Liquid Polyurethane Research Articles

Morphology and properties of cyanate ester/liquid polyurethane/silica nanocomposites

The high-speed homogeneous shearing method was applied to prepare nanocomposites of cyanate ester (CE) with liquid polyurethane elastomer (PUR) and silica. To investigate the influence of various components on the morphology and properties of the ternary composites, the binary composites of CE/PUR and CE/silica were also involved in this article. The morphology of the cured materials of binary and ternary systems was investigated by transmission electron microscopy (TEM), and the results show that silica nanoparticles were uniformly distributed in the ternary and binary matrix. Phase separation of elastomer in composites was not observed by TEM. FTIR test and dynamic mechanical analysis (DMA) proved that chemical linking was existent between PUR and CE. Scanning electron microscopy examinations and mechanical properties tests were carried out. The results show that ternary composites displayed higher fracture toughness and impact strength compared with most of the binary systems. This suggests that the addition of PUR and nanosilica can synergistically improve the toughness of CE. DMA studies confirmed that the incorporation of silica can increase the storage modulus and Tg for CE and CE/PUR system, since there are a good adhesion and a strong hydrogen bonding between silica and polymers. The thermal property of ternary composites increases with the increase of silica nanoparticle loading. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1243–1251, 2008

Polyurethane spray foam burn

The increasingly widespread use of polyurethane spray foam cans have resulted in yet another potential mechanism for causing burns. Polyurethane foams form monolithic, selfflashing surfaces which effectively seal against leaks. It is the most efficient form of thermal insulation available. Spray polyurethane foam, is a spray-applied insulating foam plastic that is installed as a liquid and then expands many times its original volume [1]. It forms an airtight, weather-resistant bond that is used as roofing and insulation system applications, conforms to the surface to which it is applied and forms a seamless layer of insulation. It fully adheres to most surfaces and can be applied to surfaces with irregular shapes and penetrations. Its use extends from amateurs to professionals and is also commonly used during do-it-yourself work. This material burns rapidly and produces intense heat, dense smoke and gases that are irritating, flammable and toxic. In this paper, we present an unusual case of a burn sustained from skin contact of burning, organic polyurethane liquid spills from burst of polyurethane foam container due to heat exposure.

Synthesis and properties of liquid crystalline polyurethanes

1,4-Bis(p-hydroxybenzoate)phenylene was prepared using 1,4-bis(trimethylsiloxy)benzene and p-hydroxybenzoyl chloride as starting materials. A series of novel 1,4-bis(p-hydroxyalkoxybenzoate)phenylene were synthesized by reaction of 1,4-bis(p-hydroxybenzoate) phenylene with 3-brompropanol and 4-bromobutanol, respectively. The liquid crystal polyurethanes were prepared by 1,4-bis(p-hydroxyalkoxybenzoate)phenylene with MDI (p-methylene diphenylenediisocyanate) and 2,4-TDI(2,4-toluenediisocyanate), respectively. The thermotropic properties, the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by DSC, IR and POM. It showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 144°C and 260°C. The transition temperature (Tm and Ti) decreased with an increase in the length of the methylene spacer.

A Study on the Curing Behavior of Silicone/Polyurethane/Epoxy Blends by Rigid-Body Pendulum Rheometer

This study explored the curing behavior of blends of liquid silicone, polyurethane (PU), and epoxy. We tried using the rigid-body pendulum rheometer (RPR) to analyze the curing behavior of silicone, PU, and epoxy. Morphology of the three-phase polyblends was evaluated by scanning electron microscopy (SEM). The result showed that the rigid-body pendulum rheometer could be used to observe the processing condition of silicon/pu/epoxy blends and their curing behavior changes from a liquid state to a solid state. From SEM, we found that the blend cross section has micropellet distribution and rough with increasing content on epoxy. Finally, we found that blends can be formed between intermolecular and self-cross-linking in interpenetrating polymer networks. Comprehension of the previous information, through the adjustment of soft–hard linkage of blends, they could be used in the future material design according to their antivibration absorption characteristic, adhesion function, and heat resistance function.

