Ethylene Vinyl Alcohol Research Articles

Liquid embolic surface area as a predictor of chronic subdural hematoma resolution in middle meningeal artery embolization

BackgroundLiquid embolic agents (LEAs) such as ethylene vinyl alcohol (EVOH) are utilized for middle meningeal artery embolization (MMAE) for chronic subdural hematomas (cSDH). LEAs may be advantageous for MMAE as...

Coil or Plug-Assisted Ethylene Vinyl Alcohol Copolymer (EVOH) Thoracic Duct Embolization in the Treatment of Postoperative Chylothorax

Eleven patients (5 men, 6 women) with post-operative thoracic duct injuries and high output chylothorax were treated with thoracic duct embolization (TDE). Six patients underwent intraprocedural thoracic duct ligation at the time of original procedure. In all cases, the pleural fluid demonstrated high triglyceride levels (414 mg/dL; interquartile range [IQR], 345 mg/dL). Median daily (IQR) chest tube outputs before and after TDE were 900 mL (1,200 mL) and 325 mL (630 mL), respectively. Coil- or plug-assisted ethylene vinyl alcohol (EVOH) copolymer was used as embolic agent in all patients. Technical and clinical success rates were 100% and 82%, respectively. Nontarget venous embolization of EVOH copolymer was not identified on subsequent imaging.

Non-target embolic events during prostatic embolization with ethylene vinyl alcohol copolymer (EVOH)

BackgroundThis study evaluated nontarget embolization (NTE) during prostatic artery embolization (PAE) with ethylene vinyl alcohol copolymer (EVOH).ResultsTen consecutive patients treated by PAE with EVOH for the presence of disabling benign prostatic hyperplasia (BPH)-related lower urinary tract symptoms (LUTS) between June 22 and January 2023 were included in this prospective study. The inclusion criteria were as follows: LUTS attributed to BPH, LUTS duration ≥ 6 months, failure to respond to standard pharmacotherapy, IPSS > 18 or QoL score > 2, and prostate volume > 40 mL. Embolization was performed under general anaesthesia. According to established techniques, a microcatheter was positioned bilaterally within the feeding arteries, and EVOH was injected slowly under X-ray control. Unenhanced pelvic computed tomography scans were carried out before and after embolization to assess the NTE. The safety of the prostatic embolization procedure with EVOH was assessed by collecting adverse effects over 3 months of evaluation that included the International Prostate Symptom Score (IPSS) and quality of life (QoL) score.-up evaluations, occurring at 3, 6, and 12months, included International Prostate Symptom Score.Bilateral PAE was technically successful in 9 patients, and unilateral injection was performed in one patient. The postoperative scanner showed a distribution of the embolization material in the two lobes of the prostate in all patients. The procedure time varied from 120 to 150 (mean: 132) minutes. Eight out of 10 patients developed pollakiuria within 24 h; none of the patients had postoperative pain. Two patients required catheterization for postoperative urinary retention. Catheters were removed successfully at the end of the first day for one of these patients and on the tenth day for the other. At the 3-month follow-up, patients showed significant improvement in the International Prostate Symptom Score (n = 10; mean = -11,5; P < 0.01) and quality of life score (n = 10; mean = -3,40; P < 0.01). Only one patient presented one asymptomatic muscular NTE.ConclusionsPAE with EVOH is safe, effective, and associated with few NTEs and no postoperative pain. Prospective comparative studies with longer follow-ups are warranted.Trial registrationIDRCB, 2021-AO29-56–35. Registered 27 May 2022, http://clinicaltrials.gov/study/NCT05395299?cond=embolization&term&rank=1.

