Cyclic strength of a calender cylinder

The first attempt to determine the fatigue resistance of a calender cylinder shell to the action of service loads is described. The stressed condition of the shell was calculated with the computer and earlier developed methods, and the fatigue strength on the basis of diagrams of the limiting amplitudes in the linear and nonlinear variations. Experimental data on the fatigue resistance of type VZ3 cast iron is presented. The necessity of making similar calculations for this structure together with traditional methods of calculation for the static action of loads is shown.Translated from Problemy Prochnosti, No. 3, pp. 57–60, March, 1990.     

Temperature Stresses in a Packet of Strips Produced from a Melt by the Stepanov Method

The authors suggest a mathematical model for describing thermoelastic stresses that appear during the growth of a packet of crystal strips that are in the state of radiation heat exchange with each other. It is assumed that the side surfaces of the strips are diffusely gray. The behavior of the stresses in the strips of the packet is investigated as a function of the pulling speed, the length of the grown strips, the distance between the shapers, their thickness, and the temperature of external shields.     

Analysis of the molecular structure of ethylene hexene-1 copolymers produced over highly active supported Ziegler-Natta catalysts

The mechanical and rheological properties of ethylene α-olefin copolymers are governed by a molecular and supramolecular structure that depends on its molecular weight characteristics, comonomer concentration, and the uniformity of branching distributions for polymer chains with different molecular weights (compositional heterogeneity). Using state-of-the-art methods, we study the parameters of molecular weight distribution, molecular structure, and compositional heterogeneity of ethylene hexene-1 copolymers with different compositions, produced over highly active supported Ti-Mg and V-Mg Ziegler-Natta catalysts, and show the possibility of controlling these parameters to improve the quality of the resulting polymers.     

Influence of fire retardants on the reaction‐to‐fire properties of coextruded wood–polypropylene composites

The reaction‐to‐fire properties of coextruded wood–plastic composites containing different fire retardants (melamine, zinc borate, ammonium polyphosphate, aluminium trihydroxide, natural flake graphite and expandable graphite) in the shell layer have been studied with the cone calorimetry technique. The effect of ammonium polyphosphate in combination with graphite has also been studied with a cone calorimeter test. A coextruded composite manufactured without any fire retardant addition has been used as a reference. The fire properties measured in the cone calorimeter are discussed, including the heat release rate, total heat release, smoke production, specific extinction area, CO yield and mass loss rate. The results show that the introduction of fire retardants in the shell layer of coextruded wood–polypropylene composites has a favourable effect on the fire resistance properties of the composite materials. The reaction‐to‐fire properties have been improved according to the fire classification of construction products based on the Euroclass system. Copyright © 2015 John Wiley & Sons, Ltd.