scholarly journals Non-Fickian Moisture Absorption in Vegetable Fiber Reinforced Polymer Composites: The Effect of the Mass Diffusivity

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 761
Author(s):  
Rafaela Q. C. Melo ◽  
Marcus V. Lia Fook ◽  
Antonio G. B. Lima

This article aims to study the non-Fickian water absorption process in vegetable fiber-reinforced polymer composite using the Langmuir-type model, evaluating the influence of mass diffusivity on the process. The numerical solutions of the governing equations were obtained using the finite-volume method. Transient results of the local and average moisture content, free and entrapped water molecules concentration considering the constant diffusivity and as a function of the average and local moisture content were presented and analyzed. It was observed that the mass diffusivity effectively influences the water absorption behavior, especially in the initial time of the process, where higher differences in the water migration rates into the material are found. The largest free and entrapped water molecule concentration gradients were found close to the composite surface, especially when considering constant mass diffusivity.

2020 ◽  
Vol 399 ◽  
pp. 164-170
Author(s):  
Wanessa Raphaella Gomes dos Santos ◽  
Rafaela Quinto da Costa Melo ◽  
Balbina Raquel de Brito Correia ◽  
Hortência Luma Fernandes Magalhães ◽  
Endyara de Morais Cabral ◽  
...  

This work presents a non-steady state and three-dimensional mathematical modeling to predict moisture transport (based on the Langmuir-Type Model) inside the vegetable fiber-reinforced composite materials. The numerical solutions of the governing equations have been obtain using the finite-volume method. The model was apply for vegetable fiber-reinforced polymer composites. Emphasis to the geometrical dimension effect of the composite in the water absorption process was given. Results of the average moisture content, free and entrapped water molecules concentration kinetics and free and entrapped water molecules concentration distributions inside the material along the process are shown and analyzed. In the distributions of the analyzed properties, it was observed that the geometric dimensions of the composite has influence in the water absorption process.


Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2503
Author(s):  
Rafaela Q. C. Melo ◽  
Marcus V. Lia Fook ◽  
Antonio G. B. de Lima

The purpose of this article was to theoretically study the non-Fickian moisture absorption process in vegetable-fiber-reinforced polymer composites using a Langmuir-type model. Here, the focus was on evaluating the effect of the water layer thickness that surrounds the composite during the water migration process. The solutions of the governing equations were obtained using the finite volume method, considering constant thermophysical properties and non-deformable material. The results for the local and average moisture content and concentration, gradient values, and the transient rates of the free and bound (water) molecules in the process were presented and analyzed. It was observed that the water layer thickness strongly influenced the water absorption kinetics, the moisture content gradient values, and the equilibrium moisture content inside the material. It is envisaged that this new approach will contribute to better interpretation of experimental data and a better understanding of the physical phenomenon of water absorption, which directly affects the properties of composite materials.


2016 ◽  
Vol 369 ◽  
pp. 17-23 ◽  
Author(s):  
L.H. de Carvalho ◽  
A.G. Barbosa de Lima ◽  
E.L. Canedo ◽  
A.F.C. Bezerra ◽  
W.S. Cavalcanti ◽  
...  

Despite the ever-growing worldwide interest in the use of lignocellulosic fibers as reinforcement in either thermoset or thermoplastic matrices, the use of these fibers to replace synthetic ones, is limited. The reasons for these limitations are associated with the vegetable fiber’s heterogeneity, lower compatibility to most polymers, inferior durability, flammability, poorer mechanical properties and higher moisture absorption when compared with synthetic fibers. Nevertheless, despite these drawbacks, vegetable fiber reinforced polymer composites are lighter in weight, more sustainable and can be used for non-structural products. Strategies to minimize these drawbacks include fiber and or matrix modification, the use of compatibilizers, fiber drying and the concomitant use of vegetable and synthetic fibers, for the production of hybrid composites, the latter being an unquestionable way to increment overall mechanical and thermal properties of these hybrid systems. Here we present data on the water sorption of polymer composites having thermoset and thermoplastic matrices as a function of vegetable fiber identity, content and hybridization with glass fibers. Our data indicates that, regardless if the matrix is a thermoset of a thermoplastic, water absorption tends to be relatively independent of vegetable fiber identity and to be significantly dependent of its content. Fiber drying prior to composite manufacturing and hybridization with glass fibers leads to lower overall water absorption and higher mechanical properties.


