Polyurethane Acrylate-based

The potential of using extrinsic (fluorescent) probes for monitoring the initial stages of oxidation was explored for the photo-oxidation of a UV-cured aliphatic polyurethane-acrylate-based adhesive [68]. The two probes investigated were p-dimethylamino salicylic acid (p-DASA) and 2, 7 -difluorescein (Oregon Green... 

The non-isothermal analysis was undertaken for nonirradiated sample of the polyurethane-acrylate-based adhesive. And from the Arrhenius plot of the CL intensity over the temperature range 60-150°C, the activation energy for CL emission was determined to be 85 kJ mol-1. 

TABLE 3.8 Kinetic Data of Chemiluminescence from the UV-Cured Aliphatic Polyurethane-Acrylate-Based Adhesive L350, at 100°C Under Nitrogen, After UV Irradiation... 

To analyze the oxidation level of the adhesive by fluorescence, the fluorescence of the two probes as a function of the CL-parameters, maximum intensity, and decay rate, for the polyurethane-acrylate-based adhesive, were plotted (Fig. 3.8). Quenching of fluorescence followed the same kinetics as the chemiluminescence increase during UV-exposure. The two fluorescent probes used were sensitive to the formation of oxidation products. Therefore, in this work, good correlations between fluorescence and chemiluminescence were established, which allow monitoring photodegradation by using extrinsic emission fluorescent probes and/or CL emission from bulk material. 

CL has been employed to study the mechanism of degradation in polymers such as UV-cured aliphatic polyurethane-acrylate-based adhesives. In styrenic block copolymers, SEBS, the order of the reaction was determined, and the efficiency of antioxidants was evaluated. Also, the relationship between thermooxidation of SEBS and morphology was established, indicating that for these copolymers the oxidation started in the interfacial region. 

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

Reaction-induced phase separation is certainly also the reason for which an inhomogeneous structure is observed for photocured polyurethane acrylate networks based on polypropylene oxide (Barbeau et al., 1999). TEM analysis demonstrates the presence of inhomogeneities on the length scale of 10-200 nm, mostly constituted by clusters of small hard units (the diacrylated diisocyanate) connected by polyacrylate chains. In addition, a suborganization of the reacted diisocyanate hard segments inside the polyurethane acrylate matrix is revealed by SAXS measurements. Post-reaction increases the crosslink density inside the hard domains. The bimodal shape of the dynamic mechanical relaxation spectra corroborates the presence of a two-phase structure. 

Carboline 133HB (a polyurethane-based paint), Macro Epoxy 646 (an epoxy-based paint) and Devflex 4206 (an acrylic-based paint). All these samples contain Ti02 as a pigment. The lines in the figure are fit according to the equation [29, 34] ... 

Since the introduction of the first commercial thermoset, Bakelite, based on phenol formaldehyde condensation, a wide range of thermoset materials have been introduced. These are typically designed for specific properties related to their chemistry and processability. Some commercially important thermosets include phenolics, ureas, melamines, epoxy resins, unsaturated polyesters, silicones, rubbers, polyurethanes, acrylics, cyanates, polyimides, and benzocyclobutenes. ... 

Cracks of this and larger dimensions are readily sealed with polyurethane grouts, which provide greater resistance to extrusion than the acrylic-based materials. 

More modem systems include polyurethane and acrylic-based adhesives and twopart curing adhesives are gaining popularity. 

The most common conformal coatings are derived from polyurethanes, acrylics, and epoxies the more special formulations for high-temperature performance are based on silicones, diallyl-phthalate esters, and polyimides. An example of a vapor deposited conformal coating is Parylene. It is obtained by vapor deposition of p-xylylene, which is formed as a transient by dehydrogenation of p-xylene at high temperature, and polymerization on the surface of the object to be coated. Because p-xylylene monomer is not stable, it is advantageous to work with the cyclic dimer, di-p-xylylene (paracyclophane), which, upon heating under reduced pressure, will produce the transient monomer which converts to the polymer at low temperatures. 

Unsaturated resins are usually mixtures of vinyl monomers and prepolymers, such as unsaturated polyesters, polyurethane acrylates, and ac-rylated epoxides of the bisphenol A type. Polymerization of styrene-based resins involves the formation of a three-dimensional network via the cross-linking of prepolymer chains by styrene radicals. These standard thermoset resins are therefore characterized by great hardness (Shore D over 80, DIN 53505, arbitrary scale 0-100 based on the penetration of a needle point in the tested material), do not melt, and are not soluble in organic solvents. 

Pigmented, two-pack, waterborne epoxy resin coatings (garages) or one-pack waterborne acrylic resin emulsion paints are used for areas that receive less wear (e.g., cellars). Wooden parquet floors are coated with one- or two-pack polyurethane varnishes that can be applied by spraying or brushing. Acrylate-based waterborne parquet varnishes are also used because they are environmentally friendly. 

Photosensitive adhesive formulations based on acrylates, epoxy acrylates, and polyurethane acrylics may be cured by exposure to ultraviolet or visible light. The key... 