Response of sandwich composites with nanophased cores under flexural loading

It is well known that in a sandwich structure, the core plays an important role in enhancing the flexural rigidity and by controlling the failure mechanisms. If the core is made from foam, the strength of the core material and the debond strength at the core–skin interface almost entirely dictate the performance of structural sandwich composites especially under flexure. In this investigation attempts have been made to improve the performance of the sandwich by strengthening the core but partially sacrificing the debond fracture toughness of the sandwich construction. Strengthening of the core has been accomplished by infusing nanoparticles into the parent polymer of the core material when it was in the liquid stage. The core material is polyurethane foam made from polymeric isocyanate (Part A) and reacting with polyol (Part B). Spherical nanoparticles such as TiO 2 of about 29 nm in diameters were dispersed in Part A of liquid polyurethane through an ultrasonic cavitation process. The amount of nanoparticles infused into liquid foam varied from 1 to 3% by weight. Once Part A was doped with nanoparticles, it was mixed with Part B, and was cast in a rectangular mold to produce the nanophased polyurethane foam. The nanophased foam was then used with regular S-2 Glass fiber preforms and SC-15 epoxy to manufacture sandwich composites in a VARTM set up. Test coupons were then extracted from foam as well as from sandwich panels to conduct flexural and various other chemical tests. A parallel set of control panels were also made with neat polyurethane core materials. Thermogravimetric and SEM analyses have indicated that the decomposition temperature of the nanophased foams increases by about 27 °C and the cell size almost doubles with nanoparticle infusion. A significant improvement in flexural strength and stiffness has also been observed with 3% loading of TiO 2 nanoparticles. Debond fracture toughness parameters ( G c) were also determined for both categories of sandwich constructions, and it was seen that nanoparticle infusion reduces the value of G c by almost a factor of three. Despite this reduction, strength of nanophased sandwich increased by about 53% over the neat system. Details of manufacturing and analyses of test results are included in the paper.

폴리우레탄 액상고무를 혼합한 불포화 폴리에스테르 모르타르의 인성 증진효과

폴리우레탄 액상고무를 혼합한 불포화 폴리에스테르 모르타르의 인성 증진효과

The study of peel resistance of silicone elastomer bonded with polyurethane sheet fabricated from liquid polyurethane when using 3 primers

The study of peel resistance of silicone elastomer bonded with polyurethane sheet fabricated from liquid polyurethane when using 3 primers

Segmented block copolymers of natural rubber and bisphenol A-toluene diisocyanate oligomers

Segmented block copolymers were synthesized from hydroxyl-terminated liquid natural rubber and polyurethane oligomers based on Bisphenol A and toluene diisocyanate by one-shot and two-shot processes in solution. Structural features were characterized by infrared and nuclear magnetic resonance spectroscopic analysis. The spectra of the one-shot materials were identical with those of the two-shot materials, indicating their chemical identity. The soft segment Tg was well defined and almost invariant around −64°C, but the hard segment Tg varied from 75 to 105°C as the hard segment content increased from 30 to 60 wt %. Two relaxation temperatures were observed for each sample in dynamic mechanical analysis (DMA). These observations and the two-stage thermal decomposition by random nucleation mechanism, as investigated in thermogravimetric analysis unambiguously confirmed complete phase segregation in these materials. The scanning electron microscopy and optical micrographs showed well-defined domains dispersed in a matrix, indicating the two-phase morphology. Systematic changes in hardness and tensile properties with hard segment content were also observed. The samples behaved like soft elastomers at lower hard segment content, toughened plastics at high hard segment content, and rigid elastomers at intermediate compositions. Variations in hardness and tear strength were consistent with this behavior. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 706–721, 1999

Synthesis and investigation of liquid polyurethane metal complexes

AbstractPolyurethane metal complexes (PUMC's) have been synthesized on the basis of the polynucleus complexes of Cu(II) and Fe(III), where the metals are connected by chlorine bridges, symmetrical aromatic diisocyanates and azoaromatic compounds; these complexes exhibit properties of thermotropic liquid crystals. The mesophase temperatures of the substances range from is 20–80 °C and 60–110°C. Specific electric resistance of the synthesized liquid crystal systems is 103‐105 ω‐cm.

