Ethylene Vinyl Alcohol Copolymer Research Articles

Abstract No. 512 Direct percutaneous treatment of peripheral vascular pathology

Abstract No. 512 Direct percutaneous treatment of peripheral vascular pathology

Influence of the Melt Extrusion Process on the Mechanical Behavior and the Thermal Properties of Ethylene Vinyl Alcohol Copolymer by Applying the Successive Self-nucleation and Annealing Thermal Fractionation

Ethylene vinyl alcohol copolymer was processed three times in a twin-screw extrusion pilot plant in order to reproduce the processing steps required to obtain EVOH nanocomposites. Thin film of the extruded EVOH was prepared by using a cast-film line. The melt flow index and rheological behavior of the film were determined. Viscoelastic parameters were evaluated in a dynamic mechanical testing instrument that revealed the presence of two signals, one attributed to the glass transition temperature and the other one related to the structural modifications associated to interlamellar separation. Thermal properties were evaluated in a differential scanning calorimetry by applying a standard evaluation and successive self-nucleation and annealing approach, finding structural modifications influenced by the melt extrusion process, although the overall percentage of crystallinity degree remains similar. Based on the structural results, the mechanical properties were evaluated considering the ethylene content and resulting on distinct mechanical behavior. Lower ethylene content allows the chain orientation induced during the processing of the film that favors the mechanical performance. Higher ethylene content promotes different deformation mechanisms and a relevant ductility.

QCL-based mid-infrared hyperspectral imaging of multilayer polymer oxygen barrier-films

In this work, mid-infrared hyperspectral images of multilayer polymer film (MLPF) cross sections are acquired with a high-speed quantum cascade laser (QCL) based mid-infrared microscope and analyzed using different data analysis techniques. The investigated MLPF is a polypropylene (PP) and ethylene-vinyl alcohol co-polymer (EVOH) composite commonly used for food packaging due to its outstanding barrier characteristics. Pure band integration of supposedly selective absorption bands for the two constituents of the MLPF is compared to principal component analysis (PCA) and multivariate curve resolution (MCR) algorithms regarding the ability to spatially resolve the differently composed areas in the MLPF. While both pure band integration and PCA are strongly affected by common physical artifacts in the spectral data, such as sample tilt, scattering or interference effects, MCR managed to give a clear picture of the composition of the MLPF, which matches the actual situation given by the manufacturing process. The obtained results can guide the way to the application of high-performance mid-infrared spectroscopic instrumentation for spatially resolved polymer analysis by meaningful interpretation of hyperspectral image data.

Effects of the blending time on the properties and non‐isothermal crystallization behavior of PA6/EVOH blends

AbstractBoth polyamide 6 (PA6) and ethylene vinyl alcohol copolymer (EVOH) have high fractional crystallinity. Non‐isothermal crystallization kinetics is highly important for the design of processing operations. Furthermore, PA6 and EVOH undergo a chemical reaction to form copolymer when melt blended for a sufficiently long time. Therefore, the effects of the blending time on the mechanical properties, rheological properties, and non‐isothermal crystallization kinetics of PA6/EVOH blends were investigated. Non‐isothermal crystallization kinetics were analyzed through the Jeziorny and Mo′s equations, and the Mo′s equation more appropriately described the crystallization behavior of the blends. Mechanical properties, melt viscosity, and storage modulus gradually enhanced with an increase in the blending time, and the elongation at break first increased and then decreased with an increase in the blending time because when the blending time increased, the degree of the reaction between PA6 and EVOH increased, causing adhesion at interfaces and intermolecular interaction to enhance and causing a decrease in molecular chain fluidity. The former leads to an increase in the mechanical properties of the blend, and the latter renders the regular arrangement of chains for crystallization highly difficulty; hence, crystallization fractions in the blend gradually decrease.

Jejunal Necrosis after Embolization with Ethylene Vinyl Alcohol Copolymer

A 61-year-old man with a left lung allograft for idiopathic pulmonary fibrosis presented with pneumonia, sepsis, and a hemoglobin level of 5.8 g/dL. The early hospital course included episodic maroon-colored stools without source identification on serial endoscopy.

