Sub-microcellular and Nanocellular Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Composites and Nanocomposites".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 5787

Special Issue Editors


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Guest Editor
Cellular Laboratory (CellMat), Universidad de Valladolid, Valladolid 47011, Spain
Interests: nanocellular polymers; gas dissolution foaming; material properties; PMMA; foams; homogeneous nucleation; transparent nanocellular polymers
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Cellular Materials Laboratory (CellMat), Condensed Matter Physics Department, University of Valladolid, 47011 Valladolid, Spain
Interests: nanocellular polymers; foams; gas dissolution foaming; extrusion foaming; bead foaming; nanocomposite foams
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Submicrocellular and nanocellular polymers are the latest generation of porous polymers. Over the last few decades, they have attracted a great amount of interest due to the new properties that appear when the pore size is reduced near and under the micron. In the case of polymeric membranes, nanoscale porosity is interesting for many applications, such as sensors, filtration, or catalysis. Furthermore, the confinement of the polymer phase in the very thin cell walls of the nanostructure results in modifications of mechanical and thermal properties. For bulk submicrocellular and nanocellular polymers, thermal conductivity through the gas phase is significantly reduced due to the so-called Knudsen effect, and recently, it was proven that these materials can also keep the transparent character of the solid if the cell size is low enough. Because of all these properties, among others, these materials have great potential to be used as advanced materials in many applications.

This Special Issue aims to collect the latest contributions in the field of submicrocellular and nanocellular polymers, combining works on new production strategies with papers dealing with property and structure characterization. We particularly encourage studies providing new information about the mechanisms that control the formation of these structures and that determine the physical properties in these systems.

Dr. Judith Martín-de León
Dr. Victoria Bernardo
Guest Editors

Manuscript Submission Information

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Keywords

  • Nanocellular polymers
  • sub-microcellular polymers
  • nanoporous polymers
  • nanoporous membranes
  • nanofoam
  • nanostructures
  • advanced materials

Published Papers (2 papers)

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Research

17 pages, 4043 KiB  
Article
Preparation and Characterisation of Sustainable Wood Plastic Composites Extracted from Municipal Solid Waste
by Shahnaz Shahani, Zhongquan Gao, Mumtaz A. Qaisrani, Naveed Ahmed, Haseeb Yaqoob, Fuad Khoshnaw and Farooq Sher
Polymers 2021, 13(21), 3670; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213670 - 25 Oct 2021
Cited by 26 | Viewed by 3628
Abstract
Municipal solid waste (MSW) contains plastic waste that can be used as a sustainable green substitute to reduce oil footprints, CO2 emissions, and environmental pollution. This study aims to recycle plastic waste by manufacturing wood-plastic composites and to improve its mechanical properties [...] Read more.
Municipal solid waste (MSW) contains plastic waste that can be used as a sustainable green substitute to reduce oil footprints, CO2 emissions, and environmental pollution. This study aims to recycle plastic waste by manufacturing wood-plastic composites and to improve its mechanical properties by using additives, coupling agents, and lubricants. These composites are prepared by mixing 40–70% of wood flour with 20–25% of a polymer matrix. Wood was degraded at 220 °C, and then the composites were processed at 50 °C. The manufacturing process carried out in the study involved wood waste meshing, drying, shredding, drying, trimming, filling, blending, compounding, and extrusion moulding. The compounding of composites was accomplished in twin-screw extruders. Once the mixture was uniformly mixed, its final shape was given by a two-step extrusion moulding. Previously, researchers aimed at enhancing the mechanical properties of the composites, but our research focus was to improve their durability for different industrial applications. The results suggest that the impact strength is 17 MPa with 50% of wood powder ratio while the maximum value for the tensile strength is 32.5 MPa. About 50% of an increase in wood powder resulted in 8.1% bending strength increase from 26.1 to 32.8 MPa. Reducing the plastic matrix and the wood-particles water swelling ratio resulted in better mechanical properties. The wood species also affected the mechanical properties with their excellent dimensional stability and less variability. A high proportion of wood fibre tends to increase its steady-state torque and viscosity. The mechanical properties against different wood-flour proportions indicate that composite materials exhibit superior water swelling behaviour and extrusion quality. Full article
(This article belongs to the Special Issue Sub-microcellular and Nanocellular Polymers)
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18 pages, 4720 KiB  
Article
Effect of the Molecular Structure of TPU on the Cellular Structure of Nanocellular Polymers Based on PMMA/TPU Blends
by Ismael Sánchez-Calderón, Victoria Bernardo, Mercedes Santiago-Calvo, Haneen Naji, Alberto Saiani and Miguel Ángel Rodríguez-Pérez
Polymers 2021, 13(18), 3055; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183055 - 10 Sep 2021
Cited by 10 | Viewed by 3088
Abstract
In this work, the effects of thermoplastic polyurethane (TPU) chemistry and concentration on the cellular structure of nanocellular polymers based on poly(methyl-methacrylate) (PMMA) are presented. Three grades of TPU with different fractions of hard segments (HS) (60%, 70%, and 80%) have been synthesized [...] Read more.
In this work, the effects of thermoplastic polyurethane (TPU) chemistry and concentration on the cellular structure of nanocellular polymers based on poly(methyl-methacrylate) (PMMA) are presented. Three grades of TPU with different fractions of hard segments (HS) (60%, 70%, and 80%) have been synthesized by the prepolymer method. Nanocellular polymers based on PMMA have been produced by gas dissolution foaming using TPU as a nucleating agent in different contents (0.5 wt%, 2 wt%, and 5 wt%). TPU characterization shows that as the content of HS increases, the density, hardness, and molecular weight of the TPU are higher. PMMA/TPU cellular materials show a gradient cell size distribution from the edge of the sample towards the nanocellular core. In the core region, the addition of TPU has a strong nucleating effect in PMMA. Core structure depends on the HS content and the TPU content. As the HS or TPU content increases, the cell nucleation density increases, and the cell size is reduced. Then, the use of TPUs with different characteristics allows controlling the cellular structure. Nanocellular polymers have been obtained with a core relative density between 0.15 and 0.20 and cell sizes between 220 and 640 nm. Full article
(This article belongs to the Special Issue Sub-microcellular and Nanocellular Polymers)
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