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To manufacture, feature and analyze the potential of materials to be used as raw material for drug delivery systems for the treatment of overactive bladder. Four distinct mixtures of oxybutynin and polymers ethylene vinyl acetate (EVA) and high-density polyethylene (PE) were prepared via compression molding and hot melt extrusion. The materials were characterized regarding their physicochemical and mechanical properties as well as drug release potential. Promising results were obtained in which the release of oxybutynin was observed for more than 250 days from both EVA and HDPE matrices. The obtained data demonstrate it is possible to manufacture HDPE- and EVA-based samples with the incorporation of oxybutynin, and the EVA samples presented an adequate release profile. The results are promising for the development of an intravesical device with drug delivery, especially because super dose risk is extinguished when considering the release from a monolithic release system. [ABSTRACT FROM AUTHOR]

A nickel-containing metal-organic framework material (MOF-74), piperazine pyrophosphate (PPAP), and a triazine charring foaming agent (CFA) were homogeneously mixed at a certain mass ratio and then incorporated into etrr ylene-vinyl-acetate resin (EVA). The performance of the resultant EVA composites was characterized. When 19 wt% PPAP/CFA (IFR) was introduced with a mass ratio of 3:1, the EVA composites obtain a UL 94 V-0 classification in the vertical burning tests as well as a limiting oxygen index (LOI) of 26. 9 %. IFR was mixed with MOF-74 at a mass ratio of 97:3, and then the resultant mixture was introduced into EVA, the resulting composites achieved a UL 94 V~0 classification along with an LOI of 27. 1 % at a IFR/MOF-74 loading of 18 %. The cone calorimetry test results indicated that the addition of MOF-74 effectively inhibited the release of heat, smoke and carbon monoxide during combustion. It was demonstrated that MOF-74 generated an excellent synergistic flame-retardant effect. Meanwhile, the compatibility between the flame-retardant additives and polymer matrix was improved. Consequently, the mechanical properties of the resultant flame-retardant EVA composites were well maintained. [ABSTRACT FROM AUTHOR]

ABSTRACT Background/Objectives Materials and Methods Results Conclusion The use of different models for the fabrication of custom‐fit mouthguards (MTGs) can affect their final thickness, adaptation, and shock‐absorption properties. This study aimed to evaluate the adaptation, thickness, and shock absorption of ethylene‐vinyl acetate (EVA) thermoplastic MTGs produced using conventional plaster or three‐dimensional (3D) printed models.A typical model with simulated soft gum tissue was used as the reference model to produce MTGs with the following two different protocols: plast‐MTG using a conventional impression and plaster model (n = 10) and 3DPr‐MTG using a digital scanning and 3D printed model (n = 10). A custom‐fit MTG was fabricated using EVA sheets (Bioart) plasticized over different models. The MTG thickness (mm), internal adaptation (mm) to the typodontic model, and voids in the area (mm2) between the two EVA layers were measured using cone‐beam computed tomography images and Mimics software (Materialize). The shock absorption of the MTG was measured using a strain‐gauge test with a pendulum impact at 30° with a steel ball over the typodont model with and without MTGs. Data were analyzed using one‐way analysis of variance with repeated measurements, followed by Tukey's post hoc tests.The 3DPr‐MTG showed better adaptation than that of the Plast‐MTG at the incisal/occlusal and lingual tooth surfaces (p < 0.001). The 3DPr‐MTG showed a thickness similar to that of the Plast‐MTG, irrespective of the measured location. MTGs produced using both model types significantly reduced the strain values during horizontal impact (3DPr‐MTG 86.2% and Plast‐MTG 87.0%) compared with the control group without MTG (p < 0.001).The MTGs showed the required standards regarding thickness, adaptation, and biomechanical performance, suggesting that the number and volume of voids had no significant impact on their functionality. Three‐dimensional printed models are a viable alternative for MTG production, providing better adaptation than the Plast‐MTG at the incisal/occlusal and lingual tooth surfaces and similar performance as the MTG produced with the conventional protocol. [ABSTRACT FROM AUTHOR]

Background/Aims: The study aimed to assess the surface characteristics of sports mouthguards under mechanical stresses during cleaning, either by brushing or immersion in disinfectant solutions. Material and Methods: Ethylene‐vinyl acetate samples, 4 mm thick, were randomly assigned to cleaning methods: control (C—no cleaning), brushing with water (B.W), brushing with neutral liquid soap (B.S), brushing with toothpaste (B.T), immersion in distilled water for 10 min (I.W), immersion in 2.25% sodium hypochlorite solution for 10 min (I.SH), and immersion in sodium bicarbonate solution for 5 min (I.SB). All cleaning methods were applied for 28 days. Surface roughness average (Ra) and wettability were measured at baseline for the control group (n = 9), and after cleaning for all the other groups. Results: One‐way ANOVA with Tukey tests (5% significance) indicated significant differences among groups (p <.05). The I.SB group had higher surface roughness than B.S and B.T (p <.05). B.W showed the lowest wettability, significantly lower than B.T, I.W, and I.SB (p <.05). I.SB exhibited the highest wettability, significantly different from sodium hypochlorite, neutral liquid soap, brushing with water, and control groups (p <.05). The sodium bicarbonate immersion group (I.SB) demonstrated greater statistical variation, displaying higher susceptibility to aging compared to brushing with neutral liquid soap. Conclusion: Cleaning mouthguards with a toothbrush, water, and neutral liquid soap emerged as the most promising method, causing minimal surface changes in the material. [ABSTRACT FROM AUTHOR]

It is known that the bonding strength of the aggregate/cement interface affects the overall durability of concrete. However, whether the modification of ethylene vinyl acetate (EVA) copolymer affects the interface interaction between aggregates and cementitious materials is unclear. This study analyzed the interface's static structure, dynamic characteristics, and binding energy. The interaction mechanisms between acid and alkali aggregates and hydrated calcium silicate and the modification effect of EVA were compared. The calculation results of relative density distribution and radial distribution function verified the difference in the structure of EVA-modified acidic or alkaline interfaces. EVA polymer chains significantly blocked the flow of Ca atoms in CaO at the CaO/C-S-H interface and weakened the van der Waals effect at the interface. The mean square displacement and time correlation function analysis indicate that all unmodified interfaces have stable interface structures. After EVA modification, the stability of CaCa-HW decreased significantly, hindered the generation of hydration products, and verified the weak Ca atom transport at the CaO/C-S-H interface. In addition, the adhesion energy of SiO2/C-S-H and CaO/C-S-H after EVA modification decreased by 6% and 14.8%, respectively, quantifying the modification effect of EVA. [ABSTRACT FROM AUTHOR]

