Macromolecular Theory and Simulations最新文献_第9页

Combining 13C-NMR Triad Sequence Data with Joint Molecular Weight and Composition Data to Estimate Parameters in a Gas-Phase Polyethylene Reactor Model 结合13c‐NMR三重序列数据与联合分子量和组成数据来估计气相聚乙烯反应器模型的参数

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-01-12 DOI: 10.1002/mats.202200073

Jakob I. Straznicky, Jennifer P. Aiello, Lauren A. Gibson, Yan Jiang, Timothy Boller, Hsu Chiang, Kimberley B. McAuley

{"title":"Combining 13C-NMR Triad Sequence Data with Joint Molecular Weight and Composition Data to Estimate Parameters in a Gas-Phase Polyethylene Reactor Model","authors":"Jakob I. Straznicky, Jennifer P. Aiello, Lauren A. Gibson, Yan Jiang, Timothy Boller, Hsu Chiang, Kimberley B. McAuley","doi":"10.1002/mats.202200073","DOIUrl":"10.1002/mats.202200073","url":null,"abstract":"A three-site metallocene catalyst is used in a gas-phase semi-batch reactor to produce ethylene/hexene copolymers. At the end of each batch, polyethylene (PE) is collected and analyzed to determine the carbon-13 nuclear magnetic resonance (13C-NMR) triad sequence distribution. Joint molecular weight (MW) and composition distribution data are obtained using gel permeation chromatography with an infrared detector (GPC-IR). Data from ten experimental runs are used for kinetic parameter estimation. Using a mean-squared error (MSE) selection methodology, 23 of the 36 model parameters are selected for estimation using the available polymerization rate and PE characterization data. The remaining parameters are held at initial guesses to avoid overfitting. Addition of the triad data to the parameter estimation problem allows for one additional parameter to be estimated and results in improved parameter estimates. Standard deviations of all but one of the estimated parameters decreased due to inclusion of triad data. The updated parameter estimates result in good fits for the triad data and for joint MW and composition data. The model accurately predicts four validation data sets not used for parameter estimation. The new model and its updated parameter estimates will be valuable for scaling up new polymer grades from laboratory-scale to commercial-scale.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42656307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Molecular Simulation and Experimental Study on the Damping and Aging Properties of 4010NA/Hydrogenated Nitrile Butadiene/Nitrile Butadiene Rubber Composites 4010NA/氢化丁腈橡胶/丁腈橡胶复合材料阻尼与老化性能的分子模拟与实验研究

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-01-06 DOI: 10.1002/mats.202200072

Meng Song, Meng Wang, Chaole Wang, Jihong Song, Yunan Li, Fengyi Cao, Guomin Yu, Qi Qin

{"title":"Molecular Simulation and Experimental Study on the Damping and Aging Properties of 4010NA/Hydrogenated Nitrile Butadiene/Nitrile Butadiene Rubber Composites","authors":"Meng Song, Meng Wang, Chaole Wang, Jihong Song, Yunan Li, Fengyi Cao, Guomin Yu, Qi Qin","doi":"10.1002/mats.202200072","DOIUrl":"10.1002/mats.202200072","url":null,"abstract":"The effects of N-isopropyl-N′-phenyl-phenylenediamine (4010NA) content on the damping and aging properties of hydrogenated nitrile butadiene rubber (HNBR)/nitrile butadiene rubber (NBR) (abbreviated as H-NBR) matrix are studied via molecular simulation and experiments. The effects of 4010NA addition on the damping and aging properties of H-NBR are analyzed by molecular simulation using solubility parameters (δ), hydrogen bonds, free volume fraction (FFV), binding energy (Ebinding), hydrogen bond dissociation energy (ΔG), and mean square displacement (MSD). The damping, mechanical, and thermo-oxygen aging properties of the 4010NA/H-NBR composites are studied experimentally using infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results indicate that 4010NA has good compatibility with HNBR and NBR, and the addition of 4010NA can effectively improve the damping properties of H-NBR. When 4010NA is added at 32 phr, the composite has better damping properties, mechanical properties, and aging resistance, which provides a new insight for the construction of high performance elastomer composites.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41316722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Effect of Topology on the Collapse Transition and the Instantaneous Shape of a Model Heteropolymer 拓扑结构对模型异聚物塌缩跃迁和瞬时形状的影响

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-01-04 DOI: 10.1002/mats.202200074

Thoudam Vilip Singh, Lenin S. Shagolsem

引用次数: 0

Random Branching and Cross-linking of Polymer Chains, Analytical Functions for the Bivariate Molecular Weight Distributions 聚合物链的随机分支和交联，二元分子量分布的分析函数

