Journal Menu

Journal Browser

Fibers, Volume 8, Issue 11 (November 2020) – 5 articles

Cover Story (view full-size image): Heat treatment of basalt- fiber- reinforced expanded clay concrete significantly accelerates strength growth during cast -in -situ construction, which significantly reduces the formwork turnover cycle and the volume of formwork sets, thus shortening the construction period and leading to lower construction costs. View this paper

Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
You may sign up for e-mail alerts to receive table of contents of newly released issues.
PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

13 pages, 2971 KiB

Open AccessArticle

Synthesis and Characterization of a Core-Shell Copolymer with Different Glass Transition Temperatures

by Panagiotis Goulis, Ioannis A. Kartsonakis and Costas A. Charitidis

Fibers 2020, 8(11), 71; https://doi.org/10.3390/fib8110071 - 23 Nov 2020

Cited by 16 | Viewed by 4316

Abstract

The aim of this study is to synthesize an organic core-shell co-polymer with a different glass transition temperature (T_g) between the core and the shell that can be used for several applications such as the selective debonding of coatings or the release of encapsulated materials. The co-polymer was synthesized using free radical polymerization and was characterized with respect to its morphology, composition and thermal behavior. The obtained results confirmed the successful synthesis of the co-polymer copolymer poly(methyl methacrylate)@poly(methacrylic acid-co-ethylene glycol dimethacrylate), PMMA@P(MAA-co-EGDMA), which can be used along with water-based solvents. Furthermore, the T_g of the polymer’s core PMMA was 104 °C, while the T_g of the shell P(MAA-co-EGDMA) was 228 °C, making it appropriate for a wide variety of applications. It is worth mentioning that by following this specific experimental procedure, methacrylic acid was copolymerized in water, as the shell of the copolymer, without forming a gel-like structure (hydrogel), as happens when a monomer is polymerized in aqueous media, such as in the case of super-absorbent polymers. Moreover, the addition and subsequent polymerization of the monomer methyl methacrylate (MAA) into the mixture of the already polymerized PMMA resulted in a material that was uniform in size, without any agglomerations or sediments. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Nanomaterials)

► Show Figures

Graphical abstract

26 pages, 22754 KiB

Open AccessArticle

Influence of the Solidification Process on the Mechanical Properties of Solid-State Drawn PCL/Sepiolite Nanocomposite Tapes

by Maria Eriksson, Han Goossens and Ton Peijs

Fibers 2020, 8(11), 70; https://doi.org/10.3390/fib8110070 - 17 Nov 2020

Cited by 4 | Viewed by 2325

Abstract

In this research, poly(ε-caprolactone) (PCL) was melt-mixed with sepiolite nanoclays in a twin-screw extruder. In a subsequent step, the extruded films were drawn in the solid state to highly oriented nanocomposite films or tapes. A twin-screw extruder equipped with a Sultzer mixer for improved mixing in combination with a bench top drawing unit was used to prepare oriented nanocomposite tapes of different sepiolite loading and draw ratios. In order to study the influence of the solidification step on the drawability of the materials, different cooling procedures were applied prior to drawing. Optical microscopy images showed that slow or fast solidification using different chill rolls settings (open or closed) for the cast films resulted in different morphological conditions for subsequent drawing. The addition of sepiolite nanofillers led to nucleation and faster crystallization kinetics and oriented tapes which deformed by homogenous deformation rather than necking. The addition of sepiolite significantly improved the mechanical properties of both undrawn and drawn PCL tapes and Young’s modulus (1.5 GPa) and tensile strength (360 MPa) for composites based on 4 wt% sepiolite were among the highest ever reported for PCL nanocomposites. Interestingly, samples cooled with open chill rolls (slow crystallization) showed the highest modulus while solidification with closed rolls (fast crystallization) showed the highest tensile strength after drawing. Full article

► Show Figures

Graphical abstract

13 pages, 1191 KiB

Open AccessArticle

Investigation of the Potential Use of Curauá Fiber for Reinforcing Mortars

by Afonso R. G. de Azevedo, Sergey Klyuev, Markssuel T. Marvila, Nikolai Vatin, Nataliya Alfimova, Thuany E.S. de Lima, Roman Fediuk and Andrej Olisov