Mastitis is an infectious disease condition resulting in inflammatory reaction which occurs when a large number of leukocytes migrate into the mammary gland. Mastitis causes significant financial losses for the global dairy industry. The present study aimed at development of transdermal film comprising of Azadirachta indica extract for treatment of mastitis, which is economical, safe and will not emerge multidrug resistance amongst pathogens. Azadirachta indica extract was prepared by sonication method. The extract was evaluated for minimum inhibitory concentration against gram-positive and gram-negative organisms. Transdermal films with Azadirachta indica extract were prepared with ethylene vinyl acetate and polyvinyl acetate then subjected for the physical characterization, drug content, In vitro dissolution, tensile strength and antibacterial activity. The minimum inhibitory concentration of extract displayed 5mg/ml. Based on quantification of azadirachtin by UV spectrophotometer 100 mg of extract was incorporated in each transdermal film. Transdermal films of Azadirachta indica extract possessed desirable physical properties, and exhibited the drug release of 91.54% in 8 hours. Transdermal film of Azadirachta indica showed sensitivity with a zone of inhibition of 19mm, 16mm, 19mm and 22mm against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa respectively. Data obtained revealed that transdermal films of Azadirachta indica extract exhibited good drug release profile and desirable physical properties, with good antibacterial activity. The present work reveals that transdermal film of Azadirachta indica extract can be considered for the treatment of mastitis. [ABSTRACT FROM AUTHOR]

The overactive bladder is a condition characterized by a sudden urge to urinate, even with small volumes of urine present in the bladder. The current treatments available for this pathology consist on conservative approaches and the continuous administration of drugs, which when made by conventional methods has limitations related to the first pass metabolism, bioavailability, severe side effects, and low patient adherence to treatments, ultimately leading to low effectiveness. Within this context, the present work proposes the design, manufacture, and characterization of an intravesical implant for the treatment of overactive bladder pathology, using EVA copolymer as a matrix and oxybutynin as a drug. The fabrication of devices through two manufacturing techniques (extrusion and additive manufacturing by fused filament fabrication, FFF) and the evaluation of the implants through characterization tests was proposed. The usability and functionality were evaluated through simulated insertion of the device/prototype in a bladder model through catheter insertion tests. The safety and effectiveness of the devices was investigated from mechanical testing as well as drug release assays. Drug release assays presented a burst release in the first 24 h, followed by a release of 1.8 and 2.8 mg/d, totalizing 32 d. Mechanical tests demonstrated an increase in the stiffness of the specimens due to the addition of the drug, showing a change in maximum stress and strain at break. The released dose was higher than that usually presented when considering the oral administration route, showing the optimization of the development of this implant has the potential to improve the quality of life of patients with overactive bladder. [ABSTRACT FROM AUTHOR]

Aging of a cable polymer sheath's composition based on ethylene vinyl acetate was studied. During accelerated tests in the temperature range from 110 to 150°C, changes in the mechanical and thermal properties of elastomer samples were monitored. Condition of samples was monitored by measuring elongation at break (EB), elastic modulus at indentation (EMI), oxidative induction temperature, and oxidative induction period. An empirical kinetic equation reflecting three stages of elastomer aging—cross linking, inhibited oxidation, and uninhibited oxidation—was used to model elongation at break during aging. Confirmation of the developed model was obtained, and a forecast of the shell elastomer tensile strain at break was presented for the maximum operating temperature of low-voltage cables specified in the technical documents. The possibility of nondestructive testing and prediction of the condition of these cables by the EMI value is shown. A system of models related by general physical parameters has been developed, which includes both models describing the change in mechanical properties during thermal aging and thermo-oxidative parameters of a polymer composition based on ethylene vinyl acetate. [ABSTRACT FROM AUTHOR]

In this paper, melt blending process was adopted to add nanocalcined kaolin into flame-retardant grade ethylene vinyl acetate (EVA) copolymer, and thus, flame-retardant ethylene vinyl acetate nano-composite with high insulation property was prepared. The structure, mechanical properties and electrical properties of ethylene vinyl acetate composite were tested and characterized. The results of the tensile test showed that the tensile strength of the composite was reduced and the tensile modulus of the composite was increased after the addition of calcined kaolin; the results of the electrical properties test showed that the breakdown strength first increased and then decreased along with more addition of calcined kaolin, and the dielectric loss first decreased and then increased along with more addition of calcined kaolin, while the volume resistivity showed a continuous rising trend. The results of small-angle X-ray scattering test showed that the addition of calcined kaolin reduced the expansion range of EVA molecular chain, which was the major reason to cause the variation in electrical properties. [ABSTRACT FROM AUTHOR]

Abstract The strongly growing interest in digitalizing society requires simple and reliable strain‐sensing concepts. In this work, a highly sensitive stretchable sensor is presented using a straightforward and scalable printing method. The piezoresistive sensor consists of conductive core–shell microspheres embedded in an elastomer. As the elastomer, ethylene vinyl acetate (EVA) is employed as an efficient and cost‐effective alternative compared to polydimethylsiloxane (PDMS). EVA allows for a significantly lower percolation threshold and low hysteresis compared with PDMS. Using 35 µm microspheres, a detection limit of 0.01% is achieved. When using 4 µm microspheres, the sensor shows a detection limit of 0.015% and electromechanical robustness against 1000 cycles of 0–1% strain. The stretchable strain sensor is successfully implemented as an impact sensor and a diaphragm expansion monitoring sensor. Fast (20 ms) and high‐resolution response as well as mechanical robustness to strain values greater than the linear working range of the sensor are demonstrated. The results of this research indicate the promising potential of employing conductive microspheres embedded in the EVA matrix for fast and precise strain detection applications.

ABSTRAK Energi terbarukan sudah mulai mendominasi dunia sejak puluhan tahun lalu, terutama listrik tenaga surya. Pada setiap instalasi PV terdapat gangguan yang sering terjadi, salah satunya adalah degradation fault. degradation fault merupakan jenis gangguan berupa perubahan warna pada lapisan Ethylene Vinyl Acetate dari yang berwarna putih menjadi kuning hingga kecoklatan. Perubahan warna tersebut disebabkan oleh usia pemakaian dan suhu yang terlalu panas dan dapat menyebabkan penurunan arus yang sangat drastis. Kejadian ini mengakibatkan penurunan Isc mencapai 13%. Hal ini tidak baik jika terus dibiarkan pada instalasi solar panel. Oleh karena itu, pada jurnal ini akan membahas pengidentifikasian degradation fault pada array PV dengan Artificial Neural Network. ANN akan mengidentifikasi adanya penurunan arus pada PV array. Dari hasil yang didapatkan bahwa penurunan arus mencapai 12% dan dapat mengidentifkasi adanya degradation fault. Kata kunci: degradation fault, discoloration, Ethylene Vinyl Acetate , short circuit current, artificial neural network  ABSTRACT Renewable energy has started to dominate the world since decades ago, especially solar electricity. In every PV installation there are disturbances that often occur, one of which is a degradation fault. Degradation fault is a type of disturbance in the form of discoloration of the Ethylene Vinyl Acetate layer from white to yellow to brownish. The discoloration is caused by age of use and temperatures that are too hot and can cause a very drastic decrease in current. This incident resulted in a decrease in Isc reaching 13%. This is not good if it continues to be left on solar panel installations. Therefore, this journal will discuss the identification of degradation faults in PV arrays with Artificial Neural Networks. ANN will identify a decrease in current in the PV array. From the results obtained that the decrease in current reaches 12% and can identify a degradation fault. Keywords: degradation fault, discoloration, Ethylene Vinyl Acetate , short circuit current, artificial neural network

