Carboxylated polyester preparation

Metal specimens coated with the various blends were immersed in water in an accelerated test to determine the effect of high humidity. Cellulose acetate butyrate blends containing carboxylated polyesters prepared with hexahydroterephthalic acid [H(NPG), T50H(NPG)] were particularly susceptible to moisture and failed the adhesion test after immersion for only 0.5 hour similar blends containing T50I(NPG) extended with dianhydride Via or with PMDA passed the adhesion test after immersion for 16 hours. When coatings on cold-rolled steel of cellulose acetate butyrate (EAB-381-0.5) blends containing 1% of each of the... 

Consider a polyester prepared the polycondensation of a hydroxy acid. From the structure of the polymer it is known that this polyester has a carboxyl group for each molecule and when titrated one mole of sodium hydroxide is used per mole of polyester. To calculate the Molecular weight of the polyester, we have only to calculate how much polyester (in grams) gets neutralised by... 

Duh, B., Method for production of a high molecular weight polyester prepared from a prepolymer polyester having an optimal carboxyl content, US Patent 4 238 593, 1980. 

Carboxylated polyesters were prepared by extending hydroxyl-terminated polyester segments with dianhydrides. Carboxylated polyesters which were soluble in common lacquer solvents were effective in improving the adhesion of coatings on a variety of substrates when 1-10% was blended with cellulose acetate butyrate, poly(vinyl chloride), poly(methyl methacrylate), polystyrene, bisphenol polycarbonates, and other soluble polymers. 

Incorporation of carboxyl groups in vinyl polymers (J) and polyolefins (1, 7) improves the adhesion of these polymers to various materials. However, many of these carboxylated polymers, particularly the carboxylated polyolefins, have limited solubility in volatile, lacquer-type solvents such as butyl acetate or methyl ethyl ketone and thus are limited in their ability to improve the adhesion of coatings applied from solvents. Carboxylated polyesters that are soluble in these solvents can be prepared. We were therefore interested in determining the effects of structure and carboxyl content on the adhesion of coatings of various classes of polymers blended with carboxylated polyesters. 

Preparation of Carboxylated Polyesters. Hydroxyl-terminated polyester segments were prepared by conventional procedures and extended with an equimolar amount of dianhydride (2). To avoid the possibility of crosslintdng the polymer, reaction1 with the dianhydride was carried out at 175 °C. Depending upon the size of the reaction mixture, about 1 to 3 hours were required for all of the dianhydride to react and for a medium-to-high melt viscosity to be obtained. Inherent viscosities were 0.3 to 0.4. 

The carboxylated polyesters were prepared by a two-step process (1) preparation of a hydroxyl-terminated polyester segment and (2) reaction with a dianhydride to extend the polyester and introduce carboxyl groups. When the dianhydride is pyromellitic (II), the equation is as follows ... 

Linear polyesters prepared by direct esterification of carboxyl groups with hydroxyl groups can be derived from one compound, viz. 

Similar ACECs (Scheme 47) were prepared in a different way [28]. The carboxylic polyesters were prepared by polycondensation of 4-cyclohexene-1,2-di-carboxylic acid anhydride with a glycol. Then the glycidylation of COOH groups with ECH followed by ep oxidation of cyclohexene rings with PA A was carried out. Depending on the COOH groups content in the intermediate polyester, various glycidyl/epoxycyclohexane ratios can be obtained. 

Fig. 13. Chevron texture with typical transition bars observed upon cooling from the nematic state for polyester prepared from di-n-propyl-p-terphenyl-, carboxylate and tetrame-thylene glycol. Crossed polarizers. From ref. 20.

Poly((3-malic acid) is the most simple carboxylated polyester [47-49]. It is prepared by ring opening polymerization of the mono-benzyl ester (3-lactone of malic acid and subsequent debenzylation. It has been explored as drug carrier. Reaction of itaconic anhydride with PCL with hydroxy terminals results in polyesters with carboxylic and C=C double bond functional terminals, suitable for further reactions to form networks and gels, (5) and (6) [50,51]. 

A novel poiyesterification procedure avoiding the need for pre-activated carboxylic acid was recently reported by Moore and Stupp [429]. This method reacts phenolic groups directly with carboxylic acids in solution and under mild conditions. It requires the use of carbodiimide dehydrating agent [431,432] and a novel catalyst which is a 1 1 molecular complex formed by 4-(dimethylamino) pyridine and p-toluenesulfonic acid [429], Under these conditions, linear polyesters with molecular weights in excess of IS 000 were obtained [429], but the molecular weights of exclusively aromatic polyesters prepared by this method may be lower. 

