Dependence of physico-mechanical properties of high-strength polyethylene film yarns on parameters of the strengthening process

Conclusions There is an optimum temperature region for performing a one-stage process for preparation of high-strength, high-modulus film yarns from low-pressure polyethylene. Under these conditions, film specimens have been obtained with a strength of 0.8 GPa and an elastic modulus of 14 GPa. The region of process stability is narrowed with increase in the stretch ratio.Studies of the process of propagation and damping of ultrasonic vibrations in the specimens obtained as functions of stretch ratio have made it possible to estimate maximum values for the elastic modulus for specimens of this type, corresponding to a pseudo-ideal structure characterized by a damping coefficient = 0. For the investigated polymer, the elastic modulus proved to be equal to about 160 GPa at a stretch ratio of about 30.Translated from Khimicheskie Volokna, No. 1, pp. 31–33, January–February, 1989.     

Specific features of the interaction of alloys of the didymium-iron-boron system with hydrogen

We study the interaction of alloys of the Dd-Fe-B system [M-82, M-83, M-84, and M-85 alloys with a mass content of 33–40% didymium, up to 0.5% aluminum, and 1–1.25% boron (the rest is iron)] with hydrogen using volumetric, X-ray phase, and differential thermal analysis. If the initial hydrogen pressure is 1.0 MPa, hydrides with 0.4–0.6 mass % of hydrogen are formed. The saturation of these alloys with hydrogen is accompanied by an increase in the spacing a of an elementary cell by 1.2–1.4% and in c by 0.8–1.1% (the general increase in volume is 3.2–3.9%). If the initial pressure is 0.15–0.2 MPa, the time of complete saturation with hydrogen is 15–20 min for most alloys. At 973–1033 K, the alloys under study in hydrogen disproportionate into DdHx didymium hydride (a = 0.5449 – 0.5458 nm), -iron (a = 0.2864 – 0.2866 nm), and Fe2 B iron boride (a = 0.5112 – 0.5117 nm, c = 0.4228 nm). An increase in the initial hydrogen pressure from 0.1 to 5.0 MPa is accompanied by a decrease in the disproportionation temperature to 930 K.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 2, pp. 105–112, March–April, 2004.