Kinetics of urethane cleavage in crosslinked polyurethanes

Singh, Ajaib; Weissbein, Leonard

doi:10.1002/pol.1966.150041019

Cited by 15 publications

(2 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 Exposure to water, water solutions, water dispersions, etc., can initiate (partial) hydrolysis of PURs, particularly at elevated temperatures. [2][3][4][5][6][7][8][9] In general, the hydrolytic stability of PURs attracts much attention because it is of primary importance for many applications.…”

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.

View full text Add to dashboard Cite

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.

show abstract

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.

View full text Add to dashboard Cite

show abstract

“…Arylcarbamates dissociate on heating to alcohols and isocyanates [1] and heating also causes carbamate linkages in synthetic polymers to dissociate [12]. This thermal dissociation of cotton cellulose carbamates has been demonstrated with the Differential Scanning Calorimeter DSC-1 2 (9].…”

Section: Introductionmentioning

confidence: 99%

Reaction of Aryl Isocyanates with Cotton Cellulose

Hobart

Mack

1969

Textile Research Journal

View full text Add to dashboard Cite

Nine cellulose N,N'-arylenedicarbamates have been formed by thermal reaction of the respective diphenyl arylenedicarbamates with cotton. Cotton print cloth was padded with a dimethylformamide (DMF) or dimethylsulfoxide (DMSO) solution of the diphenyl arylenedicarbamate and the reaction effected by in situ generation of the arylene diisocyanate in the curing step. Add-ons ranging from 3.8 to 12.0% were obtained; under comparable reaction conditions, more rapid reaction occurred with Dl\ISO solvent rather than DMF. High degrees of cross-linking were indicated by high conditioned and high wet wrinkle recoveries. Decreases in breaking strengths, tearing strengths, and flex abrasion resistance were approximately of the same extent as normally encountered in other cross-linking treatments. Resistance to microbiological degradation for more than 89 days was shown by soil burial tests on the treated samples. Ease and extent of introduction and removal of creases by ironing were used to measure breaking and re-forming of carbamate cross links (reversibility). Ring methoxyl group activation of the N-phenyl carbamates appeared to be slightly more effective in achieving reversibility.

show abstract

Degradation process of an industrial thermoplastic elastomer polyurethane-coated fabric in artificial weathering conditions

Hollande

Laurent

1999

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

ABSTRACT:The aging of an industrial thermoplastic elastomer polyurethane (TPU)-coated fabric, based on a polyether diol and an aromatic diisocyanate, is studied in artificial weathering tests. It is noticed that the degradation of this TPU-coated fabric leads to a weight loss, to the formation of a reticulated layer in sample surface, and to a change of surface relief. The degradation layer and the surface relief have been observed by optical microscopy. The weight loss has been followed with aging time. The main degradation products causing weight loss are volatile. Therefore, they have been analyzed by gas chromatography-mass spectroscopy. The weight loss degradation takes place in the exposed part of the reticulated layer by volatile products emission, which implies the urethane and the polyether bonds. Water is involved in degradation process: without external water supply, weight loss is limited; with a permanent contact of vapor or liquid water, the weight loss rate is constant and depends on aging conditions.

show abstract

Kinetics of urethane cleavage in crosslinked polyurethanes

Cited by 15 publications

References 11 publications

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

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

Reaction of Aryl Isocyanates with Cotton Cellulose

Degradation process of an industrial thermoplastic elastomer polyurethane-coated fabric in artificial weathering conditions

Contact Info

Product

Resources

About