Removal of volatile organic compounds and odorous compounds for multilayer packaging recyclates using heated air purging

Multilayer packaging (MLP) is made from Polyethylene terephthalate (PET), Polyethylene (PE), Polypropylene (PP), Ethylene vinyl alcohol (EVOH), Polyvinyl chloride (PVC), and tie layer materials. MLPs are either burned or dumped in landfills after their use, which causes many hazards to humans and the environment. MLPs are recycled in recycling facilities and converted into pellets to reuse them. However, the MLPs are strongly contaminated by volatile organic compounds and odorous compounds, which prevents their use in high-end applications, i.e., cosmetics, packaging, etc. In the research work, a remediation strategy is proposed to reduce VOCs and odorous compounds from MLP recyclates using heated air oven treatments, which are also easily scalable to pilot and industrial scales. VOCs and odor are reduced significantly without compromising the product’s mechanical, thermal, and other properties.

Investigation on the mechanical properties of composite fiber membranes with different concentration of EVOH/Ag/AC

There are several requirements of properties for filter material: adsorption, antibacterial property, air permeability, mechanical properties, etc. Electrospinning technology is a recognized method with great potential to fabricate nanofiber membrane. In particular, the mechanical properties need to be well understood for applications where the membrane is subjected external loading, e.g. tension forces which could be monotonic or cyclic. In this study, the mechanical properties of ethylene vinyl alcohol (EVOH) nanofiber membranes loaded with silver nanoparticles (AgNPs) and activated carbon (AC) were investigated in detail. Static load tensile tests were carried out for nine groups of membranes with different mass fraction of EVOH (7.5%, 10%, 12.5%) and concentration ratios of Ag/AC (2:5, 1:1, 5:2). The results showed that the tensile strength and Young’s modulus of this membrane would increase with the increase of EVOH mass fraction. When the mass fraction of EVOH is 7.5% and the concentration ratio of Ag/AC is 1:1, the fracture strength of nanofiber membrane was the highest, which was 0.1545 MPa.

Environmental Consequences of Shelf Life Extension: Conventional versus Active Packaging for Fresh-Cut Salads

The use of active coatings in fresh food packaging is an innovative technique that optimizes the functional properties of films, resulting in a longer product shelf life and reduced food waste. But, which is more sustainable, active packaging (AP) or conventional packaging (CP) for the packaging of fresh-cut products? To answer this research question, this study analyzes the environmental performance of AP during its life cycle for packaging a minimally processed fresh salad mix compared with CP, in terms of its manufacture and use. The AP is a bag that includes a bioactive component, oregano essential oil (OEO), which is an inhibitor of microbial growth, incorporated into an ethylene vinyl alcohol copolymer (EVOH) coating on a conventional polypropylene (PP) film. To this end, a Life Cycle Assessment (LCA) was carried out based on ISO 14040 and 14044, using the ReCiPe methodology. The results showed that using active packaging has a beneficial affect, reducing the amount of produced food by 30% compared with conventional packaging over the same period. The reductions in the studied impact categories were greater than 50% in most of them, with a 62% reduction in global warming. The proposed sensitivity analysis showed the difference between the disposal or treatment of waste generated by the packaging production process and the packaged product, indicating that this step is of great importance for the environmental impacts and sustainability of this process. In 80% of the scenarios analyzed, the AP achieved better results than the CP in terms of damage categories.

Resilient and Tough Conductive Polymer Hydrogel for a Low-Hysteresis Strain Sensor.

Conductive polymer hydrogels are vital in strain sensors, yet achieving high resilience and toughness is a challenge. This study employs a prestretch method to engineer a tough conductive polymer hydrogel with sufficient resilience. Initially, a blend film of polyvinylalcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH) is prepared through solution casting, followed by a swelling process to form a PVA-EVOH hydrogel. This hydrogel, with PVA crystallites as crosslinking points, exhibits high toughness. The hydrogel is then immersed in pyrrole and ferric chloride solutions for in-situ polymerization of polypyrrole (PPy), creating a conductive PPy/PVA-EVOH hydrogel. Finally, a 200% prestretch is applied, breaking short chains within the network, eliminating energy dissipation at low strains. This results in a hydrogel with a 100% elastic deformation range, while maintaining high fracture toughness (1700Jm-2 ). The prestretched PPy/PVA-EVOH hydrogel functions as a strain sensor with low hysteresis, providing consistent strain measurements during loading and unloading. This outperforms the non-prestretched sample, which shows inconsistent responses between stretching and releasing.