Introduction: Given the possibility of higher ground temperatures in the future, the pursuit of a cushioning material that can effectively reduce sports injuries during exercise, particularly one that retains its properties at elevated temperatures, has emerged as a serious concern.Methods: A total of 18 man recreational runners were recruited from Ningbo University and local clubs for participation in this study. Frequency analysis was employed to investigate whether there is a distinction between non-Newtonian (NN) shoes and ethylene vinyl acetate (EVA) shoes.Results: The outcomes indicated that the utilization of NN shoes furnished participants with superior cushioning when engaging in a 90° cutting maneuver subsequent to an outdoor exercise, as opposed to the EVA material. Specifically, participants wearing NN shoes exhibited significantly lower peak resultant acceleration (p = 0.022) and power spectral density (p = 0.010) values at the distal tibia compared to those wearing EVA shoes. Moreover, shock attenuation was significantly greater in subjects wearing NN shoes (p = 0.023) in comparison to EVA shoes. Performing 90° cutting maneuver in NN shoes resulted in significantly lower peak ground reaction force (p = 0.010), vertical average loading rate (p < 0.010), and vertical instantaneous loading rate (p = 0.030) values compared to performing the same maneuvers in EVA shoes.Conclusion: The study found that the PRA and PSD of the distal tibia in NN footwear were significantly lower compared to EVA footwear. Additionally, participants exhibited more positive SA while using NN footwear compared to EVA. Furthermore, during the 90° CM, participants wearing NN shoes showed lower PGRF, VAIL, and VILR compared to those in EVA shoes. All these promising results support the capability of NN footwear to offer additional reductions in potential injury risk to runners, especially in high-temperature conditions.

Ethylene vinyl acetate copolymer (EVA) was modified by expandable graphite (EG) and polyphosphoric acid (PPA) in melt state and the obtained EVA/EG/PPA composite was studied regarding its fire behavior, thermal endurance, water resistivity, processability, and mechanical property. The outcomes evince that the combination of EG and PPA in proper mass ratio can improve fire retardancy, thermal stability, processability, and reduce smoke and toxic gas releases of EVA upon combustion significantly. The EG/PPA combination exhibits very high flame retardant efficiency to EVA in that only 10 wt% loading is enough to make EVA obtain V‐0 rating in UL‐94 test. Moreover, the flame‐retarded EVA/EG/PPA composite displays excellent water resistance and acceptable mechanical property. The EVA/EG/PPA (90/7.5/2.5) composite can produce coherent intumescent char on composite surface, which has good heat endurance and hinders heat transmission from fire to interior of composite. The flame retardation occurs in condensed phase and the intumescent char plays a pivotal role. The presence of PPA endows EVA composite with good melt flowability, which has presented a striking contrast to other flame retardants. Highlights: The combination of EG and PPA has very high flame retardant efficiency to EVA.The EVA/EG/PPA composite has better fire safety and processability than EVA.The EVA/EG/PPA composite still maintains acceptable mechanical property.The expanded char from EVA/EG/PPA composite hinders heat transfer effectively. [ABSTRACT FROM AUTHOR]

Ethylene vinyl acetate (EVA) with a vinyl acetate (VA) content of 28 wt.% (EVA28) is frequently used in vaginal inserts and subcutaneous implants due to its biocompatibility and drug‐releasing properties. Traditionally being processed via hot melt extrusion, its processibility via filament‐based 3D‐printing was reported to be impossible. Consequently, no applicable customization concepts for vaginal inserts exist. For the first time, the fabrication of 3D‐printed vaginal inserts (urethra pessaries) of EVA28 is demonstrated by optimizing its viscosity, employing 3D‐printer adaptations, and carefully selecting printing parameters. The infill pattern of fully filled mono‐material pessaries (determining the number and orientation of weld lines) significantly affects the in vitro release of the model drug progesterone (P4), while other critical parameters (the pessary's mechanical properties and appearance) remain unaffected. Weld lines act as diffusion barriers for dissolved P4 molecules. Hence, a high number of weld lines to be crossed reduces the overall P4 diffusivity in EVA28, decreasing the P4 release rate. To further control the P4 release, innovative multi‐material pessary designs (additionally comprising EVA with a VA content of 9 wt.% that is also used in vaginal inserts) allow to tailor the in vitro drug release and the mechanics individually. Thereby, this work highly improves the mechanistic understanding on drug release modifications from 3D‐printed non‐biodegradable devices. The findings build the basis for the first application of customized vaginal inserts, as they are based on polymers used in corresponding marketed products for more than 20 years. [ABSTRACT FROM AUTHOR]

Background/Aim: Mouthguards (MTG) are used to prevent dental trauma. However, their protective effect on esthetic restorations and whether modified MTGs are beneficial is uncertain. The aim of this study was to evaluate the effect of hard inserts and air spaces in MTGs in protecting direct resin composite veneers during impact. Materials and Methods: Twenty resin composite veneers (1.0 mm) were prepared on upper right central incisors on printed maxilla models using polyether. The effect of the MTGs was evaluated in four groups (n = 5): Con‐MTG, conventional custom‐fit MTGs made with two layers of ethylene vinyl acetate (EVA); Air‐MTG, MTGs with the insertion of 2.0 mm air space between the two layers of EVA and tooth surface; PETG‐MTG, MTGs with 1.0 mm of polyethylene terephthalate glycol‐modified (PETG) inserted between the EVA layers; and No‐MTG, comprising resin composite veneers without MTG. The printed models were fixed in a pendulum device, and the impact was performed at 30°. The strain (μS) and shock absorption (%) of the MTG were recorded using strain gauges. Failure modes and cracks were evaluated using macro photography and transillumination and analyzed using the chi‐square test. Strain and shock absorption data were analyzed using the one‐way analysis of variance followed by Tukey's test (α = 0.05). Results: Mouthguards reduced strain and enhanced shock absorption, regardless of the MTG type (p <.001). Con‐MTG, Air‐MTG, and PETG‐MTG had shock absorption rates of 76.1%, 72.3%, and 33.4%, respectively (p <.001). The single No‐MTG model had a root fracture, while all the others had superficial damage. None of the MTG models had cracks or fractures. Conclusions: Mouthguards protected the resin composite veneers. The Con‐MTG and Air‐MTG groups had lower strain and greater shock absorption than the PETG‐MTG. Resin veneers had no cracks or damage following MTG use. However, 80% of the veneers had surface damage when no MTG was used. [ABSTRACT FROM AUTHOR]

