The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallin...The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallinity,T_m and T_c of PVA were obviously lower thanthose of pure PVA; the crystal growth changed from three dimensional to two dimensional andonly a single T_g was detected. These facts demonstrated that this crystalline and amorphousblend have good miscibility. TG curves showed that providing the quantity of K_2S_2O_8 added ismore than 3 wt%,in the blends PVA will form a stable CL-network, whose thermal degradationtemperature was near to that of PVP. But crosslinking reaction will not take place for PVP. Theprocesses of thermal degradation of CL-blends are based on combining both the thermaldegradation of PVP and that of PVA crosslinked with corresponding quantity of K_2S_2O_8 CL-agent, respectively. The UV measurements showed that 75 wt% of PVP may be remained in CL-blend hydrogelscrosslinked by adding (3--5 wt% )K_2S_2O_8. This is mainly due to the stable CL-network formed and the good compatibility and properentanglement between the composites in the CL-blends.展开更多
Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with differen...Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with different surfactants like poly vinyl pyrrolidone (PVP), poly vinyl alcohol (PVA) and poly oxyethylene lauryl ether (POLE). It was found that shape and size of Ir-nano particles resulted were related to kind of capping agent (surfactant) used. The characterization of the synthesized nano particle has been carried out by UV-vis, X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM) and transmission electron microscopic (TEM) techniques. UV-vis and FT-IR confirm the oxidation of IrCl3 into IrO2 while XRD confirms the amorphous nature of the iridium nanoparticles synthesized. The morphology and size of the particle were confirmed by TEM. The average particle size determined by Scherrer equation was about 4.12 nm to 4.23 nm with PVP, 2.74 to 3.36 nm with PVA and 20.41 to 42.25 nm with POLE. Poly oxyethylene lauryl ether particles were not further analyzed because of their large size and less stability. Further particle size was confirmed with TEM, which was 4.5 nm with PVP and 7.0 nm with PVA. The particles are spherical with no agglomeration tendency.展开更多
Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) ...Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.展开更多
文摘The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallinity,T_m and T_c of PVA were obviously lower thanthose of pure PVA; the crystal growth changed from three dimensional to two dimensional andonly a single T_g was detected. These facts demonstrated that this crystalline and amorphousblend have good miscibility. TG curves showed that providing the quantity of K_2S_2O_8 added ismore than 3 wt%,in the blends PVA will form a stable CL-network, whose thermal degradationtemperature was near to that of PVP. But crosslinking reaction will not take place for PVP. Theprocesses of thermal degradation of CL-blends are based on combining both the thermaldegradation of PVP and that of PVA crosslinked with corresponding quantity of K_2S_2O_8 CL-agent, respectively. The UV measurements showed that 75 wt% of PVP may be remained in CL-blend hydrogelscrosslinked by adding (3--5 wt% )K_2S_2O_8. This is mainly due to the stable CL-network formed and the good compatibility and properentanglement between the composites in the CL-blends.
文摘Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with different surfactants like poly vinyl pyrrolidone (PVP), poly vinyl alcohol (PVA) and poly oxyethylene lauryl ether (POLE). It was found that shape and size of Ir-nano particles resulted were related to kind of capping agent (surfactant) used. The characterization of the synthesized nano particle has been carried out by UV-vis, X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM) and transmission electron microscopic (TEM) techniques. UV-vis and FT-IR confirm the oxidation of IrCl3 into IrO2 while XRD confirms the amorphous nature of the iridium nanoparticles synthesized. The morphology and size of the particle were confirmed by TEM. The average particle size determined by Scherrer equation was about 4.12 nm to 4.23 nm with PVP, 2.74 to 3.36 nm with PVA and 20.41 to 42.25 nm with POLE. Poly oxyethylene lauryl ether particles were not further analyzed because of their large size and less stability. Further particle size was confirmed with TEM, which was 4.5 nm with PVP and 7.0 nm with PVA. The particles are spherical with no agglomeration tendency.
文摘Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.
