Influence of gamma radiation and temperature on the ageing of EVA cable insulation studied by DSC

Cibulková, Zuzana; Vykydalová, Anna; Plaček, V.; Šimon, Peter

doi:10.1016/j.tca.2018.08.009

Cited by 7 publications

(4 citation statements)

References 24 publications

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“…The values of R have been calculated for all samples under study and are listed also in Table 1 . In [ 16 – 18 ], it is shown that the decrease in residual stability with respect to the degradation dose often follows a first-order exponential decay: where a is the extinction coefficient associated with the corresponding ageing type, and d is the degradation dose. The obtained values for thermal, γ-irradiation and combined ageing extinction coefficients are a T = (1.41 ± 0.24) ·10 −3 h −1 ; a R = (1.14 ± 0.05) · 10 −2 h −1 and a TR = (10.8 ± 0.7) ·10 −4 h −1 , where the subscripts “T”, “R” and “TR” are related to thermal, radiation and combined stress, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…does not only normalize the material stability within 0 and 100% but also eliminates the temperature dependence present in t i as a result of fitting all data with the same value of D. The values of R have been calculated for all samples under study and are listed also in Table 1. In [16][17][18], it is shown that the decrease in residual stability with respect to the degradation dose often follows a first-order exponential decay:…”

Section: Fast Methods For the Thermooxidative Stability Assessmentmentioning

confidence: 99%

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A rapid method for approximative evaluation of thermooxidative stability of organic materials

Vykydalová

Cibulková

Dubaj

et al. 2022

J Therm Anal Calorim

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In this work, a novel procedure for fast assessment of the material residual stability is proposed. The method resides in integral isoconversional kinetic analysis of the thermal oxidation of unaged material employing the Berthelot–Hood temperature function. Subsequently, the obtained conversion-independent kinetic parameter D is also employed for samples aged in various regimes. The value of conversion-dependent parameter A for aged samples is calculated from the oxidation onset temperature measured at 5 °C min −1 . The residual stabilities are then calculated as a simple ratio of the parameter A of aged material to that of the unaged one. The method has been applied and verified for the samples of low-density polyethylene aged by thermal, radiation and combined ageing. The method can also be employed for high-throughput screening of the effect of various stabilizers and antioxidants in a given organic matrix.

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Section: Resultsmentioning

confidence: 99%

Section: Fast Methods For the Thermooxidative Stability Assessmentmentioning

confidence: 99%

A rapid method for approximative evaluation of thermooxidative stability of organic materials

Vykydalová

Cibulková

Dubaj

et al. 2022

J Therm Anal Calorim

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“…The crystallinity of EVA determines its physical and rheological properties, which may affect the pore and channel structures in the implant, thereby affecting the drug release rate. The crystallinity and physiochemical properties of EVA can be influenced by various factors, such as drug loading, , thermal annealing, − stress, and γ-irradiation sterilization. − Therefore, the measurement, quantification, and monitoring of EVA crystallinity in islatravir implants are of great importance. Herein, we utilized differential scanning calorimetry (DSC), solid-state nuclear magnetic resonance (ssNMR), and dynamic mechanical analysis (DMA) to systematically demonstrate the impact of drug loading, BaSO 4 loading, thermal annealing, and γ-irradiation on the crystallinity and physiochemical properties of EVA in islatravir implants.…”

Section: Introductionmentioning

confidence: 99%

Insights into Factors Affecting Ethylene-Vinyl Acetate Copolymer Crystallinity in Islatravir Implant

Zhu,

Punia,

Skomski

et al. 2024

Mol. Pharmaceutics

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Islatravir, a highly potent nucleoside reverse transcriptase translocation inhibitor (NRTTI) for the treatment of HIV, has great potential to be formulated as ethylene-vinyl acetate (EVA) copolymer-based implants via hot melt extrusion. The crystallinity of EVA determines its physical and rheological properties and may impact the drug-eluting implant performance. Herein, we describe the systematic analysis of factors affecting the EVA crystallinity in islatravir implants. Differential scanning calorimetry (DSC) on EVA and solid-state NMR revealed drug loading promoted EVA crystallization, whereas BaSO4 loading had negligible impact on EVA crystallinity. The sterilization through γ-irradiation appeared to significantly impact the EVA crystallinity and surface characteristics of the implants. Furthermore, DSC analysis of thin implant slices prepared with an ultramicrotome indicated that the surface layer of the implant was more crystalline than the core. These findings provide critical insights into factors affecting the crystallinity, mechanical properties, and physicochemical properties of the EVA polymer matrix of extruded islatravir implants.

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“…Crosslinked and foamed ethylene vinyl acetate (EVA) has been applied in many different fields as sound insulation, shoes material, shockproof and so on. [1][2][3] Consequently, there are the generation of EVA solid waste in its production and after its lifecycle. 4 But, because of many crosslinking chemical bonds and EVA thermoset characteristic it is difficult to directly recycle it.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of different mechanical recycling methods of EVA foam waste

Rosa

Zattera

Poletto

2021

Journal of Elastomers & Plastics

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In the present work, a proposal for the recycling of ethylene vinyl acetate (EVA) foam waste from the footwear industry using twin-screw extruder was evaluated. Parameters such as antioxidant addition, number of reprocessing, temperature, rotation speed were evaluated. The recycled material was evaluated by means of gel content, scanning electron microscopy (SEM), thermogravimetry (TG) and parallel plate rheometry. From this, the 4 samples were chosen, from the 16 extruded, with a higher probability of forming homogeneous foams to be used in the manufacture of new EVA foams. The foams were evaluated using scanning electron microscopy (SEM), dynamic mechanical analysis (DMA) and physical tests of density, abrasion and permanent compression deformation (PCD). The results showed a decrease in the content of crosslinked gel by up to 13 percentage points for the recycled material with antioxidant. However, there was a possible residual crosslinking, as the crosslinking of all recycled foams was greater than reference (foam). The greatest recycled material homogeneity, observed in the SEM, occurred in the samples processed for five repetitions without antioxidant. Some foams manufactured with recycled waste presented very similar morphological aspects to the reference foam. Foam manufactures with G1 recycled waste (extruded once, at 180°C, 450 rpm, without antioxidant), presented the most uniform and spherical cells. This foam also presented the best responses for the physical tests of PCD and abrasion, even compared to foam without recycle. As well as the lower viscosities for these same samples compared to the previous processing. It was understood that the viscosity of the recycled waste directly interferes with the formation of new EVA foam. Rheometry made it possible to identify the recycling process that resulted in an ideal viscosity material for incorporation in the manufacture of new EVA foams.

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Influence of gamma radiation and temperature on the ageing of EVA cable insulation studied by DSC

Cited by 7 publications

References 24 publications

A rapid method for approximative evaluation of thermooxidative stability of organic materials

A rapid method for approximative evaluation of thermooxidative stability of organic materials

Insights into Factors Affecting Ethylene-Vinyl Acetate Copolymer Crystallinity in Islatravir Implant

Evaluation of different mechanical recycling methods of EVA foam waste

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