Facile preparation of composite antimicrobial Al2O3 particles

Antimicrobial particles can inhibit or kill microorganisms, and have been widely used as antimicrobial filler in coatings and polymers. Herein, we present a facile method to prepare antimicrobial alumina particles by grafting epoxypropyl dimethydodecyl ammonium chloride (EPDDMAC) on γ-Al2O3 or ethylene–vinyl alcohol copolymer (EVOH) coated α-Al2O3.The results show that EPDDMAC can be grafted on γ-Al2O3 or EVOH-coated α-Al2O3 particles effectively, and the grafting rate rises with the increased EPDDMAC amount. The grafted composite particles exhibit excellent antibacterial properties against Escherichia coli and display great potential in antibacterial applications.

Embolization of brain arteriovenous malformations with squid co-polymer embolic material: Initial experience

ObjectiveTo analyze the safety and effectiveness of the ethylene-vinyl alcohol copolymer (EVOH) liquid embolic agent Squid (Emboflu, Switzerland) for the treatment of brain arteriovenous malformations. Materials and proceduresBetween April 2015 and July 2017, 46 embolization treatments for brain arteriovenous malformations (BAVM) were performed in 25 patients using two Squid formulations (18 and 12). Six female and 19 male patients with a mean age of 34 years (range, 9–62 years) were included. A total of 46 procedures were performed. The BAVMs were classified as Spetzler-Martin grade II in 4 procedures, III in 27 procedures, and 1V in 15 procedures. Among the 25 patients, 15 presented with hemorrhage, 5 with seizures, and 5 with headache and neurology. The BAVMs were located in the temporal lobe in 5 patients, parietal lobe in 7 patients, frontal lobe in 3 patients, posterior fossa in 6 patients, basal ganglia in 3 patients, and parasagittal lobe in 1 patient. ResultsThe obliteration rate of the BAVMs ranged from 10% to 100%, with a mean of 33%. Most patients underwent their first or second embolization procedure. Four patients (8%) developed intracranial bleeding post-procedure, with one death (2%). One patient (2%) experienced a seizure during the procedure; however, no intracranial bleeding was observed. Seven patients (15%) experienced perforations during catheter manipulation. One case (2%) of a fractured catheter was recorded, but no significant complications were observed. The average volume of copolymer injected was 0.6 ​ml per nidus. Thirteen procedures used the Squid-12 formulation, 29 procedures used the Squid-18 formulation, and 3 procedures used a combination of Squid-12 and -18 formulations. ConclusionSquid is a safe and effective embolic agent for treating BAVMs.

Repair of Isthmocele Following Embolization of Uterine Arteriovenous Malformation

To present a case of concurrent uterine arteriovenous malformation (AVM) and isthmocele, treated with ethylene vinyl alcohol copolymer (EVAC) embolization of the AVM followed by robotic isthmocele repair. A stepwise video demonstration with narration. A tertiary care academic hospital. Patient is a 37-year-old with one previous cesarean section who presented with persistent heavy vaginal bleeding after a dilation and evacuation procedure. Imaging showed evidence of an isthmocele and an iatrogenic uterine AVM secondary to the dilation and evacuation procedure. Both entities are morbid conditions associated with significant operative blood loss. Embolization of the acquired AVM was first performed to stabilize bleeding. In addition, owing to the extensive uterine defect and history of infertility, surgical repair of the isthmocele was recommended. A multidisciplinary approach combining interventional radiology and gynecologic surgery expertise, implementing several strategies to minimize blood loss: 1. Image-guided uterine AVM embolization with EVAC [1] 2. Hysteroscopic identification of isthmocele and residual EVAC in the cavity, with fluorescence transillumination to clearly delineate isthmocele borders 3. Robot-assisted laparoscopic approach for bladder flap creation, as well as retroperitoneal space dissection to skeletonize uterine arteries 4. Transient occlusion of uterine arteries using vascular clamps to minimize operative blood loss given the isthmocele size and its proximity to the left uterine artery 5. Resection of the isthmocele and removal of residual intracavitary EVAC 6. Multilayer, bidirectional hysterotomy closure and vascular clamp removal to restore uterine blood supply CONCLUSIONS: Successful multidisciplinary treatment of concurrent uterine AVM and isthmocele. Cesarean delivery at 36 to 37 weeks' gestational age was recommended for future deliveries.

