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Materials and Methods for New Technologies in Polymer Processing II

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

Deadline for manuscript submissions: closed (10 February 2022) | Viewed by 36406

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Special Issue Editor

Dr. Andrea Sorrentino

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Institute of Polymers, Composites and Biomaterials (IPCB), National Research Council of Italy (CNR), Via Previati 1/C, 23900 Lecco, Italy
Interests: process–properties relashionships; morphology and properties of polymeric materials; polymer processing; injection and compression moulding; nanofunctionalized polymer materials for barrier and electrical applications; polymer (bio/photo)-degradation; bionanocomposites materials; thermomechanical properties; biodegradable materials; high performances composite materials; materials for sensing; materials for drug delivery; self-healing materials
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Special Issue Information

Dear Colleagues,

Welcome to this, the second issue of “Materials and Methods for New Technologies in Polymer Processing”. Due to the great interest in the first issue, the editorial board decided to reopen this Special Issue focused on the emerging technologies in polymer processing. I am delighted to write the foreword for this second number, which once again affords us the opportunity to reflect on what is changing in our field.

Last year, we recognized the need for a programmatic approach to the difficult relationships between new technologies associated with the plastics industry and existing materials. Formally, with these new techniques, it is possible to transform, combine, and functionalize polymer and composite materials in any desired way. Practically, the lack of materials properties, as well as inadequate process modeling and control, strongly limits these amazing possibilities. Applications such as the optoelectronic, sensing, drug release, filtration, and biomedical require extremely tight dimensional tolerances and precise manipulation of the properties. Such rigorous control can be obtained only with a proper combination of the right materials and methods.

This second Special Issue will continue to collect research and review documents that examine new technologies in polymer processing from different perspectives, covering materials, machine control, and simulation software, with particular attention to the properties of the products obtained.

We encourage you to contribute to this scientific program by submitting your papers and look forward to your active involvement.

Dr. Andrea Sorrentino
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

New polymer processing
Process–properties relationships
Morphology of polymeric materials
Thermomechanical and rheological properties
Polymer functionalizations
Bionanocomposites materials
Materials for barrier and electronic applications
Filament and fibers production
Foams and lightweight materials
Coatings for surface protection
Micro parts productions
Structured and functional surfaces
Fabrication of drug delivery systems
Capsules and bubbles formations
Materials for sensing and actuation
Electrospinning
Spray coating
Laser sintering
Layer by layer deposition
Additive manufacturing
Microfluidics
Precision injection and compression molding
Extrusion and compounding
Plasma treatment
Ultrasound assisted processes
Freeze and spray dryers

Published Papers (11 papers)

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Research

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19 pages, 3177 KiB

Open AccessArticle

Thermo-Rheological and Shape Memory Properties of Block and Random Copolymers of Lactide and ε-Caprolactone

by Marco Naddeo, Andrea Sorrentino and Daniela Pappalardo

Polymers 2021, 13(4), 627; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13040627 - 19 Feb 2021

Cited by 13 | Viewed by 2528

Abstract

Biodegradable block and random copolymers have attracted numerous research interests in different areas, due to their capability to provide a broad range of properties. In this paper, an efficient strategy has been reported for preparing biodegradable PCL-PLA copolymers with improved thermal, mechanical and rheological properties. Two block-copolymers are synthesized by sequential addition of the cyclic esters lactide (L-LA or D,L-LA) and ε-caprolactone (CL) in presence of a dimethyl(salicylaldiminato)aluminium compound. The random copolymer of L-LA and CL was synthetized by using the same catalyst. Chain structure, molar mass, thermal, rheological and mechanical properties are characterized by NMR, SEC, TGA, DSC, Rheometry and DMTA. Experimental results show that by changing the stereochemistry and monomer distribution of the copolymers it is possible to obtain a variety of properties. Promising shape-memory properties are also observed in the di-block copolymers characterized by the co-crystallization of CL and L-LA segments. These materials show great potential to substitute oil-based polymers for packaging, electronics, and medicine applications. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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13 pages, 3010 KiB

Open AccessArticle

Morphology-Mechanical Performance Relationship at the Micrometrical Level within Molded Polypropylene Obtained with Non-Symmetric Mold Temperature Conditioning

by Sara Liparoti, Andrea Sorrentino and Vito Speranza

Polymers 2021, 13(3), 462; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13030462 - 31 Jan 2021

