Polymers

Research

16 pages, 1631 KiB

Open AccessArticle

Crowding-Activity Coupling Effect on Conformational Change of a Semi-Flexible Polymer

by Xiuli Cao, Bingjie Zhang and Nanrong Zhao

Polymers 2019, 11(6), 1021; https://doi.org/10.3390/polym11061021 - 10 Jun 2019

Cited by 13 | Viewed by 2905

The behavior of a polymer in a passive crowded medium or in a very dilute active bath has been well studied, while a polymer immersed in an environment featured by both crowding and activity remains an open problem. In this paper, a systematic [...] Read more.

The behavior of a polymer in a passive crowded medium or in a very dilute active bath has been well studied, while a polymer immersed in an environment featured by both crowding and activity remains an open problem. In this paper, a systematic Langevin simulation is performed to investigate the conformational change of a semi-flexible chain in a concentrated solution packed with spherical active crowders. A very novel shrinkage-to-swelling transition is observed for a polymer with small rigidity. The underlying phase diagram is constructed in the parameter space of active force and crowder size. Moreover, the variation of the polymer gyration radius demonstrates a non-monotonic dependence on the dynamical persistence length of the active particle. Lastly, the activity-crowding coupling effect in different crowder size baths is clarified. In the case of small crowders, activity strengthens the crowding-induced shrinkage to the chain. As crowder size increases, activity turns out to be a contrasting factor to crowding, resulting in a competitive shrinkage and swelling. In the large size situation, the swelling effect arising from activity eventually becomes dominant. The present study provides a deeper understanding of the unusual behavior of a semi-flexible polymer in an active and crowded medium, associated with the nontrivial activity-crowding coupling and the cooperative crowder size effect. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Figure 1

20 pages, 3080 KiB

Open AccessArticle

Morphology on Reaction Mechanism Dependency for Twin Polymerization

by Janett Prehl and Constantin Huster

Polymers 2019, 11(5), 878; https://doi.org/10.3390/polym11050878 - 14 May 2019

Cited by 1 | Viewed by 2818

Abstract

An in-depth knowledge of the structure formation process and the resulting dependency of the morphology on the reaction mechanism is a key requirement in order to design application-oriented materials. For twin polymerization, the basic idea of the reaction process is established, and important [...] Read more.

An in-depth knowledge of the structure formation process and the resulting dependency of the morphology on the reaction mechanism is a key requirement in order to design application-oriented materials. For twin polymerization, the basic idea of the reaction process is established, and important structural properties of the final nanoporous hybrid materials are known. However, the effects of changing the reaction mechanism parameters on the final morphology is still an open issue. In this work, the dependence of the morphology on the reaction mechanism is investigated based on a previously introduced lattice-based Monte Carlo method, the reactive bond fluctuation model. We analyze the effects of the model parameters, such as movability, attraction, or reaction probabilities on structural properties, like the specific surface area, the radial distribution function, the local porosity distribution, or the total fraction of percolating elements. From these examinations, we can identify key factors to adapt structural properties to fulfill desired requirements for possible applications. Hereby, we point out which implications theses parameter changes have on the underlying chemical structure. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

11 pages, 2720 KiB

Open AccessArticle

Influence of Combustion Modifiers on the Cure Kinetics of Glycidyl Azide Polymer Based Propellant-Evaluated through Rheo-Kinetic Approach

by Liming He, Jun Zhou, Sulan Dai and Zhongliang Ma

Polymers 2019, 11(4), 637; https://doi.org/10.3390/polym11040637 - 8 Apr 2019

Cited by 4 | Viewed by 2887

Abstract

To investigate the influence of combustion modifiers on the curing of glycidyl azide polymer spherical propellants (GAPSPs), the curing process of the GAPSPs was explored using an isothermal rheological measurement method. The parameters of cure kinetics were solved to further establish a kinetic [...] Read more.

To investigate the influence of combustion modifiers on the curing of glycidyl azide polymer spherical propellants (GAPSPs), the curing process of the GAPSPs was explored using an isothermal rheological measurement method. The parameters of cure kinetics were solved to further establish a kinetic model for the curing reaction of GAPSPs. The results showed that the curing process of GAPSPs under isothermal conditions conformed to the Kamal and LSK (Lu–Shim–Kim) models. The model data indicated significant agreement with the experimental data. The influence of four kinds of combustion performance modifiers on the curing process was explored and the results demonstrated that lead phthalate had a catalytic effect on the curing reaction of GAPSPs, whilst oxides of lead and copper, and copper adipate had no influence on the curing reaction. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

15 pages, 5397 KiB

Open AccessArticle

Estimation of Mechanical Performance, Thermal Stability and Flame Retardancy of High-Impact Polystyrene/Surface-Modified APP/Carboxylic-Functionalized MWCNTs Nanocomposites

by Li Ding, Zhimeng Jia, Hao Sun, Yong Pan and Jianping Zhao

Polymers 2019, 11(4), 615; https://doi.org/10.3390/polym11040615 - 3 Apr 2019

Cited by 15 | Viewed by 3921

Abstract

An ammonium polyphosphate (APP) surface-modified by silane coupling agent was used as flame retardant in high-impact polystyrene (HIPS). A series of HIPS nanocomposites containing different mass fractions of APP (k-APP) surface-modified by silane coupling agent (3-aminopropyl triethoxysilane, KH 550) and carboxylic-functionalized MWCNTs (COOH–MWCNTs) [...] Read more.