Evaluating the safety and efficacy of transvenous embolization for brain arteriovenous malformation: A systematic review and meta-analysis.

Transvenous embolization is a potential therapy for brain arteriovenous malformation, involving the use of microcatheters to guide an ethylene vinyl alcohol coil for vessel occlusion. However, the safety and efficacy of transvenous embolization are not fully established. To evaluate the safety and efficacy of transvenous embolization for brain arteriovenous malformation. A systematic review of the literature of studies investigating the safety and efficacy of transvenous embolization for brain arteriovenous malformation was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Databases, including PubMed, Cochrane Library, Web of Science, and Embase were queried. In the final analysis of 16 studies involving 368 brain arteriovenous malformation cases who received transvenous embolization, the complete occlusion was achieved in 91% (95% CI: 88%, 94%; I2 = 43%, p = 0.04) of cases. The overall rate of good outcomes after discharge was high at 89% (95% CI: 82%, 95%; I2 = 60%, p < 0.01). Ischemic complications were reported in 1% of cases (95% CI: 0%, 2%; I2 = 0%, p = 0.96), while hemorrhagic complications occurred in 6% of cases (95% CI: 3%, 8%; I2 = 8%, p = 0.37), and technical complications rate of 8% (95% CI: 4%, 11%; I2 = 8%, p = 0.36). Finally, only one death was related to the procedure. Transvenous embolization for brain arteriovenous malformation shows promising safety and effectiveness, with low mortality, a considerable rate of positive outcomes, and a relatively low incidence of complications. The majority of patients achieved complete occlusion, indicating transvenous embolization as a potential option, especially for challenging deep-seated lesions.

Cell culture design for homogeneous proliferation of cells in three-dimensional nonwoven polymer scaffolds

The objective of this study is to establish strategies to uniformly proliferate cells in a three-dimensional nonwoven polyethylene terephthalate (PET)/ethylene vinyl alcohol (EVOH) scaffold by simple adjustments in seeding and culture methods and the scaffold design. The combined dynamic and static seeding (intermittent agitations at 300 rpm with 1 h interval) resulted in the highest seeding efficiency (71%) comparing to the static and continuous agitating seeding methods. Cell-attached scaffolds were cultivated under different conditions. The stirring culture permitted cells to proliferate to a significantly greater extent than the static or agitating cultures, although faster cell proliferation in the outer region of the scaffold was observed. Next, based on this observation, scaffolds were opened with holes to alleviate the cell aggregation. The effect of hole size and number of scaffolds on the distribution of cells proliferated in the scaffold was evaluated. Two of 1-mm holes showed to be an optimal adjustment to allow cells to proliferate in a homogeneous manner. After 14 days culture, both of the holes were filled by cells proliferated with a fourfold increase in the cell number. The cell viability in the scaffolds was also high upon evaluating the live/dead and 3[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) staining examinations. Different cell types of 3T3-L1, C3H/10T1/2, and KUM6 cells showed similar behavior of cell proliferation and distribution in the scaffold, indicating the applicability of the established procedure. It is concluded that the nonwoven PET/EVOH scaffold serves as a potential cell culture substrate for an efficient cell proliferation.

