Synthesis and characterization of new vinyl acetate grafting onto epoxidized linseed oil in aqueous media

Modified poly (vinyl acetate) copolymers with epoxidized linseed oil (ELO) as co‐monomer have been prepared. The polymerization was performed in aqueous medium without any additional protective colloid in the presence of sodium persulfate as catalyst. The effect of vinyl acetate (VAc)/ELO feed ratio, reaction temperature, reaction time, and catalyst amount has been studied. FTIR spectroscopy showed that the reaction between ELO and VAc resulted in slight decrease and shift in ELO characteristic bands of oxirane groups; and new bands were detected in the copolymer spectra attributed to PVAc and ELO functional groups. Moreover, new signals attributable to the copolymer were observed in the ¹H NMR spectra (δ 4.07 and 1.62 ppm) and in the ¹³C NMR spectra (δ 15.29 and 31.0 ppm). Analysis by differential scanning calorimetry (DSC) showed a single T_g for the copolymerization product of VAc and ELO and two T_g for the PVAc/ELO blend, indicating the chemical reaction between VAc and ELO. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42089.     

A bolometer with thermal feedback: Testing of a prototype on the T-11M facility

A prototype of a bolometer with a deep thermal feedback (TF) is described. It allows stabilization of the temperature of an absorbing film at a level of 700–800°C by the control of its thermal radiation. The prototype was tested on a light-ion accelerator and a T-11M tokamak. The results obtained confirm the possibility of practically realize such advantages of the TF bolometer over conventional devices as a fast response, direct measurement of the incident power, improved stability, and a reduced influence of the drift of the intrinsic parameters of the sensor. The questions of the selection of optimal structural parameters of such bolometers and calculation of their threshold characteristics are considered.     

Obtaining of a finely dispersed powder of gadolinium hydroxide

Finely dispersed powders of gadolinium hydroxide are obtained by chemical deposition (dispersing). The influence of various factors on the powder characteristics such as dispersity, morphology, and chemical composition is investigated. The dependence that the mentioned characteristics have on the character of the anion of the gadolinium salt, the concentration and acidity of its solution, and the concentration of the precipitant and pH of precipitation, is established. The optimal results are observed with the use of diluted chloride solutions of gadolinium and a 5–10 wt % precipitant in the form of the NH₃ solution.     

Effect of the kinematics of rotary rolling on the fineness of the structure of hypereutectoid silumins

It has been established experimentally that the internal layers of cylindrical semifinished products that are made of hypereutectoid silumins and contain embedded lengthwise pins do not intermix during rotary rolling. The experiment also determined that the angles through which different concentric internal layers of the semifinished product (ω₁ > ω₂ > ω₃) are twisted are different and depend on the radii of those layers (R′₁ > R′₂ > R′₃). This finding contradicts the hypothesis of rigid sections in the classical theory of the strength of materials. An analytic relation (empirical formula) is found to describe the pitch of the internal layers of metal flow in relation to the main parameters of the rotary-rolling operation (the feed angle α and deformation ε) and the radius of the given internal layer (R′_x). Another empirical formula is proposed to determine the angle of inclination of the helical lines along which the metal inside the rolled specimen is displaced. A mathematical model is constructed to describe the dependence of the ductility properties of hypereutectoid silumin alloys on changes in the dimensions of the silicon crystals in the alloys when semifinished products made of these alloys are deformed by rotary rolling. __________ Translated from Metallurg, No. 8, pp. 68–72, August, 2006.     

Properties of hydrocellulose yarns obtained via the stage of spontaneous elongation of fibers from cellulose diacetate

Conclusions A method has been developed for preparing high-strength (up to 0.9 GPa) hydrocellulose fibers by hydrolysis of highly-oriented fibers based on cellulose diacetate.A high degree of orientation in fibers, which is attainable spontaneously on heating them in an active water-phenol medium, is connected with the generation of a nematic order in the swollen specimen, with predominant orientation of the macromolecular chains along the fiber axis.The process is accompanied by an elongation (up to 200%) along the orientation axis and a considerable strengthening of the fibers, especially of specimens with a narrow molecular weight distribution. The orientation order of spontaneously elongated films is supported by the methods of polarization luminescence, IR spectroscopy, and x-ray beam scattering.Translated from Khimicheskie Volokna, No. 1, pp. 41–42, January–February, 1985.