Degradation Studies of Polyethylene Terephthalate.

McMahon, William E.; Birdsall, H. A.; Johnson, Gerald R.; Camilli, C. T.

doi:10.1021/je60001a009

Cited by 165 publications

(59 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The hydrolysis of polyester has often been found slightly or not auto-accelerated (1,4,8,25,35) , which may explain why autocatalysis has rarely been taken into account in kinetic modeling.…”

Section: Discussionmentioning

confidence: 99%

Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters

Richaud

Pierre

Coquillat

et al. 2014

Macro Theory & Simulations

View full text Add to dashboard Cite

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. The hydrolysis of almost ideal networks based on macrodiols (poly(adipate of ethylene glycol)) of average molar mass about 2 kg/mol, with L=18 ester groups per chain has been studied. Tensile testing was used to evaluate the crosslink density through the statistical theory of rubber elasticity at two temperatures and three values of relative humidity. A kinetic model for ester consumption including an autocatalysis term was proposed and combined with two original approaches for modeling the crosslink density changes. This allowed kinetic parameters of hydrolysis to be determined, and very good predictions were obtained for the variations of crosslink density (or elastic modulus) in the three aging conditions considered.The initial curvature of elastic modulus vs. time was predicted positive for weak autocatalysis and negative for strong autocatalysis. The obtained conversion ratio at degelation was found to decrease sharply with the number of esters per elastically active chain.

show abstract

Section: Discussionmentioning

confidence: 99%

Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters

Richaud

Pierre

Coquillat

et al. 2014

Macro Theory & Simulations

View full text Add to dashboard Cite

show abstract

“…The polymer chains may be cleaved at the ester groups resulting in two fragments of carboxylic acid and hydroxyl groups [9,27,28]. Long-term in vivo chemical changes of PET vascular grafts have been attributed to hydrolytic degradation [9].…”

Section: Discussionmentioning

confidence: 99%

In vivo biostability of polymeric spine implants: retrieval analyses from a United States investigational device exemption study

Shen¹,

Zhang²,

Koettig

et al. 2011

Eur Spine J

View full text Add to dashboard Cite

The Dynesys System for stabilizing the lumbar spine was first surgically implanted in Europe in 1994. In 2003, a prospective, randomized, investigational device exemption clinical trial of the system for non-fusion dynamic stabilization began. Polycarbonate urethane (PCU) and polyethylene terephthalate (PET) components explanted from four patients who had participated in the study were analyzed for biostability. Components had been implanted 9-19 months. The explanted components were visually inspected and digitally photographed. Scanning electron microscopy was used to analyze the surface of the spacers. The chemical and molecular properties of the retrieved spacers and cords were quantitatively compared with lot-matched, shelf-aged, components that had not been implanted using attenuated total reflection Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). FTIR analyses suggested that the explanted spacers exhibited slight surface chemical changes but were chemically unchanged below the surface and in the center. New peaks that could be attributed to biodegradation of PCU were not observed. The spectral analyses for the cords revealed that the PET cords were chemically unchanged at both the surface and the interior. Peaks associated with the PET biodegradation were not detected. GPC results did not identify changes to the distributions of molecular weights that might be attributed to biodegradation of either PCU spacers or PET cords. The explanted condition of the retrieved components demonstrated the biostability of both PCU spacers and PET cords that had been in vivo for up to 19 months.

show abstract

“…All three aerogels contain fibers made with PETE, which is known to be hygroscopic (Jabarin and Lofgren 1986). Hydrolysis is a great factor in the deterioration of PETE and McMahon has studied the rate of hydrolysis as a function of temperature and RH (McMahon et al 1959). However, in AB, the fibers are encompassed by the hydrophobic aerogel, so there would be little uptake in moisture.…”

Section: Follow-up Aging Simulation Tests On Aerogel Blanketsmentioning

confidence: 99%

Prediction of Long Term Degradation of Insulating Materials

Stephenson¹,

Heffron²,

Mehnert³

et al. 2015

View full text Add to dashboard Cite

Advanced insulation materials provide resistance to heat flow. Properly insulating shelters can reduce heating and cooling costs, as well as improves comfort. However, the long-term performance of insulation materials is relatively unknown. This research investigated the long-term performance of five commercially available insulation materials including nonwoven insulation liner, aerogel blankets, closed cell spray polyurethane foam (ccSPF), extruded polysterene (XPS), and fiberglass batt. Accelerated aging simulation experiments were conducted in an environmental chamber. All materials were subjected to 5 weeks in the chamber and exposed to various temperature and humidity conditions. Thermal conductivity using a heat flow meter apparatus (HFMA) and corresponding Rvalues of each material were calculated. The results indicate that moisture absorption was a major contributor to changes in the thermal properties of the materials. Additional degradation in R-values in ccSPF was caused by loss of blowing agent over time. The results of this research are expected to help formulate an accelerated aging methodology that allows reliable prediction of long-term advanced insulation materials performance.

show abstract

Degradation Studies of Polyethylene Terephthalate.

Cited by 165 publications

References 0 publications

Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters

Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters

In vivo biostability of polymeric spine implants: retrieval analyses from a United States investigational device exemption study

Prediction of Long Term Degradation of Insulating Materials

Contact Info

Product

Resources

About