Apart from underbody coating (usually PVC based), which is not explained further, the majority of bonding and sealing products in the paint shop are also PVC compounds. Acrylate plastisols are not often used and polyurethane-based sealants are rarely found. The main applications are in seam sealing and antiflutter bonding. On a small scale there are adhesive applications to bond and seal caps and to fix sound deadeners. In addition, foams and butyls as well as bituminous or acrylic-based sealants are used to fill car body holes. 

Uses Defoamer for water-based systems Ind. polyurethane, acrylate/ polyurethane paints, wood varnishes, furniture paints, pigmented dispersion paints, plastic coatings, inks Properties Colorless to yel. liq. ether-like odor sp.gr. 1.01 g/cc dens. 8.40 Ib/gal flash pt. (Seta) > 100 C ret. index 1.448 > 96% NV Toxicology TSCA fisted... 

Chem. Descrip. Polysiloxane mixt. in dipropylene glycol methyl ether Uses Defoamer for water-based systems ind. polyurethane, acrylate/ polyurethane paints, wood varnishes, furniture varnishes, plastic coatings... 

To date, MIP microstructures have been successfully fabricated with dimethyl-formamide (DMF) as a solvent in both an acrylate-based [55] and a polyurethane based [59] imprinting system. While this solvent still swells PDMS, its effect is small. Other imprinting systems that utilize water and alcohols as the solvent may be possible since these solvents do not swell the PDMS stamps. Alcohols are the best as they have alow surface tension and wet the surface of the PDMS well. Water, however, has a high surface tension and does not wet the surface of the hydrophobic PDMS stamps. Possible solutions may be to render the stamp more hydrophilic by O2 plasma or UY irradiation to add a small percentage of alcohol ( 5 %) to the aqueous solution to wet the surface, or to use a small vacuum-assisted pump to fill the channels. 

Paint consists of a mixture of pigments which gives body and colour, and a resin or binder which is the actual film-forming component and acts as a glue to hold the pigment together and stick them to the surface. Binders include synthetic resins such as acrylics, polyurethanes, polyesters and epoxies and can be a combination of resins, e.g. epoxy/ acrylic and polyurethane/acrylic. To adjust the curing properties and reduce the viscosity so that the paint can be easily applied, a solvent or carrier is used. These evaporate after application and do not form part of the paint film. In waterborne paints, the carrier is water. With solvent-borne paints, also called oil-based paints, the carrier is a solvent such as acetone, turpentine, naphtha, toluene, xylene and white spirit. 

These two-pack cold-cure solvent-borne coatings have excellent durability and abrasion resistance. They are designed for spray applications on steel, aluminium and light alloy surfaces wMch have been suitably pretreated. Base and hardener are mixed in 3 1 or 5 1 ratios as recommended by the manufacturer and the pot life is around 2 hours under normal working conditions (20 C) and should not be used after the stated time. Polyurethane/acrylic resin combination is also available. Two-pack polyurethanes are widely used in veMcle body repair and can contain isocyanate which is a basic constituent in the production of polyurethane and is the most common cause of industrial asthma and it is also a skin irritant. It should be easily identified by a label on the container which should say contains isocyanates, harmful by inhalation and in contact with skin . Waterborne two-pack polyurethane finishes are available. 

The use of adhesives/sealants in both the industrial and consumer spheres has increased dramatically in the past 20 years. In the industrial segment, both reactive and nonreactive systems are used in a wide variety of applications. The increasing use of reactive systems has, however, tended to overshadow that of the nonreactive systems. Most prominent amongst the reactive systems favored in industrial applications are anaerobic sealants (methacrylate ester based), instant adhesives (alkyl cyanoacrylate ester based), acrylic (toughened) adhesives, epoxy resin adhesives, polyurethane/isocyanate-based adhesives, silicone adhesives/sealants, and phenolic resin adhesives. 

There is some interest in water dispersible light curable coatings and binders. Thus, Heischkel et al, reported preparation of a water based radiation curable polyurethane acrylate coating. Some of the water soluble or dispersible monomers are diethylaminoethyl acrylate, butanediol monoacrylate, vinyl caparolactam, and propylene glycol monoacrylate. 

Uses. Acrylics, both lacquers and enamels, were the topcoats of choice for the automotive industry from the early 1960s to the middle 1980s. Thermosetting acrylics are still used by the major appliance industry. Acrylics are used in electrodeposition and have largely replaced alkyds. The chemistry of acrylic-based resins allows them to be used in radiation curing applications alone or as monomeric modifiers for other resins. Acrylic-modified polyurethane coatings have excellent exterior durability. 

Zhou SX, Wu LM, Sun J, Shen WD (2000) The change of the properties of acrylic-based polyurethane via addition of nano-silica. Prog Org Coat 45 33-42... 

Acrylate resins, based on the conventional thermoplastic resins, into which two or more reactive acrylate or methacrylate groups have been introduced, are called prepolymers. The most commonly used prepolymers are acrylated epoxy resins, acrylated polyurethanes, acrylated polyesters and acrylated polyethers. 

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