Brahiman Traoré, Obré Sery Paul Jolissaint, Koffi Clement Kouadio, Conand Honoré Kouakou, Edjikeme Emeruwa

This study consists in proposing a recycling method for sewing fabrics and polystyrene waste. One way of valorization such waste is through its use as a new raw material resource in materials. The objective of this work is the development of new materials based on sewing fabrics waste and expanded polystyrene. For the elaboration of the samples, two types of fabrics, LFNF (loincloth fabrics based on natural fibers) and LFSF (loincloth fabrics based on synthetic fiber) were selected because they are the most accessible. The samples were made by varying the rate of fabric and expanded polystyrene (EPS). Tests were made on these samples to determine their physical (density and absorption) and mechanical (wear resistance and three-point bending strength) properties. The results obtained showed that the density of two types of composites decrease with increasing rate of EPS. Water absorption also decreases from 5.12% to 1.15% for MLFSF (materials with loincloth fabrics based synthetic fiber) and from 15.02% to 2.68% for MLFNF (materials with loincloth fabrics based natural fiber) with an increase in the PSE resin content. Finally, the bending strength increases from 3.23 MPa to 4.53 MPa for the MLTSF and from 3.01 MPa to 4.32 MPa for the MLTNF with a variation in the rate of the EPS resin ranging from 60 to 80%. Wear strength also decreases with increasing resin. The use of EPS as a binder in composites gives it encouraging physical and mechanical properties. The use of EPS and fabrics waste as a new raw material resource in manufacturing of new materials is therefore a way of recovering this waste.

Md. Mahbubur Rahman, Md. Mutasim Uddin, Md. Monir Hossan, Md. Mazharul Helal, Suraiya Ireen, Dr. Jagannath Biswas

The effect of soda ash on fastness properties and some physical properties of reactive dyed cotton fabric were compared with the varying concentration of soda ash. Soda ash changes the pH of the fiber-reactive dye and cellulose fiber so that the dye reacts with the fiber, making a stable connection that holds the dye to the fiber. It actually activates the fiber molecules so that they can chemically attach to the dye. Three different concentration of soda ash (10g/l, 15g/l, 20g/l) were used to compare the fastness. Different fastness properties of cotton dyed fabric such as rubbing fastness, washing fastness, water fastness, saliva fastness, perspiration fastness and physical properties such as abrasion and pilling resistance were investigated. Optimum amount of alkali helps to achieve required pH of dye liquor which facilitates the reactive dye fixation onto cellulosic materials. The extent of dye fixation was also conceptualized and observed better color fastness which was invariably in all tests. In most of the cases, the colour fastness properties and physical properties were improved at soda 20g/l.

Babacar Niang, Abdou Karim Farota, Abdoul Karim Mbodji, Nicola Schiavone, Haroutioun Askanian, Vincent Verney, Abdoulaye Bouya Diop, Diène Ndiaye, Bouya Diop

This work focuses on the comparative study of the thermal, viscoelastic and photochemical durability of biocomposites made from two matrices (PLA and HDPE) and Typha stem powder by the extrusion process. Differential scanning calorimetry analysis shows that the biocomposites have higher crystalinity values than the virgin matrices, and it is demonstrated that the variation in molecular weight or crystallinity causes a shift in compaction and a slight shift in melting temperature to higher values than the virgin matrices. The rheological tests show an increase in storage and loss moduli reflecting a more elastic behaviour at higher Typha powder weights. shear thinnig behaviour was observed for all samples. The viscoelastic properties of HDPE biocomposites are superior to those of PLA. The study of photoveiilisation revealed the existence of chain cutting and recrosslinking phenomena in our samples. The mechanisms involved in photooxidation occurred jointly within the biomaterials.

