Robustness of the Spin-Navigator Based Method for the Manipulation of the Beam Polarization Axis in a Spin-Transparent Storage Ring

Physics of Atomic Nuclei - We have investigated the robustness of the spin-navigator based method for manipulating the beam polarization to bend magnet installation errors. Toward that end,...     

One-component polyetherurethane sealing glues cured by air moisture

Results of the studies on the development of one-component polyurethane sealing glues are presented. The synthesized materials may find wide application in construction, furniture manufacturing, and other fields.     

Structure and properties of segmented polyurethane-ureas with dissimilar soft blocks

Structure and properties of segmented polyurethane-ureas with mixed nonpolar and polar soft segments were studied. Advantages of elastomers based on mixtures of oligobutadiene and oligoether diisocyanates in providing high strength properties combined with frost resistance are demonstrated.     

Structure and Properties of Polyurethane-Ureas Prepared from Blends of Thermodynamically Incompatible Oligomer Diisocyanates

The structure and properties of materials based on oligo(divinyl-isoprene) and oligoether diisocyanates cured with an aromatic diamine were studied.     

Interrelationship between ultimate mechanical properties of variously structured polyurethanes and poly(urethane urea)s and stretching rate thereof

The ultimate mechanical properties of polyurethane determine their possible applications under various conditions of mechanical action. The mechanical properties of nine polyurethane and polyurethane urea samples were investigated in a range of stretching rates 0.56÷0.002 s⁻¹. A part of experiments was performed at several temperature values under conditions of stepwise variable stretching rates. The interrelationship between rate dependence of strength–strain properties of polyurethane compositions and the structure thereof was ascertained. The influence of molecular structure’s variations, of physical network density and of segmented polyurethane and polyurethane urea morphology on said interrelationship was examined on samples subjected to large strain values. The structure of some samples was radically distorted by plasticizers oppositely influencing micro-phase segregation of soft and hard segments. Multiple kinds of dependency (direct, inverse, moderate and strong) of elastomers’ strength versus stretching rate were demonstrated. Produced data and ascertained regularities are useful to perceive reasons for diversity of mechanical behavior of polyurethane materials and to control properties thereof.     

Preparation and Properties of Frost-Resistant Room-Temperature-Curable Compounds Based on Oligoethertetraurethane Diepoxides of Various Chemical Structures

New polytetraurethane diepoxides were prepared from oligo(tetramethylene oxide)diols of various molecular masses, various diisocyanates, and glycidol. High-strength frost-resistant cold-curable elastic compounds were prepared on their basis. The use of aminoethylpiperazine as a curing agent allows the cured materials to be prepared in 24 h at room temperature. The elastomers based on isophorone diisocyanate exhibit higher mechanical and thermal characteristics than those based on 2,4-toluene diisocyanate, which is due to higher degree of microphase segregation of soft and hard blocks of elastomers based in isophorone diisocyanate.     

Characteristics of polyether urethanes with mixed soft segments,prepared by two- and three-step procedures

A three-step procedure for preparing polyurethanes with mixed polyether segments was suggested. It involves preparation of the “inverse” prepolymer by the reaction of one of oligodiisocyanates with 1,4-butanediol taken in a double excess, followed by the reaction with the other oligodiisocyanate. Polyurethanes with alternating poly(tetramethylene oxide) and poly(propylene oxide) soft segments were prepared by this procedure. Such materials surpass polyurethanes prepared from a mixture of oligodiisocyanates in the strength and softening point of the hard phase. In contrast to poly(tetramethylene oxide) urethane, elastomers with mixed polyether segments do not crystallize.     

High-dense polymeric compositions based on the thermoplastic polyuretanes

The results of investigating the properties of high-dense pollution-free hybrid composites on the basis of the new type of polyurethane thermoplastics with the low-melting diurethane plasticizer are represented. The material is shown appropriate for the processing at low temperature. Strengthening of such materials is shown caused by the crystallization of the low-melting plasticizer.     

Influence of the molecular mass of soft segments on the thermodynamic stability and physicomechanical properties of plasticized polyether urethane

The physicomechanical properties and thermodynamic stability of segmented polyether urethane containing poly(tetramethylene oxide) segments of different molecular masses (М ～ 1000, 1400, 1950) and plasticized with di(2-ethylhexyl) sebacate were analyzed in relation to the molecular mass of the soft segments, and the glass transition point of the soft phase of the polymer was determined. Based on the results obtained, a rapid method was suggested for experimental determination of the osmotic pressure (up to ～1000 kPa) in the polymer–plasticizer system. The possibilities of preparing thermodynamically stable plasticized materials of high strength (up to 22–26 MPa) with the glass transition point as low as–95 to–100°С were demonstrated.