Cited by 4 | Viewed by 1979

Abstract

The control of the structural properties of a polymeric material at the micro and nano-metrical scale is strategic to obtaining parts with high performance, durability and free from sudden failures. The characteristic skin-core morphology of injection molded samples is intimately linked to the complex shear flow, pressure and temperature evolutions experienced by the polymer chains during processing. An accurate analysis of this morphology can allow for the assessment of the quality and confidence of the process. Non-symmetric mold temperature conditions are imposed to produce complex morphologies in polypropylene parts. Morphological and micromechanical characterizations of the samples are used to quantify the effects of the processing conditions on the part performance. Asymmetric distribution of temperatures determines asymmetric distribution of both morphology and mechanical properties. The inhomogeneity degree depends on the time that one side of the cavity experiences high temperatures. The spherulites, which cover the thickest of the parts obtained with high temperatures at one cavity side, show smaller values of elastic modulus than the fibrils. When the polymer molecules experience high temperatures for long periods, the solid-diffusion and the partial melting and recrystallization phenomena determine a better structuring of the molecules with a parallel increase of the elastic modulus. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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15 pages, 5232 KiB

Open AccessArticle

Optimization of Adhesion Strength and Microstructure Properties by Using Response Surface Methodology in Enhancing the Rice Husk Ash-Based Geopolymer Composite Coating

by Mohd Salahuddin Mohd Basri, Faizal Mustapha, Norkhairunnisa Mazlan and Mohd Ridzwan Ishak

Polymers 2020, 12(11), 2709; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12112709 - 16 Nov 2020

Cited by 14 | Viewed by 2731

Abstract

As a result of their significant importance and applications in vast areas, including oil and gas, building construction, offshore structures, ships, and bridges, coating materials are regularly exposed to harsh environments which leads to coating delamination. Therefore, optimum interfacial bonding between coating and substrate, and the reason behind excellent adhesion strength is of utmost importance. However, the majority of studies on polymer coatings have used a one-factor-at-a-time (OFAT) approach. The main objective of this study was to implement statistical analysis in optimizing the factors to provide the optimum adhesion strength and to study the microstructure of a rice husk ash (RHA)-based geopolymer composite coating (GCC). Response surface methodology was used to design experiments and perform analyses. RHA/alkali activated (AA) ratio and curing temperature were chosen as factors. Adhesion tests were carried out using an Elcometer and a scanning electron microscope was used to observe the microstructure. Results showed that an optimum adhesion strength of 4.7 MPa could be achieved with the combination of RHA/AA ratio of 0.25 and curing temperature at 75 °C. The microstructure analysis revealed that coating with high adhesion strength had good interfacial bonding with the substrate. This coating had good wetting ability in which the coating penetrated the valleys of the profiles, thus wetting the entire substrate surface. A large portion of dense gel matrix also contributed to the high adhesion strength. Conversely, a large quantity of unreacted or partially reacted particles may result in low adhesion strength. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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16 pages, 3903 KiB

Open AccessArticle

Tunable Tensile Properties of Polypropylene and Polyethylene Terephthalate Fibrillar Blends through Micro-/Nanolayered Extrusion Technology

by Mahmoud Embabi, Mu Sung Kweon, Zuolong Chen and Patrick C. Lee

Polymers 2020, 12(11), 2585; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12112585 - 04 Nov 2020

Cited by 11 | Viewed by 2548

Abstract

Fiber-reinforcement is a well-established technique to enhance the tensile properties of polymer composites, which is achieved via changing the reinforcing material concentration and orientation. However, the conventional method can be costly and may lead to poor compatibility issues. To overcome these challenges, we demonstrate the use of micro-/nanolayer (MNL) extrusion technology to tune the mechanical properties of polypropylene (PP)/polyethylene terephthalate (PET) fibrillar blends. PET nanofibers-in-PP microfiber composites, with 3, 7, and 15 wt.% PET, are first prepared using a spunbond system to induce high aspect-ratio PET nanofibers. The PP/PET fibers are then reprocessed in an MNL extrusion system and subjected to shear and extensional flow fields in the channels of the uniquely designed layer multipliers. Increasing the mass flow rate and number of multipliers is shown to orient the PET nanofibers along the machine direction (MD), as confirmed via scanning electron microscopy. Tensile tests reveal that up to a 45% and 46% enhancement in elastic modulus and yield strength are achieved owing to the highly aligned PET nanofibers along the MD under strongest processing conditions. Overall, the range of tensile properties obtained using MNL extrusion implies that the properties of fiber-reinforced composites can be further tuned by employing this processing technique. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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17 pages, 3863 KiB

Open AccessArticle

Physicochemical Studies on the Surface of Polyamide 6.6 Fabrics Functionalized by DBD Plasmas Operated at Atmospheric and Sub-Atmospheric Pressures

by Larissa Nascimento, Fernando Gasi, Richard Landers, Argemiro da Silva Sobrinho, Eduardo Aragão, Mariana Fraga, Gilberto Petraconi, William Chiappim and Rodrigo Pessoa