Toughening mechanisms of modified unsaturated polyester with novel liquid Polyurethane rubber

Unsaturated polyester (UPE) has been toughened by incorporating novel liquid polyurethane (PU) rubber. PU rubber was synthesized using toluene di-isocyanate and polyols such as poly (propylene glycol) and poly (tetramethylene ether) glycoi, whose molecular weights vary from 650 to 4000. Particle size was varied from 0.1 to 3 μm by changing the polyol and the molecular weight of PU rubber, and the effects of particle size on the fracture toughness of PU rubber-modified UPE were investigated. Hydroxyl terminated PU rubber (HTPU) and isocyanate terminated PU rubber (ITPU) were used to study the effects of rubber-matrix adhesion. The toughening mechanisms observed by scanning electron microscope are debonding between rubber and matrix in HTPU-modified UPE, and cavitation in the rubber particle in ITPU-modified UPE. However, shear bands were not observed as UPE is a highly cross-linked thermoset with very short chain length between the cross-links. A 1.9-times increase in fracture toughness of UPE was achieved with the formation of cavitated particles. In order to measure the process zone size at the crack tip, the thin sections of tested double-notched four-point bending specimens were examined by optical microscope.

Toughening of unsaturated polyester with novel liquid polyurethane rubber

In this study the important parameters for rubber toughening of UPE, such as the particle size, bond strength between the rubber particles, were investigated using a novel liquid polyurethanne rubber as a toughening agent

Interpenetrating Polymer Networks from Castor Oil Based Polyurethanes and Poly(Methyl Methacrylate) XX

Abstract Two component interpenetrating polymer networks (IPNs) of castor oil based polyurethanes and poly(methyl methacrylate) were prepared by sequential polymerization. The liquid polyurethanes were formed by reacting the hydroxyl group of castor oil with diphenyl methane diisocyanate at different stoichiometric NCO/OH ratios. These polyurethanes were swollen in methyl methacrylate monomer and subsequently polymerized by radical polymerization initiated with benzoyl peroxide in presence of crosslinkers ethylene glycol dimethacrylate and 1,3-propanediamine. Novel interpenetrating polymer networks PU/PMMA IPNs were obtained as films by transfer molding technique. These IPNs were characterized in terms of crosslink density and mechanical properties. The morphology was studied by transmission electron microscopy. Thermal stability was assessed from the thermogravimetric data.

Interpenetrating polymer networks from castor oil-based polyurethane and poly(ethyl methacrylate) XVII

Two-component interpenetrating polymer networks (IPNs) of castor oil-based polyurethane (PU) and poly(ethyl methacrylate) (PEMA) were prepared by sequential polymerization. The liquid polyurethanes were formed by reacting the hydroxyl group of castor oil with isophorone diisocyanate at different NCO/OH ratios. These polyurethanes were swollen in ethyl methacrylate monomer, which was subsequently polymerized by radical polymerization initiated with benzoyl peroxide in the presence of crosslinkers, ethylene glycol dimethacrylate and 1,3-propanediamine. A series of PU/PEMA interpenetrating polymer networks (IPNs) were obtained as tough films. These IPNs were characterized in terms of: resistance to chemical reagents, thermal behaviour and dynamic mechanical thermal analysis. The morphology was determined by scanning electron microscopy, and dielectric properties at different temperatures were studied.

