The “Rheology and Processing of Polymers” Special Issue contains the most recent discoveries in the field of rheology and polymer processing, featuring cutting-edge research concentrating on the processing of sophisticated polymers and composites.
Study: Rheology and Processing of Polymers. Image Credit: Image Source Trading Ltd/Shutterstock.com
Bo Lu et al. looked at fundamental and engineering aspects of interfacial phenomena in multi-micro/nanolayered polymer coextrusion. Multilayer coextrusion processing is a top-down method capable of industrially manufacturing multilayered films, as opposed to traditional approaches like layer-by-layer assembly and spin coating, which have low growth.
Throughout multilayer coextrusion processing, several phenomena, such as interlayer diffusion, interlayer reaction, interfacial instabilities, and interfacial geometrical confinement, usually happen at the interfaces of multilayered polymers.
More comprehensive work should be done in the future in both academia and industry to better understand these interfacial processes in order to scale up multilayer coextrusion.
With the goal of shielding the stainless-steel (SS304) mold substrate surface from wear and corrosion, Najoua Barhoumi et al. developed a fluorinated ethylene propylene (FEP) polymer covering. A compact and uniform film was created using an air spray technique and curing, and the mechanical, adhesion, and corrosion properties, among other things, were examined.
The Cox–Merz rule was tested on linear high-density polyethylene (HDPE) materials with varying molecular weights by Raffael Rathner et al. The Cox–Merz rule is an empirical correlation used in research and industry to estimate shear viscosity from an oscillatory rheometry test.
It does not, however, apply to all polymer melts. The shear-rate-dependent viscosity of three distinct HDPE materials was determined using three different rheological assessment methods: oscillatory parallel plate, high-pressure capillary, and extrusion slit rheometry.
The results demonstrated that the viscosity data based on the capillary pressure flow of the high-molecular-weight HDPE accurately represented the drop in pressure within the pipe head substantially better than data based on parallel plate rheometry using the Cox–Merz rule for the HDPE grades evaluated. Both measurement methodologies were in good agreement for the low-molecular-weight HDPE.
Violette Bourg et al. developed linear and branching polybutylene succinate (PBS) blends to study their molecular framework and rheological behavior.
In comparison to linear structures, long-chain branching (LCB) structures have already proved their efficacy in boosting melt strength. Because of the more difficult synthesis or additional reactive extrusion phase required to generate LCB polymers in general, and especially recently developed (bio)polymers, they are more expensive than linear polymers.
Angelica Avella et al. examined crosslinking performance in the melt state between a water-assisted reactive melt processing (REx) and a slower PCL macroradical diffusion. The inclusion of water enhanced the PCL molecular weight and gel content compared to the dry method, from 1% to 34% with 1 wt. percent peroxide, indicating that water-assisted REx is more efficient at radical propagation.
From design through recycling, Geraldine Cabrera et al. devised an innovative technique for complicated polyethylene/polypropylene (PE/PP) and polyethylene/polystyrene (PE/PS) systems often found in industrial waste streams. Advancing from eco-design to mechanical recycling of multilayer films by forced assembly coextrusion is the way.
It was established that the design of multi-micro/nanolayer films, regardless of the polymer system analyzed, is a very promising solution for industrial difficulties associated with the valorization of recyclable materials without the usage of compatibilizers.
In the spinning process of Giesekus fluids, Geunyeop Park et al. explained the nature of stability curves—the initial stabilization and subsequent destabilization pattern with regard to the average range of the material parameter.
The changes in the stability curves of Giesekus fluids in the isothermal spinning process without cooling were investigated using a range of theoretical strategies, including steady velocity profiles and extensional deformation properties in the spinline, as well as kinematic waves traveling along the entire spinline.
The experimental method for the viscoelastic identification of a nanocomposite reinforced with polymethylsilsesquioxane nanoparticles (PMSQ–HDPE) was evaluated by Fouad Erchiqui et al. Two different types of experiments were used, one based on free membrane inflation and the other on a dynamic mechanical test (DMA).
In a warm and moist environment, Mei Fang et al. investigated the aging process of carbon fiber (CF)/polycarbonate (PC) composites. During the aging process, the moisture absorption rate was recorded and determined.
The stretching findings were similar to the effects of aging time on storage modulus and solid particle erosion resistance. Hole formation on the surface of CF/PC composites was generated by hydrothermal aging, which lowered the specimen’s sand erosion resistance. In the meantime, the physical properties of CF/PC composites have been altered.
Because of the inclusion of strain hardening, which stabilizes the foam shape, long-chain branching (LCB) of polypropylene (PP) is seen as a game-changer in foaming. Nick Weingart et al. performed a thorough analysis of a linear PP Sinopec HMS20Z, a PP/PE-block copolymer Sinopec E02ES CoPo, and a long-chain branched PP Borealis WB140 HMS in terms of rheology and crystallization properties.