An ammonium polyphosphate (APP) surface-modified by silane coupling agent was used as flame retardant in high-impact polystyrene (HIPS). A series of HIPS nanocomposites containing different mass fractions of APP (k-APP) surface-modified by silane coupling agent (3-aminopropyl triethoxysilane, KH 550) and carboxylic-functionalized MWCNTs (COOH–MWCNTs) were prepared by the melt blending method. A composite only containing APP was also prepared as a reference material. Scanning electron microscopy (SEM) was employed to investigate the dispersion of the fillers into the HIPS matrix, and it was found the hydrophobic groups on the k-APP surface would greatly enhance the dispersion and prevent agglomerations compared with APP. Furthermore, the COOH–MWCNTs also showed good dispersibility into the matrix. Mechanical tests of the nanocomposites revealed that k-APP exhibits a more beneficial effect on both tensile and flexural properties compared with APP. Thermogravimetric analysis (TGA) and cone calorimeter tests (CCT) were conducted to probe the thermal and flammability properties of the nanocomposites, respectively. The synergistic effects of k-APP and COOH–MWCNTs on mechanical, thermal and flammability properties were examined as well. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Figure 1

13 pages, 3354 KiB

Open AccessArticle

Intelligent Machine Learning: Tailor-Making Macromolecules

by Yousef Mohammadi, Mohammad Reza Saeb, Alexander Penlidis, Esmaiel Jabbari, Florian J. Stadler, Philippe Zinck and Krzysztof Matyjaszewski

Polymers 2019, 11(4), 579; https://doi.org/10.3390/polym11040579 - 1 Apr 2019

Cited by 25 | Viewed by 6109

Abstract

Nowadays, polymer reaction engineers seek robust and effective tools to synthesize complex macromolecules with well-defined and desirable microstructural and architectural characteristics. Over the past few decades, several promising approaches, such as controlled living (co)polymerization systems and chain-shuttling reactions have been proposed and widely [...] Read more.

Nowadays, polymer reaction engineers seek robust and effective tools to synthesize complex macromolecules with well-defined and desirable microstructural and architectural characteristics. Over the past few decades, several promising approaches, such as controlled living (co)polymerization systems and chain-shuttling reactions have been proposed and widely applied to synthesize rather complex macromolecules with controlled monomer sequences. Despite the unique potential of the newly developed techniques, tailor-making the microstructure of macromolecules by suggesting the most appropriate polymerization recipe still remains a very challenging task. In the current work, two versatile and powerful tools capable of effectively addressing the aforementioned questions have been proposed and successfully put into practice. The two tools are established through the amalgamation of the Kinetic Monte Carlo simulation approach and machine learning techniques. The former, an intelligent modeling tool, is able to model and visualize the intricate inter-relationships of polymerization recipes/conditions (as input variables) and microstructural features of the produced macromolecules (as responses). The latter is capable of precisely predicting optimal copolymerization conditions to simultaneously satisfy all predefined microstructural features. The effectiveness of the proposed intelligent modeling and optimization techniques for solving this extremely important ‘inverse’ engineering problem was successfully examined by investigating the possibility of tailor-making the microstructure of Olefin Block Copolymers via chain-shuttling coordination polymerization. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

10 pages, 2358 KiB

Open AccessArticle

Impact of Chemical Post-Processing in Fused Deposition Modelling (FDM) on Polylactic Acid (PLA) Surface Quality and Structure

by Ana P. Valerga, Moises Batista, Severo R. Fernandez-Vidal and Antonio J. Gamez

Polymers 2019, 11(3), 566; https://doi.org/10.3390/polym11030566 - 26 Mar 2019

Cited by 62 | Viewed by 5403

Abstract

The application of techniques to improve the surface finish of pieces obtained by fused deposition modelling, as well as other functional aspects, is of great interest nowadays. Polylactic acid, a biodegradable material, has been considered a possible substitute for petroleum-based polymers. In this [...] Read more.