Background/Aim: Contamination of ethylene vinyl acetate (EVA) during mouthguard fabrication can cause delamination. The study evaluated the effects of different EVA surface treatments on the contact angle, laminate bond strength, and elongation capacity. Materials and Methods: Specimens of two bonded EVA plates were prepared (n = 30). The Shore A hardness of standardized EVA plate specimens was measured before and after thermo‐plasticization. The EVA plates were randomly allocated to one of five different surface treatment groups: no treatment (control); isopropyl alcohol, 100%; chloroform, 99.8%; self‐cure acrylic resin monomer (methacrylate, ethylene glycol dimethacrylate, and chemical initiator—amine type); and ethyl alcohol, 70%. The maximum breaking force and elongation at the site of fracture were recorded using a universal testing machine. The contact angle surface was measured using ImageJ software. Scanning electron microscopy of the EVA surface was performed. The laminate bond strength was obtained by dividing the maximum breaking force by the bonding area between the two EVA plates. The laminate bond strength and maximum elongation data were analyzed by one‐way ANOVA, followed by the Tukey's and the Dunnet test. The failure mode data was analyzed using the chi‐square test (α =.05). Results: EVA surface treatment significantly influenced the laminate bond strength and maximum elongation (p <.001). The control group had a higher contact angle and significantly lower laminate bond strength and maximum elongation than the other groups (p <.001). The acrylic resin monomer and chloroform‐treated specimens had similar laminate bond strength and maximum elongation. The acrylic resin monomer group had a significantly lower contact angle (p <.001). Conclusions: All treatments had a significantly higher laminate bond strength and maximum elongation than the control group. The acrylic resin monomer and chloroform groups had a significantly higher laminate bond strength and maximum elongation and the acrylic resin monomer group had a lower contact angle than the other groups. The chloroform should be avoided due its hazardous effects. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6 phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT) showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy. Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend with the localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix, a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8% to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36% decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy. [ABSTRACT FROM AUTHOR]

Thermoplastic elastomer composites based on ethylene vinyl acetate (EVA), natural rubber (NR), and Mengkuang leaf fibre were prepared using the sulfur and peroxide vulcanization systems. Different curing systems and fibre loadings affecting the processing torque, tensile, thermal, and morphology of the composites were investigated. Addition of Mengkuang leaf fibre resulted in poor fibre dispersion and agglomeration in the matrix, which may have affected the efficiency of stress transfer and thus could explain a decline in tensile and thermal properties. Composites with dynamic vulcanization showed a rougher surface that might be due to the presence of crosslinking, which requires more force to fail. The increase in stabilization torque for the composites with dynamic vulcanization was observed due to the addition of curing agents, which implies some changes at the molecular level due to crosslinking. Tensile properties of Mengkuang leaf fibre filled EVA/NR composites indicated that the tensile strength, elongation at break, and Young’s modulus of the peroxide cure system were higher than the sulfur cure system and unvulcanised composites. The sulphur cure system showed better resistance towards thermal degradation compared to the peroxide cure system. This was attributed to dicumyl peroxide (DCP), which degrades the polymer chain or the composites at high temperature.

Water hyacinth (Eichhornia crassipes) with a lignin concentration of 4.15% was directly oxidized by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation without any pre-treatments (alkaline and bleaching). After oxidation, TEMPO-oxidized cellulose nanofibers (CNFs) with widths between 5 and 10 nm were successfully disintegrated. The improvement in crystallinity associated with the decrease in thermal properties was observed for TEMPO-oxidized CNFs in comparison with those features of the untreated fibers. Most lignin was eliminated after the oxidation while the remaining of hemicellulose was observed in the treated nanofibers. The transformation from hydroxyl groups to sodium carboxylic groups was confirmed by Fourier-transform infrared spectroscopy. The application of the prepared TEMPO-oxidized CNFs in ethylene vinyl acetate copolymer (EVA) nanocomposites was studied, and results showed that no degradation in the light transmittance and thermal properties was observed with the introduction of TEMPO-oxidized CNFs. The improvement of ~30% for tensile modulus was noticeable with the incorporation of 1 wt% TEMPO-oxidized CNFs while the tensile strain of the nanocomposites was close to that of the neat EVA films. CNFs from lignin-poor water hyacinth using the direct TEMPO-oxidation process would be a candidate to replace wood-derived CNFs for specific applications such as composites, coatings, packaging and electronic devices.

Nano‐sized carbon black (CB) was introduced to ethylene vinyl acetate/magnesium hydroxide (EVA/MH) composite by melt compounding and the EVA/MH/CB ternary composites were investigated in terms of their thermal, flame retardant, mechanical, and electrical properties. The results indicate that the introduction of MH and CB has no impact on thermal degradation mechanism of EVA, but inhibits its degradation substantially. The presence of CB can hinder thermo‐oxidative degradation and increase thermal stability of the EVA/MH composite significantly. The addition of CB increases the flame‐retardant efficiency of MH effectively. The EVA/MH/CB composite with 3.6% CB can achieve V‐0 rating and its peak heat release rate is 23% smaller than that of the EVA/MH composite, which only achieves V‐2 rating in UL‐94 test. The improvement in flame retardancy happens in condensed phase. On the whole, the introduction of proper CB can enhance the thermal and flame‐retardant properties of EVA/MH composite considerably without damaging its mechanical and electrical performances. This work provides a simple and cost‐effective method to further increase the properties of EVA/MH composite for wire and cable industry. [ABSTRACT FROM AUTHOR]

The rehabilitation of the cleft requires a multidisciplinary approach involving a pediatrician, surgeon, otolaryngologist, speech therapist, orthodontist, prosthodontist, and psychologist. The present case report illustrates the rehabilitation of a 12‐day‐old neonate with a cleft palate. Since the palatal arch of the neonate was very small, a feeding spoon was innovatively modified to obtain the impression. The obturator was fabricated on the same day and delivered in one appointment. [ABSTRACT FROM AUTHOR]

Low processing temperature of preceramic polymers (PCPs) makes them attractive for material extrusion based additive manufacturing (MEX-AM), earlier called fused deposition modeling (FDM). Fabrication of bulk polymer derived ceramics is challenging due to gas evolution during crosslinking leading to pores and cracks in final product. Mixture of ethylene vinyl acetate (EVA) and polyvinyl alcohol (PVA) was successfully used to generate open porosity before crosslinking step. For 3D printing, a pellet extruder was used and a PVA binder content of 50 vol% was essential for succcessful solvent debinding process in water. The effect of PVA content and different EVA grades on printability and debinding behavior was studied. EVA with a lower melt flow index (MFI) showed better compatibility with PVA additive in terms of mixing and printing. EVA with higher vinyl acetate content seems to be more favorable for later thermal debinding processes because of its higher gas permeability. [ABSTRACT FROM AUTHOR]

Abstract The rehabilitation of the cleft requires a multidisciplinary approach involving a pediatrician, surgeon, otolaryngologist, speech therapist, orthodontist, prosthodontist, and psychologist. The present case report illustrates the rehabilitation of a 12‐day‐old neonate with a cleft palate. Since the palatal arch of the neonate was very small, a feeding spoon was innovatively modified to obtain the impression. The obturator was fabricated on the same day and delivered in one appointment.

