Interface nanocavities in poly (lactic acid) membranes with dispersed cellulose nanofibrils: Their role in the gas barrier performances

Dickmann, Marcel; Tarter, S.; Egger, Werner; Pegoretti, Alessandro; Rigotti, Daniele; Brusa, R. S.; Checchetto, R.

doi:10.1016/j.polymer.2020.122729

Cited by 10 publications

(7 citation statements)

References 34 publications

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“…Since the C coefficient is generally unknown, FFV's are preferably compared against a reference sample of the same composition. [40][41][42] The material composition (e.g., high-electron-density functional groups) can directly affect both the o-Ps lifetime and intensity through quenching (faster annihilation) and inhibition (reduced o-Ps formation probability), respectively. [43,44] It is therefore recommended to verify if the results are physically meaningful and to cross-check them with complementary methods.…”

Section: Figurementioning

confidence: 99%

Porosimetry for Thin Films of Metal–Organic Frameworks: A Comparison of Positron Annihilation Lifetime Spectroscopy and Adsorption‐Based Methods

et al. 2021

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separation and storage, or catalysis. [3][4][5] In addition, there is tremendous potential in the use of MOF thin films as membranes, active sensor coatings, high-performance dielectrics, and other microelectronic applications that could benefit from the integration of porous functional materials. [6] Routine characterization of MOF powders typically involves N 2 physisorption to investigate their porosity and specific surface area. [7] The characterization of MOF thin films is more challenging due to the low amount of material in sub-micrometer films (Table 1), especially compared to the mass and volume of the substrate (e.g., a Si wafer), and often requires dedicated methods and instruments. Therefore, often only qualitative porosity characterization has been performed, e.g., through intercalation of fluorescent dyes or other labels. [8,9] Thus far, quantitative porosimetry of MOF films has relied on physisorption, by measuring the adsorbed quantity of a probe molecule through manometric/volumetric (e.g., Kr physisorption, KrP), gravimetric (e.g., quartz crystal microbalance, QCM) or spectroscopic (e.g., ellipsometry, EP) methods. [10] When performed as a function of the adsorptive relative pressure at Thin films of crystalline and porous metal-organic frameworks (MOFs) have great potential in membranes, sensors, and microelectronic chips. While the morphology and crystallinity of MOF films can be evaluated using widely available techniques, characterizing their pore size, pore volume, and specific surface area is challenging due to the low amount of material and substrate effects. Positron annihilation lifetime spectroscopy (PALS) is introduced as a powerful method to obtain pore size information and depth profiling in MOF films. The complementarity of this approach to established physisorptionbased methods such as quartz crystal microbalance (QCM) gravimetry, ellipsometric porosimetry (EP), and Kr physisorption (KrP) is illustrated. This comprehensive discussion on MOF thin film porosimetry is supported by experimental data for thin films of ZIF-8.

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Section: Figurementioning

confidence: 99%

Porosimetry for Thin Films of Metal–Organic Frameworks: A Comparison of Positron Annihilation Lifetime Spectroscopy and Adsorption‐Based Methods

et al. 2021

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“…Its combination of high elastic modulus (2–4 GPa) and strength (30–50 MPa), high optical transparency, and compostability make it the ideal material for packaging applications, especially for food and other perishable substances [ 6 , 7 , 8 , 9 ]. However, PLA is generally used only for rigid thermoformed packaging [ 10 , 11 , 12 , 13 ], due to its poor strain at break (1–5%) and impact strength, very limited UV shielding capability, and inadequate gas-barrier properties [ 14 ]. PLA’s brittleness has been mitigated by adding low-molecular-weight plasticizers, such as citrate esters [ 15 ] and poly(alkylene glycol)s [ 16 , 17 ], or tough polymers, such as poly(ε-caprolactone) [ 18 , 19 ] or polybutylene adipate-co-terephthalate [ 20 , 21 , 22 ], but their impact on PLA’s stiffness and strength is, in most cases, deleterious [ 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Compatibilization of Polylactide/Poly(ethylene 2,5-furanoate) (PLA/PEF) Blends for Sustainable and Bioderived Packaging

