chloride[J].Cellular Polymers,1998,17(5):351-361.
    [11]Collias D I,Baird D G,Borggreve R J M.Impact toughening of polycarbonate by microcellular foaming[J].Polymer,1994,35(18):3978-3983.
    [12]Collias D I,Baird D G.Tensile toughness of microcellular foams of polystyrene,styreneacrylonitrile copolymer,and polycarbonate,and the effect of dissolved gas on the tensile toughness of the same polymer matrices and microcellular foams[J].Polymer Engineering and Science,1995,35(14):1167-1177.
    [13]Seeler K A,Kumar V.Tension-tension fatigue of microcellular polycarbonate:initial results[J].Journal of Reinforced Plastics and Composites,1993,12(3):359-376.
    [14]Wing G,Pasricha A,Tuttle M,Kumar V.Time dependent response of polycarbonate and microcellular polycarbonate[J].Polymer Engineering and Science,1995,35(8):673-679.
    [15]Shimbo M,Baldwin D F,Suh N P.The viscoelastic behavior of microcellular plastics with varying cell size[J].Polymer Engineering and Science,1995, 35(17): 1387-1393.
    [16] Guria K C, Tripathy D K. Dielectric properties of closed cell microcellular ethylene propylene diene rubbers at microwave frequency [J]. International Journal of Polymeric Materials, 1997, 37(1): 53-64.
    [17] Aubert J H, Clough R L. Low density microcellular polystyrene foams [J]. Polymer, 1985,26: 2047-2054.
    [18] Raj W R P, Sasthav M, Cheung H M. Microcellular polymeric materials from microemulsions: control of microstructure and morphology [J]. Applied Polymer Science, 1993,47 (29): 499-505.
    [19] David L. Tomasko, Adam Burley, Lu Feng, Shu-Kai Yeh, Koki Miyazono, Sharath Nirmal-Kumar, Isamu Kusaka, Kurt Koelling. Development of CO_2 for polymer foam applications [J]. The Journal of Supercritical Fluids, 2009, 47: 493-499.
    [20] Dixon D J, Johnston K P, Bodmeier R P. Polymeric materials formed by precipitation with a compressed fluid antisolvent [J]. AIChE Journal, 1993, 39 (1): 127-139.
    [21] Ramesh N S, D H Rasmussen, G A Campbell. Numerical and experimental studies of bubble growth during the microcellular foaming process [J]. Polymer Engineering and Science, 1991, 31(23): 1657-1664.
    [22] G S Kumar. A process for making microcellular thermoplastic parts [J]. Polymer Engineering Science, 1990,30(20): 1323-1329
    [23] Goel S K, Beckman E J. Generation of microcellular polymeric foams using supercritical carbon dioxide. I: Effect of pressure and temperature on nucleation [J]. Polymer Engineering Science, 1994, 34(14): 1137-1147.
    [24] Lee K N, Lee H J, Kim J H. Preparation and morphology characterization of microcellular styrene-co-acrylonitrile (SAN) foam processed in supercritical CO_2 [J]. Polymer international, 2000,49(7): 712-718.
    [25] Christopher M Stafford, Thomas P Russell, Thomas J McCarthy. Expansion of polystyrene using supercritical carbon dioxide: Effects of molecular weight, polydispersity, and low molecular weight components [J]. Macromolecules, 1999, 32(22): 7610-7616.
    
    [26]王进,程兴国,袁明君,何嘉松.超临界C02在微孔聚合物制备中的应用 [J].高分子通报,2001,12:8-17.
    [27] Baldwin D F, Park C B, Suh N P. An extrusion system for the processing of microcellular polymer sheets: shaping and cell grow control [J]. Polymer Engineering Science, 1996,36(10): 1425-1435.
    [28] Park C B, Suh N P. Rapid heating for microcellular nucleation [C]. SPE ANTEC, 1992,38:1513-1518.
    
    [29] 韩布兴.超临界流体科学与技术[M].北京:中国石化出版社,2005.
    [30] Kentaro Taki. Experimental and numerical studies on the effects of pressure release rate on number density of bubbles and bubble growth in a polymeric foaming process [J]. Chemical Engineering Science, 2008, 63: 3643-3653.