Polymers 2020, 12(9), 2128; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12092128 - 18 Sep 2020

Cited by 8 | Viewed by 3032

Abstract

This work proposes the use of a dielectric barrier discharge (DBD) reactor operating at atmospheric pressure (AP) using air and sub-atmospheric pressure (SAP) using air or argon to treat polyamide 6.6 (PA6.6) fabrics. Here, plasma dosages corresponding to 37.5 kW·min·m⁻² for AP and 7.5 kW·min·m⁻² for SAP in air or argon were used. The hydrophilicity aging effect property of untreated and DBD-treated PA6.6 samples was evaluated from the apparent contact angle. The surface changes in physical microstructure were studied by field emission scanning electron microscopy (FE-SEM). To prove the changes in chemical functional groups in the fibers, Fourier transform infrared spectroscopy (FTIR) was used, and the change in surface bonds was evaluated by energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). In addition, the whiteness effect was investigated by the color spectrophotometry (Datacolor) technique. The results showed that the increase in surface roughness by the SAP DBD treatment contributed to a decrease in and maintenance of the hydrophilicity of PA6.6 fabrics for longer. The SAP DBD in air treatment promoted an enhancement of the aging effect with a low plasma dosage (5-fold reduction compared with AP DBD treatment). Finally, the SAP DBD treatment using argon functionalizes the fabric surface more efficiently than DBD treatments in air. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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10 pages, 1762 KiB

Open AccessArticle

Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

by Hsuan-Chen Wu, Aditi Pandey, Liang-Yu Chang, Chieh-Yun Hsu, Thomas Chung-Kuang Yang, I-Min Tso, Hwo-Shuenn Sheu and Jen-Chang Yang

Polymers 2020, 12(5), 1013; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12051013 - 29 Apr 2020

Cited by 4 | Viewed by 2714

Abstract

The superlative mechanical properties of spider silk and its conspicuous variations have instigated significant interest over the past few years. However, current attempts to synthetically spin spider silk fibers often yield an inferior physical performance, owing to the improper molecular interactions of silk proteins. Considering this, herein, a post-treatment process to reorganize molecular structures and improve the physical strength of spider silk is reported. The major ampullate dragline silk from Nephila pilipes with a high β-sheet content and an adequate tensile strength was utilized as the study material, while that from Cyrtophora moluccensis was regarded as a reference. Our results indicated that the hydrothermal post-treatment (50–70 °C) of natural spider silk could effectively induce the alternation of secondary structures (random coil to β-sheet) and increase the overall tensile strength of the silk. Such advantageous post-treatment strategy when applied to regenerated spider silk also leads to an increment in the strength by ~2.5–3.0 folds, recapitulating ~90% of the strength of native spider silk. Overall, this study provides a facile and effective post-spinning means for enhancing the molecular structures and mechanical properties of as-spun silk threads, both natural and regenerated. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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15 pages, 5745 KiB

Open AccessArticle

A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite

by Yuqin Ma, Jie Wang, Yatao Zhao, Xinliang Wei, Luyan Ju and Yi Chen

Polymers 2020, 12(2), 419; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12020419 - 12 Feb 2020

Cited by 24 | Viewed by 3931

Abstract

In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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16 pages, 8404 KiB

Open AccessArticle

High Throughput Manufacturing of Bio-Resorbable Micro-Porous Scaffolds Made of Poly(L-lactide-co-ε-caprolactone) by Micro-Extrusion for Soft Tissue Engineering Applications

by Xabier Mendibil, Rocío Ortiz, Virginia Sáenz de Viteri, Jone M. Ugartemendia, Jose-Ramon Sarasua and Iban Quintana

Polymers 2020, 12(1), 34; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12010034 - 24 Dec 2019

Cited by 9 | Viewed by 2787

Abstract

Porous scaffolds made of elastomeric materials are of great interest for soft tissue engineering. Poly(L-lactide-co-ε-caprolactone) (PLCL) is a bio-resorbable elastomeric copolymer with tailorable properties, which make this material an appropriate candidate to be used as scaffold for vascular, tendon, and nerve healing applications. Here, extrusion was applied to produce porous scaffolds of PLCL, using NaCl particles as a leachable agent. The effects of the particle proportion and size on leaching performance, dimensional stability, mechanical properties, and ageing of the scaffolds were analyzed. The efficiency of the particle leaching and scaffold swelling when wet were observed to be dependent on the porogenerator proportion, while the secant moduli and ultimate tensile strengths were dependent on the pore size. Porosity, swelling, and mechanical properties of the extruded scaffolds were tailorable, varying with the proportion and size of porogenerator particles and showed similar values to human soft tissues like nerves and veins (E = 7–15 MPa, σ_u = 7 MPa). Up to 300-mm length micro-porous PLCL tube with 400-µm thickness wall was extruded, proving extrusion as a high-throughput manufacturing process to produce tubular elastomeric bio-resorbable porous scaffolds of unrestricted length with tunable mechanical properties. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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25 pages, 26183 KiB