Transplantable cell-encapsulation device using a semipermeable ethylene-vinyl alcohol copolymer membrane in a mouse diabetic model

Cell-based therapy is an attractive approach, and encapsulation of therapeutic cells is a promising strategy because it prevents immune responses and allows transplanted cells to be retrieved in case of dysfunction. Bioartificial pancreas, in which insulin-secreting cells are encapsulated in a semipermeable membrane bag, is a new class of medical device for treating type-I diabetes. In this study, we developed a macroencapsulation device in which the pancreatic beta cell line MIN6 was encapsulated in a semipermeable bag made of an ethylene-vinyl alcohol copolymer membrane. Invitro evaluation of ATP and insulin levels revealed that MIN6 cells grown in Matrigelwithin the device secreted insulin in response to glucose levels. Transplantation of the device lowered blood glucose levels for 30 days in diabetic mice. Histological observation revealed that MIN6 cells formed spheroids in Matrigel, and no host cells were detected within the device. Blood levels of inflammatory cytokines in the transplanted mice were similar to those in non-transplanted mice, and antibody levels in the device were lower than those in the intraperitoneal fluid. These results suggest that the semipermeable ethylene-vinyl alcohol copolymer membrane developed in this study is useful for cell encapsulation in cell-based therapies, including beta-cell macroencapsulation for type-1 diabetes.

Computational modeling and simulation for endovascular embolization of cerebral arteriovenous malformations with liquid embolic agents

Endovascular embolization of arteriovenous malformations (AVMs) in the brain usually requires injecting liquid embolic agents (LEAs) to reduce blood flow through the malformation. In clinical procedures, the feeding artery into which the LEAs are injected, and the amount of LEAs needs to be carefully planned preoperatively. Computational fluid dynamics can simulate the injecting process of LEAs in nidus and evaluate the therapeutic effects of different procedures preoperatively. Applying a porous media model avoided the difficulties of geometric modeling of AVMs, and the complex vascular network structure within the nidus was reproduced. The multi-phase flow was applied to simulate the interaction between LEAs and blood. The viscosity of LEAs is determined by the concentration of its solute ethylene-vinyl alcohol copolymer (EVOH). The diffusion process of the solvent dimethyl sulfoxide (DMSO) was calculated by solving the species transport equation. The coagulation of LEAs was simulated by constructing the relationship between the concentration of EVOH and viscosity. The numerical simulation method of LEAs for injection and coagulation was tested on two patient-specific AVMs. The calculations predicted the flow direction of the LEAs in the nidus. The morphology of the injected LEAs could be well visualized by 3D rendering. Quantitative analysis was conducted, including flow rate changes at the feeding arteries and draining veins. The embolization process of AVMs with LEAs can be simulated by computational fluid dynamics (CFD) methods to show the therapeutic effects of different embolization procedure planning, the optimal treatment plan can be determined.

Crystallization Kinetics of Ethylene Vinyl Alcohol Copolymer Revealed by Fast Scanning Chip Calorimetry Analysis

Crystallization Kinetics of Ethylene Vinyl Alcohol Copolymer Revealed by Fast Scanning Chip Calorimetry Analysis

Endovascular Treatment of Visceral Artery Pseudoaneurysms with Ethylene-Vinyl Alcohol (EVOH) Copolymer-Based Non-Adhesive Liquid Embolic Agents (NALEAs).