Yunhua Luo

Elasticity prediction based on phase properties is an important task in the analysis and design of composite materials. Microstructure-based finite element modeling of composite representative volume element (RVE) has a number of advantages over experimental and analytical methods for the task. However, there are a number of challenges in the conventional geometry-based finite element modeling (GB-FEM) of RVE, e.g. time-consuming in the construction of workable geometric models and in the generation of high-quality finite element meshes. To overcome these challenges, we developed a voxel-based finite element modeling (VB-FEM) procedure. In contrast to GB-FEM, VB-FEM first generates a uniform grid mesh and then identifies elements that belong to the inclusions. The rest steps are the same as those in GB-FEM. We compared the performance of GB-FEM and VB-FEM in two representative numerical examples. The results show that upon convergence, elasticity constants characterized by VB-FEM and GB-FEM have excellent agreement. Regarding their computational efficiency, although for the composite having regularly-distributed and large-size inclusions, GB-FEM is significantly more efficient than VB-FEM; However, for the composite having randomly-distributed and small-size inclusions, VB-FEM has similar and even higher efficiency than GB-FEM. Besides overcoming the mentioned challenges, VB-FEM has a number of additional advantages over GB-FEM. We conclude that VB-FEM is an effective tool for elasticity prediction of particulate composites.

Titus M. Kasimu, Harun M. Mbuvi, Francis M. Maingi

Hydrogels are 3-dimensional polymer network materials with the ability to absorb a large amount of water. The current advancement in technology has increased their demand in the fields of industrial and environmental applications. This study reports the synthesis and characterization of superabsorbent hydrogels derived from lemon juice. The preparation involved linking lemon juice (LJ) with Ethylenediamine (EDA) via an amide linkage to obtain HLE-1 hydrogel. The polymer hydrogel was then cross-linked with maleic acid via an ester linkage to form HLE-2 hydrogel. Characterization was done using FT-IR, SEM, and XRD. The optimization of the swelling conditions was studied by varying contact time and the dosage of both lemon juice and the cross-linker. XRD analysis showed the conversion of amorphous hydrogel HLE-1 to crystalline hydrogel HLE-2 upon cross-linking. The FT-IR spectra showed a new strong symmetric stretching -COO- peak at 1079.83 cm-1 in HLE-2 indicating successful ester linkage. SEM analysis showed pores of different sizes and shapes in HAE-2 compared to a rigid, concrete, and smooth surface in HLE-1. Upon the optimization of the synthesis conditions of the cross-linked hydrogel, a swelling capacity of 925% was obtained. Crosslinking the hydrogel improved its water absorption ability. The high swelling capacity of the hydrogel provides a baseline for potential application in agriculture, especially in semi and arid regions.

Sudirman Habibie, Nandang Suhendra, Budiman Adi Setiawan, Muhammad Hamzah, Nuning Aisah, Diah Ayu Fitriani, Riesma Tasomara, Mahendra Anggaravidya

The needs of the textile industry for cotton natural fibers are very large and almost 100% are obtained from imports. To reduce dependence on cotton fiber, it is necessary to develop other natural fiber material sources. Ramie plant (Boehmeria nivea GAUD) has long been developed in Indonesia, but the results have not been encouraging. Ramie fiber with superior properties such as tensile strength and higher moisture regain than cotton, can be used as an alternative to replace cotton. The purpose of this paper is to illustrate that ramie fiber has the prospect of being developed in Indonesia as a substitute for cotton, given the land suitability and proven agricultural methods. In addition, the author provides an overview of one of the uses of ramie fiber is the manufacture of ramie textile-based composites which are used for various industries. The author did not deepen the study of composite technology, but slightly raised the VARI technology as well as several industrial users such as construction and aerospace industries.

Shah Alam, Samhith Shakar

This study focused on the design, modelling and the analysis of the dynamic response of sandwich composite armor system, constructed with kevlar 29/phenolic matrix, carbon fiber/epoxy (T300 6k/ Epon 862) and carbon fiber/epoxy (T300 6k/ Epon 862, with 4% carbon nanotube) as top and bottom skins. The core of the sandwich composite armor was made of triangular corrugated aluminum structure filled with prismatic silicon carbide. The triangular corrugated core was used to change the direction of bullet. The skin thickness, material composition, impact velocity etc., was varied to get their influence on the impact resistance of the armor system. The sandwich structure typically consisted of front plate, core and backing plate, which was impacted at different velocities starting at 1400 m/s to 1700 m/s, where complete armor penetration was noticed. From the dynamic analysis, the residual velocity and energy absorption capacity were obtained and the energy absorption capacity for various configurations were compared. The results of all models with 2mm, 3mm and 4mm skin thickness revealed increased energy absorption of the sandwich armors with carbon fiber/epoxy (T300 6k/ Epon 862, with 4% carbon nanotube) as skins and with kevlar 29/phenolic matrix as skins the sandwich armor yielded the least energy absorption. The sandwich composite armor model used in this research was unique in-terms of skin composition, combination of materials, geometry and assembly. Due to limitations of manufacturing and testing facilities of the sandwich composite armor, a kevlar/epoxy laminate finite element model was validated with the experimental test results found in the literature. The deviation of the results was noticed, and the reasons of deviation were discussed.