The application of techniques to improve the surface finish of pieces obtained by fused deposition modelling, as well as other functional aspects, is of great interest nowadays. Polylactic acid, a biodegradable material, has been considered a possible substitute for petroleum-based polymers. In this work, different chemical post-processing methods are applied to polylactic acid pieces obtained by fused deposition modelling and some characteristics are studied. Structural, thermal, and crystallinity property changes are analyzed according to the treatments applied. This can prevent degradation, eliminate the glass transition phase of the material, and thereby increase the thermal resistance by about 50 °C. An improvement in the roughness of the pieces of up to 97% was also found. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Figure 1

18 pages, 3748 KiB

Open AccessArticle

Solvent Effects on Radical Copolymerization Kinetics of 2-Hydroxyethyl Methacrylate and Butyl Methacrylate

by Loretta A. Idowu and Robin A. Hutchinson

Polymers 2019, 11(3), 487; https://doi.org/10.3390/polym11030487 - 13 Mar 2019

Cited by 22 | Viewed by 5751

Abstract

2-Hydroxyethyl methacrylate (HEMA) is an important component of many acrylic resins used in coatings formulations, as the functionality ensures that the chains participate in the cross-linking reactions required to form the final product. Hence, the knowledge of their radical copolymerization kinetic coefficients is [...] Read more.

2-Hydroxyethyl methacrylate (HEMA) is an important component of many acrylic resins used in coatings formulations, as the functionality ensures that the chains participate in the cross-linking reactions required to form the final product. Hence, the knowledge of their radical copolymerization kinetic coefficients is vital for both process and recipe improvements. The pulsed laser polymerization (PLP) technique is paired with size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) to provide kinetic coefficients for the copolymerization of HEMA with butyl methacrylate (BMA) in various solvents. The choice of solvent has a significant impact on both copolymer composition and on the composition-averaged propagation rate coefficient (k_p,cop). Compared to the bulk system, both n-butanol and dimethylformamide reduce the relative reactivity of HEMA during copolymerization, while xylene as a solvent enhances HEMA reactivity. The magnitude of the solvent effect varies with monomer concentration, as shown by a systematic study of monomer/solvent mixtures containing 50 vol%, 20 vol%, and 10 vol% monomer. The observed behavior is related to the influence of hydrogen bonding on monomer reactivity, with the experimental results fit using the terminal model of radical copolymerization to provide estimates of reactivity ratios and k_p,HEMA. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

28 pages, 5612 KiB

Open AccessArticle

Modeling of Miniemulsion Polymerization of Styrene with Macro-RAFT Agents to Theoretically Compare Slow Fragmentation, Ideal Exchange and Cross-Termination Cases

by Dries J.G. Devlaminck, Paul H.M. Van Steenberge, Marie-Françoise Reyniers and Dagmar R. D’hooge

Polymers 2019, 11(2), 320; https://doi.org/10.3390/polym11020320 - 13 Feb 2019

Cited by 14 | Viewed by 3645

Abstract

A 5-dimensional Smith-Ewart based model is developed to understand differences for reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization with theoretical agents mimicking cases of slow fragmentation, cross-termination, and ideal exchange while accounting for chain length and monomer conversion dependencies due to diffusional limitations. [...] Read more.

A 5-dimensional Smith-Ewart based model is developed to understand differences for reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization with theoretical agents mimicking cases of slow fragmentation, cross-termination, and ideal exchange while accounting for chain length and monomer conversion dependencies due to diffusional limitations. The focus is on styrene as a monomer, a water soluble initiator, and a macro-RAFT agent to avoid exit/entry of the RAFT leaving group radical. It is shown that with a too low RAFT fragmentation rate coefficient it is generally not afforded to consider zero-one kinetics (for the related intermediate radical type) and that with significant RAFT cross-termination the dead polymer product is dominantly originating from the RAFT intermediate radical. To allow the identification of the nature of the RAFT retardation it is recommended to experimentally investigate in the future the impact of the average particle size (d_p) on both the monomer conversion profile and the average polymer properties for a sufficiently broad d_p range, ideally including the bulk limit. With decreasing particle size both a slow RAFT fragmentation and a fast RAFT cross-termination result in a stronger segregation and thus rate acceleration. The particle size dependency is different, allowing further differentiation based on the variation of the dispersity and end-group functionality. Significant RAFT cross-termination is specifically associated with a strong dispersity increase at higher average particle sizes. Only with an ideal exchange it is afforded in the modeling to avoid the explicit calculation of the RAFT intermediate concentration evolution. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

15 pages, 4801 KiB

Open AccessArticle

Effects of Phase Morphology on Mechanical Properties: Oriented/Unoriented PP Crystal Combination with Spherical/Microfibrillar PET Phase

by Dashan Mi, Yingxiong Wang, Maja Kuzmanovic, Laurens Delva, Yixin Jiang, Ludwig Cardon, Jie Zhang and Kim Ragaert

Polymers 2019, 11(2), 248; https://doi.org/10.3390/polym11020248 - 2 Feb 2019

Cited by 22 | Viewed by 4463

Abstract

In situ microfibrillation and multiflow vibrate injection molding (MFVIM) technologies were combined to control the phase morphology of blended polypropylene (PP) and poly(ethylene terephthalate) (PET), wherein PP is the majority phase. Four kinds of phase structures were formed using different processing methods. As [...] Read more.