Water hyacinth (Eichhornia crassipes) with a lignin concentration of 4.15% was directly oxidized by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation without any pre-treatments (alkaline and bleaching). After oxidation, TEMPO-oxidized cellulose nanofibers (CNFs) with widths between 5 and 10 nm were successfully disintegrated. The improvement in crystallinity associated with the decrease in thermal properties was observed for TEMPO-oxidized CNFs in comparison with those features of the untreated fibers. Most lignin was eliminated after the oxidation while the remaining of hemicellulose was observed in the treated nanofibers. The transformation from hydroxyl groups to sodium carboxylic groups was confirmed by Fourier-transform infrared spectroscopy. The application of the prepared TEMPO-oxidized CNFs in ethylene vinyl acetate copolymer (EVA) nanocomposites was studied, and results showed that no degradation in the light transmittance and thermal properties was observed with the introduction of TEMPO-oxidized CNFs. The improvement of ~30% for tensile modulus was noticeable with the incorporation of 1 wt% TEMPO-oxidized CNFs while the tensile strain of the nanocomposites was close to that of the neat EVA films. CNFs from lignin-poor water hyacinth using the direct TEMPO-oxidation process would be a candidate to replace wood-derived CNFs for specific applications such as composites, coatings, packaging and electronic devices. [ABSTRACT FROM AUTHOR]

Inorganic repair materials have significant advantages such as high durability, high strength, and good corrosion resistance. However, their low bonding strength and inadequate tensile performance are clear disadvantages, which often results in problems like cracking, delamination, and insufficient repairing strength. In the current study, a new repair material is developed, which enhances the interfacial bonding performance of carbon nanotubes (CNTs) repair materials by introducing ethylene vinyl acetate (EVA). The bonding strength of composite specimens was tested by splitting tensile test. Then the microstructure analysis of the repaired materials was conducted by X-ray computed tomography, backscattered electron imaging, and scanning electron microscopy. The phase composition of the repair material was further analyzed by Fourier transform infrared spectroscopy. Finally, the bonding mechanisms of EVA reinforced CNTs repair materials were discussed. The results indicate that the interaction between EVA and CNTs can enhance the bonding performance of repair materials. Additionally, the polymer film formed by EVA within the repair material can refine the pores, thereby reducing the porosity of the interfacial transition zone and that of repair materials. The electrostatic repulsion between EVA and CNTs contributes to the uniform dispersion of CNTs within repair materials. [Display omitted] • A new ethylene vinyl acetate reinforced carbon nanotube repair material is developed. • Incorporating EVA into the developed CNTs repair material improves the bonding performance. • Addition of EVA can effectively reduce the porosity and improve the compactness of ITZ. • The electrostatic repulsion between EVA and CNTs facilitates dispersibility of CNTs. [ABSTRACT FROM AUTHOR]

Ethylene vinyl acetate (EVA) is a representative copolymer widely adopted across various sectors owing to its superior physiochemical properties; however, an environmentally benign protocol for the disposal of EVA waste has not yet been established owing to the various ratios of acetate to polyethylene. Therefore, in this study, we proposed an innovative thermochemical technique for converting EVA waste into energy resources, specifically syngas. CO 2 was used to enhance the environmental sustainability of pyrolysis. Thermogravimetric analysis revealed that most of the EVA (approximately 99 wt%) was converted into pyrolytic oil and gases. However, the mechanistic features of CO 2 in the pyrolysis of EVA could not be fully elucidated through single- or double-stage pyrolysis owing to the slow kinetics of the homogeneous reaction between CO 2 and volatiles. To expedite the reaction kinetics, we used a cobalt (Co)-based catalyst (Co/SiO 2). In the presence of Co/SiO 2 , the concentration of CO produced under CO 2 was approximately 30-fold higher than that under N 2. Furthermore, the homogeneous reactions resulted in fewer benzene derivatives and polycyclic aromatic hydrocarbons (PAHs) in the pyrolytic oil under CO 2 conditions. These experimental findings suggest that CO 2 and EVA could serve as valuable feedstocks for the production of energy. • An environmental benign platform for disposal of EVA waste was suggested. • EVA was converted to value-added products through pyrolysis. • CO 2 enhanced conversion of EVA into syngas (H 2 and CO) through catalytic pyrolysis. • Cobalt-based catalyst enhanced CO formation 30 times higher under the CO 2 condition. • Catalytic pyrolysis under CO 2 reduced the PAH content in pyrolytic oil. [ABSTRACT FROM AUTHOR]

Thermoplastic elastomer composites based on ethylene vinyl acetate (EVA), natural rubber (NR), and Mengkuang leaf fibre were prepared using the sulfur and peroxide vulcanization systems. Different curing systems and fibre loadings affecting the processing torque, tensile, thermal, and morphology of the composites were investigated. Addition of Mengkuang leaf fibre resulted in poor fibre dispersion and agglomeration in the matrix, which may have affected the efficiency of stress transfer and thus could explain a decline in tensile and thermal properties. Composites with dynamic vulcanization showed a rougher surface that might be due to the presence of crosslinking, which requires more force to fail. The increase in stabilization torque for the composites with dynamic vulcanization was observed due to the addition of curing agents, which implies some changes at the molecular level due to crosslinking. Tensile properties of Mengkuang leaf fibre filled EVA/NR composites indicated that the tensile strength, elongation at break, and Young’s modulus of the peroxide cure system were higher than the sulfur cure system and unvulcanised composites. The sulphur cure system showed better resistance towards thermal degradation compared to the peroxide cure system. This was attributed to dicumyl peroxide (DCP), which degrades the polymer chain or the composites at high temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recovery of polymeric layers and other materials from waste solar modules by chemical process. • The properties of recovered polymers are comparable to reference polymer materials. • Recovered polymer may be reused in encapsulation of solar cells. • ∼97 % Recovery of used solvent and purification for reuse. Economical process for recovery/recycling of materials from waste modules is important for the overall sustainable development of PV sector. In the present investigation, the polymeric layers, Ethylene Vinyl Acetate (EVA), back-sheet, and other materials were recovered using single organic solvent toluene. The recovered EVA and back-sheet were characterized by various techniques such as Raman spectroscopy, Fourier transform spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), Thermogravimetric analysis (TGA), and Differential scanning calorimetry (DSC) to check their properties. The Raman and FTIR spectroscopy revealed that the recovered EVA and back-sheet have similar peaks as that of reference materials, implying no significant changes in composition occurred during the recovery process. The recovered EVA and back-sheet have a semi-crystalline structure similar to their respective reference materials as confirmed by XRD spectra. The TGA measurements confirm that the thermal stability temperature of recovered EVA (285 °C) and back-sheet (380 °C) are comparable to their respective reference materials. The recovered polymeric layers may be reused in solar panels or in the polymer industry. Also, ∼ 97 % of toluene was recovered and the same was purified by distillation process and observed that distilled toluene has equivalent UV–visible absorption bands to fresh toluene. With the recovery of solvent, polymeric layers, and other materials, the proposed method will be economically viable for the sustainable management of waste solar modules. [ABSTRACT FROM AUTHOR]