Surface versus bulk CaCO3 crystals with ethylene vinyl alcohol co-polymers and polyamide thin-film composite membranes

We conducted experiments to study the influence of material surface chemistry and morphology on the crystallization of calcium carbonate from supersaturated solution containing mixed electrolytes. The study evaluated ethylene vinyl alcohol (EVOH) co-polymers and fluorinated and non-fluorinated polyamide thin film composite membranes to evaluate how surface functional groups impact partitioning of salt crystals between the surface and the bulk fluid. Our methodology and results can aid in developing scaling-resistant thin film composite membranes and in selecting materials for engineered structures exposed to supersaturated solutions. We analyzed turbidity, surface scale deposition, bulk crystal yield, and overall Ca balance to quantify salt crystal adhesion (aka scaling) during exposure to the supersaturated stream and subsequent desupersaturation. Through our studies, we found polyethylene was much more prone to scaling as compared to EVOH. We also show that EVOH containing 56% vinyl alcohol monomer appears to have higher scaling resistance as compared to an EVOH containing 68% vinyl alcohol monomer. These two grades of EVOH were analyzed using atomic force microscopy to elucidate if differences in co-polymer morphology existed; it appears so and this may underlie the measured differences in the salt crystal's surface adhesion. Also, the studies found that the incorporation of fluorine in the polyamide thin film composite membrane surface by means of a novel mono-fluorinated trimesoyl chloride derivative does not impact salt scaling or the total solution de-supersaturation. Our studies provide new insight that not only -OH functional group quantity but also polymer chain configuration and conformation need to be optimized for surfaces that are resistant to calcium carbonate scale buildup.

Curative embolization of a vein of Galen malformation with a dual-lumen balloon and ethylene vinyl alcohol copolymer

The endovascular approach is the standard treatment of vein of Galen malformations (VOGMs,) however the morbidity and mortality rates of VOGMs treated by embolization are still significant. Embolization with ethylene vinyl alcohol copolymer (EVOH) by a dual-lumen balloon (DLB) is a promising. In the present case we demonstrated two strategies of transarterial (TA) embolization of a mural type VOGM presenting with two direct shunts. The first shunt was embolized using coils to reduce the flow through the shunt, following by an EVOH injection which resulted in the complete occlusion of that shunt. The second shunt was embolized also with EVOH but through a DLB. In the second embolization a very precise cast of EVOH could be created resulting in a complete occlusion of the VOGM. This case demonstrated the advantages of DLB compared to other embolization techniques

Structure-Property Relationship of Cellulose Nanocrystal-Polyvinyl Alcohol Thin Films for High Barrier Coating Applications.

CO2 and O2 gas permeability are paramount concerns in food packaging. Here, the permeability of cellulose nanocrystals (CNCs) and polyvinyl alcohol (PVA) coatings was explored as it relates to varied CNC content. Specifically, this work focuses on the role of PVA in rheology and barrier performance of the CNC films. Results show that shear-casted CNC films are transparent and have a high-order parameter, which is attributed to the shear-thinning behavior of the CNCs. The barrier performance of the CNC films improved because of the synergistic effect of having both alignment of CNCs and a lower free volume. The CNC-PVA films exhibited excellent barrier performance as compared to traditional engineered polymers, even much higher than high barrier ethylene-vinyl alcohol copolymer films. Furthermore, the moisture sensitivity of the films was greatly diminished with the addition of PVA. Overall, the results show applicability of CNC-PVA coating formulations for high barrier packaging applications.

Polypropylene/Ethylene-And Polar-Monomer-Based Copolymers/Montmorillonite Nanocomposites: Morphology, Mechanical Properties, and Oxygen Permeability.

This research reports the influence of polar monomer contents in ethylene vinyl acetate copolymer (EVA) and ethylene vinyl alcohol copolymer (EVOH) on the morphology, mechanical and barrier properties of polypropylene/ethylene copolymer (PP) reinforced with organically modified montmorillonite (MMT). PP/EVA and PP/EVOH (75/25 wt %) blends were reinforced with 3 wt % MMT in an internal mixer system. Samples were compression-molded into films of 300. The structural characterization was made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the mechanical properties were obtained by tension tests and the barrier properties by oxygen transmission rate (OTR). XRD patterns showed a combination of intercalated/exfoliated morphologies for the MMT, with higher d-001 interplanar distance increments for the blends with higher content of polar functional groups. SEM and TEM micrographs complement the results of the XRD analysis and show differences in the morphologies depending on the miscibility of the polyolefin and the polar monomer copolymer. Mechanical properties and oxygen permeability of composites exhibited a higher improvement, by the addition of MMT, for higher intermolecular interactions and most miscible polymeric system of the EVA. These results show that the higher the number of interactions, given by the VA or OH polar functional groups, the morphology and the miscibility between polyolefin and copolymer imply dispersion improvements of the nanocomposites and, in consequence, a higher improvement on the mechanical and barrier properties of the composite material.

