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Polymers
Special Issues
Chemical and Mechano-Chemical Modification of Polymers and Organic Materials
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Chemical and Mechano-Chemical Modification of Polymers and Organic Materials

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

Deadline for manuscript submissions: closed (30 May 2023) | Viewed by 9785

Special Issue Editors

Dr. Roberto Avolio

E-Mail Website
Guest Editor
Institute for Polymers, Composites and Biomaterials of the National Research Council of Italy (IPCB-CNR), Via Campi Flegrei 34, 80078 Pozzuoli, Italy
Interests: multiphase polymeric materials; mechanochemical treatments; solid state NMR spectroscopy: recycling and sustainability; biodegradable polymers; composites and nanocomposites
Special Issues, Collections and Topics in MDPI journals
Dr. Rachele Castaldo

E-Mail Website
Guest Editor
National Research Council of Italy, Institute for Polymers Composites and Biomaterials (IPCB-CNR), Via Campi Flegrei 34, 80078 Pozzuoli, NA, Italy
Interests: porous and microporous materials; nanostructured materials; environmental remediation; biobased polymers; recycling and sustainability
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The chemical modification of polymers is a convenient and versatile way to tune their properties, in terms of thermomechanical response, chain arrangement, solubility, and miscibility, with other materials surface properties. Examples of chemical modifications are the introduction of new functional groups, the formation of copolymers, chain extension, and removal of crosslinks. Notably, chemical modification is the main route to tuning properties of natural polymeric materials, such as cellulose, starch, etc.

Mechanochemical treatments are emerging as versatile and green methods for the chemical and structural modification of polymers and organic materials: mechanical energy can, in fact, be exploited to efficiently promote chemical reactions (synthesis, functionalization, depolymerization, devulcanization of rubbers, grafting and copolymer formation in polymer mixtures), but also morphological/structural changes (amorphization, destructuration of complex multiphase materials, increase in surface area in porous structures, fine dispersion of nanoparticles in polymers). The reduced need for chemicals and solvents and the low-temperature operation further increase the attractiveness of mechanochemistry for the development of environmentally sustainable processing and production routes.

The possible applications of new chemical and mechanochemical methods for polymer modifications include sustainable synthetic routes for the production of chemicals; enhanced processing of complex polymers and mixtures, enabling recycling; conversion of natural products and byproducts into useful materials; and realization of micro/nanostructured materials.

Within this frame, we are pleased to launch a Special Issue on this topic, welcoming research papers and reviews focusing on chemical and mechanochemical modification strategies and processes for polymeric and organic materials, of both synthetic and natural origin. The aim is to define the state of the art of such methods and to provide a comprehensive reference basis.

Dr. Roberto Avolio
Dr. Rachele Castaldo
Guest Editors

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

  • mechanochemical treatments
  • high-energy milling
  • polymeric materials
  • composites and nanocomposites
  • morphological and structural analysis
  • process–structure–properties relationships
  • lignocellulosic materials
  • biochars
  • synthesis
  • sustainability

Published Papers (5 papers)