In recent pharmaceutical applications, an active pharmaceutical ingredient (API) can be mixed with a polymer material to yield a composite long-acting drug-delivery device. These devices boast higher patient compliance, localized drug delivery, and lower dosage concentrations, which can increase patient safety. As a laboratory-safe option, calcium carbonate (CaCO3) was used as a drug surrogate to mimic the release kinetics of a low-solubility API. The release of CaCO3 from a poly(ethylene vinyl acetate) (EVA) polymer matrix was studied in ultra-high-purity water. The geometry of CaCO3, along with the manufacturing technique, was manipulated to study the implications on surrogate drug release. It was found that injection molding proved to yield higher burst release, due to higher pressures achievable during manufacturing. The extrusion process can affect the surface concentration of the pharmaceutical ingredient when extruded through a water bath, resulting in a lower initial burst concentration. Regarding CaCO3 geometry, the particle size was more critical than the surface area in terms of CaCO3 release. Larger particles showed a higher release rate, though they also displayed higher variability in release. These data can be used to engineer specific release profiles when designing composite formulations and manufacturing methods for pharmaceutical-drug-delivery applications. [ABSTRACT FROM AUTHOR]

In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites. [ABSTRACT FROM AUTHOR]

In this study, ethylene vinyl acetate (EVA) polymer and rubber powder were used as 85/100 bitumen modifiers. First, classical bitumen tests including penetration grade and softening point were performed on the samples and improvement of bitumen base properties was observed. Then, in order to evaluate the performance of modified bitumen at high temperature and compare it with the behavior of base bitumen, the Superpave protocol was followed. In this way, dynamic shear rheometer (DSR) test was performed and G*/sinδ index was examined on bitumen samples before and after aging. In addition, the bending beam rheometer (BBR) test was performed to evaluate the low temperature behavior of the modified bitumen according to the SHRP standard based on the creep stiffness and creep rate indices. The results showed that the combination of used additives improves the performance properties of bitumen at high temperature and also at low temperature compared to base bitumen. Based on the BBR test, 3% EVA polymer and 4% rubber powder, with a 12% reduction in creep stiffness in this composition, were selected the optimal values for the mixture.

Flame retardant rubber foams of ethylene vinyl acetate (EVA)/natural rubber (NR)/layered silicate blends filled with silicon dioxide (SiO2) were prepared by using azodicarbonamide (ADC) as a blowing agent. Specifically, SiO2 was added in EVA/NR blend nanocomposites to produce good flame retardant foams. The properties of EVA/NR blend nanocomposite foams with different SiO2 loading (0, 20, 30, 40 parts per hundred rubber, phr) were investigated through transmission electron microscopy (TEM), scanning electron microscopy (SEM), rheological property test, mechanical property measurement, flammability tests, thermogravimetry analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry (Pyrolysis-GC-MS). Compared with the simple EVA/NR blend nanocomposite, the added SiO2 increased the blend compatibility between EVA and NR phases and melt strength/viscosity of the EVA/NR blend nanocomposites, thus promoting cellular structure of the EVA/NR nanocomposite foams. Increasing SiO2 loading resulted in higher cell density, smaller cell size, and lower volume of void. These improvements caused higher strength and elastomeric recovery. The LOI test results showed that flame retardancy of the EVA/NR blend nanocomposite foams increased at higher SiO2 loading as a result of formation of insulation silicon dioxide-based char. TGA and pyrolysis-GC-MS analyses also validated the finding that the silicon dioxide-based char in the foamed samples containing higher SiO2 loading was more effective on improving thermal stability, which was responsible for lower material combustibility and better flame retardancy. Based on our finding, it was concluded that a good flame retardant EVA/NR blend nanocomposite foam with the best improvement in strength and elastomeric recovery was achieved when combined with 40 phr SiO2. [ABSTRACT FROM AUTHOR]

In this work, flame‐retardant ethylene vinyl acetate (EVA) composites were prepared by compounding expandable graphite (EG) and aluminum hypophosphite (AHP). The combustion behavior and mechanical properties of EG and AHP in flame‐retardant EVA composites were tested, and flame retardant mechanism was also investigated. According to the thermogravimetric analysis (TGA) results, AHP and EG can promote the carbonization of EVA to form the char layer at high temperature. The limiting oxygen index (LOI) test and vertical burning test (UL‐94) test results show that when the mass ratio of EG to AHP is 2:1, the sample (EVA/10EG/5AHP) passes the UL‐94 V‐0 rating, and its LOI value reaches 30.5%. The cone calorimetry test (CCT) results show that the EVA/10EG/5AHP sample has a significantly reduction on heat release and smoke release. Mechanical tests show that as the content of EG decreases and the content of AHP increases, both the strength and the elongation at break of EVA composites increase and the rigidity decreases. Whatever, we used SEM, Raman, and TG‐IR to understand the flame‐retardant mechanism of the EVA composites and the synergistic effect of EG and AHP It was found that the combination of condensed‐phase and gaseous‐phase is realized in the burning process. [ABSTRACT FROM AUTHOR]

A modified kaolinite by grafting with phytic acid (PA‐g‐Kaol) is fabricated, and it was introduced into ethylene vinyl acetate (EVA) with intumescent flame retardancy (IFR) together to improve the flame retardancy of EVA composites. The results show the limiting oxygen index value of EVA/ (18.0 wt% IFR)/ (2.0 wt% PA‐g‐Kaol) is 30.8%. Meanwhile, there is only one dripping produced in the vertical burning test. What's more, the flame‐retardant mechanism is demonstrated by TG‐IR, real‐time‐IR and GC–MS analysis. The results indicate that some pyrolytic products of IFR and PA‐g‐Kaol, like ammonia and phosphoric acid, catalyze the crosslinking of EVA and flame retardant, the resultant compact char protects the substrate from further burning. [ABSTRACT FROM AUTHOR]

