Urethane Oligomers Research Articles

Mechanical properties of a soft liner made of methacrylate monomers and urethane oligomers.

Mechanical properties of a soft liner made of methacrylate monomers and urethane oligomers.

Surface modification of waterborne polyurethane

Fluorinated urethane oligomers (SMAs) having repeat unit identical to the hard segment of base polyurethane (PU) have been synthesized and blended with base PU prior to dispersion. XPS and static contact angle measurements showed that surfaces of dispersion cast film are significantly enriched with SMA although SMA and base PU were miscible in bulk phase showing a single glass transition temperature. AFM showed that surface roughness of the dispersion cast film increased over 13 times with the addition of SMA (15%) providing possible mechanism of increased water and oil resistance as well as low friction coefficient of the film.

Influence of isocyanate type of acrylated urethane oligomer and of additives on weathering of UV-cured films

The weathering of UV-cured films containing the isocyanate type of acrylated urethane oligomer, and the influence of different additives (HALS, UVA and TiO 2), was investigated by various methods. The UV-cured film containing the acrylated aromatic urethane oligomer showed worse photodegradation than that containing the acrylated aliphatic urethane oligomer. In the case of the UV-cured films containing the acrylated aromatic urethane oligomer, those stabilized using both HALS and UVA showed the highest photostability.

UV Ink Jet-Development of Unique Raw Materials

The development of heated piezo print heads for Ink Jet Applications has expanded the range of raw materials that can be utilized in the formulation of UV curable inks. While higher jetting temperatures increases the range of monomers and oligomers that can be successfully formulated, ink instability also increases. With increased viscosity and gel particle formation, head reliability decreases.A new range of monomers has been developed which demonstrate a remarkable increase in thermal stability. These materials are specifically designed to have low viscosity and fast cure at jetting temperatures up to 100 Deg C.Sartomer continues to expand their work in developing the line of dendrimers and specialty oligomers previously reported at NIP18 in San Diego. Polyester acrylates, based on dendrimer technology, exhibit low viscosity at room temperature, as well as improved cure speeds, essential elements of a UV ink jet formulation. Improved outdoor weatherability has become important for may ink jet applications. New urethane oligomers, with low viscosity profiles, have been developed which demonstrate excellent gloss retention and low yellowing.

Mechanical Properties of An Experimental Soft Lining Material Based on Urethane Oligomer

The purpose of this study was to investigate the apparent viscosities and mechanical properties of two experimental light-curing soft lining materials (SLM-1 and SLM-2) based on soft-type urethane oligomers, as well as the shear bond strength and dye penetration between the denture base resin and the polymerized SLMs after storage in water. The apparent viscosities of SLM-1 and SLM-2 were 144.0-146.9 and 1.9 Pa x s respectively. After storage in water for two prescribed periods (one day and three months), the mechanical properties of the SLMs on the overall were 10.6-20.6 MPa for elastic modulus, 69.3-72.1 for hardness, and 3.8-4.0 MPa for adhesive strength. Tensile strength was observed to decrease after three months' storage in water, when compared to that after one-day storage (p < 0.01). Water sorption rates also differed significantly (p < 0.05)--namely 3.0 and 2.8 mg/cm2 for SLM-1 after one day and three months respectively, and 2.0 and 2.2 mg/cm2 for SLM-2. As for dye penetration, no infiltration was observed at the denture base resin-SLM interface after three months' storage. Based on the results of this study, it seemed like the SLMs possess many suitable properties for use with a new technique that we recently developed for preparing denture base resin and soft lining material.

UV-curable interpenetrating polymer networks based on acrylate/vinylether functionalized urethane oligomers

The synthesis of simultaneous full interpenetrating polymer networks (IPN) based on Bisphenol A or 6F Bisphenol A bearing acrylated urethane (Bis A or 6F Bis A based Acryl-U) oligomers and vinylether functionalized polydimethyl siloxane containing urethane oligomer (PDMS-VEU) is described. The structures of the oligomers were characterized by FTIR. All resins were successfully polymerized by UV-irradiation in the presence of corresponding reactive diluents and photoinitiators. Physical properties of IPNs were determined by extraction and water absorption measurements. Extractable parts of IPNs were found to be approximately between 10 and 35 wt%. The stress–strain tests showed that an improvement was obtained on tensile properties by addition of PDMS-VEU oligomer to the Bis A based Acryl-U resin. In addition IPN sample (90/10 wt%) has higher thermo-oxidative stability compared to the neat films.