Background and Objectives: Treatment of visceral artery pseudoaneurysms (VAPs) is always indicated regardless of their diameters, as their risk of rupture is significantly higher than that of visceral artery aneurysms. The invasiveness of surgery and its associated complications have led to a shift in favor of radiological interventions as the initial treatment of choice. However, there are still some unanswered questions on endovascular treatment of VAPs regarding the optimal endovascular technique and the efficacy and safety outcomes. The purpose of this multicenter study was to retrospectively evaluate the effectiveness and safety of endovascular treatment of visceral pseudoaneurysms using Ethylene-Vinyl Alcohol (EVOH) Copolymer-Based Non-Adhesive Liquid Embolic Agents (NALEAs). Materials and Methods: Consecutive patients who underwent endovascular embolization with EVOH-based NALEAs for visceral artery pseudoaneurysms between January 2018 and June 2023 were retrospectively evaluated. Results: 38 embolizations were performed. Technical success was achieved in all patients. The clinical success rate was high (92.1% overall), with no significant differences between ruptured and unruptured VAPs (p = 0.679). Seven patients (18.4%) experienced procedure-related complications, related to one case of non-target embolization, four splenic abscesses due to end-organ infarction, and two femoral pseudoaneurysms. The rates of procedure-related complications, end-organ infarction, and vascular access-site complications did not significantly differ between ruptured and unruptured VAPs (p > 0.05). Conclusions: Both ruptured and unruptured visceral pseudoaneurysms can be effectively and safely treated with NALEA-based endovascular embolization. We suggest considering the use of NALEAs, particularly in specific clinical cases that highlight their advantages, including patients with coagulopathy, fragile vessels, and embolization targets that are located at a considerable distance from the microcatheter tip and are otherwise difficult to reach.

Lidocaine for headache prevention during chronic subdural hematoma embolization.

Middle meningeal artery embolization (MMAE) for the management of chronic subdural hematomas (CSDH) with ethylene vinyl alcohol (EVOH) causes an evident patient discomfort due to meningeal nociceptors stimulation. The aim of this study was to assess safety and efficacy of intra-arterial lidocaine (IAL) before MMAE of CSDH with EVOH. We analyzed all consecutive patients with bilateral CSDH undergoing MMAE with EVOH. We used a monolateral IAL injection, with casual allocation. We assessed the headache felt by patients during embolization with the visual analog scale (VAS) and compared scores obtained after embolization of both sides. We followed the STROBE guidelines for case-control studies. Paired t-test and χ2 test were used to compare the distribution of variables in IAL vs control group. Between September 2021 and March 2023, 32 patients underwent bilateral MMAE with EVOH for a CSDH. Lidocaine treatment resulted in a substantially lower VAS score compared to the control group (median 3 vs 7, p < 0.001), with no substantial side effect. Compliance also benefited from lidocaine administration. In patients with CSDH undergoing MMAE, IAL seems to reduce pain sensation associated with EVOH injection and to increase patients' compliance during treatment.

Extensive Characterization of Alginate, Chitosan and Microfibrillated Cellulose Cast Films to Assess their Suitability as Barrier Coating for Paper and Board.

The vast amount of synthetic polymers used in packaging is putting a strain on the environment and is depleting finite, non-renewable raw materials. Abundantly available biopolymers such as alginate, chitosan and microfibrillated cellulose (MFC) have frequently been suggested in the literature to replace synthetic polymers and their barrier properties have been investigated in detail. Many studies aim to improve the properties of standalone biopolymer films. Some studies apply these biopolymers as barrier coatings on paper, but the solids content in most of these studies is quite low, which in turn would result in a high energy demand in industrial drying processes. The aim of this study is to suggest a laboratory procedure to investigate the suitability of these biopolymers at higher and such more industrially relevant solids content as potential coating materials for paper and board in order to improve their barrier properties. First, biopolymer solutions are prepared at a high solids content at which the viscosity at industrially relevant higher shear rates of 50,000 s-1 (1000 s-1 for MFC) is in the same range as a synthetic reference material (in this case ethylene vinyl alcohol EVOH) at 10 wt%. These solutions are analyzed regarding properties such as rheology and surface tension that are relevant for their coatability in industrial coating processes. Then, free-standing films are cast, and the films are characterized regarding important properties for packaging applications such as different surface, mechanical and barrier properties. Based on these results suitable biopolymers for future coating trials can be easily identified.