2021 ◽  
Vol 22 (2) ◽  
pp. 316-326
Author(s):  
Ikhwan Yusuff ◽  
Norshahida Sarifuddin ◽  
Siti Norbahiyah Mohamad Badari ◽  
Afifah Mohd Ali

The potential of natural fibers as one of the candidate materials in the production of fiber-reinforced polymer composites have been widely investigated. In the current study, natural fiber-reinforced polymer composite was fabricated by employing woven kenaf fiber as a reinforcing agent with epoxy resin that acts as a matrix constituent. This composite sample was fabricated using the application of the vacuum infusion method in which the content of kenaf fibers was varied from 30 vol.%, 40 vol.%, and 50 vol.%. The effects of different fiber loadings toward mechanical and physical properties as well as failure properties of kenaf composite were then evaluated. Kenaf composites were subjected to mechanical tests including tensile and flexural tests. The result shows that the highest tensile strength and modulus were attained at 76.67 MPa and 2.31 GPa, respectively with kenaf composite fabricated with 40 vol.% fiber content. Meanwhile, the highest flexural strength and modulus were recorded at 61.24 MPa and 4.20 GPa, also corresponding to kenaf composite that is loaded with 40 vol.% fibers. Fiber pull-out failure was able to be detected in fabricated kenaf composites. Meanwhile, fiber breakage resulting from flexural failure could also be observed in the kenaf composite samples. Apart from that, it was found that as more kenaf fiber was loaded in the composites, the rate of water absorption tended to increase where the highest rate of water absorption was found at 43.33%, displayed by kenaf composite with 50 vol.% of fiber content. ABSTRAK: Potensi gentian semula jadi sebagai salah satu bahan dalam penghasilan komposit polimer bertetulang gentian telah banyak dikaji. Dalam kajian terkini, komposit polimer yang diperkuat dengan gentian semula jadi dibuat dengan menggunakan serat kenaf tenunan sebagai agen penguat dan resin epoksi yang bertindak sebagai matriks. Sampel komposit ini dibuat menggunakan kaedah infusi vakum di mana kandungan serat kenaf digunakan adalah 30 vol.%, 40 vol.%, dan 50 vol.%. Kesan kandungan serat yang berbeza terhadap sifat mekanikal dan fizikal serta sifat kegagalan komposit kenaf kemudiannya dinilai. Komposit Kenaf diuji dengan ujian tegangan dan lenturan. Hasilnya menunjukkan bahawa kekuatan tegangan dan modulus tertinggi dicapai pada 76.67 MPa dan 2.31 GPa, milik komposit kenaf yang dibuat dengan kandungan serat 40 vol.%. Sementara itu, kekuatan dan modulus lenturan tertinggi dicatatkan pada 61.24 MPa dan 4.20 GPa juga milik komposit kenaf yang dimuatkan dengan serat 40% vol. Kegagalan serat terkeluar dapat dikesan pada komposit kenaf buatan. Sementara itu, kerosakan serat akibat kegagalan lenturan juga dapat dilihat pada sampel komposit kenaf. Selain itu, didapati bahawa semakin banyak serat kenaf yang dimuatkan dalam komposit, cendurung meningkatkan kadar penyerapan air di mana kadar penyerapan air tertinggi didapati pada 43.33% yang ditunjukkan oleh komposit kenaf dengan kandungan serat 50% vol.


2017 ◽  
Vol 14 ◽  
pp. 1-20 ◽  
Author(s):  
R.Q. da Costa Melo ◽  
A.G. Barbosa de Lima

This chapter provides information in the area of vegetable fiber-reinforced polymer composites. It includes discussion about definition and classification of the composites and their constituents, composite manufacturing process and current application in different industrial sectors. Factors affecting the fiber/matrix interfacial adhesion and physic-chemical and mechanical properties of vegetable fiber-reinforced polymer composites are also revealed. The aim is to show for both academy and industry the viability on the use of vegetable fibers as reinforcement in polymer materials, because it offers many advantages and high potential in terms of unlimited availability, lightweight, reasonable cost, acceptable mechanical properties, and socio-economic and environmental benefits.