Structure and water sorption of polyurethane nanocomposites based on organic and inorganic components

Organic–inorganic polymer composites, consisting of a polyurethane organic phase and a mineral inorganic phase were prepared by the joint polymerization of the urethane oligomer with the water solution sodium silicate. The structure and the morphology of the composites, at a fixed weight fraction of the inorganic component of 20%, and of the corresponding pure polyurethane matrices were investigated by wide-angle and small-angle X-ray scattering (WAXS and SAXS, respectively). The results show similar size (5–7 nm) of the scale of heterogeneity of the composites due to the microphase separation of the rigid and the flexible blocks of the amorphous polyurethane matrix and due to the inorganic crystalline inclusions, i.e. the materials prepared are nanocomposites. The WAXS measurements indicate that the individual properties of the block inorganic component are lost in the nanocomposites, probably due to physical and chemical interactions between the two components. Water sorption from the liquid phase was studied gravimetrically in a composite and in the corresponding polyurethane. The results show high sorption capacity of the composite, due to the hydrophilicity of the inorganic phase and the elasticity of the polyurethane matrix, and allow to estimate the layer thickness of water adsorbed on the inorganic nanoparticle surface to about 20 nm, in reasonable agreement with a model adopted from the literature. WAXS and SAXS measurements on the swelled composite and the swelled-and-dried composite indicate changes in the structure of the inorganic component induced by water, which are, however, to a large extent reversible. These materials may find applications as gel electrolytes and as hydrogels in drug delivery systems.

Light-curing Reinforcement for Denture Base Resin Using a Glass Fiber Cloth Pre-impregnated with Various Urethane Oligomers

The purpose of this study was to investigate the flexural properties of denture base resin reinforced using glass fiber cloth and a urethane oligomer. The five types of oligomer used in this study were S5, S9, S3, U4, and U6, which have varying functional groups and viscosities. The flexural properties of S9 with glass fiber cloth could not be measured because S9 is elastic. In the heat-cured resin reinforced with S9, the reinforcement peeled away from the resin. In the self- and light-cured resins reinforced with S9, the flexural properties increased significantly. When reinforced with the other four oligomers (S5, S3, U4, and U6), the flexural strength and flexural modulus of the self-, heat-, and light-cured resins increased significantly (p<0.01).

Coating compositions based on modified phenol-formaldehyde resin and urethane prepolymers

New polymer compositions were synthesised on the base of butyloxylated phenol-formaldehyde resin and three kinds of urethane oligomers. These oligomers were obtained from TDI and selected commercial oligoetherols Rokopol. Coatings based on these compositions were manufactured and their various properties were determined. The coatings exhibited a very good adhesion to metallic substrate, good elasticity and an excellent chemical resistance to selected corrosive media.

Synthesis and characterization of UV-curable vinyl ether functionalized urethane oligomers

Vinyl ether functional group bearing urethane-based oligomers were synthesized by reacting toluene (2,4-2,6) diisocyanate (TDI) with 4-hydroxybutyl vinyl ether (HBVE) and three different diols, namely poly(ethylene glycol), poly(propylene glycol) and α-ω-hydroxy terminated organofunctional poly(dimethyl siloxane). The structures of the oligomers were characterized by FTIR. All resins, except the poly(ethylene glycol) containing one, were successfully polymerized cationically by UV irradiation in the presence of a diaryliodonium photoinitiator and isopropyl thioxanthone (ITX) photosensitizer. Physical properties of UV-cured films such as gel content, solvent resistance, stress–strain and water absorption behaviors, were examined. The stress–strain tests showed that PDMS containing oligomer gives better tensile strength and elongation values when compared with PPG containing one. The curing process was followed quantitatively by monitoring the disappearance of vinyl ether groups by real-time infrared spectroscopy. The reactivity of PDMS containing oligomer was found higher than PPG containing one. In addition, thermal gravimetric analysis of PDMS containing polymeric films gave higher char yield due to their silicone containing structure.

