النشر العلمي

  • 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.

published in Applied Mechanics and Materials

  • 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.

published in The Journal of The Textile Institute

  • 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.

published in Textile Research Journal

  • 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.

published in DE GRUYTER

  • (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.

published in BioResources.com

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