•Summarizing the latest research on vegetable fiber cement-based composites.•Reviewing the fibers used, procedures, mechanical performance and durability.•Durable cement composites with optimized ...fiber–matrix adhesion have been developed.•Best performance with vegetable fiber textile reinforcements.
In the last few years, an increase in interest has been given to the use of cellulose fibers as alternatives for conventional reinforcements in composites. The development of commercially viable environmentally friendly and healthy materials based on natural resources is on the rise. In this sense, cellulosic fibers as reinforcements for cement mortar composites constitute a very interesting option for the construction industry.
This paper presents a review of the research done during the last years in the area of the cement-based composites reinforced with cellulose fibers. The fibers used, processing methods, mechanical behavior and durability are presented. The main achievements found have been the development of durable cement composites with optimized fiber–matrix adhesion. Moreover, the recently developed textile composites will allow obtaining high performance materials reinforced with vegetable fibers.
Most of the decisions taken during the early design and development steps of a new product compromise a large part of its cost, including its environmental footprint and energy consumption. This is ...of special interest for the automotive industry that has made an effort to increase its sustainability. Adjectives like bio-based, recyclable or biodegradable are commonly used as synonyms of greener; nonetheless, such materials must achieve the requirements of the industry. This paper researches the use of alternative materials instead of glass fiber reinforced polypropylene, a commodity material. The authors propose using a wood fiber reinforced polyamide 11 composite as replacement. The research discussed the mechanical properties of such composites, obtaining values similar to the currently used materials. Moreover, a case study was performed to assess the behavior of the composites when used to manufacture a door car handle. The materials with reinforcement contents ranging from 40 to 60% showed its ability to replace the commodity materials. Furthermore, a preliminary LCA analysis was performed to evaluate the environmental footprint of the researched materials. In was found, that, in terms of energy and carbon footprint, the PA11 composites were penalized by the energy cost of the PA11 monomer production.
•Bio-based PA11-wood fibers composites were tested as substitutes to PP-GF materials.•A test cased based on an interior door car handle was used.•PA11 materials with high fiber contents showed competitiveness under use conditions.•PA11-based composites needed higher energy consumption than PP-based materials.•The carbon footprint of both kinds of composites was similar.
•Mechanical performance and durability of OPC/flax nonwovens composites for façade pieces is explored.•The effect of two pozzolanic additions combined with nonwoven treatment is ...evaluated.•Significant improvements in the durability using treated nonwovens.
This experimental research analyzes the mechanical performance and durability of façade pieces based on Portland cement matrix and flax nonwovens as reinforcement. Two types of pozzolanic additions (silica fume and metakaolin) combined with nonwovens subjected to different treatments to decrease their water absorption are analyzed as potential materials for fiber-cement sheets for building envelopes with high strength and durability. For this purpose, on the one hand, the mechanical performance and chemical composition of various ternary compositions were studied. On the other hand, various treatments were performed on the nonwovens and the nonwoven–matrix adherence was also analyzed. Finally, composites were prepared from some selected treated nonwovens and matrix mixtures, and their mechanical properties and durability were evaluated under four-point bending tests after 28days of curing in a humidity chamber and after accelerated aging. The composites developed with the treated nonwovens presented very high performance combined with enough durability to be potential candidates for the development of sustainable materials for building envelopes.
The aim of this work was to develop and characterize polyurethane-based shape memory polymer filament yarns of a suitable diameter and thermo-mechanical performance for use in tailored ...multi-sectorial applications. Different polymer compositions – pure shape memory polyurethane and shape memory polyurethane composites with 0.3 and 0.5 wt.% of multi-walled carbon nanotubes or carbon black as additives – were studied. Filaments were obtained using a melt spinning process that allowed the production of the permanent and temporary shape of the shape memory polyurethane filament. Two drawing speeds (20 and 32 m/min) were studied. Characterization techniques such as the tensile test, differential scanning calorimetry, and dynamic mechanical analysis were used to investigate the shape-memory effect of the filaments. Pure and additive shape memory polyurethane filament yarns of a controlled diameter were produced. The results indicated that the pure shape memory polyurethane on the temporary shape had the highest tensile strength (234 MPa). Filaments with carbon black revealed a significant strain (335%) in the permanent shape with respect to the other filaments. The melt spinning process influenced the soft segment glass transition temperature (Tgs) significantly, with a decrease in the temporary shape (first heating) as compared to the permanent shape (second and third heating). However, only the 0.5% multi-walled carbon nanotubes additive clearly influenced the filament, increasing the Tgs by 10°C. The additives also influenced the shape-memory effect, obtaining an increased fixity ratio (up to 97%) with the multi-walled carbon nanotubes additive and an increased recovery ratio (up to 86%) with the carbon black additive.