Portal vein embolization with ethylene-vinyl alcohol copolymer for contralateral lobe hypertrophy before liver resection: safety, feasibility and initial experience.

To report our preliminary experience with preoperative portal vein embolization (PVE) using liquid ethylene vinyl alcohol (EVOH) copolymer. Retrospectively review of patients with primary or secondary liver malignancies scheduled for extensive hepatectomy after the induction of future liver remnant (FLR) hypertrophy by right or left PVE with EVOH as the only embolic agent between 2014 and 2018 at two academic centers. Cross-sectional imaging liver volumetry data obtained before and 3-6 weeks after PVE were used to assess the FLR volume (FLRV) increase, degree of FLR hypertrophy and the FLR kinetic growth rate (KGR). Twenty-six patients (17 males; mean age, 58.7±11 years; range, 32-79 years) were included. The technical and clinical success rate was 100%. PVE produced adequate FLR hypertrophy in all patients. Embolization occurred in all targeted portal branches and in no non-target vessels. The %FLRV increased by 52.9%±32.5% and the degree of FLR hypertrophy was 16.7%±6.8%. The KGR was 4.4%±2.0% per week. Four patients experience minor complications after PVE which resolved with symptomatic treatment. The resection rate was 84.5%. One patient died during surgery for reasons unrelated to PVE. Preoperative PVE with EVOH copolymer is feasible, safe, and effective in inducing FLR hypertrophy.

Embolization of Brain Arteriovenous Malformations With Versus Without Onyx Before Stereotactic Radiosurgery.

Embolization of brain arteriovenous malformations (AVMs) using ethylene-vinyl alcohol copolymer (Onyx) embolization may influence the treatment effects of stereotactic radiosurgery (SRS) differently than other embolysates. To compare the outcomes of pre-SRS AVM embolization with vs without Onyx through a multicenter, retrospective matched cohort study. We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Embolized AVMs treated with SRS were selected and categorized based on embolysate usage into Onyx embolization (OE+SRS) or non-Onyx embolization (NOE+SRS) cohorts. The 2 cohorts were matched in a 1:1 ratio using de novo AVM features for comparative analysis of outcomes. The matched cohorts each comprised 45 patients. Crude AVM obliteration rates were similar between the matched OE+SRS vs NOE+SRS cohorts (47%vs 51%; odds ratio [OR]=0.837, P=.673). Cumulative probabilities of obliteration were also similar between the OE+SRS vs NOE+SRS cohorts (subhazard ratio=0.992, P=.980). Rates of post-SRS hemorrhage, all-cause mortality, radiation-induced changes, cyst formation, and embolization-associated complications were similar between the matched cohorts. Sensitivity analysis for AVMs in the OE+SRS cohort embolized with Onyx alone revealed a higher rate of asymptomatic embolization-associated complications in this subgroup compared to the NOE+SRS cohort (36%vs 15%; OR=3.297, P=.034), but the symptomatic complication rates were similar. Nidal embolization using Onyx does not appear to differentially impact the outcomes of AVM SRS compared with non-Onyx embolysates. The embolic agent selected for pre-SRS AVM embolization should reflect both the experience of the neurointerventionalist and target of endovascular intervention.

Transvenous Coil Embolization of a Transverse-Sigmoid Sinus Dural Arteriovenous Fistula: 2-Dimensional Operative Video.

This case is a 66-yr-old woman with a 2-mo history of left-sided tinnitus. Workup with magnetic resonance angiography showed early opacification of the left sigmoid sinus and internal jugular vein as well as asymmetric and abundant opacification of the left external carotid artery branches, suspicious for a dural arteriovenous fistula (dAVF). Diagnosis was confirmed with cerebral angiography, consistent with a left-sided Cognard type I dAVF.1 Initial treatment attempt was made with transarterial 6% ethylene-vinyl alcohol copolymer (Onyx 18) embolization of feeders from the occipital and middle meningeal arteries. However, embolization was not curative and there was a recurrence of a highly bothersome tinnitus 3 wk following treatment. Angiography redemonstrated the transverse sinus dAVF with new recruitment arising from several feeders, including the left external carotid artery, middle meningeal artery, and superficial temporal artery, now Cognard type IIa. Definitive treatment through a transvenous coil embolization provided permanent obliteration of the fistula without recrudescence of symptoms on follow-up. In this video, the authors discuss the nuances of treating a dAVF via a transvenous embolization. Patient consent was given prior to the procedure, and consent and approval for this operative video were waived because of the retrospective nature of this manuscript and the anonymized video material.

