The Effect of Polymer Structure on the Gas Permeability of Model Polyurethanes

Kaplan, W. A.; Tabor, R.L.

doi:10.1177/0021955x9403000303

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…However, it is important to note that removing dissolved oxygen completely from the PRESAGE ® precursor does not necessarily eliminate the presence of oxygen in the final product as oxygen may diffuse into PRESAGE ® precursor during the curing process or upon contact of the cured dosimeter with the atmosphere. Nevertheless, it is expected that diffusion of oxygen from the atmosphere in to solid PRESAGE ® dosimeters would be extremely slow, given that the permeability and diffusion coefficients of polyurethane resins to gases under atmospheric conditions are very low (Kaplan andTabor 1994, Matsunaga et al 2005). Therefore, it was presumed that the diffusion of atmospheric oxygen into the anaerobic PRESAGE ® dosimeter would be negligible within the timeframe of the experiment.…”

Section: Methodsmentioning

confidence: 99%

Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter

Alqathami

Blencowe

2016

Phys. Med. Biol.

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It is generally accepted that the PRESAGE(®) radiochromic dosimeter is not sensitive to oxygen, however, this claim has not been supported or verified experimentally. Therefore, the aim of this study was to experimentally determine the potential influence of oxygen on dose sensitivity of the PRESAGE(®) dosimeter and its reporting system. Batches of PRESAGE(®) and its radical initiator-leuco dye reporting system were prepared in aerobic and anaerobic conditions. The anaerobic batches were deoxygenated by bubbling nitrogen through the dosimeter precursors or reporting system for 10 min. The dosimeters and reporting systems were prepared in spectrophotometric cuvettes and glass vials, respectively, and were irradiated with 6 MV photons to various radiation doses. Changes in optical density of the dosimeters and reporting system before and after irradiation were measured using a spectrophotometer. The overall results show that oxygen has some influence on the dosimetric characteristics of PRESAGE(®), although the radical initiator does appear to oxidize the leucomalachite green even in the presence of oxygen. Deoxygenation of the reporting system leads to an increase in sensitivity to radiation dose by ~30% when compared to the non-deoxygenated system. A minor increase in sensitivity (~5%) was also achieved by deoxygenating the PRESAGE(®) precursor prior to casting. In addition, dissolved oxygen measurements revealed low levels of dissolved oxygen (0.40 ± 0.04 mg l(-1)) in the polyurethane precursor used to fabricate the PRESAGE(®) dosimeters, as compared to water (8.60 ± 0.03 mg l(-1)) and the reporting system alone (1.30 ± 0.10 mg l(-1)). The results suggest that the presence of oxygen does not inhibit the radiochromic properties of the PRESAGE(®) system. However, deoxygenation of the dosimeter precursors prior to casting improves the dosimeters dose sensitivity by ~5%, which might be particularly useful for measuring low radiation doses. Nevertheless, we believe this is not sufficient enough to recommend the deoxygenation of commercial PRESAGE(®) precursor prior to casting. In addition, there were no observed changes in the dose linearity, absorption spectrum and post-response photofading characteristics of the PRESAGE(®) under the conditions investigated.

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Section: Methodsmentioning

confidence: 99%

Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter

Alqathami

Blencowe

2016

Phys. Med. Biol.

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“…In relation to this, Kaplan and Tabor searched the relation between the gas permeability property and the structure of model polyurethane. 40 They found that the gas permeability of polyurethane showed decreasing trend with the increasing of the molecular packing efficiency which is closely related to the polymer chain mobility.…”

Section: Introductionmentioning

confidence: 98%

Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2

Soykan

Khaleel

Çetin

et al. 2022

Journal of Cellular Plastics

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Rigid polyurethane foams (RPUFs) were modified with 0–15 wt.% turkey feather fibers (TFFs) produced from waste turkey feathers. One-shut free rising method was used for the production of TFFs-filled-RPUFs in a closed mold. The dependence of mechanical performance and water vapor permeability (WVP) feature of the final foams on TFFs loading was evaluated with free volume change. The free volume analysis was performed via Positron Annihilation Lifetime Spectroscopy (PALS), while the mechanical and WVP characteristics were determined with the use of the universal tester machines. PALS findings showed that the incorporation of TFFs with RPUF matrix caused the considerable diminishment in the free volume due to TFFs serving as a filling material and formation of strong secondary bonds between components. Moreover, tensile strength and extension of the foams decreased with the increasing of TFFs, which caused by the occurrence of noteworthy restriction on the spatial alignment and orientation capability of polyurethane chains due to the lack of sufficient free volume allowing the chains to move freely. As for the compression tests, all the TFFs-loaded RPUFs depicted substantially lower performance due to TFFs interfering with the ordered organization of isocyanate domains. Moreover, impact test results showed that the addition of TFFs into RPUF matrix brought about the insufficient impact energy delocalization throughout the matrix due to the restriction on the mobility of polymer chains. Additionally, the remarkable diminishment in WVP was recorded due to the reduction in the number of vacancies and constitution of keratin composed of roundly 60% of hydrophilic protein (especially cystine). All in all, this study established a strong links between free volume and characteristics of TFFs-loaded RPUFs.

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“…The determination of such parameters is expensive and timeconsuming, especially since it depends on the foam density, the cell morphology etc. [9,10]. Cell orientation and density will vary within a laminate, among different manufacturers and between plant sites, making it necessary to measure such parameters for each individual foam sample.…”

Section: Introductionmentioning

confidence: 99%

Long Term Thermal Resistance of Pentane Blown Polyisocyanurate Laminate Boards

Singh¹,

Ntiru

Dedecker

2003

Journal of Cellular Plastics

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The accurate estimation of the thermal performance of insulation products over their expected lifetime has been a recognized challenge for over twenty years. This is because the lifetime of such products is long (10-25 years), thermal aging is caused by the diffusion of a multitude of gases, and the insulation product is not homogeneous. Two classical approaches to accelerating diffusion controlled phenomena, namely aging at higher temperature and aging a thin slice, have limitations when applied to insulation materials like polyisocyanurate (PIR) laminate board. Raising temperature does not change the diffusion coefficients of all the different gases involved in the aging process at the same rate. In the case of pentane blown PIR board, these gases are CO2, air and the different pentane isomers used to blow the foam. Thin slicing of core foam and scaling techniques, such as those in the ASTM C 1303 -00 procedure, do not account for the fact that PIR laminate boards are denser at the surface layer than in the core foam.

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The Effect of Polymer Structure on the Gas Permeability of Model Polyurethanes

Cited by 5 publications

References 15 publications

Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter

Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter

Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2

Long Term Thermal Resistance of Pentane Blown Polyisocyanurate Laminate Boards

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The Effect of Polymer Structure on the Gas Permeability of Model Polyurethanes

Cited by 5 publications

References 15 publications

Experimental determination of the influence of oxygen on the PRESAGE®dosimeter

Experimental determination of the influence of oxygen on the PRESAGE®dosimeter

Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2

Long Term Thermal Resistance of Pentane Blown Polyisocyanurate Laminate Boards

Contact Info

Product

Resources

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Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter

Experimental determination of the influence of oxygen on the PRESAGE^®dosimeter