Open AccessArticle

Electrical Current Map and Bulk Conductivity of Carbon Fiber-Reinforced Nanocomposites

by Liberata Guadagno, Luigi Vertuccio, Carlo Naddeo, Marialuigia Raimondo, Giuseppina Barra, Felice De Nicola, Ruggero Volponi, Patrizia Lamberti, Giovanni Spinelli and Vincenzo Tucci

Polymers 2019, 11(11), 1865; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11111865 - 12 Nov 2019

Cited by 19 | Viewed by 3198

Abstract

A suitably modified resin film infusion (RFI) process was used for manufacturing carbon fiber-reinforced composites (CFRCs) impregnated with a resin containing nanocages of glycidyl polyhedral oligomeric silsesquioxane (GPOSS) for enhancing flame resistance and multi-wall carbon nanotubes (MWCNTs) to contrast the electrical insulating properties of the epoxy resin. The effects of the different numbers (7, 14 and 24) of the plies on the equivalent direct current (DC) and alternating current (AC) electrical conductivity were evaluated. All the manufactured panels manifest very high values in electrical conductivity. Besides, for the first time, CFRC strings were analyzed by tunneling atomic force microscopy (TUNA) technique. The electrical current maps highlight electrically conductive three-dimensional networks incorporated in the resin through the plies of the panels. The highest equivalent bulk conductivity is shown by the seven-ply panel characterized by the parallel (σ_//0°) in-plane conductivity of 16.19 kS/m. Electrical tests also evidence that the presence of GPOSS preserves the AC electrical stability of the panels. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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15 pages, 7158 KiB

Open AccessArticle

Preparation and Evaluation of Glucose Based Non-Isocyanate Polyurethane Self-Blowing Rigid Foams

by Xuedong Xi, Antonio Pizzi, Christine Gerardin, Hong Lei, Xinyi Chen and Siham Amirou

Polymers 2019, 11(11), 1802; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11111802 - 02 Nov 2019

Cited by 47 | Viewed by 4787

Abstract

A partially biobased self-blowing and self-hardening polyurethane foam from glucose-based non-isocyanate polyurethanes (g-NIPU) was prepared by reaction of glucose with dimethyl carbonate and hexamethylene diamine. However, these foam types generally require a high foaming temperature. In this paper, a self-blowing foam based on g-NIPU was prepared at room temperature by using maleic acid as an initiator and glutaraldehyde as a crosslinker. Water absorption, compression resistance, and fire resistance were tested. Scanning electron microscopy (SEM) was used to observe the foam cells structure. Middle infrared (ATR FT-MIR) and Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry were used to help to analyze the reactions during the foaming process. The results obtained showed that self- blowing rigid foams have good compression, this being directly proportional to the foam density. Increasing the amount of glutaraldehyde or reducing maleic acid thickens the cell walls and increases the density of the foams. MALDI-TOF analysis showed that g-NIPU reacts with both maleic acid and glutaraldehyde. The foams presented poor fire resistance indicating that, as for isocyanate based polyurethane foams, addition of a fire retardant would be necessary. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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Review

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34 pages, 3285 KiB

Open AccessReview

3D-MID Technology for Surface Modification of Polymer-Based Composites: A Comprehensive Review

by Jiratti Tengsuthiwat, Mavinkere Rangappa Sanjay, Suchart Siengchin and Catalin I. Pruncu

Polymers 2020, 12(6), 1408; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12061408 - 23 Jun 2020

Cited by 20 | Viewed by 5229

Abstract

The three-dimensional molded interconnected device (3D-MID) has received considerable attention because of the growing demand for greater functionality and miniaturization of electronic parts. Polymer based composite are the primary choice to be used as substrate. These materials enable flexibility in production from macro to micro-MID products, high fracture toughness when subjected to mechanical loading, and they are lightweight. This survey proposes a detailed review of different types of 3D-MID modules, also presents the requirement criteria for manufacture a polymer substrate and the main surface modification techniques used to enhance the polymer substrate. The findings presented here allow to fundamentally understand the concept of 3D-MID, which can be used to manufacture a novel polymer composite substrate. Full article

(This article belongs to the Special Issue Materials and Methods for New Technologies in Polymer Processing II)

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