    [31] Ioannis Tsivintzelis, Anastasia G, Angelopoulou, Costas Panayiotou. Foaming of polymers with supercritical CO2: An experimental and theoretical study [J]. Polymer, 2007,48: 5928-5939.
    [32] ZhiMei Xu, XiuLei Jiang, Tao Liu, GuoHua Hu, Ling Zhao, ZhongNan Zhu, WeiKang Yuan. Foaming of polypropylene with supercritical carbon dioxide [J]. The Journal of Supercritical Fluids, 2007,41: 299-310.
    [33] Collias D I, Baird D G.Impact behavior of microcellular foams of polystyrene and styrene-acrylonitrile copolymer, and single-edge-notched tensile toughness of microcellular foams of polystyrene, styrene-acrylonitrile copolymer, and polycarbonate [J]. Polymer Engineering and Science, 1995, 35(14): 1178-1183.
    [34] Bernd Krause, Geert Henk Koops, Nico F. A. van der Vegt, Matthias Wessling, Michael Wubbenhorst, Jan van Turnhout. Ultralow-k dielectrics made by supercritical foaming of thin polymer films [J]. Advanced Materials, 2002, 14(15): 1041-1046.
    [35] Masami Okamoto, Pham Hoai Nam, Pralay Maiti, Tadao Kotaka, Takashi Nakayama, Mitsuko Takada, Masahiro Ohshima, Arimitsu Usuki, Naoki Hasegawa, Hirotaka Okamoto. Biaxial flow-induced alignment of silicate layers in polypropylene/clay nanocomposite foam [J]. Nano Letters, 2001, 1(9): 503-505.
    [36] D.F.Baldwin, C.B.Park, N.P.Suh. A microcellular processing study of poly(ethylene terephthalate) in the amorphous and semicrystalline states. Part I: Microcell nucleation [J]. Polymer Engineering and Science, 1996, 36: 1437-1445.
    [37] Doroudiani S, Park C B, Kortschot M T S, Doroudiani, C.B. Park, M.T. Kortschot. Effect of the crystallinity and morphology on the microcellular foam structure of semicrystalline polymers [J]. Polymer Engineering and Science, 1996, 36: 2645-2662.
    [38] Ramesh N S, Kweeder J A, Campell G A, Rasmussen D H, An experimental study of the nucleation of microcellular foams in high impact polystyrene [C]. ANTEC, 1992, 38: 1078-1081.
    [39] Baldwin D F, Park C B, Suh N P. A microcellular processing study of poly(ethylene terephthalate) in the amorphous and semicrystalline states. Part Ⅱ:Cell growth and process design[J].Polymer Engineering and Science,1996,36(11):1446-1453.
    [40]Han C D,Yoo H J.Studies on structural foam processing.Ⅳ.Bubble growth during mold filling[J].Polymer Engineering Science,1981,21:518-533.
    [41]Biesenberger J,Lee S T.A fundamental study of polymer melt devolatilization.Part Ⅱ:A theory for foam enhanced devolatilization[C].ANTEC,1986,86:846-850.
    [42]Han J.H.,Han C.D.A study of bubble nucleation in a mixture of molten polymer and volatile liquid in a shear flow field[J].Polymer Engineering and Science,1988,24(28):1616-1627.
    [43]ChangYun Gao,NanQiao Zhou,XiangFang Peng,Lei Kong,Ping Zhang.Effect of oscillatory shear on polystyrene cell morphology[J].Journal of Cellular Plastics,2006,42(3):191-206.
    [44]孙兴华,李刚,廖霞,何嘉松.分次降压法研究微孔聚合物发泡的成核及增长过程[J].高分子学报,2004,1:93-97.
    [45]Han C D,Ma C Y.Foam extrusion characteristics of thermoplastic resin with fluorocarbon blowing agent.I.Low-density polyethylene foam extrusion[J].Journal of Applied Polymer Science,1983,28(9):2961-2982.
    [46]Goel S K,Beckman E J.Generation of microcellular polymers using supercritical CO2[J].Cellular polymers,1993,12(4):251-271.
