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Pivot Concepts:
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Target Concepts:
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Query: UMLS:C0267964 (
PAA
)
2,561
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Polyimide/SiO(2) composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (
PAA
) based on aromatic diamine (4-aminophenyl sulfone) (4-
APS
) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO(2) composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-
APS
/BTDA) and the formation of SiO(2) particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO(2) particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO(2) composite films were investigated using TGA in N(2) atmosphere. The activation energy of the solid-state process was calculated using Flynn-Wall-Ozawa's method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions.
...
PMID:Preparation, characterization and thermal degradation of polyimide (4-APS/BTDA)/SiO(2) composite films. 2260 14
In the present project, graft polymerization was employed to synthesis a novel adsorbent using acrylic acid (AA) and xanthan gum (XG) for cationic methylene dye (MB
+
) removal from aqueous solution. The XG was rapidly grafted with acrylic acid (CH
2
=CHCOOH) under microwave heating. Fourier-transform infrared spectroscopy (FTIR), Proton Nuclear magnetic resonance spectroscopy (
1
H NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA) techniques were used to verify the adsorbent formed under optimized reaction conditions. Optimum reaction conditions [AA (0.4M),
APS
(0.05M), XG (2gL
-1
), MW power (100%), MW time (80s)] offer maximum %G and %GE of 484 and 78.3, respectively. The removal ratio of adsorbent to MB
+
reached to 92.8% at 100mgL
-1
. Equilibrium and kinetic adsorptions of dyes were better explained by the Langmuir isotherm and pseudo second-order kinetic model respectively. The results demonstrate xanthan gum grafted polyacrylic acid (mw XG-g-
PAA
) absorbent had the universality for removal of dyes through the chemical adsorption mechanism.
...
PMID:Fast microwave-assisted green synthesis of xanthan gum grafted acrylic acid for enhanced methylene blue dye removal from aqueous solution. 2892 14