Urethane oligomers as raw materials and intermediates for polyurethane elastomers. Methods for synthesis, structural studies and analysis of chemical composition

Based on earlier models developed for polyaddition of diisocyanates and polyols, a non-stoichiometric process was provided for step-by-step polymerisation of 2,4- and 2,6-tolylene diisocyanate (TDI) with diols which had various molecule sizes and the nature of polyethers and polyesters. Said process yielded urethane oligomers which had –NCO or –OH groups as their chain end groups. After elimination of excess monomer, these compounds were—at subsequent stages (2–5)—subjected to further reaction with diisocyanate or with selected polyol. The process was operated in bulk and excess monomers were eliminated with the use of the selective extraction method. Linear products were obtained in that way which had well defined chain structures and narrow distribution of their molecular weights (MWD) PD= M ̄ w / M ̄ n =1.1–1.3. On the basis of IR and mass spectrometry (MS) (electrospray ionization (ESI) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)) structural analyses, the expected structures of oligomers were confirmed and the actual compositions of polyurethane mixtures formed at every stage of the polymerisation process could be verified against the data obtained from the model, from the balance calculations (based on determinations of free isocyanate groups) and from the findings of the gel-permeation chromatography (GPC) analysis. Applicability of the presented method was demonstrated and the general scheme was suggested for the process discussed.

A study on the synthesis of urethane oligomers

A method of preparation of isocyanate- or hydroxy-terminated urethane oligomers of narrow molecular weight distribution was developed and the products used for preparation of polyurethane elastomers. The method consists of the controlled step-wise reaction of 2,4- and 2,6-toluene diisocyanate (TDI) with butan-1,4-diol (BD) (in the first step) or with polyoxyethylene glycols of molecular weight varying from 200 to 1000 (following steps). All reactions were carried out in bulk. The clue was that the isocyanate- or hydroxy-terminated oligourethanes obtained in a previous step were used as the substrates in the next preparation step where they reacted with an excess of appropriate glycol or TDI, respectively. The unreacted monomer excess was removed by extraction. The products of subsequent steps characterized by spectral analysis IR and NMR and their molecular weight were determined by matrix-assisted laser desorption ionization–time of flight and electrospray ionization mass spectroscopy and gel-permeation chromatography. The oligomers were cross-linked with trifunctional low-molecular chain extenders yielding polyurethane elastomers.

Kompozycje polimerowe na podstawie butoksylowanej zywicy melaminowo-formaldehydowej modyfikowanej prepolimcrani i uretanowymi z koncowymi grupami izocyjanianowymi

Butoxylated melamine-formaldehyde resins (BMF) and two grades of urethane oligomers with isocyanate end-groups (PUR-izo) based on toluilene diisocyanate and oligooxypropylenediol or oligooxyalkylenetriol have been obtained. Physicochemical properties of these products were ermined (Tables 1, 2) and basing on the IR and H-1 NMR spectra their chemical structures were determined (Figs 1-6). Varnish coatings have been prepared from BMF and PUR-izo, differing with the type and the content (3-10 weight %) of the oligourethane modifiers. The effects of these two factors on the functional properties of coatings have been determined. It has been stated that the coatings showed very good adhesion to the substrate, high impact strength and their elasticity and hardness were much better than of unmodified BMF resin (Table 3). There was also found the cured BMF-PUR-izo compositions showed good thermal stability (Table 4) and excellent chemical resistance.

Regulating the Properties of ED-20 Epoxy Resin with Urethane Oligomers

Regulating the Properties of ED-20 Epoxy Resin with Urethane Oligomers

MODIFICATION OF WET BLUE LEATHER SURFACE BY PHOTO-CURING WITH URETHANE ACRYLATE CONTAINING DYE

ABSTRACT Wet blue leather was coated with a number of formulated solutions that contained urethane oligomer, acrylated monomers and dye. The coating was cured under UV radiation. Various rheological properties such as hardness, adhesion, tensile properties, water absorption, and gloss were studied. The effect of simulated weathering on these properties was also investigated. The treated leather gained enhanced tensile strength by 70% and elongation by 95%. The adhesion of the coating on leather was high (2.3 N/mm2) and the gloss was 75% with minimum abrasion. Water absorption was less than 4% by the coated leather surface. Polymer films were also prepared with the formulated solutions under the UV radiation. These films were characterized.