This paper analyses the influence of the addition of low content (0.1 to 0.8 wt%) of nanofibrillated cellulose (NFC) or cellulose nanocrystals (CNC) on the flexural performance, durability and ...microstructure of calcium aluminate cement (CAC) cured at 20 °C or 60 °C. The relationship between the mechanical properties and the microstructure of the cement was evaluated after curing and further after accelerated aging by flexural testing and X-ray diffraction and by backscattered electron imaging, respectively. The addition of 0.1–0.2 wt% of either nanocellulose led to an increase in the modulus of rupture (MOR) and modulus of elasticity (MOE) values. Moreover, CNC was effective to counteract the negative effects of increased porosity of CAC cements before and after aging, significantly improving their mechanical performance and durability. This effect was not observed in Portland cement systems, in which the addition of this low nanocellulose content did not lead to significant changes.
The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure-thickness and ...entanglement-on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE) images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility.
The aim of the study was to dye polyester fabric with a low molecular weight anthraquinone type disperse dye (C.I. Disperse Blue 56), with n-butylacetate as co-solvent in the microemulsion system and ...the presence of two bio-based auxiliaries (ortho-vanillin and coumarin), at temperatures lower than 100℃. In order to investigate the influence of temperature and auxiliaries on the kinetic dyeing process, the energy of the activation was determined by the kinetic rates constants. The activated entropy values were obtained by the theory of absolute rates of dyeing and diffusion of the activated state of the dye for the disorder state of the dyeing system. Higher activated energies were found, as well as higher activated entropy, meaning higher dye absorption, for polyester samples dyed with ortho-vanillin/n-butylacetate compared with polyester samples dyed with coumarin/n-butylacetate. Color strength values of the polyester fabric dyed using the proposed microemulsion dyeing system at low temperature (95℃) were similar to polyester fabric dyed with a conventional dyeing system at high temperature (135℃). Regarding color fastness to washing and ironing, it was found that the use of the auxiliaries did not significantly modify the fastness values of the dyed samples.
This study was performed to study the effects of the cement paste composition (calcium aluminate cement—CAC and a geopolymer in comparison to Portland cement—OPC) on bamboo pulp and nanofibrillated ...cellulose (NFC). The changes in the composition and chemical structure of the fibers were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The changes in the mechanical strength were evaluated through tensile tests on the fibers after immersion on the cement pastes, in the form of sheets. The XPS results showed that the immersion of the pulp and NFC in the different pastes (CAC, geopolymer and OPC) modified the chemical surface of these fibers: it was found removal of lignin and extractives and some degradation of hemicellulose and cellulose. The FTIR analysis indicated modifications in the hydrogen bonds energy. The tensile strength of pulp sheets decreased in 70% and 34% after immersion in OPC and geopolymer, respectively. The tensile strength of the NFC sheets decreased 36%, 68% and 54% after immersion in OPC, CAC and geopolymer, respectively. Thus, the response of the bamboo pulp and NFC immersed in different cement pastes was different due the inherent characteristics of such fibers, and not only the Portland cement should be considered as harmful to lignocellulosic fibers. Although CAC and geopolymer are free of calcium hydroxide, the high alkalinity of these pastes also accelerated the degradation process of lignocellulosic fibers.
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This paper examines the influence of weaving variables such as yarn count, number of layers, warp and weft ratio, materials of the top layer, weft density and interlocking cell shape, and size on the ...thermal performance of multilayer interlocked woven fabrics. A split-plot design was used to construct a total of 64 fabric structures, which were assessed for thermal performance in terms of resistance to convective, conductive, and radiative heat. It was found that, for equal weft density and yarn number, protective performance improved with the number of fabric layers and with the presence of air cells between these layers, especially if air was not trapped within and could rather pass freely between the cells. An optimal combination of factors for the thermal response to the three types of heat was established via a Derringer–a much needed desirability function. The results of this paper are useful for identifying the interaction between configuration parameters and thermal performance, and hence for the design of improved heat protective clothing.
In this work, polyamide 11 (PA11) and stone ground wood fibres (SGW) were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. ...The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of PA11-based composites were studied. Natural fibres have lower degradation temperatures than PA11, thus, composites showed lower onset degradation temperatures than PA11, as well. The thermal transition and the semi-crystalline structure of the composites were similar to PA11. On the other hand, when SGW was submitted to an annealing treatment, the composites prepared with these fibres increased its crystallinity, with increasing fibre contents, compared to PA11. The differences between the glass transition temperatures of annealed and untreated composites decreased with the fibre contents. Thus, the fibres had a higher impact in the composites mechanical behaviour than on the mobility of the amorphous phase. The crystalline structure of PA11 and PA11-SGW composites, after annealing, was transformed to α' more stable phase, without any negative impact on the properties of the fibres.
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