Finite element simulation of the physical gelation of rennet casein

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	Finite element simulation of the physical gelation of rennet casein
	Feng Ligang 1; Jia Yuxi 1,2; Chen Xiliang 1; An Lijia 2
刊名	ACTA POLYMERICA SINICA
	2008-06-01
期号	6 页码:529-536
关键词	Physical Gel Rennet Casein Finite Element Simulation Temperature Field Complex Shear Modulus Field
ISSN号	1000-3304
英文摘要	A physical gel is a three-dimensional network of polymer chains cross-linked by physical junctions, and it can arise either as the result of a phase transition or through some specific molecular association or as a result of entanglements. Due to the complexity of the inner structure and gelation mechanism, it is difficult to obtain purposefully polymer physical gel materials with specific constitution and properties. Thus, the controllable preparation and application of polymer physical gels are a long-term work. As a numerical simulation method in macro-scale the finite element method has been used to the study of chemical gelation,but rarely to physical gelation presently. The reasons may be: compared with chemical gels the gelation process of physical gels is more complex resulting from the bigger complexity of the system composition and physical interactions. Several kinds of interactions and steps may be involved in one physical gelation proeess. And under different conditions the gelation mechanisms are frequently different. By now the understanding of the gelation mechanisms of many kinds of physical gels is far from being intensive; the phenomenological gelation kinetics models are usually nonlinear; the theory describing the relation between the microscopic and mesoscopic structure and the macroscopic properties is still immature. For all the factors mentioned above the numerical simulation of physical gelation process in macro-scale comes to be a difficult work. In order to optimize raw material formulation and physical gelation conditions, and then obtain polymer physical gels according to requirements, the spatial distribution and time evolution characteristics of the temperature field during the gelation process were studied via the finite element method. On the basis of the temperature field calculated, the complex shear modulus field of gel system was numerically simulated according to a first-order gelation kinetic equation, and the effects of raw material concentration, sample size and cooling modes on the physical gelation were discussed. Rennet casein gel is a kind of particle gel, whose formation is controlled by physical forces including steric-hydration force and van der Waals force, and whose structure and properties are influenced by many parameters including emulsifying salts I pH, thermal and shear history. The formation process of the gel network can be divided into three steps, molecules-particles-flocs-network. Casein floes are fractal objects that can be partially filled by the constructing units (particles). The fractal dimension of the floes and the size of the particles are two important parameters determining the gel microscopic structure and rheological properties. Experimental results show that cooling modes will influence the rheological properties of the gel through influencing the size of the particles. The formation of rennet casein gels is a first-order kinetics process. Three examples were studied. The raw material concentrations of example I and example 2 are both 18% but the sample size of the former is five times as that of the latter; the raw material concentration of example 3 is 25%, and the sample size is same with example 1. The gel zone is divided into 136 unites and 163 nodes; the prototype zone is divided into 28 unites and 40 nodes; four representative nodes were selected in the gel zone, and were emphatically studied.
语种	英语
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000257127900004
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/65553]
专题	中国科学院化学研究所
通讯作者	Feng Ligang
作者单位	1.Shandong Univ, Sch Mat Sci & Engn, Jinan 250061, Peoples R China 2.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China
推荐引用方式 GB/T 7714	Feng Ligang,Jia Yuxi,Chen Xiliang,et al. Finite element simulation of the physical gelation of rennet casein[J]. ACTA POLYMERICA SINICA,2008(6):529-536.
APA	Feng Ligang,Jia Yuxi,Chen Xiliang,&An Lijia.(2008).Finite element simulation of the physical gelation of rennet casein.ACTA POLYMERICA SINICA(6),529-536.
MLA	Feng Ligang,et al."Finite element simulation of the physical gelation of rennet casein".ACTA POLYMERICA SINICA .6(2008):529-536.