Heba Al-Khlaifat, Raid Banat

The effect of the oil shale ash (OSA) addition on the impact, tensile, flexural, water uptake, and morphological behavior of the chlorinated polyvinylchloride (CPVC) was investigated. Adding OSA filler to CPVC matrix yielded a greater impact strength of 498 kJ/m². While the tensile stress at yield and at break increased by an average of 50% and 100%, respectively, the tensile strain at yield and at break increased by an average of 20% and 10%, sequentially. The tensile and flexural modulus of OSA/CPVC increased by 16% and 65%, respectively. The results of this work demonstrated that the OSA could be used as a reinforcement material for the CPVC polymer, providing superior mechanical properties with respect to the neat polymer, as long as an appropriate OSA filler proportion, 5% - 15-%, is included into the CPVC polymer composite. Water absorption was increased with the increase of the OSA filler content. Scanning electron microscopy microphotographs evidenced the improvement in the mechanical behavior of the OSA/CPVC polymer composite by low level of both filler pullout and voids.

Guodong Guo, Shah Alam, Larry D. Peel

Ceramic mosaics have been used in lightweight armor systems to gain additional multi-hit capacity. However, the tile-to-tile interfaces in ceramic mosaics are inherently vulnerable and thus require special attention. In this research, we present finite element analysis of bilayer armor systems that consist of a ceramic mosaic front layer and a Kevlar-29/epoxy composite backing layer. The objective was to investigate the effect of various tile-to-tile interface designs on the ballistic performance. Two different interface design philosophies are investigated. In the first design, adjacent ceramic tiles are bonded together using epoxy at the interface, considered as a gap filling material. In the second design, adjacent ceramic tiles are separated by metallic webs at the interface, where a titanium honeycomb structure has ceramic tiles inserted into it. The same thickness was imposed for each interface wall to enable a direct comparison of their impact behaviour. Impact location was designated as the central ceramic tile centre. It was found that different interface designs affect stress wave propagation in the armor due to impedance mismatch. The stress state induced in the ceramic tile can be drastically changed and therefore the ballistic resistance of the armor. These results can be used to for the tailoring of mosaic armor systems to achieve the best ballistic performance.

Andrianainarivelo Mahandrimanana, Andriamirindramanana Herison Lunard, Rasolomampianina Rado

The main objective of this research is to find a system capable of treating urban wastewater, both in terms of physico-chemical and bacteriological quality. The composite material made from clay and particles of TiO₂ appears to be effective in eliminating pollution from urban wastewater: case of the Marais Masay lake. Physicochemical analysis (pH, conductivity, MES, turbidity, nitrate, phosphate and chloride levels, COD, BOD) and bacteriological analysis (ASR, fecal coliforms, fecal streptococci and Escherichia Coli) have made it possible to assess the quality of treated waters. The model reduced the amount of physicochemical pollution of wastewater at the end of the treatment. The pH is between 6 and 9, the conductivity is reduced, it goes from 429.33 to 273 μS/cm, the turbidity is 17.8 NTU, the SS varies from 12.5 mg/l. Nitrite and phosphate levels are 0 mg/l. The COD is less than 50 mg/l, the BOD is less than 150 mg/l all values meet the release standard. Based on these results, 99.78% of Streptococci fecal germs, 99.64% of ASR, 97.84% fecal coliforms, 98.43% Escherichia Coli package are eliminated. Microbiological and physico-chemical reveal that the treated waters are qualitatively improved.