In situ microfibrillation and multiflow vibrate injection molding (MFVIM) technologies were combined to control the phase morphology of blended polypropylene (PP) and poly(ethylene terephthalate) (PET), wherein PP is the majority phase. Four kinds of phase structures were formed using different processing methods. As the PET content changes, the best choice of phase structure also changes. When the PP matrix is unoriented, oriented microfibrillar PET can increase the mechanical properties at an appropriate PET content. However, if the PP matrix is an oriented structure (shish-kebab), only the use of unoriented spherical PET can significantly improve the impact strength. Besides this, the compatibilizer polyolefin grafted maleic anhydride (POE-g-MA) can cover the PET in either spherical or microfibrillar shape to form a core–shell structure, which tends to improve both the yield and impact strength. We focused on the influence of all composing aspects—fibrillation of the dispersed PET, PP matrix crystalline morphology, and compatibilized interface—on the mechanical properties of PP/PET blends as well as potential synergies between these components. Overall, we provided a theoretical basis for the mechanical recycling of immiscible blends. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

16 pages, 4715 KiB

Open AccessArticle

New Approach to Optimize Mechanical Properties of the Immiscible Polypropylene/Poly (Ethylene Terephthalate) Blend: Effect of Shish-Kebab and Core-Shell Structure

by Yingxiong Wang, Dashan Mi, Laurens Delva, Ludwig Cardon, Jie Zhang and Kim Ragaert

Polymers 2018, 10(10), 1094; https://doi.org/10.3390/polym10101094 - 2 Oct 2018

Cited by 13 | Viewed by 4476

Abstract

Improving the mechanical properties of immiscible PP/PET blend is of practical significance especially in the recycling process of multi-layered plastic solid waste. In this work, a multi-flow vibration injection molding technology (MFVIM) was hired to convert the crystalline morphology of the PP matrix [...] Read more.

Improving the mechanical properties of immiscible PP/PET blend is of practical significance especially in the recycling process of multi-layered plastic solid waste. In this work, a multi-flow vibration injection molding technology (MFVIM) was hired to convert the crystalline morphology of the PP matrix from spherulite into shish-kebab. POE–g–MA was added as compatibilizer, and results showed that the compatibilization effect consisted in the formation of a core-shell structure by dispersing the POE–g–MA into the PP matrix to encapsulate the PET. It was found that the joint action of shish-kebab crystals and spherical core-shell structure enabled excellent mechanical performance with a balance of strength and toughness for samples containing 10 wt % PET and 4 wt % POE–g–MA, of which the yield strength and impact strengths were 50.87 MPa and 13.71 kJ/m², respectively. This work demonstrates a new approach to optimize mechanical properties of immiscible PP/PET blends, which is very meaningful for the effective recycling of challenging plastic wastes. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

16 pages, 1837 KiB

Open AccessArticle

Kinetic Monte Carlo Simulation Based Detailed Understanding of the Transfer Processes in Semi-Batch Iodine Transfer Emulsion Polymerizations of Vinylidene Fluoride

by Florian Brandl, Marco Drache and Sabine Beuermann

Polymers 2018, 10(9), 1008; https://doi.org/10.3390/polym10091008 - 10 Sep 2018

Cited by 21 | Viewed by 4492

Abstract

Semi-batch emulsion polymerizations of vinylidene fluoride (VDF) are reported. The molar mass control is achieved via iodine transfer polymerization (ITP) using IC₄F₈I as chain transfer agent. Polymerizations carried out at 75 °C and pressures ranging from 10 to 30 [...] Read more.

Semi-batch emulsion polymerizations of vinylidene fluoride (VDF) are reported. The molar mass control is achieved via iodine transfer polymerization (ITP) using IC₄F₈I as chain transfer agent. Polymerizations carried out at 75 °C and pressures ranging from 10 to 30 bar result in low dispersity polymers with respect to the molar mass distribution (MMD). At higher pressures a significant deviation from the ideal behavior expected for a reversible deactivation transfer polymerization occurs. As identified by kinetic Monte Carlo (kMC) simulations of the activation–deactivation equilibrium, during the initialization period of the chain transfer agent already significant propagation occurs due to the higher pressure, and thus, the higher monomer concentration available. Based on the kMC modeling results, semi-batch emulsion polymerizations were carried out as a two pressure process, which resulted in very good control of the MMD associated with a comparably high polymerization rate. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Connecting the Fields of Polymer Reaction Engineering and Processing

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (11 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI