هارون عبد الرحمن محمدسعيد

  • 11/7/2013
  • Non-isothermal crystallization kinetics and nucleation activity of hyperbranched polyester (HBPET) in recycled PET

    The non-isothermal crystallization of pure recycled polyethylene terephthalate
    (RPET) and its blends with 3 and 5 wt% hyperbranched polyester
    (HBPET) were investigated by differential scanning calorimetry (DSC). The DSC
    curves demonstrate that the melt-crystallization temperatures of the blends are
    always higher than that of pure RPET regardless of the cooling rate. Their nonisothermal
    crystallization kinetics was further analyzed with modified Avrami
    equation, Ozawa equation and Mo method. The analysis reveals that the crystallization
    half-time (t1/2) of the blends is shorter than pure RPET. The activation energy
    of crystallization of RPET was also determined according to Kissinger method and
    it is found to decrease remarkably in RPET-3 and RPET-5 blends. All the results
    indicate that HBPET serves as an effective nucleating agent for RPET.

  • 6/25/2014
  • Properties of recycled poly (ethylene terephthalate) (PET)/hyperbranched polyester (HBPET) composite fibers

    Hyperbranched polyester (HBPET) with aliphatic–aromatic structure was synthesized and extruded with recycled poly
    (ethylene terephthalate) (RPET) chips obtained from used water bottles, with ratio of 0.5% and 1 wt% of HBPET.
    Filament fibers from pure recycled PET (RPET-0) and (RPET-0.5 and RPET-1) composite were spun using a melt
    spinning process and drawn by a thermal drawing process to improve their mechanical properties. The effects of
    addition of HBPET on the properties of produced fibers as well as draw ratio are investigated by means of differential
    scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD), universal tensile analysis, and sonic velocity. It was
    found that mechanical properties of the (RPET-0.5 and RPET-1) fibers were improved with respect to pure recycled PET
    (PET-0) fibers. Moreover, the crystallinity of composites fibers was also increased with an increasing of HBPET content.
    The improvement in mechanical properties may be due to the increase of orientation of fiber molecules along the fiber
    axis. Moreover, addition of HBPET serves as lubricant within recycled PET matrix which increased its mechanical
    properties.

  • 6/16/2013
  • Synthesis and Characterization of A2 + B3 Type Hyperbranched Aromatic-Aliphatic Polyester with Carboxyl End Groups

    New types of carboxyl-terminated hyperbranched polyesters (HBPEs) with aromatic-aliphatic structure
    were synthesized by single step-melt polycondensation of adipic acid (as A2 monomer) and phloroglucinol (as
    B3 monomer) as a core via A2 + B3 approach, at three different monomer mole ratios (A2/B3 = 1 : 1, 1.5 : 1, 2 :
    1, respectively). FTIR spectroscopy indicated that the polymers contained hydroxyl groups, ester bonds, benzene
    ring, methyl and methylene groups, which were in agreement with the expected HBPEs. The HBPEs have inherent
    viscosities about 0.24 to 0.27 dL/g. The degree of branching of the HBPEs was estimated to be 0.45–0.49%
    by 1H-NMR and 13C-NMR measurements. The melting temperature of HBPE-1, HBPE-2 and HBPE-3 were 154,
    155 and 160°C respectively measured by differential scanning calorimetry (DSC). The synthesized polymers were
    thermally stable; the thermogravimetric analysis (TGA) measurement revealed that HBPEs had 10% weight loss
    at 310°C in nitrogen.

  • 10/8/2014
  • Synthesis and Characterization of A2 +B4 Hyperbranched Polyesters with Hydroxyl end Groups

    Hydroxyl-terminated hyperbranched polyesters (HBPET) with aromatic-aliphatic
    structure were synthesized by melt polycondensation of isophthalic acid and pentaerythritol via A2+
    B4 approach, at three different monomer mole ratios (A2/B4 =1:1, 1.5:1, 2:1, respectively). Fourier
    transform infrared (FTIR) spectroscopy indicated that the expected HBPET. The degree of
    branching of the HBPET was estimated to be between 0.39–0.45 by 1H-NMR and 13C-NMR
    measurement. The thermogravimetric analysis ( TGA ) measurement revealed that HBPET had a
    10 % weight-loss at 350°C in N2.

  • 4/2/2014
  • Synthesis and Characterization of Aliphatic–Aromatic Hyperbranched Polyesters with High Organosolubility

    Carboxyl-terminated, water soluble, hyperbranched polyesters (HBPET) with aliphatic–aromatic
    structure were synthesized at three different monomer mole ratios (A3/B3 = 1 : 1, 2 : 1, 1 : 2, respectively) by melt
    polycondensation of aconitic acid and phloroglucinol via A3+ B3 approach. Fourier transform infrared (FTIR)
    spectroscopy indicated as that was expected HBPET, which showed excellent solubility in a variety of polar
    solvents such as N,N-dimethyl formamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO),
    and tetrahydrofuran (THF). The weight-average molecular weight of HBPET ranged from 7792 to 9214 g mol–1
    and their intrinsic viscosity were varied from 0.17 to 0.34 dL g–1. The degree of branching of the HBPET was
    estimated to be 0.44–0.49 by 1H and 13C NMR measurement. The thermogravimetric analysis (TGA) measurement
    revealed that HBPET was of 10% weight-loss at 340°C in N2.

  • 5/25/2015
  • Prospects of Textile Industry in Sudan (A technical Vision).

    Sudan has been known in Africa with many
    characteristics regarding its land suitable for
    agriculture and the river Nile, making a
    continuous irrigation source. However, in
    regard of the textile industry, Sudan was
    famous in producing different cotton
    varieties and grades and the Sudanese cotton
    was very famous worldwide with its high
    quality. This initiated the earlier beginning
    of textile industry which was first started
    with some governmental projects followed
    by the private sector. The raw material, in
    fact, represents a high percentage of the final
    product cost. Nowadays, textile industry is
    suffering from many problems, facing acute
    challenges, and becoming less attractive,
    though it can be very attractive if these
    constrains can be solved. This article
    highlights the current situation of the
    industry, the problems facing its
    development, and proposing a technical
    solution to overcome these constrains. It
    also shows the opportunities for investment
    in the traditional textile industry and other
    related industries.

  • 5/2/2014
  • The Effect of Fabric Type and Quality on the Quality of Readymade Garments

    The Effect of Fabric Type and Quality on the Quality of Readymade Garments

  • 11/28/2017
  • Suitable approach using agricultural residues for pulp and paper manufacturing

    The chemical compositions, fibre
    dimensions, elemental analysis and paper characteristics
    of sesame, karkadeh and okra stalks were studied in this
    work. It was found that the α-cellulose content of karkadeh,
    sesame and okra stalks were 45.8, 42.3 and 37.9%,
    respectively. Klason lignin was found to be the highest in
    okra 21.4% while it was 20.8 and 19.3% in sesame and
    karkadeh, respectively. Soda and soda-anthraquinone (AQ)
    pulping as sulfur-free processes were applied on these raw
    materials for producing pulp fibers. The results showed
    that a lower kappa number, higher screened pulp yield, and
    better paper handsheet properties were obtained for the
    pulp produced via soda-AQ pulping than the soda process.
    The soda-AQ and soda pulping of karkadeh generated pulp
    with the highest yields of 46.6% and 43.5% and kappa
    numbers of 18.0 and 19.4, respectively. Papers produced
    from karkadeh pulp showed the highest brightness of
    77.64 and 75.50%, tensile index of 52.3 and 51.7 N.m/g,
    tear index of 4.6 and 5.5 mNm2/g and burst index of 3.9
    and 3.5 KPa m2/g for soda-AQ and soda pulp, respectively.
    Furthermore, the morphological analysis and chemical
    compositions of karkadeh, sesame and okra stalks showed
    their suitability for pulp and paper production.

  • 5/27/2017
  • Evaluation of Sudanese Sorghum and Bagasse as a Pulp and Paper Feedstock

    The suitability of specific Sudanese agrowastes, sorghum straw, bagasse, and their 50% blend, were investigated for pulp and papermaking initiatives. A chemical analysis of sorghum straw and bagasse revealed levels of cellulose, lignin, hemicellulose, and ash for sorghum straw and bagasse that signalled a suitable relation to traditional wood feedstocks for pulping and papermaking applications. Moreover, the pulp yield and viscosity of sorghum straw were lower and higher, respectively, compared with the bagasse and the blend. More specifically, the papers obtained from bagasse showed better physical properties (tensile strength, tearing index, bursting index, and folding) compared to those of sorghum straw and the blend. The surface morphologies of the papers were analysed using scanning electron microscopy (SEM), which showed that the fibres had a long, swollen, compact, and closely packed arrangement and were more homogeneous and well-blended for the bagasse compared with the pure sorghum straw and the 50% blend.

  • 7/6/2017
  • CHARACTERISATION AND EVALUATION OF PULP AND PAPER FROM SUDANESE WOOD SPECIES FOR PULP AND PAPER MAKING

    Chemical composition, fibre dimensions and morphology, elemental analysis and paper
    characterisation of Acacia seyal (A. seyal), Ziziphus spina-christi (Z. christi) and Tamarindus indica
    (T. indica) were investigated. Kraft and soda-anthraquinone (so-AQ) pulping as sulfur-free
    processes were applied. It was found that, the cellulose content of Z. Christi, A. seyal and T. indica
    48.50%, 46.00% and 44.60%, respectively, which is in the range of hardwood. Klason lignin was
    found to be highest in T. indica 22.20% while it was 20.82% and 19.70% in A. seyal and T. indica,
    respectively. The solubility with 1% NaOH was 24.40%, 22.00% and 21.40% for T. indica, A. seyal
    and Z. Christi, respectively. Moreover, Z. Christi showed highest pulp yield (46.60% and 45.30%)
    with viscosity of (650 ml/g and 590 ml/g) and kappa number of (21.50 and 19.80) for kraft and
    soda-AQ pulping, respectively. T. indica reached the brightness of 75.30% and 71.72% for soda-AQ
    and kraft pulps, while it was (69.20% and 67.42%) and (75.30% and 71.72% ) for soda-AQ and
    kraft pulps of A. seyal and Z. Christi, respectively. Z. christi showed slightly high average fibre
    length 0.88 mm compared to 0.77 mm and 0.76 mm of A.seyal and T. indica, respectively. The
    studied materials have a potential application in pulp and paper making due to the good mechanical
    properties (tensile, tear, burst and fold).

  • 10/29/2017
  • Deep Eutectic Solvents (DESs) for the Isolation of Willow Lignin (Salix matsudana cv. Zhuliu)

    Deep eutectic solvents (DESs) are a potentially high-value lignin extraction methodology.
    DESs prepared from choline chloride (ChCl) and three hydrogen-bond donors (HBD)—lactic acid
    (Lac), glycerol, and urea—were evaluated for isolation of willow (Salix matsudana cv. Zhuliu) lignin.
    DESs types, mole ratio of ChCl to HBD, extraction temperature, and time on the fractionated
    DES-lignin yield demonstrated that the optimal DES-lignin yield (91.8 wt % based on the initial
    lignin in willow) with high purity of 94.5% can be reached at a ChCl-to-Lac molar ratio of 1:10,
    extraction temperature of 120 C, and time of 12 h. Fourier transform infrared spectroscopy (FT-IR) ,
    13C-NMR, and 31P-NMR showed that willow lignin extracted by ChCl-Lac was mainly composed of
    syringyl and guaiacyl units. Serendipitously, a majority of the glucan in willow was preserved after
    ChCl-Lac treatment.

  • 8/3/2017
  • Production of Xylose from Diluted Sulfuric Acid Hydrolysis of Wheat Straw

    The objectives of this study were to generate fermentable xylose by sulfuric acid hydrolysis of wheat straw and investigate the effect of hemicellulose removal on the physical and chemical properties of the unhydrolyzed solid residue (USR). Different reaction conditions, including concentration of sulfuric acid (COS), temperature, and time, were tested for their effects on the yield of xylose and the USR. The ideal hydrolysis conditions for xylose production were 0.5% of COS at 140 °C for 90 min, with the xylose yield of 0.185 g/g wheat straw. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the acid hydrolysis only caused slight changes in the functional groups and the crystal form of wheat straw at mild conditions, while higher temperature or higher COS exacerbated these change

  • 4/18/2017
  • Sudanese Agro-residue as a Novel Furnish for Pulp and Paper Manufacturing