    [47]Goel S K,Beckman E J.Generation of microcellular polymeric foams using supercritical carbon dioxide.Ⅱ:Cell growth and skin formation[J].Polymer Engineering and Science,1994,34(14):1148-1156.
    [48]Zeldovich J.B.On the theory of new phase formation:cavitation[J].Acta Physicochem.U.S.S.R.1943,18:1-22.
    [49]Yuan M J,Winardi A,Gong S Q,Turng L S.Effects of nano-and micro-fillers and processing parameters on injection-molded microcellular composites[J].Polymer Engineering and Science,2005,45:773-788.
    [50]Colton J S,Suh N P.Nucleation of microcellular foam:theory and practice[J].Polymer Engineering and Science,1987,27:500-503.
    [51]Lee Chen,Xiang Wang,Rich Straff,Blizard Kent.Shear stress nucleation in microcellular foaming process[J].Polymer Engineering and Science,2002,42(6):1151-1158.
    [52]Epstein P S,Plesset M S.On the stability of gas bubbles in liquid-gas solutions [J].Journal of Chemical Physics,1950,18:1505-1509.
    [53]Hoobs S.Bubble growth in thermoplastic structural foams[J].Polymer Engineering and Science, 1976,16(4):270-275.
    [54] D.C. Venerus, N. Yala, B. Bernstein. Analysis of diffusion-induced bubble growth in viscoelastic liquids [J]. Journal of Non-Newtonian Fluid Mechanics, 1998, 75: 55-75.
    [55] James J. Feng. Prediction of bubble growth and size distribution in polymer foaming based on a new heterogeneous nucleation mode [J]. Journal of Rheology, 2004,48(2): 439-462.
    [56] Vivek Pai, Moshe Favelukis. Dynamics of spherical bubble growth [J]. Journal of Cellular Plastics, 2002, 38: 403-419.
    [57] Moris Amon, Costel D.Denson. A study of the dynamics of foam growth: Analysis of the growth of closely spaced spherical bubbles [J]. Polymer Engineering and Science, 1984,24(13): 1028-1034.
    [58] Muhammad A. Shafi, James G. Lee, Raymond W. Flumerfelt. Prediction of cellular structure in dree expansion polymer foam processing [J]. Polymer Engineering and Science, 1996, 36(14): 1950-1959.
    [59] S.L. Everitt, O.G.Harlen, H.J. Wilson, et al. Bubble dynamics in viscoelastic fluids with application to reacting and non-reacting polymer foams [J]. Journal of Non-Newtonian Fluid Mechanics, 2003,114: 83-107.
    [60] Dmitri Lastochkin, Moshe Favelukis. Bubble growth in a variable diffusion coefficient liquid [J]. Chemical Engineering Journal, 1998, 69: 21-25.
    [61] A. B. Metzner, W. T. Houghton, R. A. Sailor, J. L. White. A method for the measurement of normal stresses in simple shearing flow [J]. Journal of Rheology, 1961,5:133-147.
    [62] Han C. D. On the rheological interpretation of die swell in molten polymers [J]. Journal of Applied Polymer Science, 1970,14: 1775-1780.
    [63] Tanner R.I. A theory of die-swell [J]. Journal of Polymer Science,1970, 8(12): 2067-2078.
    
    [64] Nakajima,B.F.Goodrich,Chem.Corp Report 1972[R]
    [65] W.Graessley, S.D.Glasscock, and E.L.Crawley. Die swell in molten polymers [J]. Journal of Rheology, 1970,14: 519-544.
    [66] Nickell R E, Tanner R 1, Caswell B. The solution of viscousin compressible jet and free-surface flows using finite-element methods [J]. Journal of Fluid Mechanics 1974, 65(1), 189-206.
    
    [67] Tanner R 1. Engineering Rheology. Oxford: Clarendon, 1985.
    [68] Chang P W, Pattern T W, Finlayson B A. Collocation and Galerkin finite element methods for viscoelastic fluid flow. I. Description of method and problems with fixed geometry [J]. Comp. Fluids, 1979, 7(4): 267-283.
    [69]Crochet M J,Keunings R.Die swell of a maxwell fluid:numerical prediction[J].Journal of Non-Newtonian Fluid Mechanics,1980,7:199-212.