The effect of ethylene vinyl acetate (EVA) concentration and vinyl acetate (VA) content of EVA on the mechanical, morphological, and rheological properties of bio-based high-density polyethylene (BioPE)/EVA blends was investigated. The blends were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and rheological measurements under oscillatory shear flow. The degree of crystallinity of BioPE decreased with the increase in the EVA concentration and was unaffected with the increase in the VA content. DMTA results showed a decrease in the storage modulus (E′) with the increase in EVA content and that the BioPE/EVA19 blends showed higher E′ values than BioPE/EVA28 blend. The impact strength substantially increased with the addition of EVA concentration above 5 mass% and was higher for the blends containing the highest VA content. The blends containing a higher content of VA exhibited the higher EVA dispersed phase domain size, which increased with the increase in EVA concentration. The complex viscosity increased with the increase in the EVA content, being higher for the BioPE/EVA blends containing higher VA content. The storage modulus increased, at low frequencies, with the increase in the EVA content and can be ascribed to the increase in the EVA dispersed phase domain size. [ABSTRACT FROM AUTHOR]

Due to layer by layer printing, the interlayer adhesion of resin used in extrusion-based additive manufacturing (AM) is poor, while thermal curing affects the accuracy of the resin. Therefore, methods of photo-curing and nanomodification were used in this work to improve the adhesion between layers and the overall performance of AM resins. Specifically, ethylene-vinyl acetate (EVA) copolymer with dual curing agent of benzophenone/triallyl isocyanurate (BP/TAIC) and nano-silica (NS) were introduced. The results of light transmittance, scanning electron microscopy and gel content test showed that BP/TAIC with NS were proved to be able to improve the curing process of EVA. The filling of a small amount of NS did not act as ultraviolet light barrier, but instead improved the photo-curing of the resin and reduced the amount of agents. UV curing also improved the adhesion between layers of EVA resin. The tensile strength was 7.1% higher than that of EVA/NS/BT without curing. At the same time, due to good interface bonding and dispersion, the thermal conductivity of resin improved from 0.212 W/m*k to 0.252 W/m*k. A 16.1% raise in tensile strength and a 10.0% increase in the volume resistivity were demonstrated for the 3.0 wt% NS. Furthermore, this resin is potential to be used in AM. KEYWORDS additive manufacturing, ethylene-vinyl acetate, nano-silica, photo-curing, property, 1 | INTRODUCTION Additive manufacturing (AM) often referred to as 3D printing. Unlike traditional manufacturing processes, materials were stacked layer by layer to fabricate three-dimensional parts during AM. [1,2] There [...]

Ethylene vinyl acetate (EVA) is a random copolymer of ethylene and varying amounts of vinyl acetate that interfere with poly-ethylene chain packing reducing crystallinity, thus improving transparency and lowering the melting temperature to 40[degrees]C-60[degrees]C. The material viscoelastic properties in its working conditions may thus depend on the crystallinity degree. The crystallization process is here rheologically studied in non-isothermal conditions and the frequency spectra are measured at different temperatures to investigate the viscoelasticity of EVA. Coupling the crystallization kinetics and the viscoelastic spectra at different temperatures, that is, at different degree of crystallinity, we here determine two independent shift factors, one for the timecrystallinity shift, the other for the time-temperature shift, so to propose a new time-temperature-crystallinitysuperposition to reconcile all the data on a single master curve. In this way, the experimentally observable frequency range has been widened significantly so to detect all the relaxation times of the material from the shortest to the largest ones., INTRODUCTION In polymer processing, like injection molding, fiber spinning, film casting, and so on, a forming step of the melt is followed by solidification due to cooling. This implies that [...]

Waste tire rubber is commonly recycled by blending with other polymers. However, the mechanical properties of these blends were poor due to lack of adhesion between the matrix and the waste tire rubber. In this research, the use of electron beam irradiation and (3-Aminopropyl)triethoxy silane (APTES) on enhancing the performance of 50 wt% reclaimed tire rubber (RTR) blend with 50 wt% poly(ethylene-co-vinyl acetate) (EVA) was investigated. Preparation of RTR/EVA blends were carried out in the internal mixer. The blends were then exposed to electron beam (EB) irradiation at doses ranging from 50 to 200 kGy. APTES loading was varied between 1 to 10 wt%. The processing, morphological, mechanical, and calorimetric properties of the blends were investigated. The stabilization torque and total mixing energy was higher in compatibilized blends. Mechanical properties of RTR/EVA blends were improved due to efficiency of APTES in further reclaiming the RTR and compatibilizing the blends. APTES improved the dispersion of embedded smaller RTR particles in EVA matrix and crosslinking efficiency of the blends. Calorimetric studies showed increased crystallinity in compatibilized blends which corresponds to improved mechanical properties. However, the ductility of the blend was decreased due to increased interaction between EVA and APTES. Presence of APTES increased the efficiency of electron beam irradiation induced crosslinking which was shown through gel content analysis and Charlesby-Pinner equation. [ABSTRACT FROM AUTHOR]

Series of ethylene vinyl acetate (EVA) copolymer/layered double hydroxide (LDH) nanocomposite membranes with 40 wt% vinyl acetate content (EVA/12AA–LDH) were prepared by solution blending and casting, and applied in membrane gas separation. The organically modification of LDH nanolayers (12AA–LDH) was manufactured by using 12‐aminododecanoic acid (12AA) as an intercalation agent via co‐precipitation method. The distance between the 12AA–LDH nanolayers was approximately 2.10 nm from calculation of the XRD diffraction pattern, which resulted from the successful intercalation of 12AA within the LDH. The result of CO2 adsorption isotherms shows that 12AA–LDH is much more attractive than the neat LDH, which enhances the performance in membrane separation. Furthermore, the exfoliated/intercalated morphology of 12AA–LDH/LDH structures within EVA matrix was prepared successfully and can be observed clearly by transmission electron microscopy micrographs. The gas permeation performance of the EVA/12AA–LDH nanocomposite membranes was measured, and the results show that the best selectivity of CO2/N2 increased to 20 with a CO2 permeability of 119.21 barrer for the composite membrane containing 1.0 wt% 12AA–LDH. This result not only attributed to the exfoliation of the 12AA–LDH nanolayers within the EVA matrix, but also the amino group of 12AA interacted more with CO2 compared with N2 and O2. This result illustrated that 12AA–LDH shows highly potential for use as an additive in CO2 capture membranes. [ABSTRACT FROM AUTHOR]

