oxygen permeability
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Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 52
Author(s):  
Ainara Sangroniz ◽  
Leire Sangroniz ◽  
Shaghayegh Hamzehlou ◽  
Nora Aranburu ◽  
Haritz Sardon ◽  
...  

Lactide-valerolactone copolymers have potential application in the packaging sector. Different copolymers were synthesized, and the kinetics of the copolymerization reactions and the microstructure of the copolymers were analysed. Lactide showed higher reactivity than valerolactone which leads to composition drift through the reaction. Thermal, mechanical and barrier properties of the selected copolymers were studied. Overall, the incorporation of valerolactone results in copolymers with higher ductility than poly(lactide) with intermediate water and oxygen permeability which makes these materials appropriate candidates for use in the packaging sector.


Author(s):  
Yue Ji ◽  
Samantha Waters ◽  
Eunhyang Lim ◽  
Augustus W. Lang ◽  
Peter N. Ciesielski ◽  
...  
Keyword(s):  

2021 ◽  
Vol 5 (1) ◽  
pp. e32-e43
Author(s):  
Obinwanne Junior Chukwuemeka ◽  
Damian C. Echendu ◽  
Isaura Ilorena D'Alva Brito dos Santos ◽  
Sharon Onwuka ◽  
Osazee Agbonlahor

Purpose: To determine if regional variation in post lens fluid reservoir thickness (PLFT) during scleral lens wear leads to regional variation in oxygen transmissibility and corneal edema during 4 hours of non-fenestrated scleral lens wear.Methods: About 20 healthy subjects (mean age, 28.8 ± 4.2 years) were fitted with nonfenestrated rotationally symmetric scleral lenses. Anterior segment optical coherence tomography was used to measure cornea thickness before and after lens wear, PLFT 10 minutes and 4 hours after lens application, and scleral lens thickness (with the scleral lens in situ) 4 hours after scleral lens application. These measurements were limited to the central 6 mm and divided into three zones (central, mid-peripheral, and peripheral zones). In the mid-peripheral and peripheral zones, eight principal meridians were measured, generating 17 measurement points in total. Scleral lens thickness and PLFT measurements were corrected for optical distortions by a series of equations. Oxygen transmissibility was calculated by dividing the scleral lens oxygen permeability by the optically-corrected scleral lens thickness, taking into account the oxygen permeability of saline and fluid reservoir thickness.Results: A significant regional variation in PLFT (F = 12.860, P = 0. 012) was observed after 10 minutes of the lens application, PLFT was thickest and thinnest in the inferotemporal and the superonasal region of the peripheral zones( 322.6 ± 161.8 µm and 153.8 ± 96.4 µm, respectively); however, this variation was not statistically significant at 4 hours of scleral lens wear (F = 4.692; P = 0.073). Despite significant regional variation in oxygen transmissibility (F = 48.472; P = 0.001) and relatively low oxygen transmissibility through the scleral lens, induced corneal edema did not vary significantly in different regions (F = 3.346; P = 0.126). In the central corneal region, the induced corneal edema correlated moderately with PLFT (r = 0.468; P = 0.037) and oxygen transmissibility (r = -0.528; P = 0.017). This relationship was insignificant in the peripheral cornea.Conclusion: The inferotemporal peripheral region had the thickest PLFT and least oxygen transmissibility, and the superonasal region had the vice versa. Despite significant variation in PLFT and oxygen transmissibility initially, in healthy corneas, this variation does not seem to induce statistically significant regional variation in corneal edema. Increased central PLFT and decreased oxygen transmissibility moderately correlate with central corneal edema.


2021 ◽  
Author(s):  
Lin Ju

Poly(ethylene terephthalate) (PET) is widely used in the packaging industry. The oxygen barrier properties of PET are acceptable for many food and beverage products, but do not meet the stringent requirements for packaging highly oxygen-sensitive products. Blending PET with aromatic polyamides, such as poly(m-xylyene adipamide) (MXD6), reduces the inherent oxygen permeability of the polyester matrix. Due to the immiscibility of these two parent polymers, a compatibilizer is necessary to achieve an efficient and stable mixing


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7189
Author(s):  
Joanna Ludwiczak ◽  
Stanisław Frąckowiak ◽  
Karol Leluk

In order to improve the properties of biodegradable polylactide (PLA), mixtures with polybutylene adipate-co-terephthalate (PBAT) were prepared. PLA is a bio-based and renewable biodegradable material, made from starch. PBAT is a biodegradable polyester for compostable film. In order to improve the composite properties, two types of additives were implemented via melt mixing, a chain extender (CE) and montmorillonite (MMT). CE was used as an interfacial modifier to enhance the adhesion between components. Montmorillonite is a widely studied clay added to polymer nanocomposites. Due to the lamellar structure, it improves the barrier properties of materials. PLA/PBAT films were oriented in the extrusion process and the amounts of filler introduced into the PLA/PBAT nanocomposites were 1.0, 3.0, and 5.0%. The improvement in the PLA barrier properties by the addition of PBAT and 5% of MMT was confirmed as the oxygen permeability decreased almost by a factor of 3. The addition of the biodegradable polymer, chain extender, montmorillonite, and the implemented orientation process resulted in a decrease in composite viscosity and an increase in the PLA crystallinity percentage (up to 25%), and the wettability tests confirmed the synergic behavior of the selected polymer blend.


Author(s):  
R.A. Ilyas ◽  
Ashraf Azmi ◽  
N.M. Nurazzi ◽  
A. Atiqah ◽  
M.S.N. Atikah ◽  
...  
Keyword(s):  

2021 ◽  
Author(s):  
Manar Elkhial ◽  
Nesrin Elhadidi

Abstract The increasing demand for applying modified inert atmosphere (MIA) systems for insect eradication in museums has led to the desire for lower-cost consumable materials, particularly laminated plastic films. An ultra-low oxygen-permeable laminate is required for creating successful MIA systems to keep the oxygen concentration lower than 0.3%, which is commercially available but at a high cost. The wide use of local laminated films for food preservation makes them a perfect target for testing and improvement for MIA applications. However, the lack of laboratory oxygen permeability test methods to gauge the potential of local laminates for inclusion in MIA applications distracts attention from looking at them as alternatives and encourages the expense on extremely expensive imported ones. Therefore, the present work investigates the potential of employing two laminates (one local and one imported) to create a successful leak-proof MIA system. A laboratory easy-to-use test method was developed to assess the oxygen-gas retention property of each laminate by measuring its oxygen permeability and consequently oxygen transmission rate (OTR). The test method is a sealed static diffusion chamber separated in the middle by a known area (cm2) of the test laminate to be tested. The test relies on measuring the concentration of oxygen in either sides of the laminate membrane within the sealed system and monitors the change over time to assess the OTR of the laminate. The specifications and design of the test chamber are adapted from the ASTM Designation: E2945 − 14, to meet the facilities of a typical artefact fumigation laboratory. The test is undertaken at standard MIA conditions (temperature of 25°C, relative humidity of 45%, and target oxygen concentration of 0.3). Results indicated that the new method is useful for an unlimited number of tests of an unlimited number of laminates. The conducted tests proved that the local laminate normally used for food packaging has superior advantages over the long-used imported ones.


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