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-12-23 DOI: 10.1002/mats.202200062

Rolf Bachmann, Marcel Klinger, Jan Meyer

{"title":"Random Branching and Cross-linking of Polymer Chains, Analytical Functions for the Bivariate Molecular Weight Distributions","authors":"Rolf Bachmann, Marcel Klinger, Jan Meyer","doi":"10.1002/mats.202200062","DOIUrl":"10.1002/mats.202200062","url":null,"abstract":"Cross-linking and branching of primary polymer molecules are investigated using the Galton–Watson (GW) process. Starting with the probability generating function (pgf) of the primary molecular weight distribution (MWD), analytical expressions are derived for the bivariate pgfs g(nbr, s) of branched polymers which depend also on the number of branch points nbr. The bivariate MWDs n(nbr, i) (i: number of molecular units) are then derived as Taylor expansions in s. All three cases of random branching: X-shaped (cross-linking), T-shaped (only one end takes part in the branching process), and H-shaped (both ends can take part in the branching process) are treated. An extension of the formalism does not require the construction of the pgf and allows the direct use of the MWD of the primary chains. However, using pgfs allows to go past the gel point and to determine the MWD and content of the sol. Explicit expressions are given for special distributions: the mono modal, the most probable, the Schulz-Zimm, the Poisson, and the Catalan distribution for the cases of X-shaped and T-shaped branching.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44506970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Polyimide/Silica Nanocomposites with Enhanced Tensile Strength: Size Effects and Covalently Bonded Interface 增强拉伸强度的聚酰亚胺/二氧化硅纳米复合材料：尺寸效应和共价键合界面

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-12-07 DOI: 10.1002/mats.202200066

Yu Wang, Wenlong Yang, Jiaqi Lin, Xinmei Liu, Yuhang Zuo, Hongguo Sun, Ying Yang

{"title":"Polyimide/Silica Nanocomposites with Enhanced Tensile Strength: Size Effects and Covalently Bonded Interface","authors":"Yu Wang, Wenlong Yang, Jiaqi Lin, Xinmei Liu, Yuhang Zuo, Hongguo Sun, Ying Yang","doi":"10.1002/mats.202200066","DOIUrl":"10.1002/mats.202200066","url":null,"abstract":"In this work, the tensile strength of polyimide/silica composites with the covalently bonded interface (bonded PI/SiO2) is investigated by molecular dynamic simulation. It is found that the nanofiller with smaller size can bring out a larger number of hydrogen bonds and interfacial non-bond energy in the composites, resulting in higher tensile strength. As the immobilization of the PI chains in the vicinity of SiO2, the covalently bonded interface is found to offer a greater reinforcing effect than the unbonded interface that is confirmed by the self-diffusion coefficient. The tensile strength of 9 wt.% bonded PI/SiO2 composites is 11.34% higher than that of the unbounded composites. The tensile strength of PI/SiO2 composites is enhanced with the increase of SiO2 concentration up to critical mass percent (Xc), beyond which it will be decreased. To quantitatively predict Xc of PI/SiO2 composites, an empirical equation based on the non-bond energy of the composites is proposed. The empirical equation showed that the Xc of PI/SiO2 composites ranged from 8.03 to 10.36 wt.%, which is consistent with experimental values. These results provided the understanding of size-dependent covalently bonded interface structure, which would be beneficial to the design of nanocomposites with excellent mechanical performances.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45908224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Processing Properties and Thermal Stability of Poly(vinyl chloride-co-vinyl acetate) by Experiments and Molecular Dynamics Simulations 聚氯乙烯-醋酸乙烯共聚物的加工性能及热稳定性的实验和分子动力学模拟

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-11-25 DOI: 10.1002/mats.202200054

