Heterogeneous polymer materials based on oligodienetetraurethanediepoxide and oligoetherdiisocyanate

Based on mixtures of oligodienetetraurethanediepoxide and oligoetherdiisocyanate with low thermodynamic compatibility of the components, microheterogeneous elastomers are obtained and their properties are studied. The advantages of the new materials in strength and adhesion to steel over cross-linked elastomers based on individual oligovinylisoprenetetraurethanediepoxide are shown.     

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.     

Introduction of Low-Molecular Digicidylurethane: Effect on the Properties of Oligoetherurethane-Diepoxide Compositions

The preparation of elastomers based on blends containing oligoetherurethane diepoxide (OUDE) and low-molecular-weight diglycidylurethane (DGU) has been described. For both the composition and cured elastomer, the dependence of the properties on the DGU fraction in the initial blend has been studied. It is shown that, at an equimolar ratio of DGU and OUDE, the physicomechanical characteristics properties of the elastomers have been shown to be significantly higher than those for OUDE-based elastomers. A 1.5- to 2-fold decrease in the degree of equilibrium swelling has been observed at a 0.5 mole fraction of DGU, if compared to OUDE-based elastomers.     

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.     

A high-strength technological compound on the basis of oligobutane diendiol,isophorone diisocyanate,and aromatic diamine

2,4-Toluene diisocyanate is substituted with isophorone diisocyanate during the synthesis of polybutadiene urethane urea. The obtained polydiene urethane urea is shown to be superior to the physicomechanical and rheological properties of the traditional material synthesized with the use of 2,4-toluene diisocyanate. It is established that polybutadiene urethane urea is more than twice as good as steel adhesion to polydiene urethane epoxy compounds.     

The Effect of the Isocyanate–Hydroxyl Ratio on the Structure and Properties of Hard Polyurethanes

A comprehensive study has been carried out of the structure and rheological and physicomechanical properties of low-temperature curing polyurethane compositions based on polyisocyanate and a blend of hydroxyl-containing oligomers of different reactivity. The maximum curing rate and strength parameters (tensile strength and Young’s modulus) have been shown to be achieved at the ratio of the reacting groups NCO : OH = 1.1.     

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.     

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.     

Polyurethane adhesive composition cured at room temperature

The influence of polyfunctional hydroxyl-containing oligomer on the rheological, physicomechanical, and adhesive properties of polyurethane composite based on multicomponent oligomer blend and polyisocyanate is investigated. The kinetics of curing is investigated by the viscometric method, and the composition lifetime is determined. It is shown that the polyurethanes under investigation can be used as fast-curing adhesive composites of cold curing operating in a temperature interval of up to +90°C.