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Monte Carlo studies of the conformational statistics of polymers. Polyethylene 聚合物构象统计的蒙特卡罗研究。聚乙烯
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-11-01 DOI: 10.1002/MATS.1993.040020604
R. Raucci, M. Vacatello
{"title":"Monte Carlo studies of the conformational statistics of polymers. Polyethylene","authors":"R. Raucci, M. Vacatello","doi":"10.1002/MATS.1993.040020604","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020604","url":null,"abstract":"The conformational distribution of unperturbed polyethylene (PE) has been studied utilizing the Monte Carlo approach. The results are in excellent agreement with experiments on the average dimensions of PE chains, as well as with the molecular scattering function obtained in mixtures of deuterated and hydrogenous PE at 400 K. Maps of the free energy as a function of two consecutive torsional angles confirm that an approximate description of the conformational distribution of PE can be given in terms of three rotational isomeric (RIS) states. The location of the states and the corresponding energy and entropy parameters, which can be separately evaluated from the Monte Carlo results, are compared with literature results obtained by internal energy calculations for butane and pentane.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125816706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Isomerism and symmetry of stacked polymeric phthalocyaninnes and related polymers 叠层聚合物酞菁及其相关聚合物的异构性和对称性
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-11-01 DOI: 10.1002/MATS.1993.040020607
G. Knothe
{"title":"Isomerism and symmetry of stacked polymeric phthalocyaninnes and related polymers","authors":"G. Knothe","doi":"10.1002/MATS.1993.040020607","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020607","url":null,"abstract":"The number of isomers ir,t for stacked polymeric phthalocyanines in which each phthalocyanine ring is tetrasubstituted or octasubstituted with two different substituents (each benzene moiety substituted with both substitutents) is determined to be \u0000 \u0000 \u0000 \u0000 \u0000 \u0000 \u0000where m is the number of substituted phthalonitrile molecules incorporated into the polymer and x is the number of phthalocyanine macrocycles (degree of polymerization; m = 4x). Specifically, for a stacked polymeric phthalocyanine with x = 2; there exist 298 isomers. The stacked polymeric phthalocyanines with substituted phthalocyanine rings possess different symmetry groups (D2h, D2d, C4, C2V or CS E as sole symmetry operation). The results are valid for stacking of other macrocycles similar to phthalocyanine such as prophyrins.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127144387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
A model for the creep of oriented high‐modulus fibers 取向高模量纤维的蠕变模型
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-09-01 DOI: 10.1002/MATS.1993.040020503
A. Schuppert
{"title":"A model for the creep of oriented high‐modulus fibers","authors":"A. Schuppert","doi":"10.1002/MATS.1993.040020503","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020503","url":null,"abstract":"Recently it has been shown that the creep of oriented high-modulus fibers satisfies a logarithmic time law over very long time intervals. Moreover, the modulus of these fibers increases due to the creep. This was interpreted by the annihilation of conformation defects during creep. In structures with strong intermolecular interactions as in aramides, however, the direct annihilation of defects is difficult to explain. Moreover a direct annihilation leads to a false time law if no further assumption about the properties of the defects are made. In this paper a model for the transport of conformation defects in oriented polymer chains imbedded into an oriented fibrillary structure with strong intermolecular interactions is presented. This modified transport model leads directly to the experimentally observed time law without any further assumptions about the defect properties.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114468796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Monte Carlo simulation of kinetics and chain-length distribution in radical polymerization 自由基聚合动力学和链长分布的蒙特卡罗模拟
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-09-01 DOI: 10.1002/MATS.1993.040020511
Jianming Lu, Hong-dong Zhang, Yuliang Yang