Runyue Li, Daolei Lin, Shiqin Xu, Xingzheng Chen, Guofeng Tian, Dezhen Wu

{"title":"Processing Properties and Thermal Stability of Poly(vinyl chloride-co-vinyl acetate) by Experiments and Molecular Dynamics Simulations","authors":"Runyue Li, Daolei Lin, Shiqin Xu, Xingzheng Chen, Guofeng Tian, Dezhen Wu","doi":"10.1002/mats.202200054","DOIUrl":"https://doi.org/10.1002/mats.202200054","url":null,"abstract":"The effects of copolymerized monomer vinyl acetate (VAc) on processing properties and thermal stability of poly(vinyl chloride-co-vinyl acetate) (PVCA) are investigated via experiment and molecular dynamics simulation. Experimental results showed that PVCA with higher VAc content has larger loss tangent (tanδ), lower complex viscosity (η*), and glass transition temperature (Tg), which improved the processing properties of PVCA. A series of PVCA models are constructed to study the microstructure on the processing properties of PVCA, and the results showed the PVCA with higher VAc content exhibits larger molecular chain mobility and free volume fraction (FFV), smaller intermolecular interactions, and the mean square end-to-end distance (<Ree2>). Furthermore, the IR spectra of gas products indicated that thermal degradation of PVCA mainly generated hydrogen chloride (HCl), carboxylic acid, and aliphatic hydrocarbons between 200 and 500 °C, and the removal of HCl and carboxylic acid is almost simultaneous. The degradation models of PVCA chains demonstrated the CCl bond in vinyl chloride (VC) and CO bond in VAc have similar thermal stability, which corresponded to the experimental results. In a word, the work provides a promising technique to study the structure and property of PVCA at molecular dynamic level.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50154334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Copolymerization Reactivity Ratio Inference: Determining Confidence Contours in Parameter Space via a Bayesian Hierarchical Approach 共聚反应性比推断:通过贝叶斯层次方法确定参数空间中的置信轮廓

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-11-24 DOI: 10.1002/mats.202200063

Robert Reischke

{"title":"Copolymerization Reactivity Ratio Inference: Determining Confidence Contours in Parameter Space via a Bayesian Hierarchical Approach","authors":"Robert Reischke","doi":"10.1002/mats.202200063","DOIUrl":"10.1002/mats.202200063","url":null,"abstract":"Confidence contours in parameter space are a helpful tool to compare and classify determined estimators. For more intricate parameter estimations of nonlinear nature or complex error structures, the procedure of determining confidence contours is a statistically complex task. For polymer chemists, such particular cases are encountered in determination of reactivity ratios in copolymerization. Hereby, determination of reactivity ratios in copolymerization requires nonlinear parameter estimation. Additionally, data may possess (possibly correlated) errors in both dependent and independent variables. A common approach for such nonlinear estimations is the error-in-variables model yielding statistically unbiased estimators. Regarding reactivity ratios, to date published procedures neglect the non-Gaussian structure of the error estimates that is a consequence of the nonlinearity of the model. In this publication, this issue is addressed by employing a Bayesian hierarchical model, which correctly propagates the errors of all variables. The statistical procedure is discussed in chemist friendly language to encourage confident usage of the tool. The approach is based on a Python program requiring minimal installation effort. A detailed manual of the code is included in the appendix of this work, in an effort to make this procedure available to all interested polymer chemists.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mats.202200063","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47639267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Masthead: Macromol. Theory Simul. 6/2022 刊头：Macromol.理论模拟6/2022

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-11-18 DOI: 10.1002/mats.202270012

引用次数: 0

Effects of Primary Structure of Reactive Polymers on Network Structure and Mechanical Properties of Gels 反应性聚合物一级结构对凝胶网络结构和力学性能的影响

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-11-18 DOI: 10.1002/mats.202270011

Tsutomu Furuya, Tsuyoshi Koga

引用次数: 0

Atomistic Modeling of Mechanical Properties and Creep Behavior of Graphene Oxide Reinforced Natural Rubber Composites 氧化石墨烯增强天然橡胶复合材料力学性能和蠕变行为的原子模拟

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2022-11-09 DOI: 10.1002/mats.202200053

Aviral Srivastava, Sumit Sharma, Pramod Rakt Patel

{"title":"Atomistic Modeling of Mechanical Properties and Creep Behavior of Graphene Oxide Reinforced Natural Rubber Composites","authors":"Aviral Srivastava, Sumit Sharma, Pramod Rakt Patel","doi":"10.1002/mats.202200053","DOIUrl":"https://doi.org/10.1002/mats.202200053","url":null,"abstract":"In the realm of polymer composites, the research of nanoparticles has risen in prominence. Graphene oxide (GO) is one of the best nanofillers in natural rubber (NR). In this work, GO nanosheets are utilized as reinforcement in an NR composite to anticipate mechanical characteristics. The researchers project the effect of GO sheets in NR with varied volume percentages and defective GO sheet reinforcement in NR composites. When the volume percentage of GO sheet in the NR nanocomposite is 4.6% and 7.2%, respectively, the value of Young's modulus rose by 68.8% and 166.2%. GO/NR with a 7.2% volume fraction has the highest ultimate tensile strength as compared with lower volume fractions of GO/NR nanocomposites. An increase of 63.49% in ultimate tensile strength in GO/NR nanocomposites (7.2% vol fraction) is seen as compared with pristine NR. Creep characteristics of NR nanocomposites are also investigated. The results reveal that the addition of GO sheets considerably increases the creep resistance strength of NR nanocomposites. The zone of secondary creep grows narrower as the continuous stress level increases.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50136787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0