et al. 2022

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Despite the advantages of polylactide (PLA), its inadequate UV-shielding and gas-barrier properties undermine its wide application as a flexible packaging film for perishable items. These issues are addressed in this work by investigating the properties of melt-mixed, fully bioderived blends of polylactide (PLA) and poly(ethylene furanoate) (PEF), as a function of the PEF weight fraction (1–30 wt %) and the amount of the commercial compatibilizer/chain extender Joncryl ADR 4468 (J, 0.25–1 phr). J mitigates the immiscibility of the two polymer phases by decreasing and homogenizing the PEF domain size; for the blend containing 10 wt % of PEF, the PEF domain size drops from 0.67 ± 0.46 µm of the uncompatibilized blend to 0.26 ± 0.14 with 1 phr of J. Moreover, the increase in the complex viscosity of PLA and PLA/PEF blends with the J content evidences the effectiveness of J as a chain extender. This dual positive contribution of J is reflected in the mechanical properties of PLA/PEF blends. Whereas the uncompatibilized blend with 10 wt % of PEF shows lower mechanical performance than neat PLA, all the compatibilized blends show higher tensile strength and strain at break, while retaining their high elastic moduli. The effects of PEF on the UV- and oxygen-barrier properties of PLA are also remarkable. Adding only 1 wt % of PEF makes the blend an excellent barrier for UV rays, with the transmittance at 320 nm dropping from 52.8% of neat PLA to 0.4% of the sample with 1 wt % PEF, while keeping good transparency in the visible region. PEF is also responsible for a sensible decrease in the oxygen transmission rate, which decreases from 189 cc/m2·day for neat PLA to 144 cc/m2·day with only 1 wt % of PEF. This work emphasizes the synergistic effects of PEF and J in enhancing the thermal, mechanical, UV-shielding, and gas-barrier properties of PLA, which results in bioderived blends that are very promising for packaging applications.

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“…The diffusion of PLA in the packaging field is mainly due to the synthesis of low-enantiomeric-purity statistical copolymers . Despite their interesting mechanical and optical properties, these polymers are relatively brittle, which limits their application to rigid thermoformed packaging. − To address such shortcomings and improve the ductility and the fracture toughness of PLA, several synthetic plasticizers have been added, such as citrate esters, poly(ethylene glycol), and poly(propylene glycol), but the effect of these plasticizers on the material stiffness is generally detrimental. , Another option can be blending PLA with tough polymers such as poly(ε-caprolactone) , and other biodegradable polymers, − but also in this case, a negative side effect is a significant reduction of the stress at yield and the high-temperature dimensional stability. Finding a suitable biobased additive for PLA that improves its ductility without negatively affecting the other mechanical properties is still an open research question.…”

Section: Introductionmentioning

confidence: 99%

Novel Biobased Polylactic Acid/Poly(pentamethylene 2,5-furanoate) Blends for Sustainable Food Packaging

Rigotti

Soccio

Dorigato

et al. 2021

ACS Sustainable Chem. Eng.

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Here, solution-cast blends of polylactic acid (PLA) and a novel bioderived poly(pentamethylene 2,5-furanoate) (PPeF) in variable concentrations (1–50 wt %) are prepared and investigated. The characterization of the thin films (thickness 50 μm) highlights that PPeF strongly improves the UV-shielding properties of PLA, with a decrease in transmittance at 275 nm from 47.3% of neat PLA to 0.77% with only 1 wt % of PPeF, while the transmittance decrease in the visible region at these PPeF fractions is marginal, allowing the production of optically transparent films. Despite the complete immiscibility of PLA/PPeF blends, PPeF effectively enhances the ductility of PLA as the tensile strain at break increases from 7% of neat PLA to 200% of the blend with 30 wt % of PPeF. This composition is the most promising also from the gas-barrier point of view as the gas transmission rates of CO2 and O2 drop to one-fourth of those of neat PLA, comparable to those of poly(ethylene terephthalate). These results highlight that PLA/PPeF blends with PPeF fractions of 30 wt % are very promising for food packaging applications, and their properties could be further enhanced by applying suitable compatibilizers.

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Interface nanocavities in poly (lactic acid) membranes with dispersed cellulose nanofibrils: Their role in the gas barrier performances

Cited by 10 publications

References 34 publications

Porosimetry for Thin Films of Metal–Organic Frameworks: A Comparison of Positron Annihilation Lifetime Spectroscopy and Adsorption‐Based Methods

Porosimetry for Thin Films of Metal–Organic Frameworks: A Comparison of Positron Annihilation Lifetime Spectroscopy and Adsorption‐Based Methods

Compatibilization of Polylactide/Poly(ethylene 2,5-furanoate) (PLA/PEF) Blends for Sustainable and Bioderived Packaging

Novel Biobased Polylactic Acid/Poly(pentamethylene 2,5-furanoate) Blends for Sustainable Food Packaging

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