2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Layth Mohammed ◽  
M. N. M. Ansari ◽  
Grace Pua ◽  
Mohammad Jawaid ◽  
M. Saiful Islam

Natural fibers are getting attention from researchers and academician to utilize in polymer composites due to their ecofriendly nature and sustainability. The aim of this review article is to provide a comprehensive review of the foremost appropriate as well as widely used natural fiber reinforced polymer composites (NFPCs) and their applications. In addition, it presents summary of various surface treatments applied to natural fibers and their effect on NFPCs properties. The properties of NFPCs vary with fiber type and fiber source as well as fiber structure. The effects of various chemical treatments on the mechanical and thermal properties of natural fibers reinforcements thermosetting and thermoplastics composites were studied. A number of drawbacks of NFPCs like higher water absorption, inferior fire resistance, and lower mechanical properties limited its applications. Impacts of chemical treatment on the water absorption, tribology, viscoelastic behavior, relaxation behavior, energy absorption flames retardancy, and biodegradability properties of NFPCs were also highlighted. The applications of NFPCs in automobile and construction industry and other applications are demonstrated. It concluded that chemical treatment of the natural fiber improved adhesion between the fiber surface and the polymer matrix which ultimately enhanced physicomechanical and thermochemical properties of the NFPCs.


Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2621
Author(s):  
Ummu Raihanah Hashim ◽  
Aidah Jumahat ◽  
Mohammad Jawaid ◽  
Rudi Dungani ◽  
Salman Alamery

This work aims to give insight on the effect of accelerated weathering, i.e., the combination of ultraviolet (UV) exposure and water spraying, on the visual and mechanical properties of basalt fiber reinforced polymer (BFRP) composites. The solvent exchange method, sonication and high shear milling technique were used to prepare the nanocomposite laminates. Three types of laminates were fabricated, i.e., unmodified BFRP, nanosilica modified BFRP and graphene nanoplatelet (GNP) modified BFRP composites with the total fiber loading of 45 wt.%. Glass fiber reinforced polymer (GFRP) laminate was also prepared for performance comparison purposes between the natural and synthetic fibers. The laminates were exposed to UV with a total weathering condition of 504 h using a Quantum-UV accelerated weathering tester. The weathering condition cycle was set at 8 h 60 °C UV exposure and 4 h 50 °C condensation. The discoloration visual inspection on the tested specimen was observed under the optical microscope. The obtained results showed that the UV exposure and water absorption caused severe discoloration of the laminates due to photo-oxidation reaction. The effect of weathering conditions on tensile and flexural properties of unmodified BFRP composites indicated that the UV exposure and water absorption caused reduction by 12% in tensile strength and by 7% in flexural strength. It is also found that the reduction in tensile and flexural properties of nanomodified BFRP composites was smaller than the unmodified system. It concluded from this work, that the mineral based composites (i.e., BFRP) has high potential for structural applications owing to its better properties than synthetic based composites (i.e., GFRP).


2015 ◽  
Vol 5 (1) ◽  
pp. 137
Author(s):  
Kristin B. Labasan ◽  
Aldrine Jay G. Espinosa ◽  
Rebecca C. Nueva Espana

<p>Fiber-reinforced polymer composites are composed of a polymer matrix (PE-PS) combined with a fiber (bamboo fibers) to provide conspicuous reinforcement. In light of recycling plastic and natural fibers, the research aim to fabricate and characterize bamboo fiber-reinforced polyethylene-polystyrene composites using glycerol as plasticizer. Specifically, the study investigated the effect on the physical and mechanical properties and water absorption of the composites by varying the following parameters: substitution of glycerol instead of the usual cooking oil in fabrication of DRM, and bamboo fiber loading. Using 1:3 PE-PS ratio, glycerol incorporation was done in DRM by melting together plastic and styrofoam wastes using a densifying machine at 150˚C. DRM samples with 70% (w/w) glycerol incorporation were then compared to the original DRM samples with 70% (w/w) cooking oil. The modified DRM were then loaded with 1, 2 and 3% bamboo fiber-reinforcement using a two-roll mill at 200˚C and compression molding machine at 200˚C and 50 kg/cm2 for 5 mins in the aluminium mold. The composites were characterized by Universal Testing Machine (tensile strength) following the ASTM standard D638. In addition, water absorption of the fabricated composites was tested using the standard method specified by ASTM D570.The bamboo fiber-reinforced polyethylene-polystyrene composites at 1:3 PE: PS ratio rendered better tensile strength and less water absorbed using 70% (w/w) glycerol as plasticizer and at 1% bamboo fiber loading. For future studies, it is recommended to study the impact of different parameters (glycerol percentage, time, temperature, pressure, fiber type and dimensions, fiber extraction, etc.) in the fabrication of the fiber-reinforced recycled plastic composites. Other characterizations of the fabricated plastic composite including thermal properties, leaching and biodegradation experiments and compressive and flexural strengths can also be done.</p><p>Keywords: Fiber-reinforced polymer, plasticizer, composites.</p>


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