Ahmed Jalal Uddin

• PhD
• Head of Department at Ahsanullah University of Science and Technology

PVA is reinforced with SWCNTs using green tea extract as a dispersant to achieve good dispersion of the SWCNTs in an organic solvent and finally high-performance composite fibers. A combination of green tea extract/DMSO/SWCNT/PVA is found to disperse larger aggregates of SWCNTs to individual or thin bundles of a few nanotubes. Incorporation of 0.5?...

Green tea has recently been reported to be a good dispersant of single-walled carbon nanotubes (SWCNTs) in aqueous media. In the current work, green tea extract powder was examined for dispersion of SWCNTs in organic solvents. Dimethyl sulfoxide (DMSO) was found to be a good solvent of green tea extract for dispersing SWCNTs. A combination of green...

Nanocomposite fibers were prepared from chitin whiskers (ChWs) as the reinforcing phase and poly(vinyl alcohol) (PVA) as the matrix. Colloidal suspensions of ChWs, obtained by acid hydrolysis of chitin from crab shell, were thoroughly mixed with aqueous PVA. The homogeneous PVA–ChW suspensions were gel-spun into a methanol coagulating bath. Wide-an...

The elastic modulus (El) of crystalline regions in the direction parallel to the chain axis in a new semiaromatic polyamide 9-T (PA9-T) containing a long aliphatic chain unit was measured by X-ray diffraction and the derived El value was discussed in terms of its molecular conformation and mechanical properties. For low and high molecular weight PA...

To utilize the extreme reinforcing performance of chitin whiskers (ChWs), the current work was undertaken to fabricate nanocomposites embedded with highly uniaxial oriented ChWs into the matrix polymer. Fibers of poly(vinyl alcohol) (PVA)/ChWs were prepared by gel spinning and the fibers were subjected to a hot drawing to their maximal draw ratio....

In order to utilize the excellent mechanical properties of cellulose whiskers (CWs) along their length, the present work was undertaken to embed CWs with highly oriented forms in a polymer matrix. Nanocomposite fibers were prepared using poly(vinyl alcohol) (PVA; degree of polymerization of 1500) as the matrix and a stable aqueous suspension of CWs...

The current work reports the preparation and characterization of the nanocomposites reinforced with highly oriented cellulose whiskers (CWs) in a polymer matrix. The nanocomposites were prepared using polyvinyl alcohol (PVA) and a stable suspension of CWs prepared from cotton. The macroscopically homogeneous PVA–CW suspensions were gel spun. The pr...

Carbon fibers were fabricated from electrospun poly(vinyl alcohol) (PVA) nanofibers. Electrospun PVA nanofibers were treated with iodine vapor for different periods, subsequently carbonized at different temperatures, and the structural changes of the PVA nanofibers were analyzed. The nanofibers iodinated at 80 °C for 24 h led to a good carbon yield...

High strength polyvinyl alcohol (PVA) fibers with a conventional degree of polymerization of 1500 were prepared by doping iodine with PVA spinning solution. The iodine-doped PVA (I-PVA) aqueous solution was extruded into cold methanol that provides dark purple PVA-iodine complex gel fibers. Only a small amount of iodine was required to enhance draw...

Sugarcane bagasse, a cheap cellulosic waste material, was investigated as a raw material for producing lyocell fibers at a reduced cost. In this study, bagasse was dissolved in N-methylmorpholine-N-oxide (NMMO) 0.9 hydrate, and fibers were prepared by the dry jet-wet spinning method with coagulation in an aqueous NMMO solution. The effects of NMMO...

The present study explored, for the first time, the potential for using cellulose whiskers (CWs) for reducing the fibrillation properties of highly oriented and crystalline fibres such as poly(vinyl alcohol) (PVA). The CWs were prepared from native cotton, and their aqueous suspension was homogeneously mixed with the PVA solution. The PVA-CW suspen...

To exploit the maximum potential of cellulose whiskers (CWs), we report here for the first time the successful fabrication of nanocomposites reinforced with highly oriented CWs in a polymer matrix. The nanocomposites were prepared using polyvinyl alcohol (PVA) and a colloidal suspension of cotton-derived CWs. The macroscopically homogeneous PVA-CW...

To produce cellulose regenerated fibres with high mechanical properties at low cost, sugarcane bagasse was chosen as a cheap raw material. In this study, bagasse was dissolved in N-methylmorpholine-N-oxide (NMMO) 0.9 hydrate, and fibres were prepared by the dry jet-wet spinning method by using dilute water/NMMO mixture as a coagulant, as is done in...

High-strength composite fibers were prepared from polyvinyl alcohol (PVA) (Degree of polymerization: 1500) reinforced by single-walled carbon nanotubes (SWCNTs) containing few defects. The SWCNTs were dispersed in a 10 wt.% PVA/dimethylsulfoxide solution using a mechanical homogenizer that reduced the size of SWCNT aggregations to smaller bundles....

High-strength composite fibers were prepared from polyvinyl alcohol (PVA) (Degree of poly-merization: 1500) reinforced by single-walled carbon nanotubes (SWCNTs) containing few defects. The SWCNTs were dispersed in a 10 wt.% PVA/dimethylsulfoxide solution using a mechanical homogenizer that reduced the size of SWCNT aggregations to smaller bundles....

A new semiaromatic polyamide, PA9-T was melt-spun at take-up speeds from 200 to 1000 m min(-1). The as-spun fibers were drawn with CO2 laser-heated drawing to their maximal draw ratio (DRmax). The drawing stress was recorded during this process. The effects of take-up speed of melt-spinning on maximally drawn fibers were characterized through measu...

Drawing behavior, flow drawing, and neck drawing, was studied for isotacticpolypropylene fibers in CO2 laser drawing system, and the fiber structure and the mechanical properties of drawn fibers were analyzed. For a certain laser power, flow drawing of polypropylene (PP) was possible up to draw ratio (DR) 19.5. Though the drawing stress was very lo...

Hydration in a new semiaromatic polyamide, named polyamide 9-T (PA9-T), a copolymer of terephthalic acid with n- and iso-nonanediamines, is studied by dynamic viscoelastic analysis under controlled humidity conditions and wide-angle X-ray diffraction analysis in comparison with common polyamide nylon 6. The storage modulus of PA9-T is retained at u...

Fibers of PA9-T, a new semiaromatic polyamide containing a long aliphatic chain, were prepared by melt spinning. As-spun fibers were subsequently drawn with a CO2 laser-heated drawing system at different draw ratios and various drawing velocities. On-line observations of drawing points deciphered two drawing states; namely, flow drawing and neck dr...

The effect of moisture on the mechanical relaxation processes of semiaromatic semicrystalline polyamides synthesized by a long-chain aliphatic diamine and terephthalic acid was investigated by dynamic viscoelastic analysis (DVA) and differential scanning calorimetry (DSC). Moreover, the implication of moisture with the amorphous and crystalline dom...

For monofilament biodegradable sutures fabricated from the L-lactide–ε-caprolactone (75/25) copolymer [P(LLA/CL)], there have been some concerns regarding their mechanical properties, such as the knot-pull strength and stiffness. This article demonstrates the further potentiality of these sutures through improvements in those properties. With the a...