    [70]Wesson R D,Papanastasiou A C.Flow singularity and slip velocity in plane extrudate swell computations[J].Journal of Non-Newtonian Fluid Mechanics,1988,26:277-295.
    [71]Rajagopalan D,Armstrong R C,Brown R A.Comparison of computational efficiency of flow simulations with multimode constitutive equations:integral and differential models[J].Journal of Non-Newtonian Fluid Mechanics,1993,46:243-273.
    [72]申长雨.塑料模具计算机辅助工程[M].河南:河南科学技术出版社,1998.
    [73]顾尔祚.流体力学有限差分法基础[M].上海:上海交通大学出版社,1988.
    [74]O.C.Zienkiewicz.The finite element method[M].Oxford:Butterworth-Heinemann,2000.
    [75]王福军.计算流体动力学分析—CFD软件原理与应用[M].北京:清华大学出版社,2005.
    [76]汪鸿振,郭芃.用边界元法计算声辐射时高次奇异积分的处理方法[J].声学技术,1996,15(3):97-100.
    [77]Luo X L,Tanner R I.A streamline element scheme for solving viscoelastic flow problems.Part Ⅰ Differential constitutive equations[J].Journal of Non-Newtonian Fluid Mechanics,1986,21:179-199.
    [78]范毓润.挤出胀大的有限元分析和实验[D].杭州:浙江大学博士学位论文,1988.
    [79]Crochet M J,Davies A R,Waiters K.Numerical simulation of non-Newtonian flow[M].Amsterdan:Elsevier,1984.
    [80]黄树新.粘弹聚合物熔体挤出胀大的数值模拟研究[D].华东理工大学博士学位论文,2001.
    [81]阎超.计算流体力学方法及应用[M].北京:北京航空航天大学出版社,2007.
    [82]金日光.高聚物流变学及其在加工中的应用[M].北京:化学工业出版社,1986.
    [83]何曼君,陈维孝,董西侠.高分子物理[M].上海:复旦大学出版社,2002.
    [84]陈天翔.幂率流体圆管非定常流动的数值分析[J].力学学报,1987,19(1):30-37.
    [85]梁基照.聚合物材料加工流变学[M].北京:国防工业出版社,2008.
    [86]林师沛.塑料加工流变学[M].成都:成都科技大学出版社,1989.
    [87]Kishore Joshi,James G.Lee,Muhammad A.Shaft,Raymond W.Flumerfelt.Prediction of Cellular Structure in Free Expansion of Viscoelastic Media[J].Journal of Applied Polymer Science,1998,67:1353-1368.
    [88]Yasuhiko Otsuki,Toshitaka,Kanai.Numerical simulation of bubble growth in viscoelastic fluid with diffusion of dissolved foaming agent[J].Polymer Engineering and Science,2005,45(9):1277-1287.
    [89]唐志玉.塑料挤塑模与注塑模优化设计[M].北京:机械工业出版社,2008.
    [90]Ichiro Tanasawa,Wenjei Yang.Dynamics behavior of a gas bubble in viscoelastic liquids[J].Journal of applied physics,1970,41(11):4526-4531.
    [91]Moshe Favelukis,Zhihui Zhang,Vivek Pai.On the growth of a non-ideal gas bubble in a solvent-polymer solution[J].Polymer Engineering and Science,2000,40(6):1350-1359.
    [92]Zehev Tadmor.Non-Newtonian tangential flow in cylindrical annuli[J].Polymer Engineering and Science,1966,6(3):203-212.
    [93]章本照,印建安,张宏基.流体力学数值方法[M].北京:机械工业出版社,2003.
    [94]T.J.Chung.流体动力学的有限元分析[M].北京:电力工业出版社,1980.
    [95]朱伯芳.有限单元法原理与应用[M].北京:中国水利水电出版社,1998.
    [96]吴其晔,巫静安.高分子材料流变学导论[M].北京:化学工业出版社,1994.
    [97]D.S.Malkus,T.J.R.Hughs.Mixed finite element methods-reduced and selective integration techniques:a unification of concepts[J].Computer Methods in Applied Mechanics and Engineering,1978,15:63-81.
