Effect of an oxidative environment on the creep compliance of poly(ether urethane urea)

Wu, Yan; Sletten, K. R.; Topolkaraev, V. A.; Lodoen, G. A.; Anderson, James M.; Baer, E.; Hiltner, A.

doi:10.1002/app.1994.070530806

Cited by 9 publications

(15 citation statements)

References 12 publications

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“…Apparently, under the influence of an applied strain, cracks that form in the brittle degraded PEUU surface layer can propagate into the bulk and cause failure. 10 In contrast to the previous creep experiments that were performed under conditions of constant load, the effect of strain state was examined in the present study. The PEUU was exposed to an in vitro oxidative environment under conditions of constant uniaxial or biaxial strain.…”

Section: Introductionmentioning

confidence: 97%

The effect of strain state on the biostability of a poly(etherurethane urea) elastomer

Schubert

Wiggins

Anderson

et al. 1997

J. Biomed. Mater. Res.

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The effect of deformation state on degradation of a PEUU without added stabilizers was examined in an oxidative environment that simulates the in vivo biodegradation of the polymer. Polymer tubes were stressed uniaxially and biaxially over glass mandrels and treated in 20% hydrogen peroxide/0.1 M cobalt chloride solution for 12 days at 37 degrees C. The amount of degradation was determined from the ATR-FTIR peak height of the amorphous aliphatic ether absorbance at 1110 cm-1. If a uniaxial stress was applied, degradation was inhibited and the amount of surface ether remaining after treatment increased linearly with strain. If the stress was biaxial, the amount of degradation was not reduced unless the strain was greater than 200%. Decreased degradation correlated with the amount of soft-segment orientation. The decreased degradation rate was attributed to compaction of the polyether phase by orientation, which resulted in lower permeability to oxidative agents, particularly oxygen. Macroscopic damage was confined to a thin peeling surface layer if the stress was uniaxial. In comparison, biaxially stressed PEUU ruptured.

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Section: Introductionmentioning

confidence: 97%

The effect of strain state on the biostability of a poly(etherurethane urea) elastomer

Schubert

Wiggins

Anderson

et al. 1997

J. Biomed. Mater. Res.

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“…The relationship between mechanical deformation and chemical degradation of PU has been studied in vitro and in vivo under various loading conditions, including uniaxial creep 10,11 and uniaxial and biaxial stress relaxation. 8,12 To explain the results of uniaxial deformation, two effects that work in opposition are proposed.…”

Section: Introductionmentioning

confidence: 99%

Effect of strain and strain rate on fatigue‐accelerated biodegradation of polyurethane

Wiggins

Anderson

Hiltner

2003

J Biomedical Materials Res

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A diaphragm-type film specimen was used to study in vitro degradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading. This geometry allowed both uniaxial and biaxial loading in a single experiment. During testing, the film was exposed to a H(2)O(2)/CoCl(2) solution that simulated in vivo oxidation of PEUU. The combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation. The effects of biaxial strain magnitude and strain rate were examined separately by increasing the frequency of fatigue loading from 0 to 1 Hz with constant maximum biaxial strain and by changing the maximum biaxial strain while maintaining constant strain rate. In the ranges of biaxial strain energy (0.17 to 0.55 MPa) and strain rate (0 to 46% s(-1)) tested, the rate of degradation increased with increasing strain rate whereas strain magnitude had essentially no effect on degradation rate. Although loading conditions affected the rate of oxidative degradation, ATR-FTIR analysis suggested that in all cases the mechanism of degradation did not change. Chemical degradation produced a brittle crosslinked surface layer marked by dimpling and pitting, as observed with scanning electron microscopy. Pits served as stress concentrators and initiated environmental stress cracks under dynamic loading but not under static (creep) loading. Small pits were sufficient to initiate cracks at higher strain rates whereas only large pits initiated cracks at lower strain rates. Consequently, a higher strain rate produced more profuse cracking.

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“…On the other hand, it has been found that uniaxial stress inhibited chemical degradation of a poly(etherurethane urea) by causing stress-induced crystallization of the ether soft segments. 40 Such inhibition was observed in the case of PCU and FPCU-A as well. As shown in Table VII, the decrease of peak heights in the stressed specimens under H 2 O 2 /CoCl 2 incubation was less than that of the unstressed analogues.…”

Section: Possible Degradation Mechanismsmentioning

confidence: 80%

“…Apparently, under the influence of applied strain, cracks formed on the surface can propagate into bulk and cause failure, as shown in Figure 4(a). On the other hand, it has been found that uniaxial stress inhibited chemical degradation of a poly(etherurethane urea) by causing stress‐induced crystallization of the ether soft segments 40. Such inhibition was observed in the case of PCU and FPCU‐A as well.…”

Section: Discussionmentioning

confidence: 99%

Fluorocarbon chain end‐capped poly(carbonate urethane)s as biomaterials: Blood compatibility and chemical stability assessments

Xie

Wang

et al. 2008

J Biomed Mater Res

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Previous work has shown the synthesis of fluorocarbon chain (CF(3)(CF(2))(6)CH(2)O-) end-capped poly(carbonate urethane)s (FPCUs) and confirmed the presence of a novel bilayered surface structure in FPCUs, that is, the top fluorocarbon and subsurface hard segment layers (Xie et al., J Biomed Mater Res Part A 2008; 84:30-43). In this work, the effects of such surface structure on blood compatibility were investigated using hemolytic test and platelet adhesion analysis. The chemical stability of the polymers was also determined by Zhao's glass wool-H(2)O(2)/CoCl(2) test and phosphate-buffered saline (PBS, pH = 3.1-3.3) treatment. One of the FPCUs, FPCU-A, and two control materials, a poly(ether urethane) (PEU) and a poly(carbonate urethane) (PCU), were investigated. No significant difference in hemolytic indices was observed among the three materials, whereas the adherent density and deformation of platelets were much lower on FPCU-A compared with on PCU and PEU. Severe surface cracking and surface buckling developed in prestressed PEU and PCU films after H(2)O(2)/CoCl(2) treatment, respectively, whereas smooth surface was observed for the FPCU-A. PBS incubation resulted in parallel ridge-like morphology in PCU whereas PEU and FPCU-A retained their smooth surfaces. Under relatively high stress conditions, all the materials developed well-oriented strip-like surface patterns. Results from ATR-FTIR spectra revealed a surface oxidation mechanism as described in literature. However, observations of universal decrease of molecular weights under stress conditions further suggested the presence of another bulk stress oxidation mechanism. Regardless the degradation mechanisms involved, the unique bilayered surface structure really improved the blood compatibility and chemical stability of FPCU-A, indicating that further in vivo investigations are worthwhile.

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Effect of an oxidative environment on the creep compliance of poly(ether urethane urea)

Cited by 9 publications

References 12 publications

The effect of strain state on the biostability of a poly(etherurethane urea) elastomer

The effect of strain state on the biostability of a poly(etherurethane urea) elastomer

Effect of strain and strain rate on fatigue‐accelerated biodegradation of polyurethane

Fluorocarbon chain end‐capped poly(carbonate urethane)s as biomaterials: Blood compatibility and chemical stability assessments

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