{"title":"Monte Carlo simulation of kinetics and chain-length distribution in radical polymerization","authors":"Jianming Lu, Hong-dong Zhang, Yuliang Yang","doi":"10.1002/MATS.1993.040020511","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020511","url":null,"abstract":"In this paper, the Monte Carlo method for numerically simulating the kinetics and chain-length distribution in radical polymerization is described. Because the Monte Carlo method is not subject to the assumption of steady-state, it is particularly suitable for studying the kinetic behaviour before the steady-state has been reached and for systems in which the steady-state assumption may be violated. Illustrative applications of the algorithm given in this paper not only demonstrate convincingly both the feasibility and usefulness of the algorithm, but also provide some new insight into the illustrative examples. For the case of pseudostationary radical polymerization such as rotating-sector and pulsed-laser initiations, we have found that the pseudostationary radical concentration can be reached after two or three initiation periods. However, the number-average chain-length xn reaches the pseudostationary value much slower than the radical concentration. It is oscillatively reaching the pseudostationary value, and the amplitudes of the oscillations are decreasing with time. We have also found that the chain-length distribution of the resulting polymer in the case of pseudostationary radical polymerization with termination by combination has stronger periodic modulation. Hence, it should be easier to locate the points of inflection in practice. Therefore, the rate constant of propagation, kp, can be determined precisely for systems which are dominated by a combination-type of termination.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"118063725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 60
Conformational characteristics of poly(vinylpyrrolidone). solvent‐dependence of the chain dimensions 聚乙烯基吡咯烷酮的构象特征。链尺寸的溶剂依赖性
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-09-01 DOI: 10.1002/MATS.1993.040020507
M. Tarazona, E. Saiz, L. Gargallo, D. Radić
{"title":"Conformational characteristics of poly(vinylpyrrolidone). solvent‐dependence of the chain dimensions","authors":"M. Tarazona, E. Saiz, L. Gargallo, D. Radić","doi":"10.1002/MATS.1993.040020507","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020507","url":null,"abstract":"Conformational energies as function of rotational angles over two consecutive skeletal bonds for both meso and racemic diads of poly(Nvinyl-2-pyrrolidone) have been computed. The results of these calculations were used to formulate a statistical model that was then employed to calculate the unperturbed dimensions of this polymer. The conformational energies are sensitive to the Coulombic interactions, which are governed by the dielectric constant, of the solvent, and to the size of the solvent molecules. Consequently, the calculated values of the polymeric chain dimensions are strongly dependent on the nature of the solvent, as it was experimentally found before.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126828882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
On the sol fraction of Aa1 Bb1−Aa2 Bb2 copolymerisations Aa1 - Bb1 - Aa2 - Bb2共聚的溶胶组分
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-05-01 DOI: 10.1002/MATS.1993.040020307
Zesheng Li, X. Ba, Chia-Chung Sun, A. Tang
{"title":"On the sol fraction of Aa1 Bb1−Aa2 Bb2 copolymerisations","authors":"Zesheng Li, X. Ba, Chia-Chung Sun, A. Tang","doi":"10.1002/MATS.1993.040020307","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020307","url":null,"abstract":"By means of probability theory, the sol fraction of an Aa1 Bb1−Aa2 Bb2 type copolymerisation reaction, in which intramolecular reactions are neglected, is investigated in the post-gel regime to give the gelation condition explicitly. (Aa1 Bb1 is a monomer with a1 functional groups of type A and b1 functional groups of type B.)","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124279821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A global-update simulation method for polymer systems 聚合物系统的全局更新仿真方法
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-05-01 DOI: 10.1002/MATS.1993.040020301
D. Heermann, L. Yixue
{"title":"A global-update simulation method for polymer systems","authors":"D. Heermann, L. Yixue","doi":"10.1002/MATS.1993.040020301","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020301","url":null,"abstract":"We describe a hybrid Monte Carlo algorithm, combining molecular dynamics with the Monte Carlo method, applied to the simulation of polymer systems. It is shown that observables are independent of the discretization error, and the performance, i.e., autocorrelation times of observables, is analyzed. For a dense system representing a polyethylene melt, we present data for the pair distribution function and the mean square displacement of a chain in the bulk. We also investigate the possibility of using a scaled Hamiltonian in the algorithm.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126140436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 17
Modelling free‐radical copolymerization kinetics—evaluation of the pseudo‐kinetic rate constant method, 1. Molecular weight calculations for linear copolymers 模拟自由基共聚动力学——伪动力学速率常数法的评价，1。线性共聚物的分子量计算