    [98]David Roylance.Use of "penalty" finite elements in analysis of polymer melt processing[J].Polymer Engineering and Science,1980,20(15):1029-1034.
    [99]秦升学.异型材聚合物挤出与钢塑共挤过程的有限元模拟关键技术及其机理研究[D].济南:山东大学博士学位论文,2006.
    [100]范毓润,范西俊,路甬祥.挤出胀大流动的有限元方法研究[J].力学学报.1990,22(3):285-292.
    [101]Luo XL,Tanner RI.A streamline element scheme for solving viscoelastic flow problems Part Ⅱ integral constitutive models[J].Journal of Non-Newtonian Fluid Mechanics,1986,22:61-89.
    [102]Caswell B,Viriyayuthakorn M.Finite element simulation of die swell for a Maxwell fluid[J].Journal of Non-Newtonian Fluid Mechanics,1983,12:13-29.
    [103]Ki Byung Sunwoo,Seung Joon Park,Seong Jae Lee,Kyung Hyun Alan,Seung Jong Lee.Numerical simulation of three-dimensional viscoelastic flow using the open boundary condition method in coextrusion process[J].Journal of Non-Newtonian Fluid Mechanics,2001,99:125-144.
    [104]C.R.Beverly,R.I.Tanner.Numerical analysis of three-dimensional Newtonian extrudate swell[J].Rheologica Acta,1991,30:341-356.
    [105]W.A.Gifford.A Three-dimensional analysis of coextrrsion[J].Polymer Engineering and Science,1997,37(2):2315-320.
    [106]Tran-Cong T,Phan-Thien N.Three-dimensional study of extrusion processes by boundrv element method[J].Rheologica Acta,1988(27):21-30.
    [107]Caswell B.Viriyayuthakom M.Journal of Non-Newtonian Fluid Mechanics[J].1984,37:16.
    [108]Karagiannis A.et al.Three-dimensional non-isothermal extrusion flows[J].Rheologica Acta,1989,28:121-133.
    [109]赵建才.聚合物挤出成型中模拟技术的研究及应用[D].上海:上海交通大学,2004.
    [110]Evan Mitsoulis.Annular extrudate swell of pseudoplastic and viscoplastic fluids [J].Journal of Non-Newtonian Fluid Mechanics.2007,141:138-147.
    [111]王建军,陆明万,张雄.流体力学Petrov-Galerkin有限元法研究进展[J].计算力学学报,1998,15(4):495-502.
    [112]Brooks A N,Hughes T J R.Streamline Upwind/Petrov-Galerkin formulations for convection dominated flowswith particular emphasis on the incompressible Navier-Stokes equations[J].Computer Methods in Applied Mechanics and Engineering,1982,32:199-259.
    [113]GHIA K N,GHIA C T,SHIN.Highi-Re solution for incompressible flow using the Navier-Stokes equations and a multigird method[J].Journal of Computational Physics,1982,48:209-233.
    [114]Wei Yong-Tao,Yu Jian-Hua,Cao Shu-You.A new artificial diffusion factor in the streamline Upwind/Petrov-Galerkin formulation[J].Journal of Hydrodynamics,Ser.B,2002,3:76-82.
    [115]魏泳涛.不可压缩Navier-Stokes方程的有限元分析[D].成都:四川大学,2003.
    [116]N.Phan-Thien,R.T.Tarmer.A new constitutive equation derived from network theory[J].Journal of Non-Newtonian Fluid Mechanics,1977,2:353-365.
    [117]N.Phan-Thien.A non-linear network viscoelastic model[J].Journal of Rheology,1978,22:259-283.
    [118]V.Ngamaramvaranggul,M.F.Webster.Simulation of pressure-tooling wire-coating flow with Phan-Thien/Tanner models[J].International Journal For Numerical Methods In Fluids,2002,38:677-710.
    [119]F.T.Akyildiz.Dispersion of a solute in a Poiseuille flow of a viscoelastic fluid[J].International Journal of Engineering Science,2002,40:859-872.
    [120]D.Rh.Gwynllyw,T.N.Phillips.The influence of Oldroyd-B and PTT lubricants on moving journal bearing systems[J].Journal of Non-Newtonian Fluid Mechanics,2008,150:196-210.