This paper reports a study into the effect of nanoclays on the water-resistance of the intumescent system ammonium polyphosphate/melamine/pentaerythritol/titanium dioxide/polymer (ethylene vinyl acetate (EVA) or styrene acrylate (SA) It has been established that adding nanoclay to a coating based on ethylene vinyl acetate increases the fire resistance limit of a metal plate by 30 %, and to a coating based on styrene acrylate – by 50 %. At the same time, coatings that include the EVA polymer are characterized by greater fire-retardant efficiency and less water resistance than coatings containing the SA polymer. It has been shown that intumescent coatings, regardless of the nature of the polymer, under the conditions of 80 % humidity over 800 days their reduce fire-protective properties by an average of 10 %. The loss of coating fire resistance occurs due to the leaching of pentaerythritol, ammonium polyphosphate, and polymer degradation by hydrolysis. The admixtures of nanoclays with a high degree of exfoliation to the studied system create a barrier effect and maximize the chemical formulation of the intumescent coating. The fireproof properties of coatings with organically-modified montmorillonite admixtures are maintained or reduced to 5 % under the conditions of 80 % humidity over 800 days. It has been determined that the direct effect of water on the coating over a period of more than 2 days leads to a significant decrease in the swelling coefficient of intumescent coatings, regardless of the content of a nanoclay admixture in their composition. At the same time, the half-decay period of coatings without nanoclay, calculated on the basis of solubility constant in water, is 0.5 days. For coatings, which include the admixtures of organically-modified nanoclays, the half-decay period increases to 2 days. The results reported in this paper could be recommended for designing water-proof fire-resistant reactive-type nano-coatings with prolonged service life. [ABSTRACT FROM AUTHOR]

The current study analyses the compressive behaviour of ethylene vinyl acetate specimens processed through extrusion-based additive manufacturing. The compression specimens have been fabricated using an in-house developed fused layer modelling process. Response surface methodology technique has been adopted to generate the experimental runs by selecting raster angle, layer thickness and infill percentage as input process parameters. Further, analysis of variance has been used to analyze the obtained compression data. The infill percentage is found to be the most significant parameter for compressive strength; however, raster angle has shown an insignificant effect. The empirical relation has been established between the selected input process parameters and compressive strength. The predicated and experimental results have also been compared to validate the derived empirical model. Results showed good conformity. [ABSTRACT FROM AUTHOR]

In recent pharmaceutical applications, an active pharmaceutical ingredient (API) can be mixed with a polymer material to yield a composite long-acting drug-delivery device. These devices boast higher patient compliance, localized drug delivery, and lower dosage concentrations, which can increase patient safety. As a laboratory-safe option, calcium carbonate (CaCO3) was used as a drug surrogate to mimic the release kinetics of a low-solubility API. The release of CaCO3 from a poly(ethylene vinyl acetate) (EVA) polymer matrix was studied in ultra-high-purity water. The geometry of CaCO3, along with the manufacturing technique, was manipulated to study the implications on surrogate drug release. It was found that injection molding proved to yield higher burst release, due to higher pressures achievable during manufacturing. The extrusion process can affect the surface concentration of the pharmaceutical ingredient when extruded through a water bath, resulting in a lower initial burst concentration. Regarding CaCO3 geometry, the particle size was more critical than the surface area in terms of CaCO3 release. Larger particles showed a higher release rate, though they also displayed higher variability in release. These data can be used to engineer specific release profiles when designing composite formulations and manufacturing methods for pharmaceutical-drug-delivery applications.

Rubber nanocomposite foams based on 60/40 ethylene vinyl acetate (EVA)/natural rubber (NR) were melt-mixed with flame retardant silicon dioxide (SiO2) (20 parts per hundred rubber, phr), and foamed by compression molding process. In this study, the effect of mixing phenomena of SiO2 through two different compounding techniques such as direct mixing (DM) and phase selective mixing (PSM) methods on structure, thermal stability, combustility and flame retardancy of EVA/NR blend nanocomposite foams were investigated. DM method is a melt mixing of EVA, NR, layered silicate and SiO2, followed by foaming. PSM is a new method based on pre-mixing EVA with SiO2, then melt mixing of EVA/SiO2 masterbatch with NR and layered silicate, and finally foaming. Based on TEM technique, it was found that the SiO2 was exclusively located in dispersed NR phase for the sample prepared by DM method, and the SiO2 was preferably dispersed in continuous EVA matrix when PSM method was employed. However, the different mixing methods did not significantly alter their cellular structures. The thermal stability and char residue content of foamed samples with SiO2 increased obviously when compared with those of corresponding foams without SiO2. The results based on limiting oxygen index (LOI) test and oxygen bomb calorimetry indicated that the foams combined with SiO2 had better combustion resistance and flame retardancy due to barrier effect of thermally stable silicon-based char layer. Further, the SiO2 filled foamed system obtained from the PSM method showed a higher degree of improvement in thermal stability, combustion resistance and flame retardancy than that of DM method because the homogeneous dispersion of SiO2 in EVA matrix rather than the selective dispersion in NR phase. This resulted in the continuity of flame retardant EVA/SiO2 phase in the 60/40 EVA/NR nanocomposite foams, which exerted more efficient fire barrier of the silicon-based char layer. [ABSTRACT FROM AUTHOR]

In bovine estrus synchronization, intravaginal devices made of silicone are used to administer exogenous progesterone with the aim of maintain plasmatic levels above 2 ng ml−1 during the treatment. After their use, devices must be discarded. There is an important concern on the environmental impact of the disposal of these used products due mainly to the non-degradability of the silicone and to the residual content of the hormone. Different alternatives are being studied, and the use of ecological materials appears as the more important. The objective of the present contribution was to design and evaluate a recyclable intravaginal prototype using ethylene vinyl acetate copolymer (EVA). Devices were fabricated by an injection-molding technique and characterized in terms of dimensions, loading efficiency, release rate, and wing tension. An analysis was first conducted to compare three different matrices and two supports. Secondly, the best candidate prototype was assayed in both beef and dairy cattle. Finally, used matrices were recycled measuring the progesterone content in the resulting devices and testing them in vitro. According to release tests, no differences were observed between the three matrices both in vitro and in vivo. On the contrary, a better performance was achieved when a support with a more flexible Y shape was used in comparison with a rigid T geometry. Successful results were observed in non-lactating cows, with plasma concentrations above the threshold value defined for the synchronization therapy. However, lower progesterone levels resulted when devices were tested in animals with large milk production. By last, recycled matrices presented a similar initial content and in vitro release rate than original matrices. These findings could open the possibility to use recyclable EVA devices as an alternative to the non-degradable silicone intravaginal inserts. Future research must be carried out to optimize the performance of the recycled matrices in dairy cattle. Modifications of the release surface and/or the initial loading can give a solution to the lower values observed in these animals. [ABSTRACT FROM AUTHOR]