Facial palsy after embolization with Squid\xae 12

Endovascular procedures with liquid embolic agents such as ethylene-vinyl alcohol (EVOH) copolymers are indicated before surgical treatment of cervical paraganglioma. Consequently, these agents are now available as low viscosity formulations, one of which is Squid 12, which are demonstrating superior vascular penetration. Cases of facial paralysis secondary to embolization of cervical vascular lesions with classic embolic agents have been reported in the English literature, however, this complication has not been described with new generation options such as Squid 12.We describe the case of a 43-year-old patient with a left neck carotid paraganglioma. Embolization was performed under general anaesthesia before surgical excision. In the immediate postoperative period, the patient developed total left facial palsy. Since the imaging tests (Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)) and neurological examination showed no involvement of additional cranial nerves (CN), we hypothesise that the main cause of this complication is ischemia of the vasa nervorum of CN VII secondary to embolization. Almost six months later, the patient continues to present total facial paralysis (Grade VI House-Brackmann facial paralysis scale), and palsy of the left CN X and XII as a complication secondary to surgical resection of the paraganglioma.This case is relevant since it is the first clinical case of permanent facial paralysis secondary to embolization with Squid 12.

Clean manufacturing of nanocellulose-reinforced hydrophobic flexible substrates

In this study, for the first time, a flexible substrate made from nanofibrillated cellulose in slurry form was fabricated using a hydrophobic polymer base. Previous studies practiced energy-intensive dry cellulose nanofiber dispersion to produce olefin-based composites: ecological and economic viability and industrial practicability are often neglected due to lack of innovation in cleaner production processes. In this context, a low-energy process, which is economically attractive and free of harmful organic solvents, was developed to achieve homogeneous distribution of nanofibrillated cellulose (NFC) in high-density polyethylene (HDPE). The dual interfacial role of the ethylene vinyl alcohol copolymer (EVAL – 48 mol% ethylene content) enhanced interfacial adhesion through the formation of nanobridges between HDPE and NFC. This method led to well-dispersed NFC in the HDPE, at 5 wt% NFC concentration, without the need of any chemical modification, solvent exchange or freeze-drying of NFC. The low interfacial tension between HDPE and EVAL and the presence of NFC in the ternary system led to enhanced dispersion during melt-mixing. Improvement in mechanical properties was achieved, with a 22% and 98% increase in the tensile strength and Young’s modulus, respectively, without significantly compromising thermal stability and barrier properties. The results shown in this study indicate a significant potential to replace synthetic and costly reinforcement additives while making nanofiber-reinforced flexible composites more sustainable and mechanically robust. In this context, a paradigm shift from fossil-based production technology to a cleaner production strategy such as those exemplified in this study will help achieve a circular production economy concept without hindering functionalities.

Transarterial Embolization of a Pelvic Arteriovenous Malformation Using Squid-12

We describe a complex congenital pelvic arteriovenous malformation (AVM) with multiple feeding arteries arising from branches sides of the right internal iliac artery and a dominant draining vein in a male patient. Transarterial embolization was performed in a patient with a congenital pelvic AVM, using Squid® 12 (Balt Extrusion, Montmorency, France) composed of ethylene vinyl alcohol (EVOH) copolymer dissolved in dimethyl sulfoxide (DMSO) and micronized tantalum powder for radiopacity. The patient showed prompt resolution of the symptoms and complete occlusion of the AVM which was observed on the CT and angiography control exams.

Bioplastic films with unusually good oxygen barrier properties based on potato fruit-juice.

In this study, the use of potato fruit juice (PFJ) to make plastic films is presented. PFJ is an interesting raw material as it is obtained as a by-product from the potato-starch industry. The films showed uniquely high oxygen barrier properties, and the PFJ material is therefore a potential replacement for the most commonly used, expensive and petroleum-based ethylene-vinyl alcohol copolymer (EVOH) as a barrier layer in future packaging. The films also exhibit good grease resistance. As expected for hydrophilic materials, they exhibited high water vapour transmission rate, which shows that they, as for EVOH, have to be laminated with hydrophobic polymers in food packaging. The films, having a glass transition temperature between −5 °C and 10 °C, showed elastic–plastic behaviour with stable crack growth.