Low-temperature pyrolysis products from a polyether-based urethane

The pyrolysis products from a polyether-based polyurethane were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), direct probe chemical ionization mass spectrometry (CI-MS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Pyrolysis of the urethane was found to ensue about 250°C in inert atmosphere. The initial degradation products (∼250–275°C) may be explained by three decomposition pathways. Dissociation to isocyanate and alcohol yields as pyrolyzates diphenylmethane diisocyanate, an ‘amine–isocyanate’, 1,4-butanediol, and hydroxyl-terminated polyurethane and polyether oligomers. Dissociation to amine, olefin, and carbon dioxide is less prevalent initially; this produces an amine-isocyanate, methylene dianiline, and butenyl-terminated polyurethane and polyether oligomers. ‘Intramolecular exchange’ produces cyclic urethane oligomers. At about 300°C, more oligomeric pyrolyzates are observed with aromatic amine and/or butenyl end groups. These indicate that contributions from dissociation to amine, olefin, and carbon dioxide increase with increasing degradation temperature. Also at about 300°C, some oligomeric pyrolyzates are observed that have alkyl and/or aldehyde end groups. These are formed via free radical processes. By 325°C, all nitrogen-containing oligomeric pyrolyzates have decomposed. The remaining nitrogen is in the form of methylene dianiline (MDA) or methylated MDA.

Effect on the toughness and adhesion properties of epoxy resin modified with silyl-crosslinked urethane microsphere

In order to give a toughness and improve adhesion properties of the cured epoxy system, modified epoxy resins, which have pre-reacted urethane microspheres formed using dynamic vulcanization method in liquid diglycidylether of bisphenol A, were prepared. It was found that the size of the particles decreased to sub-micro order with increase in solubility of urethane oligomers in epoxy resin, and coefficient of variance in the particle size distribution resulted in less than 15%. Fracture energy G 1c of the cured system was highly improved. Lap shear strength and peel strength were also improved. These mechanical and adhesion properties do not depend on any curing condition of epoxy resin because of the existing stable particles in the epoxy resin before curing.

Study on the synthesis of urethane oligomers as intermediate products for the production of linear polyurethanes

On the basis of kinetic scheme for step-growth polyaddition, a method was developed for the synthesis of urethane oligomers and linear polyurethanes with isocyanate and hydroxyl end groups arranged alternately 2,4-TDI, 2,6-TDI and 1,4-butanediol were used as the feedstock materials and the polymerisation process was carried out in a tetrahydrofuran solution at constant concentration. Complex mixtures of diisocyanate and hydroxyl compounds were obtained, which were then utilised as parent materials at further stages of the process. The mixtures of urethane oligomers were produced where the molecular weights were gradually higher and the molecular weight distribution was wider and wider. However, the chemical composition was pre-defined as resulted from the reaction stoichiometry. The products were subjected to structural investigation. The following analytical procedures were especially useful in the analysis of the linear polyurethanes obtained: gel-permeation chromatography and mass spectroscopy, which employed gentle excitation due to electro-spraying. These methods made it possible to identify oligomers, which were formed at the successive stages of step-growth polyaddition. The findings made a basis for the discussion of the technological aspects of the polymerisation method developed.

Badania nad synteza oligomerycznych prepolimerow uretanowych jako polproduktow do otrzymywania poliuretanow

Badania nad synteza oligomerycznych prepolimerow uretanowych jako polproduktow do otrzymywania poliuretanow

Cure of secondary carbamate groups by melamine-formaldehyde resins

Melamine-formaldehyde (MF) resins have been used as crosslinkers for hydroxyl-functional coreactants in thermoset coatings for about 60 years. Crosslink densities of films prepared from oligomeric urethane polyols suggested that the methoxymethyl groups of MF resins could react with urethane groups (i.e., secondary carbamate groups) as well as reacting with hydroxyl groups. Co-reactants that contain secondary carbamate groups and no hydroxyl groups have been prepared with several types of backbone structures. Cure of such co-reactants by MF resins has been studied using a gradient oven with determination of impact resistance, solvent resistance, and hardness. Several formulations from these cure profile sets have been selected for crosslink density determinations by dynamic mechanical analysis (DMA). Crosslink densities of cured films are consistent with complete conversion of secondary carbamate groups at temperatures only slightly higher than those used for cure of hydroxyl groups. The -OH groups on certain acrylic polyols were converted to secondary carbamate groups. The original acrylic and the converted acrylic were both cured with MF resins. Acid resistance was much better for films prepared from the acrylic that contained secondary carbamate groups.