    [121]G.S.de Paulo,M.F.Tome,S.McKee.A marker-and-cell approach to viscoelastic free surface flows using the PTT model[J],Journal of Non-Newtonian Fluid Mechanics,2007,147:149-174.
    [122]Takehiro Yamamoto,Masakazu Ishiyama,Masaki Nakajima,Kiyoji Nakamura,Noriyasu Moil.Three-dimensional viscoelastic flows through a rectangular channel with a cavity[J].Journal of Non-Newtonian Fluid Mechanics,2003,114:13-31.
    [123]R.Guenette,M.Fortin.A new mixed finite method for computing viscoelastic flows[J].Journal of Non-Newtonian Fluid Mechanics,1995,60:27-52.
    [124]F.P.T.Baaijens.An iterative solve for the DEVSS/DG method with application to smooth and non-smooth flows of the upper convected Maxwell fluid[J].Journal of Non-Newtonian Fluid Mechanics,1998,75:119-138.
    [125]M.A.Hulsen,A.P.G.van Heel,B.H.A.A.van den Brule.Simulation of viscoelastic flows using Brownian configuration fields[J].Journal of Non-Newtonian Fluid Mechanics,1997,97:79-101.
    [126]牟玥.挤出加工流场中聚合物成型机理及其工艺模拟与优化研究[D].济南:山东大学博士学位论文,2008.
    [127]Hughes T J R,Brooks A N.A multidimensional upwind scheme with no crosswind diffusion,in finite element method for convection dominated flows [J].ASME,N Y.1979.
    [128]Brooks A N,Hughes T J R.Streamline upwind/petrov-galerkin formulations for convective dominated flows with particular emphasis on the incompressible N-S equations[J].Computer Method in Applied Mechanics and Engineering,1982,32:199-258.
    [129]Hughes T J R.Recent progress in the development and understanding of SUPG methods with special reference to the compressible euler and Navier-Stokes equations[J].International Journal for Numerical Methods in Fluids,1987,7:1261-1275.
    [130]Tanner R.I.,Jin H.A study of some numerical viscoelastic schemes[J].Journal of Non-Newtonian Fluid Mechanics,1991,41:171-196.
    [131]牟文杰,吴舜英.微孔泡沫塑料成型研究进展[J].中国塑料,2002,16(5): 6-10.
    
    [132]Ramesh N.S, Rasmussen D.H, Campbell G.A. The heterogeneous nucleation of microcelluar foams by the survival of microvoids in polymers containing low glass transition particles. Part I: mathematical modeling and numerical simulation [J]. Polymer Engineering and Science, 1994, 34: 1685-1697.
    
    [133]Ramesh N.S, Rasmussen D.H, Campbell GA. The heterogeneous nucleation of microcellular foams by the survival of microvoids in polymers containing low glass transition particles. Part II: experimental results and discussion [J]. Polymer Engineering and Science, 1994, 34: 1698-1706.
    
    [134] 翟文涛,余坚,何嘉松.超临界流体制备微发泡聚合物材料的研究进展[J].高分子通报,2009,3:1-10.
    [135]Kung E, Lesser A.J, McCarthy T.J. Morphology and mechanical performance of polystyrene/polyethylene composites prepared in supercritical carbon dioxide [J]. Macromolecules, 1998, 31(13): 4160-4169.
    [136]Arora K.A, Lesser A.J, McCarthy T.J. Preparation and characterization of microcellular polystyrene foams processed in supercritical carbon dioxide [J]. Macromolecules, 1998, 31(14): 4614-4620.
    [137]Arora K.A, Lesser A.J, McCarthy T.J. Compressive behavior of microcellular polystyrene foams processed in supercritical carbon dioxide [J]. Polymer Engineering and Science, 1998, 38(12): 2055-2062.
    [138]Wang J, Cheng X G, Yuan M J, He J S. An investigation on the microcellular structure of polystyrene/LCP blends prepared by using supercritical carbon dioxide [J]. Polymer, 2001,42(19): 8265-8275.
    [139]Gerhardt L.J, C.W. Manke et al. Rheology of polydimethylsiloxane swollen with supercritical carbon dioxide [J]. Journal of Polymer Science Part B: Polymer Physics, 1997, 35: 523-534.