    Sudan has rich sources of lignocellulose materials from agricultural waste that have potential to be used as a papermaking furnish following adequate chemical compositions, elemental analysis, fibre dimensions, and morphology of millet stalks and date palm leaves. Paper sheet properties from the various pulps made were investigated, and it was found that there was no difference in the polysaccharide (cellulose and hemicelluloses) content between millet stalks and date palm leaves, although millet stalks had a high lignin content of 18.20% relative to date palm leaves’ content of 15.34%. Moreover, millet stalks showed a high pulp yield (42.04%) with a viscosity of 665 mL/g compared to that (34.43%, 551 mL/g) and (38.50% and 534 mL/g) of date palm leaves and the blend, respectively. Papers produced from date palm leaves and millet stalk blends showed better physical properties compared to that of pure millet stalks and date palm leaves. The Scanning Electron Microscopy (SEM) analysis showed that fibres in the blend were more closely packed than that of the pure millet stalks and date palm leaves fibers. Based on their physical and chemical composition properties, millet stalks and date palm leaves have a high potential as a furnish for pulp and papermaking.

  • 5/1/2018
  • (Analytical Pyrolysis Characteristics of Enzymatic/Mild Acidolysis Lignin (EMAL)

    Fast pyrolysis is a promising method that is being investigated for
    application in the degradation of lignin into phenolic chemicals. In this
    study, enzymatic/mild acidolysis lignin (EMAL) isolated from eucalyptus
    (E-EMAL) and wheat straw (W-EMAL) were characterized by pyrolysisgas
    chromatography/mass spectrometry. The results showed that the
    compositions and yields of the products were determined by the lignin type
    and pyrolysis temperature. The identified products from the E-EMAL and
    W-EMAL pyrolysis mainly included G-phenols such as 2-methoxy-4-
    vinylphenol and guaiacol, S-phenols such as syringol and 2,6-
    dimmethoxy-4-(2-propenyl)-phenol, and H-phenols such as phenol, 2-
    methylphenol, and 4-vinylphenol. The overall yield of these phenolics
    varied with the investigated conditions. The G- and S-phenols were the
    primary products during the E-EMAL pyrolysis, while more H-phenols were
    produced during the W-EMAL pyrolysis. A compromise mild pyrolysis
    temperature of 450 °C to 650 °C resulted in a high phenolics yield, while
    a temperature greater than 650 °C led to the production of more aromatic
    hydrocarbons.

  • 3/4/2014
  • Parameters characterizing the kinetics of the non-isothermal crystallization of polyamide 5,6 determined by differential scanning calorimetry

    The non-isothermal crystallization behavior of
    polyamide 5,6 (PA56) was investigated by differential scanning
    calorimeter (DSC), and the non-isothermal crystallization
    kinetics were analyzed using the modified Avrami
    equation, the Ozawa model, and the method combining
    the Avrami and Ozawa equations. It was found that the
    Avrami method modified by Jeziorny could only describe
    the primary stage of non-isothermal crystallization kinetics
    of PA56, the Ozawa model failed to describe the nonisothermal
    crystallization of PA56, while the combined
    approach could successfully describe the non-isothermal
    crystallization process much more effectively. Kinetic
    parameters, such as the Avrami exponent, kinetic crystallization
    rate constant, relative degree of crystallinity, the
    crystallization enthalpy, and activation energy, were also
    determined for PA56.

  • 6/3/2014
  • Effect of hot drawing on the structure and properties of novel polyamide 5,6 fibers

    Polyamide 5,6 (PA 5,6) fibers were prepared using the melt-spinning method. The effects of draw ratio and temperature
    on the structure and properties of PA 5,6 fibers were investigated by means of differential scanning calorimetry (DSC),
    wide-angle X-ray diffraction, sonic velocity and tensile test measurements. DSC results revealed that the melting temperature
    showed no considerable variation, while the heat of fusion increased with increments with draw ratio and
    temperature. It was found that the crystallinity and crystal size of PA 5,6 fibers were directly proportional to the draw
    ratio and temperature and the orientation factor increases as expected upon drawing. The tenacity and Young’s modulus
    were found to be increased, while the elongation at break decreased with the draw ratio and temperature. The
    improvement in mechanical properties may be attributed to the increase of orientation along the fiber axis and the
    crystallinity.

