Polyurethane aromatic polyester

Aromatic Polyester Polyurethane. The hindered-amine light stabilizer (LS-1) or a 1 1 blend of LS-1 and LS-2 provided about five to six times better performance than the best UV absorber (LS-2) alone in... 

Chem. Descrip. Waterborne aromatic polyester polyurethane polymer Uses Urethane for plastic, concrete, and paper coatings Features Med. hard polymer... 

Chem. Descrip. Waterborne aromatic polyester polyurethane polymer Uses Urethane for specialty coatings, adhesives, sealants Features Heat reactivatible exc. adhesion to many substrates Properties Opaque dens. 8.8 Ib/gal vise. 1500 cps pH 8.5 tens. str. 4550 psi elong. 550% (break) hardness (Sward) 27 VOC 306 g/l 35% solids 11.3% NMP Sancure 2019 [Noveon]... 

Polyester Polyols. Initially polyester polyols were the preferred raw materials for polyurethanes, but in the 1990s the less expensive polyether polyols dominate the polyurethane market. Inexpensive aromatic polyester polyols have been introduced for rigid foam appHcations. These are obtained from residues of terephthaHc acid production or by transesterification of dimethyl terephthalate (DMT) or poly(ethylene terephthalate) (PET) scrap with glycols. 

Linear polyurethanes, 26 Linear step-growth polymerizations, 13 Lipase-catalyzed polyesterifications, 83 Lipases, 82, 84 catalytic site of, 84 Liquefied MDIs, 211, 226-227 Liquid carbon dioxide, 206 Liquid-castable systems, 201 Liquid crystal devices (LCDs), alignment coating for, 269-270 Liquid crystalline aromatic polyesters, 35 Liquid crystalline polyesters, 25, 26, 48-53... 

The nature of the hard domains differs for the various block copolymers. The amorphous polystyrene blocks in the ABA block copolymers are hard because the glass transition temperature (100°C) is considerably above ambient temperature, i.e., the polystyrene blocks are in the glassy state. However, there is some controversy about the nature of the hard domains in the various multiblock copolymers. The polyurethane blocks in the polyester-polyurethane and polyether-polyurethane copolymers have a glass transition temperature above ambient temperature but also derive their hard behavior from hydrogen-bonding and low levels of crystallinity. The aromatic polyester (usually terephthalate) blocks in the polyether-polyester multiblock copolymer appear to derive their hardness entirely from crystallinity. 

We report here that polyethylene adipate (PEA) and polycaprolactone (PCL) were degraded by Penicillium spp., and aliphatic and alicyclic polyesters,ester type polyurethanes, copolyesters composed of aliphatic and aromatic polyester (CPE) and copolyamide-esters (CPAE) were hydrolyzed by several lipases and an esterase. Concerning these water-insoluble condensation polymers, we noted that the melting points (Tm) had a effect on biodegradability. 

Some polymers show discoloration as well as reduction of the mechanical properties (e.g. aromatic polyesters, aromatic polyamides, polycarbonate, polyurethanes, poly (phenylene oxide, polysulphone), others show only a deterioration of the mechanical properties (polypropylene, cotton) or mainly yellowing (wool, poly(vinyl chloride)). This degradation may be less pronounced when an ultraviolet absorber is incorporated into the polymer. The role of the UV-absorbers (usually o-hydroxybenzophenones or o-hydroxyphenylbenzotriazoles) is to absorb the radiation in the 300-400 nm region and dissipate the energy in a manner harmless to the material to be protected. UV-protection of polymers can be well achieved by the use of additives (e.g. nickel chelates) that, by a transfer of excitation energy, are capable of quenching electronically excited states of impurities (e.g. carbonyl groups) present in the polymer (e.g. polypropylene). 

The chemical participation of lignin macromonomers in polymerization or copolymerization reactions has been focussed mostly on the reactivity of both types of OH groups, and hence in the synthesis of polyesters, polyurethanes and polyethers, although some research has also dealt with their intervention through the unsubstituted aromatic sites in different formaldehyde-based resins in partial replacement of phenol [58, 59]. 

Mannich polyols, aromatic polyester polyols, novolak-based polyols) lead, by the reaction with crude MDI, to very rigid polyurethane structures [2] (see Chapter 15). 

The most important oligo-polyols for rigid polyurethanes are polyether polyols and aromatic polyester polyols [1-4, 6]. The aromatic polyether polyols, based on condensates of aromatic compounds with aldehydes, become very important polyols, especially after the introduction of new blowing agents (see Chapter 21). 

From low MW oligo-polyols (400-1000 daltons polyethers, polyesters, Mannich polyols, aromatic polyesters, oleochemical polyols, etc.), are obtained rigid, hard polyurethane structures (rigid PU foams, wood substitutes, etc). 

Selected chemolysis processes for PET are illustrated in Figure 9.8 and tabulated in Table 9.6. These reactions yield either the original monomers or products that can be converted to other monomers. Hydrolysis can be effectively used with PET and polyurethane waste plastics in feedstock recovery (Zia et al., 2007). Reaction conditions employed are varied and these selected references do not cover them exhaustively. Aromatic polyesters, PET and poly(butylene terephthalate), have been studied intensively for feedstock recovery. PET is extensively used in soda bottles and less than 30% of the product is mechanically recycled. 

Polyurethane-modified polyisocyanurate (PIR) foams have a reputation for being the most flame resistant of the PU related foams used for insulation. They are increasingly being made from an aromatic polyester polyol (APP) and the isocyanate is most often MDI. Unlike pol5mrethanes, however, the amount of MDI is comparatively high. Isoeyanate indices of 250 or higher are used... 

As already mentioned, photolytic decomposition is not a major problem with urethane adhesives. However, thermal oxidation should be considered when the durability of polyurethane bonds is of concern. Aromatic isocyanates are typically more resistant towards this type of oxidation than are aliphatic isocyanates. XDI or HMDI polyester polyurethanes are reported to lose 60-70% of their initial tensile strength after 23 days at 80 C. Similar materials derived from TDI or MDI actually gain 30-40% of their tensile strength after this time. This increase is most likely due to an increase in crosslink density. 

As already mentioned, the hydrolytic stability of polyurethanes is influenced by the nature of the macroglycol used in their preparation. Polyesters prepared from sterically hindered glycols, such as neopentyl glycol (18), and a long-chain diacid, or aromatic diacid, for example, terphthalic acid (19), will maximize moisture stability. Polyester polyols have been developed which are claimed to be similar in hydrolytic stability to PTMO polyurethanes. Increasing the crosslink density in polyester polyurethanes has been shown to improve hydrolytic stability as well however, this may not always be a viable solution, since the crosslink density can have a profound influence on other properties of the polymers as already described. 

The polyols used include PO adducts of polyfiinctional hydroxy compoimds or amines (see Table 4). The amine-derived polyols are used in spray foam formulations where high reaction rates are required. Crude aromatic polyester diols are often used in combination with the multifunctional polyether polyols. Blending of polyols of different functionality, molecular weight, and reactivity is used to tailor a polyol for a speciflc application. The high functionality of the polyether polyols combined with the higher functionality of PMDI contributes to the rapid network formation required for rigid polyurethane foams. 

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