    [140]Gerhardt L.J, A. Garg et al. Concentration-dependent viscoelastic scaling models for polydimethylsiloxane melts with dissolved carbon dioxide [J]. Journal of Polymer Science Part B: Polymer Physics, 1998,36: 1911-1918.
    [141]Kwag C, C.W. Manke et al. Effect of dissolved gas on viscoelastic scaling and glass transition temperature of polystyrene melts [J]. Industrial & Engineering Chemistry Research, 2001,40: 3084-3052.
    [142]Royer J.R, Y.J. Gay et al. High-pressure theology of polystyrene melts plasticized with carbon dioxide: experimental measurement and predictive scaling relationships [J]. Journal of Polymer Science Part B: Polymer Physics, 2000,38:3168-3180.
    [143]Williams M.L, R.F. Landel et al. The temperature dependence of relaxation mechanisms in amorphous polymers and other glass-forming liquids [J]. Journal of the American Chemical Society, 1955, 77: 3701-3707.
    [144]Condo P.D, I.C. Sanchez et al. Glass transition behavior including retrograde vitrification of polymers with compressed fluid diluents [J]. Macromolecules, 1992,25:6119-6127.
    [145] Chow T.S. Molecular interpretation of the glass transition temperature of polymer-diluent systems [J]. Macromolecules, 1980,13: 362-364.
    [146]Penwell R.C, R.S. Porter. Effect of pressure in capillary flow of polystyrene [J]. Journal of Polymer Science Part A: Polymer Chemistry, 1971, 9: 463-482.
    [147]O.Muth, Th.Hirth, H.Vogel. Investigation of sorption and diffusion of supercritical carbon dioxide into poly(vinyl chloride) [J]. Journal of Supercritical Fluids, 2001,19: 299-306.
    [148]Gaines GL. Surface and interfacial tension of polymer liquids [J]. Polymer Engineering and Science, 1972, 12(1): 1-11.
    [149]O. Almanza, M.A.Rodriguez-Perez, J.A.de Saja. The microestructure of polyethylene foams produced by a nitrogen solution process [J]. Polymer, 2001, 42:7117-7126.
    1.N.Sombatsompop,N.O-Charoen,"Extrudate Swell Behavior of PS and LLDPE Melts in a Dual Die with Mixed Circular/Slit Flow Channels in an Extrusion Rheometer",Polymer for Advanced Technologies,14,699-710(2003).
    2.Narongrit Sombatsompop,Naret Intawong,"Extrudate swell and flow analysis of polystyrene melt flowing in an electro-magnetized die in a single screw extruder",Polymers for advanced technologies,16,505-514(2005).
    3.J.H.Carneiro de Araujo,V.Ruas,"A stable finite element method for the axisymmetric three-field Stokes system",Computer Methods Applied Mechanics and Engineering,164,267-286(1998).
    4.M.F.Tome,L.Grossi,A.Castelo,J.A.Cuminato,S.McKee,K.Waiters,"Die-swell,splashing drop and a numerical technique for solving the Oldroyd B model for axisymmetrc free surface flows",Journal of Non-Newtonian Fluid Mechanics,141,148-166(2007).
    5.M.F.Tome,A.Castelo,V.G.Ferreira,S.McKee,"A finite difference technique for solving the Oidroyd-B model for 3D-unsteady free surface flows",Journal of Non-Newtonian Fluid Mechanics,154,179-206(2008).
    6.X.Huang,N.Phan-Thien,R.I.Tanner,"Viscoelastic flow between eccentric rotating cylinders:unstructured control volumemethod",Journal of Non-Newtonian Fluid Mechanics,64,71-92(1996).
    7.Junsuo Sun,Nhan Phan-Thien,Roger Ian Tanner,"Extrudate swell through an orifice die" Rheologica Acta,35,1-12(1996).
    8.A.N.Beds,R.C.Armstrong,R.A.Brown,"Spectral finite-element calculalons of the flow of a Maxwell fluid between excentric rotating cylinders",Journal of Non-Newtonian Fluid Mechanics,22,129-167(1987).