Naked-Eye Food Freshness Detection: Innovative Polymeric Optode for High-Protein Food Spoilage Monitoring

An innovative smart label for naked-eye protein food freshness evaluation, based on polymeric sensing films, is presented. The proposed device consists of six miniaturized sensors, obtained by covalently binding six pH indicators, namely, m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), chlorophenol red (5), and bromophenol blue (6), to an ethylene vinyl alcohol (EVOH) copolymer. All of the synthetic procedures for the functionalized polymers and their application as smart labels are thoroughly described and discussed. The innovative sensors are characterized using several instrumental techniques (DSC, FT-IR, EDX, SEM, and UV–vis). The application of the array of sensors to poultry meat and cod fillet spoilage monitoring by naked-eye evaluation and modeling by PCA is presented. Eventually, the composition of the food and the food’s headspace in the selling tray is investigated and qualitatively characterized to validate the attributes of the array of sensors. The polymeric devices seem to be very promising for industrial scale-up, with the starting EVOH copolymer being extrudable and already employed in food packaging, as well as for large-scale application, being clear, efficient, and easy to read, even by untrained people.

Melt-Processed Bioactive EVOH Films Incorporated with Ferulic Acid.

In this work, antimicrobial and antioxidant films based on ethylene vinyl alcohol (EVOH) copolymer containing low amounts of ferulic acid (FA) were successfully developed by melt extrusion. Optically transparent films were obtained, and the presence of FA provided some UV blocking effect. The characterization of the thermal and barrier properties of the developed films showed that the addition of FA improved the thermal stability, decreased the glass transition temperature (Tg) and increased the water vapor and oxygen transmission rates when ferulic acid was loaded above 0.5 wt.%, associated with its plasticizing effect. Mechanical characterization confirmed the plasticizing effect by an increase in the elongation at break values while no significant differences were observed in Young’s modulus and tensile strength. Significant antioxidant activity of all active films exposed to two food simulants, 10% ethanol and 95% ethanol, was also confirmed using the 2,2-diphenyl-1-pricylhydrazyl (DPPH) free radical scavenging method, indicating that FA conserved its well-known antioxidant properties after melt-processing. Finally, EVOH-FA samples presented antibacterial activity in vitro against Escherichia coli and Staphylococcus aureus, thus showing the potential of ferulic acid as bioactive compound to be used in extrusion processing for active packaging applications.

Cost-Effectiveness Analysis of Transcatheter Arterial Embolization Techniques for the Treatment of Gastrointestinal Bleeding in the United States

ObjectivesGastrointestinal (GI) bleeding is a common medical emergency associated with significant mortality. Transcatheter arterial embolization first was introduced by Rosch et al as an alternative to surgery for upper GI bleeding. The clinical success in patients with GI bleeding treated with transcatheter arterial embolization previously has been reported. However, there are no cost-effectiveness analyses reported to date. Here we report cost-effectiveness analysis of N-butyl 2-cyanoacrylate glue (NBCA) and ethylene-vinyl alcohol copolymer (Onyx) versus coil (gold standard) for treatment of GI bleeding from a healthcare payer perspective. MethodsFixed-effects modeling with a generalized linear mixed method was used in NBCA and coil intervention arms to determine the pooled probabilities of clinical success and mortality with complications with their confidence intervals, while the Clopper-Pearson model was used for Onyx to determine the same parameters. Models were provided by the “Meta-Analysis with R” software package. A decision tree was built for cost-effectiveness analysis, and Microsoft Excel was used for probabilistic sensitivity analysis. The cost-effective option was determined based on the incremental cost-effectiveness ratio and scatter plots of incremental cost versus incremental quality-adjusted life-years. ResultsComparing scatter plots and incremental cost-effectiveness ratio results, –$1024 and –$1349 per quality-adjusted life-year for Onyx and N-butyl 2-cyanoacrylate glue, respectively, Onyx was the least expensive and most effective intervention. ConclusionOnyx was the dominant strategy regardless of threshold values. Our analyses provide a framework for researchers to predict the target clinical effectiveness for early-stage TAE interventions and guide resource allocation decisions.

Selective, Catalytic Oxidations of C–H Bonds in Polyethylenes Produce Functional Materials with Enhanced Adhesion

Summary The synthesis of functional and processable polyethylenes from simple vinyl monomers with controlled molecular weights and architectures has been a grand challenge of polymer chemistry. Post-polymerization modification of the homopolymers of ethylene is attractive for this purpose but has been hampered by the lack of efficient methods for the selective functionalization of C–H bonds in polyolefins. We report the selective, catalytic oxidation of C–H bonds in commodity polyethylenes with varying molecular weights and architectures. Remarkably, the functionalized materials, even at low levels of functionalization, exhibit physical properties that are absent in unmodified polyolefins, such as strong adhesion and the ability to be painted with common waterborne latex paint. Such observations indicate that selectively modified polyethylenes as described here may help to transform existing commodity plastics into more valuable and potentially more sustainable materials.