Transesterification of dimethyl terephthalate with ethylene glycol

Conclusion For the first time, data are given on the quantitative composition of the transesterification products of dimethyl terephthalate with ethylene glycol at various molar ratios of the starting materials.During the transesterification process, oligomerization reactions take place rather intensively. Thereupon the linear oligomers are formed both in the transesterification process of carbomethoxy groups and also as a result of the interaction of carbohydroxyethoxy groups. The ethylene glycol formed in the latter case ensures further transesterification of the carbomethoxy groups.It is possible in principle to reduce the molar ratio of ethylene glycol to dimethyl terephthalate in the transesterification stage. Thereupon a polyethylene terephthalate can be obtained which has properties similar to the serially produced product.Translated from Khimicheskie Volokna, No. 5, pp. 18–20, September–October, 1983.     

Intensification of convective heat exchange in channels with a porous high-thermal-conductivity filler. Heat exchange with local thermal equilibrium inside the permeable matrix

Results are presented from analytical and experimental studies of intensification of convective heat exchange in a channel with a porous high-thermal-conductivity filler in the case of moderate external heating.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 1, pp. 13–24, July, 1984.     

Excitation of a quasi-plane shear wave by a surface acoustic source producing normal stresses

The generation of elastic volume waves by a source which is widely used in acoustic flaw detection is considered. This source produces normal stresses at the boundary of an elastic solid. The source is large compared to the wavelength of the waves that are launched. The possibility of exciting a shear wave with a plane front in the near zone is established, and an estimate of its intensity is made. Pis’ma Zh. Tekh. Fiz. 23, 91–94 (December 12, 1997)