Polyurethane-acrylic blends

Over the years many blends of polyurethanes with other polymers have been prepared. One recent example is the blending of polyurethane intermediates with methyl methacrylate monomer and some unsaturated polyester resin. With a suitable balance of catalysts and initiators, addition and rearrangement reactions occur simultaneously but independently to give interpenetrating polymer networks. The use of the acrylic monomer lowers cost and viscosity whilst blends with 20% (MMA + polyester) have a superior impact strength. 

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Figure 14.19. ATR spectra for polyurethane-acrylic blends under quick ultra violet exposure.

Figure 14.20. XPS spectra for uastabilized polyurethane-acrylic blends for zero (upper) and 43 days (lower) quick ultra...

Another area of recent interest is covulcanization in block copolymers, thermoplastic rubbers, and elasto-plastic blends by developing an interpenetrating network (IPN). A classical example for IPN formation is in polyurethane elastomer blended acrylic copolymers [7]. 

Table 10.3 Properties of polyurethane/acrylic IPNs compared with blends and homopolymers...

The major polymers with whieh PVC ean be alloyed are aerylonitrile-butadiene eopolymers, aerylonitrile-butadiene-styrene terpolymer, ethylene-vinylacetate copolymers, chlorinated polyethylene, chlorosulfonated polyethylene, thermoplastic polyurethanes, acrylics and methacrylics, and polycaprolactone. Table 18 lists the property enhancements achieved by blending these polymers with PVC. 

Newer types of high-performance paints used on ship exteriors include those based on epoxy resins, polyurethane resins, vinyl resins (also vinyl/ alkyd or vinyl/acrylic blends) or chlorinated rubber. Epoxies and polyurethanes are chemically-curing types and present curing problems at low temperatures, whilst the overcoating intervals are critical for best adhesion... 

MAA) and the resultant polymerization gave a urethane/acrylate hybrid dispersion [568]. The urethane/acrylic hybrid had markedly improved water resistance over the physical blend of the components. Polyurethane/acrylic hybrids were compared with polyurethane/acrylic waterborne blends, with increased phase mixing in the hybrids observed, resulting in improved mechanical properties [569]. 

Other blends of polycarbonate have limited markets so far. The most significant blends are with polyurethanes, polyetherimides, acrylate—styrene-acrylonitrile (ASA), acrylonitrile—ethylene—styrene (AES), and styrene—maleic anhydride (SMA). 

Acrylic Resins. The first synthetic polymer denture material, used throughout much of the 20th century, was based on the discovery of vulcanised mbber in 1839. Other polymers explored for denture and other dental uses have included ceUuloid, phenolformaldehyde resins, and vinyl chloride copolymers. Polystyrene, polycarbonates, polyurethanes, and acryHc resins have also been used for dental polymers. Because of the unique combination of properties, eg, aesthetics and ease of fabrication, acryHc resins based on methyl methacrylate and its polymer and/or copolymers have received the most attention since their introduction in 1937. However, deficiencies include excessive polymerization shrinkage and poor abrasion resistance. Polymers used in dental appHcation should have minimal dimensional changes during and subsequent to polymerization exceUent chemical, physical, and color stabiHty processabiHty and biocompatibiHty and the abiHty to blend with contiguous tissues. 

Most dyes, including sulfonated azo dyes, are nonvolatile or thermally unstable, and therefore are not amenable to GC or gas-phase ionisation processes. Therefore, GC-MS techniques cannot be used. GC-MS and TGA were applied for the identification of acrylated polyurethanes in coatings on optical fibres [295]. Although GC-MS is not suited for the analysis of polymers, the technique can be used for the study of the products of pyrolysis in air, e.g. related to smoke behaviour of CPVC/ABS and PVC/ABS blends [263],... 

Estapol, a blend of polyester/polyether resins NA, not available PBA, polybutyl acrylate PUV, polyurethane varnish PVAL, polyvinylalcohol SVF, silicone vacuum fluid fiber volume fraetion. 

PVC can be blended with numerous other polymers to give it better processability and impact resistance. For the manufacture of food contact materials the following polymerizates and/or polymer mixtures from polymers manufactured from the above mentioned starting materials can be used Chlorinated polyolefins blends of styrene and graft copolymers and mixtures of polystyrene with polymerisate blends butadiene-acrylonitrile-copolymer blends (hard rubber) blends of ethylene and propylene, butylene, vinyl ester, and unsaturated aliphatic acids as well as salts and esters plasticizerfrec blends of methacrylic acid esters and acrylic acid esters with monofunctional saturated alcohols (Ci-C18) as well as blends of the esters of methacrylic acid butadiene and styrene as well as polymer blends of acrylic acid butyl ester and vinylpyrrolidone polyurethane manufactured from 1,6-hexamethylene diisocyanate, 1.4-butandiol and aliphatic polyesters from adipic acid and glycols. 

An acrylate-terminated polyurethane modified epoxy compound and a polyethylene polyamine homologue and fatty acid combination were formulated into a two-component adhesive system. The adhesive is useful for bonding various thermoplastic resins such as ABS, PC, PBT-PC blends, and PPO.22... 

Superabsorbents. Water-swellable polymers are used extensively in consumer articles and for industrial applications. Most of these polymers are cross-linked acrylic copolymers of metal salts of acrylic acid and acrylamide or other monomers such as 2-acrylamido-2-methylpropanesulfonic acid. These hydrogel forming systems can have high gel strength as measured by the shear modulus (134). Sometimes inorganic water-insoluble powder is blended with the polymer to increase gel strength (135). Patents describe processes for making cross-linked polyurethane foams which contain superabsorbent polymers (136,137). 

Adhesives may include styrene, styrene/isoprene blends, vinyl alcohol, vinyl acetate, epoxy resins, acrylates, cyanoacrylates (superglue), ethylene/vinylacetate (hot-melt), polyurethanes, etc. [19]. 

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