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Research

13 pages, 3909 KiB  
Article
Sustainable and Green Production of Nanostructured Cellulose by a 2-Step Mechano-Enzymatic Process
by Martina Aulitto, Rachele Castaldo, Roberto Avolio, Maria Emanuela Errico, Yong-Quan Xu, Gennaro Gentile and Patrizia Contursi
Polymers 2023, 15(5), 1115; https://doi.org/10.3390/polym15051115 - 23 Feb 2023
Viewed by 1568
Abstract
Nanostructured cellulose (NC) represents an emerging sustainable biomaterial for diverse biotechnological applications; however, its production requires hazardous chemicals that render the process ecologically unfriendly. Using commercial plant-derived cellulose, an innovative strategy for NC production based on the combination of mechanical and enzymatic approaches [...] Read more.
Nanostructured cellulose (NC) represents an emerging sustainable biomaterial for diverse biotechnological applications; however, its production requires hazardous chemicals that render the process ecologically unfriendly. Using commercial plant-derived cellulose, an innovative strategy for NC production based on the combination of mechanical and enzymatic approaches was proposed as a sustainable alternative to conventional chemical procedures. After ball milling, the average length of the fibers was reduced by one order of magnitude (down to 10–20 μm) and the crystallinity index decreased from 0.54 to 0.07–0.18. Moreover, a 60 min ball milling pre-treatment followed by 3 h Cellic Ctec2 enzymatic hydrolysis led to NC production (15% yield). Analysis of the structural features of NC obtained by the mechano-enzymatic process revealed that the diameters of the obtained cellulose fibrils and particles were in the range of 200–500 nm and approximately 50 nm, respectively. Interestingly, the film-forming property on polyethylene (coating ≅ 2 μm thickness) was successfully demonstrated and a significant reduction (18%) of the oxygen transmission rate was obtained. Altogether, these findings demonstrated that nanostructured cellulose could be successfully produced using a novel, cheap, and rapid 2-step physico-enzymatic process that provides a potential green and sustainable route that could be exploitable in future biorefineries. Full article
(This article belongs to the Special Issue Chemical and Mechano-Chemical Modification of Polymers and Organic Materials)
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19 pages, 3133 KiB  
Article
Thermomechanical Properties and Biodegradation Behavior of Itaconic Anhydride-Grafted PLA/Pecan Nutshell Biocomposites
by Sarai Agustin-Salazar, Marco Ricciulli, Veronica Ambrogi, Pierfrancesco Cerruti and Gennaro Scarinzi
Polymers 2022, 14(24), 5532; https://doi.org/10.3390/polym14245532 - 17 Dec 2022
Cited by 2 | Viewed by 1321
Abstract
The use of lignocellulose-rich biowaste as reinforcing filler in biodegradable polymers represents a sustainable option to obtain cost-effective bio-based materials to be used for several applications. In addition, the scarce polymer–biofiller interaction can be improved by reactive functionalization of the matrix. However, the [...] Read more.
The use of lignocellulose-rich biowaste as reinforcing filler in biodegradable polymers represents a sustainable option to obtain cost-effective bio-based materials to be used for several applications. In addition, the scarce polymer–biofiller interaction can be improved by reactive functionalization of the matrix. However, the obtained biocomposites might show high thermal deformability and possibly a slow biodegradation rate. In this work, polylactic acid (PLA) was first chemically modified with itaconic anhydride, and then biocomposites containing 50 wt.% of pecan (Carya illinoinensis) nutshell (PNS) biowaste were prepared and characterized. Their physical and morphological properties were determined, along with their biodegradation behavior in soil. Moreover, the effects of two environmentally friendly physical treatments, namely ball-milling of the filler and thermal annealing on biocomposites, were assessed. Grafting increased PLA thermal-oxidative stability and crystallinity. The latter was further enhanced by the presence of PNS, achieving a 30% overall increase compared to the plain matrix. Accordingly, the biocomposites displayed mechanical properties comparable to those of the plain matrix. Thermal annealing dramatically increased the mechanical and thermomechanical properties of all materials, and the heat deflection temperature of the biocomposites dramatically increased up to 60 °C with respect to the non-annealed samples. Finally, PNS promoted PLA biodegradation, triggering the swelling of the composites under soil burial, and accelerating the removal of the polymer amorphous phase. These results highlight the potential of combining natural fillers and environmentally benign physicochemical treatments to tailor the properties of PLA biocomposites. The high biofiller content used in this work, in conjunction with the chemical and physico-mechanical treatments applied, increased the thermal, mechanical, and thermomechanical performance of PLA biocomposites while improving their biodegradation behavior. These outcomes allow for widening the application field of PLA biocomposites in those areas requiring a stiff and lightweight material with low deformability and faster biodegradability. Full article
(This article belongs to the Special Issue Chemical and Mechano-Chemical Modification of Polymers and Organic Materials)
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11 pages, 4227 KiB  
Article
Construction and Characterization of Polyolefin Elastomer Blends with Chemically Modified Hydrocarbon Resin as a Photovoltaic Module Encapsulant
by Jin Hwan Park and Seok-Ho Hwang
Polymers 2022, 14(21), 4620; https://doi.org/10.3390/polym14214620 - 31 Oct 2022
Cited by 3 | Viewed by 2986
Abstract
