Kinetics of Hydrolytic Aging of Polyester Urethane Elastomers

Brown, Daniel W.; Lowry, Robert E.; Smith, Leslie E.

doi:10.1021/ma60074a009

Cited by 85 publications

(75 citation statements)

References 3 publications

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“…The catalytic effect of carboxylic acid end-groups on ester-hydrolysis and the hydrolysis-inhibiting results of end-capping has been shown in many studies on polyester hydrolysis. [32][33][34][35][36][37] Reduced rate of chain-scission by partial ethoxylation of poly (caprolactone) was seen by Pitt and Gu in 1987 34 and improved hydrolytic stability was obtained when the amount of carboxylic end-groups was reduced in a poly(butylene terephthalate) polymer. 35 Increased hydrolysis rate of star-shaped PLA 36 was seen when the arms were functionalized with carboxylic end-groups compared to À ÀOH, À ÀCl, and À ÀNH 2 end-groups.…”

Section: Migration Of Hydrolysis Products From Pvc/pba Filmsmentioning

confidence: 99%

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Lindström

Hakkarainen

2007

J of Applied Polymer Sci

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Flexible films of poly(vinyl chloride) (PVC) and linear or branched poly(butylene adipate) (PBA), synthesized from 1,4-butanediol and adipic acid or dimethyl ester of adipic acid, were aged in an aqueous environment for 10 weeks to study how branching, molar mass, and end-group functionality affect the leaching of polyester plasticizer from thin films. Principal component analysis was applied to reveal patterns and correlations between mechanical properties, material characteristics, and aging behavior. Introduction of branches in the polyester structure increased the miscibility between PVC and the polyester, resulting in improved mechanical properties and lower water absorption. Methyl ester end-group in PBA polyester stabilized the polymeric plasticizer toward hydrolysis, and reduced the formation and migration of monomeric degradation products from the blends during aging in water. The combination of branched structure with methyl ester end-groups resulted in a migration resistant polymeric plasticizer.

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Section: Migration Of Hydrolysis Products From Pvc/pba Filmsmentioning

confidence: 99%

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Lindström

Hakkarainen

2007

J of Applied Polymer Sci

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“…The 1:l stoichiometry in reaction (1) (6) This has the reduced form (dx/xX), where x = [A] and X = ux2 + bx + c.…”

Section: Kinetic Considerationsmentioning

confidence: 99%

Equilibrium acid concentrations in hydrolyzed polyesters and polyester–polyurethane elastomers

Brown

Lowry

Smith

1983

J of Applied Polymer Sci

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SynopsisEquilibrium acid concentrations, [Ae], were determined in butylene adipate and caprolactone polyesters, of low molecular weight, and in thermoplastic polyurethane elastomers based on these polyesters. Values of [Ae] of the polyesters a t 85°C were 0.7,1.3, and 3-4 X mol/g a t relativehumidities (RH) of 25%,50%, and 93%, respectively.[Ae] of the thermoplastic elastomers a t 85°Cwere about 3 and 7 X lop4 mol/g at 10% and 25% RH, respectively. Values of [Ae] were not very dependent on temperature at constant RH. Equilibrated thermoplastic elastomers had low molecular weights and poor physical properties. Consequently, equilibration does not set a practical limit on hydrolytic degradation, even a t low RH. Equations were developed that described the variation in acid content with time. Rate constants for hydrolysis and esterification increased as RH decreased. Reesterification in the elastomers in the absence of water is too slow to be a useful method of decreasing hydrolytic damage.

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“…1,7 Kinetics of the hydrolysis of PesURs was successfully treated as a pseudofirst-order reaction. 7,10,11 Although the percentage of hydrolyzed ester groups may be rather small, they are likely to account for a significant reduction of average molar mass and, consequently, deterioration of mechanical properties. To slow down the hydrolysis of polyester groups, polycarboimides can be added to PesURs that act as acid scavengers and suppress the autocatalytic effect.…”

Section: Introductionmentioning

confidence: 99%

Hydrolytic resistance of model poly(ether urethane ureas) and poly(ester urethane ureas)

Pegoretti

Fambri

Penati

et al. 1998

J. Appl. Polym. Sci.

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Poly(ester urethane ureas) (PesURUs) and poly(ether urethane ureas) (PetURUs) synthesized from diphenylmethane-4,4Ј-diisocyanate and poly(butylene adipate) diol, and poly(tetramethylene oxide) diol or poly(propylene oxide) diol, respectively, were hydrolyzed at 70°C for various periods up to 16 weeks. Differences in thermal and mechanical properties of as-received dry samples are correlated with the number and strength of hydrogen bonds formed between urea/urethane groups of hard segments and polyester or polyether groups of soft segments. Gel permeation chromatography measurements show that the molar mass of linear PesURUs markedly decreases with the hydrolysis time, whereas that of linear PetURUs remains almost unaffected. PesURU crosslinked by polymeric isocyanate has lower crystallinity, but shows somewhat better resistance to hydrolysis than its linear counterpart because of its more stable three-dimensional molecular structure. Water uptake at 37°C, dynamic mechanical thermal analysis, and differential scanning calorimetry thermograms determined for redried hydrolyzed specimens concurrently show that advancing hydrolysis accounts for decrease in the crystallinity (if any) of soft polyester segments, in the efficacy of hydrogen bonding and in crosslinking density. Experimental data indicate that hydrolytic resistance of PetURUs is primarily determined by (1) the hydrolytic stability of individual types of present groups, (2) steric hindrances affecting the access of water molecules to these groups, and (3) the hydrophilicity of backbones.

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Kinetics of Hydrolytic Aging of Polyester Urethane Elastomers

Cited by 85 publications

References 3 publications

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Equilibrium acid concentrations in hydrolyzed polyesters and polyester–polyurethane elastomers

Hydrolytic resistance of model poly(ether urethane ureas) and poly(ester urethane ureas)

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