  • 1/7/2015
  • Mechanical properties, moisture absorption, and dyeability of polyamide 5,6 fibers

    Polyamide 5,6 (PA56) and polyamide 6 (PA6) fibers were spun by melt spinning process and drawn by a thermal
    drawing in order to improve their mechanical properties. The effects of drawing conditions on mechanical properties,
    moisture absorption, and dyeing behavior were investigated by means of tensile testing measurements, moisture
    absorption test, as well as color strength measurements. It was found that the tenacity and Young’s modulus were
    significantly increased, while the elongation at break decreased as the draw ratio (DR) and temperature increased due to
    the increase in molecular orientation along the fiber axis and the crystallinity. PA56 fibers showed a little lower
    mechanical properties and much higher moisture regain than PA6 fibers at different DRs. This can be attributed to the
    amide group content in the polymer backbone, which yields higher moisture regain in PA56 fibers than PA6 fibers. The
    dyeing behaviors of PA56 fiber, in terms of dyebath exhaustion, color strength, and wash fastness are similar as those of
    PA6. Those results indicated that PA56 is a competitive novel fiber for textile material.

  • 3/1/2015
  • Modification of PLA with Chain Extender

    In this study, oligomer JoncrylTM ADR was used to extend the chains and improve the
    mechanical properties. The chain extender multifunction epoxide was used with concentrations of
    0.5 and 0.9 wt %. Pure and modified PLAs were characterized using DSC, MFI and FT-IR. The
    DSC results showed that Tg shifted to the high temperature and Tm increased slightly after chain
    extending. The MFI of the blends decreased with increasing the content of the CE which means the
    increase of molecular weight. The coupling between epoxy groups of CE and end groups of PLA
    was confirmed by FTIR tests. This coupling led to significant improvement in tensile strength and
    modulus.

  • 5/20/2018
  • Exploring Sudanese agricultural residues as alternative fibres for pulp and paper manufacturing

    In this work, the chemical composition, fibre dimensions and morphology, elemental analysis and paper characterisation of sesame, millet, karkadeh and sorghum stalks were studied. Soda and soda-anthraquinone pulping as sulfur-free processes were applied. It was found that, the cellulose content of karkadeh, sesame, millet and sorghum stalks were 45.80, 42.30, 40.99 and 35.40%, respectively. Klason lignin was found to be highest in sesame 20.85% while it was 19.32, 18.20 and 10.32% in karkadeh, millet and sorghum, respectively. Moreover, karkadeh showed highest pulp yield (46.60% and 43.50%) with viscosity of (655 ml/g and 640 ml/g) and kappa number of (18.00 and 19.40) for soda-AQ and soda pulps, followed by sesame, okra and sorghum, respectively. Overall strength properties of the handsheet made from karkadeh pulp were significantly higher than those made from sesame, millet, and sorghum pulps. Morphological analysis and chemical composition of the studied fibrous materials showed their suitability for producing paper of various grades including writing and printing paper as well as packaging applications.
  • 5/23/2018
  • Sudanese Dicots as Alternative Fiber Sources for Pulp

    The suitability of the stems from two Sudanese dicotyledonous annual plants, namely castor bean
    (Ricinus communis) and Leptadenia pyrotechnica (L. pyrotechnica) were investigated for pulp and papermaking.
    Chemical compositions, elemental analysis, fi ber dimensions, paper physical properties and morphology revealed
    a relatively high α-cellulose content (46.2 and 44.3 %) and low lignin (19.7 and 21.7 %) in the stems of castor
    bean and L. pyrotechnica, respectively. The average fiber length of castor bean and L. pyrotechnica is 0.80 and
    0.70 mm with fi ber width of 16.30 μm and 18.20 μm, respectively, which makes them acceptable candidates. Soda-
    AQ pulping of castor bean stem led to a higher pulp yield of 43.2 % at kappa number 18.2 compared to 40.3 % at
    kappa 20.3 for L. pyrotechnica. This yield is less than that obtained for wood plants and similar to that observed
    for annual plants. Paper handsheets produced from castor bean showed better mechanical properties than L. pyrotechnica.
    SEM images indicated that the produced papers were quite homogeneous, compact, closely packed,
    and well assembled

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