    9.X.J.Fan,N.Phan-Thien,R.Zheng,"A direct simulation of fibre suspensions",Journal of Non-Newtonian Fluid Mechanics,74,113-135(1998).
    10.Bogaerds ACB,Vcrbeeten WMH,Peters GWM,Baaijens FPT,"3D viscoelastic analysis of a polymer solution in a complex flow",Computer Methods Applied Mechanics and Engineering,180,413-430(1999).
    11.E.Mitsoulis,F.L.Heng,"Extrudate swell of Newtonian fluids from converging and diverging annular dies",Rheologica Acta,26,414-417(1987).
    12.A.Garcia-Rejon,R.W.DiRaddo,M.E.Ryan,"Effect of die geometry and flow characteristics on viscoelastic annular swell",Journal of Non-Newtonian Fluid Mechanics,60,107-128(1995).
    13.Evan Mitsoulis,"Annular extrudate swell of pseudoplastic and viscoplastic fluids",Journal of Non-Newtonian Fluid Mechanics,141,138-147(2007).
    14.Vivek Ganvir,Ashish Lele,Rochish Thaokar,B.P.Gautham,"Prediction of extrudate swell in polymer melt extrusion using an Arbitrary Lagrangian Eulerian(ALE) based finite element method",Journal of Non-Newtonian Fluid Mechanics,156,21-28(2009).
    15.N-T.Intawong,Sombatsompop,"Experimental studies on radial extrudate swell and velocity profiles of flowing PS melt in an electro-magnetized die of an extrusion rheometer",Polymer Engineering and Science,44(12),2298-2307(2004).
    16.Vincent Warichet,Vincent Legat,"Adaptive hp-finite element viscoelastic flow calculations",Computional Methods in Applied Mechanics Engineering,136,93-110(1996).
    17.Frank P.T.Baaijens,Sjaak H.A.Selen,Hans P.W.Baaijens,Gerrit W.M.Peters,Han E.H.Meijer,"Viscoelastic flow past a confined cylinder of a low density polyethylene melt",Journal of Non-Newtonian Fluid Mechanics,68,173-203(1997).
    18.G.S.de Paulo,M.F.Tome,S.McKee,"A marker-and-cell approach to viscoelastic free surface flows using the PTT model",Journal of Non-Newtonian Fluid Mechanics,147,149-174(2007).
    19.Evan Mitsoulis.Annular extrudate swell of pseudoplastic and viscoplastic fluids.Journal of Non-Newtonian Fluid Mechanics.141,138-14(2007).
    20.Ki Byung Sunwoo,Seung Joon Park,Seong Jae Lee,Kyung Hyun Ahn,Seung Jong Lee,"Numerical simulation of three-dimensional viscoelastic flow using the open boundary condition method in coextrusion process",Journal of Non-Newtonian Fluid Mechanics,99,125-144(2001).
    21.C.R.Beverly,R.I.Tanner,"Numerical analysis of three-dimensional Newtonian extrudate swell",Rheologica Acta,30,341-356(1991).
    22.W.A.Gifford,"A Three-Dimensional Analysis of Coextrrsion" Polymer Engineering and Science,37(2),2315-320(1997).
    23.F.T.Kokkinos,J.N.Reddy,"Bern and penalty FEM models for viscous incompressible Fluids",Computers & Structures.56(5),849-859(1995).
    24.J.Sun,M.D.Smith,R.C.Armstrong,R.A.Brown,"Finite element method for viscoelastic flows based on the discrete adaptive viscoelastic stress splitting and the discontinuous Galerkin method:DAVSS-G/DG",Journal of Non-Newtonian Fluid Mechanics.86,281-307(1999).
    25.Junsuo Sun,Nhan Phan-Thien,Roger I.Tanner,"An adaptive viscoelastic stress splitting scheme and its applications:AVSS/SI and AVSS/SUPG",Journal of Non-Newtonian Fluid Mechanics,65,75-91(1996).
    26.Guo Jilin,Zhou Guofa,Zhou Yongfei,Yan Li.The full three dimensional isothermal viscoelastic numerical simulation on the extrusion die swell of polymer profile(in Chinese).Journal of Nanchang University(Engineering & Technology),29(1),4-8(2007).

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700