Ultrasonic absorption and velocity measurements were made on aqueous solutions of poly (ethylene glycol)(PEG)of different molecular weights and concentrations, using a pulse sender-receiver ultrasonic generator, Measu...Ultrasonic absorption and velocity measurements were made on aqueous solutions of poly (ethylene glycol)(PEG)of different molecular weights and concentrations, using a pulse sender-receiver ultrasonic generator, Measurements were obtained at a frequency of 2MHz. , and a temperature of 293 K. The results show a linear increase of the Values of velocity, density and viscosity with increase of molecu lar weight and concentration of PEG. On the contrary, the attenuation values decreased with increase of molecular weight and concentration of PEG. A mathematical equation correlating relaxation amplitude and molecular weight of the polymer is suggested. This was applied to calculate the molecular weights of unknown samples of PEG from their measured relaxation amplitude. The results obtained were in good agreement with those obtained from osmometry.展开更多
The infrared divergence response theory is applied to reorientational relaxation process of magnetic clusters in cluster spin glass(CoF2)0.5 (BaF2)0.2 (NaPO3)0.3 to study the behaviour of low temperature ultrasonic ab...The infrared divergence response theory is applied to reorientational relaxation process of magnetic clusters in cluster spin glass(CoF2)0.5 (BaF2)0.2 (NaPO3)0.3 to study the behaviour of low temperature ultrasonic absorption in this system . Our calculation results showed that the reorientational relaxation process makes the main contributions to the magnetic part of the ultrasonic absorption for T < 4.0 K ; as for T > 4.0 K , the contributions of the internal process inside the clusters must be considered.展开更多
文摘Ultrasonic absorption and velocity measurements were made on aqueous solutions of poly (ethylene glycol)(PEG)of different molecular weights and concentrations, using a pulse sender-receiver ultrasonic generator, Measurements were obtained at a frequency of 2MHz. , and a temperature of 293 K. The results show a linear increase of the Values of velocity, density and viscosity with increase of molecu lar weight and concentration of PEG. On the contrary, the attenuation values decreased with increase of molecular weight and concentration of PEG. A mathematical equation correlating relaxation amplitude and molecular weight of the polymer is suggested. This was applied to calculate the molecular weights of unknown samples of PEG from their measured relaxation amplitude. The results obtained were in good agreement with those obtained from osmometry.
文摘The infrared divergence response theory is applied to reorientational relaxation process of magnetic clusters in cluster spin glass(CoF2)0.5 (BaF2)0.2 (NaPO3)0.3 to study the behaviour of low temperature ultrasonic absorption in this system . Our calculation results showed that the reorientational relaxation process makes the main contributions to the magnetic part of the ultrasonic absorption for T < 4.0 K ; as for T > 4.0 K , the contributions of the internal process inside the clusters must be considered.