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-05-01 DOI: 10.1002/MATS.1993.040020311
T. Xie, A. E. Hamielec
{"title":"Modelling free‐radical copolymerization kinetics—evaluation of the pseudo‐kinetic rate constant method, 1. Molecular weight calculations for linear copolymers","authors":"T. Xie, A. E. Hamielec","doi":"10.1002/MATS.1993.040020311","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020311","url":null,"abstract":"The moment equations for binary copolymerization in the context of the terminal model have been solved numerically for a batch reactor operating over a wide range of conditions. Calculated number- and weight-average molecular weights were compared with those found using pseudo-kinetic rate constants with the method of moments and with the instantaneous property method for homopolymerization. With the pseudo-kinetic rate constant method under polymerization conditions where number-average molecular weights (Mn) are below about 103 the error in calculating Mn exceeds 5%. The error increases rapidly with decrease in molecular weight for Mn < 103. Mn measured experimentally for polymer chains (homo- and copolymers) have error limits of greater than ±5% at the 95% confidence level. Therefore, for all practical purposes, the pseudo-kinetic rate constant method is valid for Mn greater than 103. Errors in calculating weight-average molecular weights (Mw) or higher averages are always smaller than those for Mn when applying the pseudo-kinetic rate constant method. The assumptions involved in molecular weight modelling using the pseudo-kinetic rate constant approach are thus proven to be valid, and therefore it is recommended that the pseudo-kinetic rate constant method be employed with the instantaneous property method to calculate the full molecular weight distribution and averages for linear chains synthesized by multicomponent chain growth polymerization.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126014146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 41
Diffraction modelling of poly(vinyl chloride): An approach to the crystallinity enigma 聚氯乙烯的衍射模型:结晶度之谜的一种方法
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-03-01 DOI: 10.1002/MATS.1993.040020207
R. Hobson, A. Windle
{"title":"Diffraction modelling of poly(vinyl chloride): An approach to the crystallinity enigma","authors":"R. Hobson, A. Windle","doi":"10.1002/MATS.1993.040020207","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020207","url":null,"abstract":"This paper demonstrates that changes which are seen to occur in experimental X-ray diffraction patterns of poly(vinyl chloride) (PVC) with varying sample tacticity are indicative of a crystal structure in which both isotactic and syndiotactic sequences are incorporated within the same lattice. The isotactic sequences are in a conformation first suggested by Juijn et al. which enables them to emulate the shape of the syndiotactic chain. We present a short summary of molecular and diffraction modelling results which show how the intensities of the 200 and 110 peaks change with crystallite tacticity. The results provide a rational explanation for the long standing enigma that the observed crystallinity of atactic PVC is too high to be accounted for in terms of crystallization of syndiotactic sequences only.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125863604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 11
Statistics of stiff polymer chains near an adsorbing surface 吸附表面附近的硬聚合物链的统计
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-03-01 DOI: 10.1002/MATS.1993.040020201
A. Khokhlov, F. F. Ternovsky, E. A. Zheligovskaya
{"title":"Statistics of stiff polymer chains near an adsorbing surface","authors":"A. Khokhlov, F. F. Ternovsky, E. A. Zheligovskaya","doi":"10.1002/MATS.1993.040020201","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020201","url":null,"abstract":"The exact solution of the problem of adsorption of a long ideal polymer chain with variable degree of stiffness on a plane surface is presented. It is shown that the adsorption of stiff polymer chains is a second-order phase transition; in the adsorbed state “train” (i.e. adsorbed) sections are relatively longer and loop sections relatively shorter than for flexible chains. This effect is very pronounced: already for moderately stiff chains the number of Kuhn segment lengths in one “train” section at the temperature T = Tcr/2 (Tcr is the critical temperature for adsorption transition) can reach several thousands, and deviation from the surface occurs only in the form of small “hairpins”. The maximum length of the chain, which at the given conditions would flatten completely on the surface, is estimated.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126735118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 19
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