Transitions with the participation of liquid crystals sometimes show characteristic phenomena. If a nematic modification turns to a smectic A or smectic C phase, transient stripes in the form of a myelinic texture (also called chevron texture or striated texture) are often visible. Typically for the polyester prepared from di-w-propyl-/ -terphenyl-4,4" carboxylate and tetramethylene glycol, the nematic phase separates from the isotropic liquid on cooling in droplets which coalesce and form large domains. Cooling of the threaded-schlieren texture produces a transition to the smectic A phase this change is characterized by transition phenomena, mostly stripes, which broaden into larger areas ( transition bars ). 

Fig. 2.26. Paramorphotic arced focal-conic fan texture observed upon cooling from the smectic A state (cf Fig. 2.22) for the polyester prepared from di-n-propyl-p-terphenyl-4,4"-carboxylate and HO—CH(CH3)—CH(CH3)—OH.

The carboxylic acid produced m the greatest amounts is 1 4 benzenedicarboxylic acid (terephthahc acid) About 5 X 10 Ib/year is produced m the United States as a starting material for the preparation of polyester fibers One important process converts p xylene to terephthahc acid by oxidation with nitric acid... 

Carboxylic acid hydiazides are prepared from aqueous hydrazine and tfie carboxylic acid, ester, amide, anhydride, or halide. The reaction usually goes poody with the free acid. Esters are generally satisfactory. Acyl halides are particularly reactive, even at room temperature, and form the diacyl derivatives (22), which easily undergo thermal dehydration to 1,3,4-oxadiazoles (23). Diesters give dihydtazides (24) and polyesters such as polyacrylates yield a polyhydrazide (25). The chemistry of carboxyhc hydrazides has been reviewed (83,84). 

PET is the polyester of terephthalic acid and ethylene glycol. Polyesters are prepared by either direct esterification or transesterification reactions. In the direct esterification process, terephthalic acid is reacted with ethylene glycol to produce PET and water as a by-product. Transesterification involves the reaction of dimethyl terephthalate (DMT) with ethylene glycol in the presence of a catalyst (usually a metal carboxylate) to form bis(hydroxyethyl)terephthalate (BHET) and methyl alcohol as a by-product. In the second step of transesterification, BHET... 

As a first step in the prepartion of polymers patterned after the repeating unit of nonactin 56, Moore and Kelley53 synthesized 3,8-dioxabicyclo[3.2.1 ]octan-2-one 57 and its corresponding polyester 58. The monomer was prepared from 5-hydroxy-methylpyran-2-carboxylic acid in overall yield of 20%. It was heated with a catalytic amount of tert-butoxytitanate under nitrogen for 3 hr at 100 °C. The temperature... 

In the first part of this activity, you will prepare a polyester. As the name polyester implies, this polymer contains many ester functional groups. One technique for preparing an ester is by the reaction of a carboxylic acid with an alcohol. RCOOH + R OH —> RCOOR + H20... 

Those polyester FBAs containing a benzoxazole group are usually prepared from the appropriate o-aminophenol and carboxylic acid (11.45 Y = OH) or one of its derivatives, as shown in Scheme 11.10. The reaction proceeds via an intermediate amide and it can be advantageous to start from an acid derivative such as the acid chloride (11.45 Y = Cl) or ester (11.45 Y = OEt), which are both more effective acylating agents. The preparation of compound 11.36, shown in Scheme 11.11, illustrates this process, but the optimum conditions for ring closure vary considerably from one structure to another. The article by Gold contains a valuable and detailed summary [4]. 

If the dicarboxylic acid has been present in excess in the reaction mixture, then the resulting polyester uses up more sodium hydroxide for the same Molecular weight of the polyester which has been prepared by the complete equivalencies of the monomers. If the amount of dicarboxylic acid during the synthesis of the ester is very high and if all the molecules of the polymers contain carboxyl groups at both ends, then the consumption of sodium Organisation and Qualities... 

The hydrogenation of HMF in the presence of metal catalysts (Raney nickel, supported platinum metals, copper chromite) leads to quantitative amounts of 2,5-bis(hydroxymethyl)furan used in the manufacture of polyurethanes, or 2,5-bis(hydroxymethyl)tetrahydrofuran that can be used in the preparation of polyesters [30]. The oxidation of HMF is used to prepare 5-formylfuran-2-carboxylic acid, and furan-2,5-dicarboxylic acid (a potential substitute of terephthalic acid). Oxidation by air on platinum catalysts leads quantitatively to the diacid. [32], The oxidation of HMF to dialdehyde was achieved at 90 °C with air as oxidizing in the presence of V205/Ti02 catalysts with a selectivity up to 95% at 90% conversion [33]. 

Unsaturated polyesters are prepared through a classical esterification process. Typically, a dihydroxy compound, or mixtures of dihydroxy compounds, are treated with maleic anhydride and/or together with other dicarboxylic acids such as aromatic or aliphatic dicarboxylic acids under elevated temperature to remove the water produced during esterification process. Although various catalysts will catalyze this esterification reaction, there is enough carboxylic acid in the mixture so that it is not necessary to add extra catalyst. 

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