INVESTIGATION RHEOLOGICAL PROPERTIES OF PVC-BASED

Summary. Obtained hydrophobic filler compositions based on PVC from calcium carbonate, which is a byproduct in the preparation of mineral nitrogen fertilizers. The methods for pretreatment of the chalk used as a filler in PVC compositions. Conducted modifying the properties of chalk with hydrophobic additives: stearic acid, zinc stearate, calcium stearate. When stearic acid treated chalk heating leads to an interaction with the surface layers of calcium carbonate, a thin film of calcium stearate. Therefore, more cost-effective to create compositions with PVC content of one percent of calcium stearate as its hydrophobic surface is easily wetted by the polymer matrix, which provides rapid mixing of PVC compounds. As a result, the excipient serves as an additional stabilizer, providing higher thermal stability of PVC products, compared with its values for the composition of the compared with the other ingredients. Extrusion processes that are central to the processing of PVC compounds filled by acting them filler, fractional increase heat and accelerate melting and increase output. The rheological properties of polymeric compositions created PVC. A significant reduction in viscosity observed for water repellent based on stearic acid. Study viscosity characteristics for hydrophobic additives showed that their activity increased in the series: zinc stearate, calcium stearate, stearic acid. It was established that modifying additives used in the preparation of hydrophobic carbonate filler PVC compositions exhibit both plasticizers and stabilizing properties

The Influence of Weak Tin Doping on the Thermoelectric Properties of Zinc Antimonide

ZnSb would be a good thermoelectric material with carrier concentration above 10^(19)/cm^3, but unfortunately this has been shown to be difficult to achieve, particularly with Sn as a dopant. Two series ZnSb samples doped with Sn and ZnSn were prepared using hot-pressing technics, and their thermoelectric properties were investigated in the temperature range from 300 K to 700 K. The tin content of the samples was in the range from 0.1 to 0.5 at.%. Surprisingly, samples with lower tin content achieved higher carrier concentration, which is beneficial for thermoelectric performance. Samples doped with 0.1 at.% Sn achieved Hall carrier concentration above 1 × 10^(19)/cm^3, reaching ZT of 0.9, while for samples doped with 0.5 at.% Sn, the Hall carrier concentration was close to the hole concentration of pure ZnSb. Also, by analyzing hysteresis present in the heating–cooling cycles, we conclude that the role of intrinsic defects in ZnSb is important and that these defects clearly determine the ability of ZnSb to achieve ZT near 1