Despite the fact that only LCB-PP showed strain hardening and had five times the melt strength of all the other grades, it did not have the highest foam quality in terms of density (140 g/L) or cellular shape.
In DSC investigations, these observations were validated, with Sinopec HMS20Z crystal perfection occurring at a significantly slower rate, resulting in a longer gel-like state preceding solidification. This PP grade, once again, showed no signs of strain hardening.
Finally, the contributions focus on fundamental and experimental data in a thematic range that includes both traditional and novel processing technologies, as well as material-based macromolecular research. The goal of the Special Issue is to consolidate the present state-of-the-art and showcase the numerous applications.
Lamnawar, K., & Maazouz, A. (2022) Rheology and Processing of Polymers. Polymers, 14(12), p. 2327. Available Online: https://www.mdpi.com/2073-4360/14/12/2327/htm
References and Further Reading
- Lu, B., et al. (2021) Interfacial Phenomena in Multi-Micro-/Nanolayered Polymer Coextrusion: A Review of Fundamental and Engineering Aspects. Polymers, 13(3), p. 417. doi.org/10.3390/polym13030417
- Barhoumi, N., et al. (2022) Fluorinated Ethylene Propylene Coatings Deposited by a Spray Process: Mechanical Properties, Scratch and Wear Behavior. Polymers, 14(2), p. 347. doi.org/10.3390/polym14020347
- Rathner, R., et al. (2021) Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses. Polymers, 13(8), p. 1218. doi.org/10.3390/polym13081218.
- Bourg, V., et al. (2021) Shear and Extensional Rheology of Linear and Branched Polybutylene Succinate Blends. Polymers, 13(4), p. 652. doi.org/10.3390/polym13040652.
- Avella, A., et al. (2021) Substantial Effect of Water on Radical Melt Crosslinking and Rheological Properties of Poly(ε-Caprolactone). Polymers, 13(4), p. 491. doi.org/10.3390/polym13040491.
- Cabrera, G., et al. (2021) Multi-Micro/Nanolayer Films Based on Polyolefins: New Approaches from Eco-Design to Recycling. Polymers, 13(3), p. 413. doi.org/10.3390/polym13030413
- Chou, P. -Y., et al. (2021) Fabrication of Drug-Eluting Nano-Hydroxylapatite Filled Polycaprolactone Nanocomposites Using Solution-Extrusion 3D Printing Technique. Polymers, 13(3), p. 318. doi.org/10.3390/polym13030318.
- Park, G., et al. (2021) Effect of Material Parameter of Viscoelastic Giesekus Fluids on Extensional Properties in Spinline and Draw Resonance Instability in Isothermal Melt Spinning Process. Polymers, 13(1), p. 139. doi.org/10.3390/polym13010139.
- Parres, F., et al. (2020) Study of the Properties of a Biodegradable Polymer Filled with Different Wood Flour Particles. Polymers, 12(12), p. 2974. doi.org/10.3390/polym12122974.
- Erchiqui, F., et al. (2020) Reliability of Free Inflation and Dynamic Mechanics Tests on the Prediction of the Behavior of the Polymethylsilsesquioxane–High-Density Polyethylene Nanocomposite for Thermoforming Applications. Polymers, 12(11), p. 2753. doi.org/10.3390/polym12112753.
- Wang, J., et al. (2020) Multiscale Structural Evolution and Its Relationship to Dielectric Properties of Micro-/Nano-Layer Coextruded PVDF-HFP/PC Films. Polymers, 12(11), p. 2596. doi.org/10.3390/polym12112596.
- Fang, M., et al. (2020) Effects of Hydrothermal Aging of Carbon Fiber Reinforced Polycarbonate Composites on Mechanical Performance and Sand Erosion Resistance. Polymers, 12(11), p. 2453. doi.org/10.3390/polym12112453.
- Hel, C. L., et al. (2020) TPV: A New Insight on the Rubber Morphology and Mechanic/Elastic Properties. Polymers, 12(10), p. 2315. doi.org/10.3390/polym12102315.
- Guan, X., et al. (2020) Design and Synthesis of Polysiloxane Based Side Chain Liquid Crystal Polymer for Improving the Processability and Toughness of Magnesium Hydrate/Linear Low-Density Polyethylene Composites. Polymers, 12(4), p. 911. doi.org/10.3390/polym12040911.
- Weingart, N., et al. (2020) Comparison of the Foamability of Linear and Long-Chain Branched Polypropylene—The Legend of Strain-Hardening as a Requirement for Good Foamability. Polymers, 12(3), p. 725. doi.org/10.3390/polym12030725.