Nanocellulose-Reinforced Composites: Challenges and Opportunities

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

Deadline for manuscript submissions: closed (31 October 2020) | Viewed by 12202

Special Issue Editors


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Special Issue Information

Dear Colleagues,

Since 1985, when Turbak and Snyder developed for the first time the precursor of nanocellulose, its production has increased significantly, moving from the laboratory scale to the pilot/industrial scale. In fact, in 2010, the global production of nanocellulose accounted for 17 tons per year and, five years later, in 2015, it had increased to 400 tons. In addition, it is expected that in 2025, the global production of nanocellulose will account for 10,500 tons per year.

The figures above reveal the relevance that nanocellulose will have in the 21st century. In addition, there is the need of combining them with bio-based and biodegradable plastics, aiming at facing the waste generation. Nanocellulose, due to its interesting properties, has potential applications in several fields, including electronics, biomedicine, packaging, and the environment, among others. However, there is still a lack of knowledge around incorporating such nanostructured cellulose into thermoplastic matrices, mainly due to the bad dispersion thereof, the presence of water, and the poor interphase between polymer and reinforcement.

This Special Issue aims at covering nanocellulose-reinforced composites from the development stage to the final application. In this sense, manuscripts dealing with dispersion strategies, the matrix–reinforcement interphase, processing strategies, degradation studies, and potential applications are welcome. Some non-exclusive examples of interest of this Special Issue include applications such as active and intelligent packaging, printed electronics, biomedical devices, additive manufacturing, aerogels, and hydrogels. As a matrix, bio-based and biodegradable polymers are of special interest for this Special Issue.

Dr. Marc Delgado-Aguilar
Dr. Quim Tarrés
Guest Editors

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Keywords

  • nanocellulose
  • nanocomposites
  • biodegradable polymers
  • composites
  • thermoplastic matrices
  • additive manufacturing
  • interphase
  • dispersion

Published Papers (3 papers)

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Research

14 pages, 2036 KiB  
Article
Improved Process to Obtain Nanofibrillated Cellulose (CNF) Reinforced Starch Films with Upgraded Mechanical Properties and Barrier Character
by Luis Angel Granda, Helena Oliver-Ortega, Maria José Fabra, Quim Tarrés, Maria Àngels Pèlach, José Maria Lagarón and José Alberto Méndez
Polymers 2020, 12(5), 1071; https://doi.org/10.3390/polym12051071 - 07 May 2020
Cited by 18 | Viewed by 3616
Abstract
Nowadays, the interest on nanofibrillated cellulose (CNF) has increased owing to its sustainability and its capacity to improve mechanical and barrier properties of polymeric films. Moreover, this filler shows some drawbacks related with its high capacity to form aggregates, hindering its dispersion in [...] Read more.
Nowadays, the interest on nanofibrillated cellulose (CNF) has increased owing to its sustainability and its capacity to improve mechanical and barrier properties of polymeric films. Moreover, this filler shows some drawbacks related with its high capacity to form aggregates, hindering its dispersion in the matrix. In this work, an improved procedure to optimize the dispersability of CNF in a thermoplastic starch was put forward. On the one hand, CNF needs a hydrophilic dispersant to be included in the matrix, and on the other, starch needs a hydrophilic plasticizer to obtain a thermoformable material. Glycerol was used to fulfil both targets at once. CNF was predispersed in the plasticizer before nanofibrillation and later on was included into starch, obtaining thin films. The tensile strength of these CNF–starch composite films was 60% higher than the plain thermoplastic starch at a very low 0.36% w/w percentage of CNF. The films showed a noticeable correlation between water uptake, and temperature and humidity. Regarding permeability, a ca. 55% oxygen and water vapor permeability drop was found by nanofiller loading. The hydrolytic susceptibility of the composite was confirmed, being similar to that of the thermoplastic starch. Full article
(This article belongs to the Special Issue Nanocellulose-Reinforced Composites: Challenges and Opportunities)
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19 pages, 1521 KiB  
Article
Research on the Strengthening Advantages on Using Cellulose Nanofibers as Polyvinyl Alcohol Reinforcement
by Quim Tarrés, Helena Oliver-Ortega, Manel Alcalà, F. Xavier Espinach, Pere Mutjé and Marc Delgado-Aguilar
Polymers 2020, 12(4), 974; https://doi.org/10.3390/polym12040974 - 22 Apr 2020
Cited by 22 | Viewed by 3871
Abstract
The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating [...] Read more.
The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling factors near to 0.2, indicating good interphase between CNF and PVA. Overall, it was found that the use of CNF is clearly advantageous to the use of common cellulosic fibers if superior mechanical properties are desired, but there are still some limitations that are related to processing that restrict the reinforcement content at low contents. Full article
(This article belongs to the Special Issue Nanocellulose-Reinforced Composites: Challenges and Opportunities)
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12 pages, 3660 KiB  
Article
Robust Silica-Cellulose Composite Aerogels with a Nanoscale Interpenetrating Network Structure Prepared Using a Streamlined Process
by Huazheng Sai, Jing Zhang, Zhiqiang Jin, Rui Fu, Meijuan Wang, Yutong Wang, Yaxiong Wang and Litong Ma
Polymers 2020, 12(4), 807; https://doi.org/10.3390/polym12040807 - 03 Apr 2020
Cited by 9 | Viewed by 4091
Abstract
Silica aerogels can be strengthened by forming a nanoscale interpenetrating network (IPN) comprising a silica gel skeleton and a cellulose nanofiber network. Previous studies have demonstrated the effectiveness of this method for improving the mechanical properties and drying of aerogels. However, the preparation [...] Read more.
Silica aerogels can be strengthened by forming a nanoscale interpenetrating network (IPN) comprising a silica gel skeleton and a cellulose nanofiber network. Previous studies have demonstrated the effectiveness of this method for improving the mechanical properties and drying of aerogels. However, the preparation process is generally tedious and time-consuming. This study aims to streamline the preparation process of these composite aerogels. Silica alcosols were directly diffused into cellulose wet gels with loose, web-like microstructures, and an IPN structure was gradually formed by regulating the gelation rate. Supercritical CO2 drying followed to obtain composite aerogels. The mechanical properties were further enhanced by a simple secondary regulation process that increased the quantity of bacterial cellulose (BC) nanofibers per unit volume of the matrix. This led to the production of aerogels with excellent bendability and a high tensile strength. A maximum breaking stress and tensile modulus of 3.06 MPa and 46.07 MPa, respectively, were achieved. This method can be implemented to produce robust and bendable silica-based composite aerogels (CAs). Full article
(This article belongs to the Special Issue Nanocellulose-Reinforced Composites: Challenges and Opportunities)
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