Predictive techniques and models for durability tests

Brown, Roger H.

doi:10.1016/0142-9418(95)00006-e

Cited by 29 publications

(5 citation statements)

References 6 publications

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“…The methodology for the test has been previously utilized and it is understood that the degrading agent of the EDS appears in greater concentration in the test than would be seen in service. 48 While modeling the degradation as a function of time, is convenient for the purposes of this project, it should be noted that this is only a portion of the requisite information to complete the picture of degradation rate in vivo. It is recognized that additional tests of copolymer degradation at varying levels of the degrading agent would allow for better in vivo predictions.…”

Section: Discussionmentioning

confidence: 99%

Modeling the microstructurally dependent mechanical properties of poly(ester‐urethane‐urea)s

Warren

Sycks

McGrath

et al. 2013

J Biomedical Materials Res

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Poly(ester-urethane-urea) (PEUU) is one of many synthetic biodegradable elastomers under scrutiny for biomedical and soft tissue applications. The goal of this study was to investigate the effect of the experimental parameters on mechanical properties of PEUUs following exposure to different degrading environments, similar to that of the human body, using linear regression, producing one predictive model. The model utilizes two independent variables of poly(caprolactone) (PCL) type and copolymer crystallinity to predict the dependent variable of maximum tangential modulus (MTM). Results indicate that comparisons between PCLs at different degradation states are statistically different (p < 0.0003), while the difference between experimental and predicted average MTM is statistically negligible (p < 0.02). The linear correlation between experimental and predicted MTM values is R(2) = 0.75.

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Section: Discussionmentioning

confidence: 99%

Modeling the microstructurally dependent mechanical properties of poly(ester‐urethane‐urea)s

Warren

Sycks

McGrath

et al. 2013

J Biomedical Materials Res

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“…Relaxation times at room temperature (25 8C) were calculated through an Arrhenius-type fit [15][16][17] of the t 2 's measured at 85 8C, 65 8C and 35 8C (Equation (1) with frequency factor A, activation energy E a and the Boltzmann constant k).…”

Section: Polymersmentioning

confidence: 99%

Second Order Nonlinear Optical Performances of Polymers Containing Imidazole and Benzimidazole Chromophores

Carella

Centore

Sirigu

et al. 2004

Macro Chemistry & Physics

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Summary: Condensation polymers based on two different NLO‐active chromophores, namely 2‐[4‐[(4‐N,N‐dihydroxyethylamino)phenylazo]phenyl]‐5(6)‐nitrobenzimidazole (BZI) and 2‐[4‐(4‐N,N‐dihydroxyethylamino)phenylazo]‐4,5‐dicyanoimidazole (IMI), have been synthesized and their basic properties measured. The second order NLO properties of poled polymers were investigated by SHG procedures at different temperatures (35, 65 and 85 °C) and exposure times. Resonance free d33 coefficients (λ = 1 368 nm) took values in the range 1.8–4.0 pm · V−1, but the time stability of their SHG signal was fairly acceptable, particularly for the high Tg (e.g. 188 °C) polymer for which a relaxation time (at 25 °C) of 2.8 years has been determined.

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“…The development of marine-degradable materials requires accelerated testing of durability such as hydrolysis to shorten the evaluation time. Generally, the Arrhenius plot estimates the durability of polymer materials [15]. PLA crystallizes rapidly at Tg and above the temperature in hydrolysis tests [16], although crystallization progresses gradually near room temperature [13].…”

Section: Introductionmentioning

confidence: 99%

Changes in Crystal Structure and Accelerated Hydrolytic Degradation of Polylactic Acid in High Humidity

Kobayashi¹,

Ueda

Ishigami

et al. 2021

Polymers

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Highly crystallized polylactic acid (PLA) is suitable for industrial applications due to its stiffness, heat resistance, and dimensional stability. However, crystal lamellae in PLA products might delay PLA decomposition in the environment. This study clarifies how the initial crystal structure influences the hydrolytic degradation of PLA under accelerated conditions. Crystallized PLA was prepared by annealing amorphous PLA at a specific temperature under reduced pressure. Specimens with varied crystal structure were kept at 70 °C and in a relative humidity (RH) of 95% for a specific time. Changes in crystal structure were analyzed using differential calorimetry and wide-angle X-lay diffraction. The molecular weight (MW) was measured with gel permeation chromatography. The crystallinity of the amorphous PLA became the same as that of the initially annealed PLA within one hour at 70 °C and 95% RH. The MW of the amorphous PLA decreased faster even though the crystallinity was similar during the accelerated degradation. The low MW chains of the amorphous PLA tended to decrease faster, although changes in the MW distribution suggested random scission of the molecular chains for initially crystallized PLA. The concentrations of chain ends and impurities, which catalyze hydrolysis, in the amorphous region were considered to be different in the initial crystallization. The crystallinity alone does not determine the speed of hydrolysis.

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Predictive techniques and models for durability tests

Cited by 29 publications

References 6 publications

Modeling the microstructurally dependent mechanical properties of poly(ester‐urethane‐urea)s

Modeling the microstructurally dependent mechanical properties of poly(ester‐urethane‐urea)s

Second Order Nonlinear Optical Performances of Polymers Containing Imidazole and Benzimidazole Chromophores

Changes in Crystal Structure and Accelerated Hydrolytic Degradation of Polylactic Acid in High Humidity

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