Middle Meningeal Artery Embolization for Subdural Hematoma: An Institutional Cohort and Propensity Score-Matched Comparison with Conventional Management

BackgroundThe treatment of non-acute subdural hematoma (NASDH) is challenging due to its high recurrence rates and comorbidities of mostly elderly patients. Middle meningeal artery embolization (MMAE) recently emerged as an alternative to surgery in the treatment of NASDH. ObjectiveTo describe a single center’s experience of MMAE with Onyx for NASDH and compare it to a surgically treated historical cohort. MethodsWe performed a retrospective analysis of patients undergoing MMAE for NASDH from 2019 to 2021. MMAE was performed with ethylene vinyl alcohol copolymer (Onyx). Comparisons were made with a historical cohort from 2010 to 2018 who underwent surgical evacuation only, before and after propensity score matching. Outcomes were assessed clinically and radiographically. ResultsWe included 44 consecutive patients (55 MMAEs) who underwent MMAE, with a median follow-up of 63.5 days. Twenty-four NASDHs underwent upfront embolization, 17 adjunctive, and 14 for recurrence after prior surgical evacuation, with no significant differences in hematoma and mRS reduction between them. Two patients died during hospitalization and 2 during follow-up, unrelated to the procedure. Mean SDH thickness decreased by 48.3% ± 38.1% (P < 0.001) on last follow-up, which did not correlate with the amount of Onyx injected. Six (13.6%) patients required surgical rescue after embolization. There were no procedure-related complications. The mean modified Rankin Scale (mRS) on admission was 2.8 ± 1.5, which decreased significantly to 1 [1,4] at the last follow-up (P = 0.033). The MMAE (41 hematomas; upfront and adjunctive embolization) and Surgical Evacuation-only (461 hematomas) cohorts were balanced with propensity score mathing. Matching was successful for 41 MMAE and 41 surgical-only hematoma pairs, and only hypertension remained significantly different between the two groups, but there was no significant difference in any outcome. ConclusionMMAE for NASDH seems safe and effective in appropriately selected patients, non-inferior to surgery, and may become a minimally-invasive alternative. Given our encouraging results, large-scale clinical randomized trials are warranted.

Prediction of water vapor permeation and desiccant saturation in vacuum insulation panels with a glass fiber core

The permeation of dry air in vacuum insulation panels (VIPs) with a glass fiber core has been often prevented using laminated films with metallized ethylene vinyl alcohol copolymer (EVOH) layers; meanwhile, desiccants are incorporated to control the increasing pressure due to the permeation of water vapor. Previously proposed models can predict the changes in long-term performance caused by dry-air permeation, but a method that accounts for water-vapor permeation and desiccant saturation has not been reported before. Predicting the long-term performance of VIPs when exposed to outdoor temperature and humidity is essential for using it as a building insulation material. In this study, we investigated the dependence of the water-vapor transmission rate (WVTR) of metallized EVOH film on temperature and relative humidity, and the effect of ambient water-vapor pressure on the WVTR of metallized EVOH film. To reduce the measurement time of WVTR, we developed a new measurement method using a small sensor device and confirmed that its accuracy is equivalent to that of the conventional method. We measured the water-vapor transmission coefficient of glass fiber core VIPs under various temperature and humidity conditions using this measurement method. For the same water-vapor pressure, the amount of transmission significantly depended on the temperature and humidity conditions. Therefore, the WVTR of metallized EVOH films should be more concerned with the effect of relative humidity than that of the water vapor pressure of the ambient air. Based on these results, a new model that accounts for desiccant saturation was proposed and validated based on the conventional model to predict the long-term performance under permeation of mixed gases. The new model accurately evaluated the long-term performance of VIPs with confirmed desiccant saturation, supporting the long-term performance of glass fiber core VIPs.