Fibers 2020, 8(11), 69; https://doi.org/10.3390/fib8110069 - 11 Nov 2020

Cited by 72 | Viewed by 4024

Abstract

Curauá is a bromeliad of Amazonian origin, present in some states in the northern region of Brazil and in other countries in South America. Its natural fibers have several technological advantages for application in composite materials. The objective of this research was to investigate the potential of using the fiber of Curauá as a reinforcement element in mortars for wall covering. Mortars were made with a 1:1:6 ratio (cement:lime:sand) in relation to their mass, evaluating the effect of adding 1%, 2% and 3% of Curauá fiber natural and fiber treated in NaOH solution in relation to the mass of cement, compared to the reference mixture (0%). Technological properties such as consistency, water retention and incorporated air content, compressive strength, water absorption and durability in wetting and drying cycles were evaluated. The results showed that the addition of the Curauá fiber causes an improvement in the mechanical properties of mortars, and at levels of addition 3% or more, it causes problems of workability and incorporation of air into the dough, thus, the fiber addition in 2% presented better results for application in coating mortars, in relation a Brazilian norm, even improving the durability of external coatings. Full article

(This article belongs to the Special Issue Fiber Reinforced Composites (FRCs) for Construction Applications)

► Show Figures

Graphical abstract

18 pages, 5155 KiB

Open AccessArticle

Effects of Different Test Setups on the Experimental Tensile Behaviour of Basalt Fibre Bidirectional Grids for FRCM Composites

by Jennifer D’Anna, Giuseppina Amato, Jianfei Chen, Giovanni Minafò and Lidia La Mendola

Fibers 2020, 8(11), 68; https://doi.org/10.3390/fib8110068 - 8 Nov 2020

Cited by 7 | Viewed by 2662

Abstract

Fibre-reinforced cementitious matrix (FRCM) composites have been effectively used during the last ten years for the strengthening of existing concrete and masonry structures. These composite materials are made of medium- and high-strength fibre meshes embedded in inorganic matrices. Synthetic fibres are the ones that are currently the most used; however, natural fibres, such as basalt fibres, have recently been receiving growing attention. This work presents an extensive experimental study on the mechanical characterisation of a primed basalt fibre bidirectional grid. Fifty monotonic tensile tests on basalt grid strips were performed by varying different parameters, such as the dimension of the specimens, the clamping system, the measurement system and the test rate. Some of the tests were carried out using a video-extensometer to measure each specimen’s strain. The aim of the study was to find the most suitable setup for the tensile characterisation of basalt textiles, in particular, to prevent slippage of the samples at the gripping area and fully exploit the tensile capacity of the grid. Full article

► Show Figures

Figure 1

16 pages, 1383 KiB

Open AccessEditor’s ChoiceArticle

Heat Treatment of Basalt Fiber Reinforced Expanded Clay Concrete with Increased Strength for Cast-In-Situ Construction

by Makhmud Kharun, Sergey Klyuev, Dmitry Koroteev, Paschal C. Chiadighikaobi, Roman Fediuk, Andrej Olisov, Nikolai Vatin and Nataliya Alfimova

Fibers 2020, 8(11), 67; https://doi.org/10.3390/fib8110067 - 2 Nov 2020

Cited by 49 | Viewed by 3742

Abstract

Expanded clay concrete (ECC) is a promising structural material for buildings due to its light weight and heat- and sound-insulating properties. Adding basalt fibers (BFs) in ECC reduces its brittleness and enhances its mechanical properties. The heat treatment (HT) of BF-reinforced ECC can significantly accelerate the strength growth during cast-in-situ construction, which allows the reduction of the turnover of the formwork and the construction period, as well as leading to lower construction costs. This paper presents an HT technology for load-bearing structures, containing a BF-reinforced ECC mix and using infrared rays for cast-in-situ construction. The issue of the strength growth of BF-reinforced ECC during HT has been studied. Microsilica and fly ash were added to the ECC mix to obtain a compressive strength of more than 20 MPa. Four different mixes of ECC with chopped BFs in the ratios of 1:0, 1:0.0045, 1:0.009 and 1:0.012 by weight of cement were studied. Test specimens were heated by infrared rays for 7, 9, 11, 13, 16 and 24 h. Then, the heat-treated specimens were tested for compressive strength after 0.5, 4, 12 and 24 h cooling periods. The analysis and evaluation of the experimental data were carried out based on probability theory and mathematical statistics. Mathematical models are proposed for forecasting the strength growth of BF-reinforced ECC during cast-in-situ construction. Full article

(This article belongs to the Special Issue Fiber Reinforced Composites (FRCs) for Construction Applications)

► Show Figures