Interpenetrating polymer network from castor oil‐based polyurethanes and poly(methyl acrylate). XIV

AbstractCastor oil containing hydroxyl functionality was reacted with 4,4′‐diphenylmethanediisocyanate under different stoichiometric ratios of NCO/OH to obtain liquid polyurethanes. These polyurethanes were subsequently interpenetrated with methyl acrylate monomer using ethylene glycol dimethacrylate as a crosslinker by radical polymerization using benzoyl peroxide as an activator. The polyurethane/poly(methyl acrylate) interpenetrating polymer networks (PU/PMA IPNs) were obtained as tough films by transfer molding techniques. All IPNs were characterized by their resistance to chemical reagents, optical properties, thermal behavior, and mechanical properties: tensile strength, Young's modulus, elongation at break (%) and hardness Shore A. The morphology of the IPNs was studied by scanning electron microscopy and dielectric properties: electrical conductivity (σ), dielectric constant (ϵ′), dielectric loss (ϵ″), and loss tangent (tan δ) at different temperatures.

Interpenetrating polymer networks from castor oil based polyurethanes, XI

AbstractUnder different experimental conditions, various liquid polyurethanes (PU) were synthesized from castor oil and isophorone diisocyanate varying NCO/OH ratio. These polyurethanes were then subsequently interpenetrated with n‐butyl acrylate (nBA) monomer and ethylene glycol di‐methacrylate as crosslinker by radical polymerization using benzoyl peroxide as an initiator. This leads to the formation of novel PU/PnBA interpenetrating polymer networks (IPNs) by transfer molding. These IPNs were characterized by their resistance to chemical reagents, thermal behavior (TGA), mechanical properties, namely; tensile strength, Young's modulus, elongation at break (%) and hardness (Shore A). The morphology of the IPNs was studied by Scanning Electron Microscopy. The dielectric behavior was computed in terms of electrical conductivities, dielectric constant (ε′), loss tangent (tan δ) and dielectric loss (ε″).

Interpenetrating Polymer Networks from Castor Oil Based Polyurethanes and Poly(n-Butyl Acrylate). VI

Abstract Castor oil—a naturally occurring triglyceride of ricinoleic acid containing a special functionality of —OH group was reacted with hexamethylene diisocyanate to obtain liquid polyurethanes under different stoichiometric conditions varying NCO/OH ratio. These polyurethanes were then individually interpenetrated with n-butyl acrylate and ethylene glycol dimethacrylate as crosslinker by radical polymerization using benzoyl peroxide as initiator. The polyurethane/poly(n-butyl acrylate) interpenetrating polymer networks (IPNs) were obtained as tough films by transfer molding. These IPNs were characterized by their chemical resistance, thermal behavior (TGA, DSC), mechanical properties namely tensile strength, Young' s modulus, elongation at break (%) and Shore A hardness. The morphological behavior was analyzed by scanning electron microscopy and dielectrical properties namely, electrical conductivity (σ), dielectric constant (ε′), dielectric loss (ε″) and loss tangent (tan δ) at different temperature were studied.

Additives for paints and inks: some new developments

Servo B.V. PO Box 1, 7490 AA Delden, Holland has introduced a liquid polyurethane thickener SER AD FX1010.

Applicability of liquid radiopaque polyurethane for transcatheter embolization

Polyurethane Bayer was tested as an occlusive agent for experimental embolization in postmortem and postnephrectomy kidneys which served as a tumor model. Coaxial and balloon catheters were used for the embolization. To make polyurethane radiopaque, the material was labeled with different water-soluble, oily and solid contrast agents. Best results were achieved with oily contrast materials, e.g., Pantopaque. We found that polyurethane can easily be injected during a predetermined working time of 8-10 min. The embolization results in a complete, permanent, and homogeneous occlusion of the proximal arterial branches and small peripheral vessels.

Polyurethane Coating in the Prevention of Nickel Dermatitis

Eleven patients with allergic contact dermatitis to nickel, as proven by history and positive patch test reactions, were used to evaluate the effectiveness of a liquid polyurethane plastic material for coating various offending metallic articles. The plastic film proved to be quite effective and worthwhile by protecting sensitized patients, preventing dermatitis, and allowing the wear of previously unworn items.