In this study, polyolefin elastomer (POE) was blended with a chemically modified hydrocarbon resin (m-HCR), which was modified through a simple radical grafting reaction using γ-methacryloxypropyl trimethoxy silane (MTS) as an adhesion promotor to the glass surface, to design an [...] Read more.
In this study, polyolefin elastomer (POE) was blended with a chemically modified hydrocarbon resin (m-HCR), which was modified through a simple radical grafting reaction using γ-methacryloxypropyl trimethoxy silane (MTS) as an adhesion promotor to the glass surface, to design an adhesion-enhanced polyolefin encapsulant material for photovoltaic modules. Its chemical modification was confirmed by 1H and 29Si NMR and FT-IR. Interestingly, the POE blends with the m-HCR showed that the melting peak temperature (Tm) was not changed. However, Tm shifted to lower values with increasing m-HCR content after crosslinking. Additionally, the mechanical properties did not significantly differ with increasing m-HCR content. Meanwhile, with increasing m-HCR content in the POE blend, the peel strength increased linearly without sacrificing their transmittance. The test photovoltaic modules comprising the crosslinked POE blend encapsulants showed little difference in the electrical performance after manufacturing. After 1000 h of damp-heat exposure, no significant power loss was observed. Full article
(This article belongs to the Special Issue Chemical and Mechano-Chemical Modification of Polymers and Organic Materials)
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14 pages, 3763 KiB  
Article
Mechanochemical Treatment in High-Shear Thermokinetic Mixer as an Alternative for Tire Recycling
by Otávio Bianchi, Patrícia Bereta Pereira and Carlos Arthur Ferreira
Polymers 2022, 14(20), 4419; https://doi.org/10.3390/polym14204419 - 19 Oct 2022
Cited by 1 | Viewed by 1107
Abstract
This publication highlights the use of a high-speed thermokinetic mixer as an alternative to recycling ground tire rubber (GTR) using mechanochemical treatment. The GTR initially had a gelled fraction of 80% and presented a reduction of up to 50% of gel fraction in [...] Read more.
This publication highlights the use of a high-speed thermokinetic mixer as an alternative to recycling ground tire rubber (GTR) using mechanochemical treatment. The GTR initially had a gelled fraction of 80% and presented a reduction of up to 50% of gel fraction in the most intensive condition (5145 rpm, n2). The processing condition at the lowest speed (2564 rpm, n1) resulted in greater selectivity in chain scission (K~1). However, in the most intense processing condition (10 min to n2), more significant degradation was observed via random scission, reduction in the glass transition temperature, Tg (11 °C), increase in the soluble polymeric fraction, and a more significant reduction in the density of bonds occurs. The artificial neural network could describe and correlate the thermal degradation profile with the processing conditions and the physicochemical characteristics of the GTR. The n2 velocity resulted in the formation of particles with a smoother and more continuous surface, which is related to the increase in the amount of soluble phase. The approach presented here represents an alternative to the mechanochemical treatment since it can reduce the crosslink density with selectivity and in short times (1–3 min). Full article
(This article belongs to the Special Issue Chemical and Mechano-Chemical Modification of Polymers and Organic Materials)
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9 pages, 4417 KiB  
Article
Influence of Incorporating 5% Weight Titanium Oxide Nanoparticles on Flexural Strength, Micro-Hardness, Surface Roughness and Water Sorption of Dental Self-Cured Acrylic Resin
by Rasha M. Abdelraouf, Rania E. Bayoumi and Tamer M. Hamdy
Polymers 2022, 14(18), 3767; https://doi.org/10.3390/polym14183767 - 8 Sep 2022
Cited by 15 | Viewed by 1801
Abstract
Background: Polymethyl methacrylate (PMMA) is used in fabricating acrylic denture bases. Repairing a fractured acrylic denture base can be done by self-cured PMMA, yet this is still a weak point after repair. The aim of this study was to evaluate the effect of [...] Read more.
Background: Polymethyl methacrylate (PMMA) is used in fabricating acrylic denture bases. Repairing a fractured acrylic denture base can be done by self-cured PMMA, yet this is still a weak point after repair. The aim of this study was to evaluate the effect of incorporating 5% weight titanium oxide nanoparticles (TiO2) to self-cured PMMA on flexural strength, surface micro-hardness, roughness, and water sorption. Methods: A total of 160 acrylic–resin specimens were used in this study. They were divided in two main groups; (a) control group, prepared by mixing self-cured PMMA powder to its liquid monomer, (b) treated group, prepared by blending 5% weight TiO2 nanoparticles to self-cured PMMA powder then this blend was mixed with the liquid monomer. Flexure strength, surface micro-hardness, roughness, and water sorption were evaluated. Data were analyzed using independent sample t-tests (p ≤ 0.05). Results: There was a significant increase in the flexural strength of PMMA of the treated group after the addition of TiO2 (137.6 MPa) compared with the control (75.4 MPa) (p ≤ 0.001). No significant difference between the two groups in terms of micro-hardness (p = 0.385) and surface roughness (p = 0.269). Water sorption showed a significant reduction in the treated group (p ≤ 0.001). Conclusions: Addition of 5% weight TiO2 nanoparticles to the self-cured acrylic resin improved its flexural strength and reduced its water-sorption without impairing the surface micro-hardness and roughness. Full article
(This article belongs to the Special Issue Chemical and Mechano-Chemical Modification of Polymers and Organic Materials)
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