Investigation of the supermolecular structure of polyformaldehyde in an injection-molded block

The process of variation of the spherulitic and "superspherulitic" structure in an injection-molded block of polyformaldehyde has been investigated as a function of the molding conditions with allowance for the structural inhomogeneity of the block. The molding conditions corresponding to the formation of "superspherulitic" structures have been determined. The thermal stability of these structures has been investigated.Mekhanika Polimerov, Vol. 4, No. 3, pp. 394–401, 1968     

Effect of supermolecular structure on the relaxation properties of polyformaldehyde in tension and compression

An experimental investigation of the stress relaxation at various strain values in polyformaldehyde blocks has revealed two regions with different stress relaxation mechanisms. The effect of the supermolecular structure on each of these regions is discussed.Scientific Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 787–792, September–October, 1969.     

Effect of molding conditions on the structure and properties of polyformaldehyde

The effect of molding conditions-melt temperature, dwell time in molten state, and cooling rate-on the structure and mechanical properties of polyformaldehyde is investigated.Mekhanika Polimerov, Vol. 3, No. 5, pp. 782–786, 1967     

Effect of deformation on the supermolecular structure of PN-1 copolymer

It is shown that under the combined influence of temperature and tensile stresses the spherical structure of crosslinked PN-1 copolymer becomes ellipsoidal. The change of shape is associated with the zone of high-elastic deformation.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 1129–1131, November–December, 1969.     

Behavior of the supermolecular structure of oriented amorphous-crystalline polymers under cyclic loading

Equipment has been developed for investigating small-angle X-ray diffraction in various phases of the loading period in cyclically extended polymers. The behavior of the large-period structure of oriented polycaprolactam (kapron) films in cyclic extension has been studied. The results are compared with the data on the behavior of the same structure in static tests.Mekhanika Polimerov, Vol. 4, No. 2, pp. 195–199, 1968     

Concerning the investigation of the supermolecular structure of polymers with a three-dimensional network

The results of an investigation of the structure and properties of a series of crosslinked polymers are presented. It is shown that the structure is determined by the chemical structure of the starting components and the method of synthesis.Institute of Chemistry of High-Molecular Compounds, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 5, pp. 934–936, September–October, 1970.     

Effect of heat treatment on the strength and supermolecular structure of oriented polycaproamide

The mechanical properties of stabilized polycaproamide have been studied in relation to changes in supermolecular structure, preliminary orientation and duration of heat treatment. The deformation of the spherulites during the orientation of stabilized polycaproamide has been investigated together with the changes in supermolecular structure in the course of heat treatment. Certain relations between strength, type of deformation, and degree of preliminary orientation have been obtained for stabilized and heat-treated polycaproamide. The cause of the formation of inhomogeneous structural elements during polyamide processing are discussed.Mekhanika Polimerov, Vol. 4, No. 3, pp. 402–405, 1968     

Effect of a filler,aging, and remelting on the distribution of the spherulitic structure in polyformaldehyde

The distribution of the spherulitic structure of a crystalline polymer has been experimentally investigated with reference to the example of polyformaldehyde (PF). Experimental histograms and distribution curves have been constructed for the distances between the centers of the spherulites in unfilled PF and PF filled with mullite particles of varying shape and size before and after aging and multiple melting. Similar data have also been obtained for the angles between the lines of centers of the spherulites. The results are closely correlated with the changes in the structure and the physicochemical and mechanical properties of PF accompanying the above-mentioned processes.Shevchenko Kiev State University, Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 1, pp. 11–16, January–February, 1971.     

On the number of relaxation regions in polyformaldehyde

The mechanical relaxation of a polyformaldehyde homopolymer free from surface grease and the additives normally used as stabilizers has been studied at a frequency of 10^–2 Hz in the temperature region 77–413°K. Six relaxation regions are observed on the curve of tangent of angle of mechanical losses as a function of temperature.T. G. Shevchenko Kiev State University. Translated from Mekhanika Polimerov, No. 5, pp. 925–927, September–October, 1973.     

Effect of supermolecular structure on deformation and strength properties of low-pressure polyethylene

The effect of the supermolecular structure on the mechanical properties of polyethylene was studied. A change in the structure of films was achieved by varying the isothermal crystallization conditions. Films have been prepared from low-pressure polyethylene (LPPE) which have fine spherulitic and lamellar structures. It has been demonstrated that the strength of unorientated films with a fine spherulitic structure is twice that of unorientated lamellar specimens. This difference in the strengths was also retained after orientational elongation to 20 times the length at a high temperature (102°C). The conclusion was reached that the casting of LPPE plays an important part in preparing high-strength orientated polyethylene films.A. F. Ioffe Physicotechnic Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 6, pp. 963–966, November–December, 1972.     

Changes in the supermolecular structure and physico-mechanical properties of a polycarbonate subjected to supplementary heat treatment

The possibility of modifying the supermolecular structure of polycarbonate by suitable supplementary heat treatment is demonstrated. An improvement in the physico-mechanical and service properties controlled by the supermolecular structure of the polycarbonate is noted.Departmental Plastics Laboratory, Ministry of the Machine-Tool and Tool Industry of the USSR, Moscow. Moscow Mendeleev Chemical Engineering Institute. State Scientific-Research Institute of Machine Science, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 347–349, March–April, 1969.     

Role of the supermolecular structure of PMM in the morphology of fracture and features introduced by the type of loading

The spherulitic supermolecular structure of PMM, expressed in the fracture surface, determines the fracture pattern and kinetics. The effect of the type of loading on the morphology of the fracture surface is described. Banding of the fracture surface is attributed to periodic energy pulses leading to quasi-brittle fracture at the moving crack front and selective local crack development at the band edges.Riga Lenin Komsomol Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 776–782, September–October, 1968.     

Kinetic theory of creep and lifetime of oriented crystalline polymers with allowance for supermolecular structure

A previously proposed model [7] is used as the basis for a study of the kinetics of failure under load of an amorphous-crystalline oriented polymer with allowance for the unequal length of the chains in the amorphous zone. A constant-load creep curve is constructed. An expression is given for the lifetime t of the specimen. The relation _mt = const, where _m is the steady-state creep rate, is proved. The kinetics of free radical concentration in time in a specimen under load are investigated. The results are compared with experimental data.Mekhanika Polimerov, Vol. 3, No. 1, pp. 8–18, 1967     

Product constructions for cyclic block designs. I. Steiner quadruple systems

Let CSQS(ν) denote a cyclic Steiner quadruple system of order ν. Various product constructions for CSQS(uν) are given. Amongst other results we show how to construct a CSQS(uν) (ν ? 0 (mod 4)) from a CSQS(u), a CSQS(2u) and a CSQS(ν).     

On the structure of some abstract differential problems. - I.

Summary Some differential type problems are formulated abstractly in terms of diagrams of Hilbert spaces and related Schwartz kernels and their structure is studied. Research supported in part by the National Science Foundation under grant GP-1448 and GP-4575.     

Influence of diffusion of a liquid on the flexural rigidity of polyformaldehyde specimens

A correlation has been established between the flexural rigidity of polyformaldehyde specimens and the diffusional characteristics of water, acetic acid, and benzine into this material.     

An observation on the module structure of block algebras

Let B be a p-block of the finite group G. We observe that the p-fusion of G constrains the module structure of B: Any basis of B that is closed under the left and right multiplications of a chosen Sylow p-subgroup S of G must in fact form a semicharacteristic biset for the fusion system on S induced by G. The parameterization of such semicharacteristic bisets can then be applied to relate the module structure and defect theory of B.