POLYESTER-MODIFIED SYSTEMS

In the late 1960s, Nutt developed an unsaturated polyester-modified systemP lt2i] called Estercrete. In the preparation of this system, unsaturated polyester resin dissolved in styrene is mixed with portland cement at a polymer-cement ratio higher than 30%, together with a water-soluble redox catalyst. Table 7.3 ° gives the typical formulations of Estercrete. 

The resin can be produced using a wide range of polycarboxylic acids and polyhydric alcohol by polycondensation. Immediately before use, it is mixed with aggregates and water. When the catalyst is activated by the addition of the water, polymerization and cement hydration occur simultaneously. The optimum water-cement ratio is about 22%. The aggregate content can be selected depending on the application. 

1-day-20 C-moist (in molds) plus 13-day-20°C- water cure ------ 20°C-dry cure to desired age 

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Ionic polymers are also formulated from TDI and MDI (43). Poly(urethane urea) and polyurea ionomers are obtained from divalent metal salts of /)-aminohen2oic acid, MPA, dialkylene glycol, and 2,4-TDI (44). In the case of polyureas, the glycol extender is omitted. If TDI is used in coatings apphcations, it is usually converted to a derivative to lower the vapor pressure. A typical TDI prepolymer is the adduct of TDI with trimethyl olpropane (Desmodur L). Carbodiimide-modified MDI offers advantages in polyester-based systems because of improved hydrolytic stabihty (45). Moisture cure systems based on aromatic isocyanates are also available. 

P.R.122 baked 5% in full shade in polyester-modified silicone resin system 60 min, 200°C 60 min, 300°C 245xlO"10m 295xlO-10m... 

Use For polyester modifiers, fast cure processes, and pigmentable systems. 

Similar systems have also been examined by Dikeou, Steinberg, et al.,122] Sarny Abdel Monem El-Garf,(2 l Birkimer and Lindeman,(251 and Ye and Wu.(2 l Figure 7.9 represents the effects of curing conditions on the strength development of polyester-modified mortars. 

Chem. Descrip. PTFE-modified polyethylene wax Uses Surf, modifier, slip agent, abrasion resist, aid, mar resist, aid for wood finishes, UV-cured coatings, can and coil coatings, powd. and industrial coatings based on acrylics, alkyds, PU, NC and blends, epoxies, polyesters, hybrid systems... 

Elastomer-Modified Unsaturated Polyester Resin Systems... 

C.C. Yau, and C. Cherry, Polyesters modified with 1,4-cyclohexanedimethanol having high clarity prepared utilizing an antimony containing catalyst/stabilizer system, US Patent 5608031, assigned to Eastman Chem. Co., March 4,1997. 

In addition to these systems, polyesters modified with silicone are important binders for coatings with excellent weather resistance and mechanical properties coupled with improved heat resistance. 

Azoic dyes and pigment-binder systems have also found limited use on polyesters. Polyester modified with appropriate comonomeis can be (fyed at lower temperatures or with acid or basic dyes depending on the nature of the modifying groups. 

PAs have also been copolymerized with other polymer systems and, in particular", with polyesters and poly ethers. In the copoly esteramides the crystallinity is decreased by copolymerization, as the crystalline structure of the amide unit is very different from the ester unit. However, alternating polyesteramides behave as homopolymers with a glass ttansition temperature and a melting temperature intermediate to the polyester and the PA polymer (Figs. 3.10 and 3.11).23,24 Polyesters, such as PBT and PET, modified with a small amount of diamide are also copolymers that have a high order.24,73... 

Siloxane containing interpenetrating networks (IPN) have also been synthesized and some properties were reported 59,354 356>. However, they have not received much attention. Preparation and characterization of IPNs based on PDMS-polystyrene 354), PDMS-poly(methyl methacrylate) 354), polysiloxane-epoxy systems 355) and PDMS-polyurethane 356) were described. These materials all displayed two-phase morphologies, but only minor improvements were obtained over the physical and mechanical properties of the parent materials. This may be due to the difficulties encountered in controlling the structure and morphology of these IPN systems. Siloxane modified polyamide, polyester, polyolefin and various polyurethane based IPN materials are commercially available 59). Incorporation of siloxanes into these systems was reported to increase the hydrolytic stability, surface release, electrical properties of the base polymers and also to reduce the surface wear and friction due to the lubricating action of PDMS chains 59). 

Composite Particles, Inc. reported the use of surface-modified rubber particles in formulations of thermoset systems, such as polyurethanes, polysulfides, and epoxies [95], The surface of the mbber was oxidized by a proprietary gas atmosphere, which leads to the formation of polar functional groups like —COOH and —OH, which in turn enhanced the dispersibility and bonding characteristics of mbber particles to other polar polymers. A composite containing 15% treated mbber particles per 85% polyurethane has physical properties similar to those of the pure polyurethane. Inclusion of surface-modified waste mbber in polyurethane matrix increases the coefficient of friction. This finds application in polyurethane tires and shoe soles. The treated mbber particles enhance the flexibility and impact resistance of polyester-based constmction materials [95]. Inclusion of treated waste mbber along with carboxyl terminated nitrile mbber (CTBN) in epoxy formulations increases the fracture toughness of the epoxy resins [96]. 

Block copolymers were synthesized by a combination of fipase-catalyzed polymerization and atom transfer radical polymerization (ATRE). " " At first, the polymerization of 10-hydroxydecanoic acid was carried out by using lipase CA as catalyst. The terminal hydroxy group was modified by the reaction with a-bromopropionyl bromide, followed by ATRP of styrene using CuCE2,2 -bipyridine as catalyst system to give the polyester-polystyrene block copolymer. Trichloromethyl-terminated poly(e-CL), which was synthesized by lipase CA-catalyzed polymerization with 2,2,2-trichloroethanol initiator, was used as initiator for ATRP of styrene. 

Improve both impact strength and rigidity of thermoplastics by using up the energy of crack propagation. Elastomers are prototypical toughening additives. Examples of high-polymeric impact modifier/thermoplastic matrix systems are EVA, CPE and MBS in PVC, EP(D)M and SBS in PA, and acrylic rubbers in polyesters. 

Another specialty area is coil coating, which involves coating metal coils by continuous operation. Modern roller systems afford speeds of up to 200 m/min. Most coils are made of cold-rolled and surface treated steel, aluminum, or alloys of the latter with manganese or magnesium. Coating systems are based on alkyd or acrylic resins, oil-free polyester, silicone-modified polyester or acrylic resin, poly(vinylidene fluoride), or poly(vinyl fluoride). Water-reducible systems, mainly based on acrylic resins, have been developed for aluminum as well as for steel coils [21-24], Drying is carried out by continuous operation in gas- or oil-heated multichamber ovens. 

D. Schmaljohan, B.I. Voit, J.F.G.A. Jansen, P. Hendrdriks, J.A. Loontjens, New Coating Systems Based on Vinyl Ether- and Oxetane-modified Hyperbranched Polyester, Macromol. Mater. Eng. 275,31-41 (2000)... 

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