Ethylene Vinyl Acetate Resin Research Articles

Preparation and Investigation of Laser-Assisted Hot Melt Adhesives Based on Polypropylene (PP)/Ethylene-Vinyl Acetate (EVA)

In recent years, with the advancement of laser equipment and technology, several papers have documented the utilization of laser technology in the domain of plate edge sealing. However, there is currently a lack of research on suitable materials for laser edge sealing. Therefore, in our research described in this paper we mainly explored the use of a functional layer of a kind of edge sealing material used in laser edge sealing technology, namely a laser hot melt adhesive material. In this study we used polypropylene (PP) and ethylene-vinyl acetate (EVA) as matrix materials to prepare laser hot melt adhesive materials which can be activated by a 1065 nm near-infrared laser. Compared with the traditional edge sealing technology, our operation process is simpler, the beauty of the product is better and all its performances meet the relevant standards. The thermogravimetric analysis (TGA) and other thermal analysis methods demonstrated that the laser adhesive can undergo melting upon laser activation, provided an appropriate amount of inorganic laser-sensitive agent is added, without undergoing any thermal decomposition. The influence of the elastomeric EVA resin on the crystallinity of the PP was investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC), demonstrating a significant impact on the resulting blend properties. X-ray photoelectron spectroscopy (XPS) shows a partial reduction of Cu2+ to Cu+ within the laser sensitizer after activation of the adhesive by the laser. The optimal mass ratio of PP and EVA in the laser adhesive was investigated through experimental analysis. The morphological changes of the laser adhesive before and after laser activation were observed using scanning electron microscopy (SEM). We believe the research conducted by our team has significantly advanced the progress of laser edge banding technology and expedited its application in the field of furniture manufacturing.

Fabrication and Characterization of EVA Resins as Adhesives in Plywood.

The practical problem of free formaldehyde pollution in the plywood industry is that polyethylene films have been shown to be able to replace some urea-formaldehyde resins for wood adhesives. To broaden the variety of thermoplastic plywood, reduce the hot-press temperature, and save energy consumption, an ethylene-vinyl acetate (EVA) film was selected as a wood adhesive to manufacture a novel wood-plastic composite plywood via hot-press and secondary press processes. The effects of the hot-press and secondary press processes at different levels on the physical-mechanical properties of EVA plywood (tensile shear strength, 24 h water absorption, and immersion peel performance) were evaluated. The results showed that the properties of the resulting plywood using the EVA film as an adhesive could meet the type III plywood standard. The optimum hot-press time was 1 min/mm, the hot-press temperature was 110-120 °C, the hot-press pressure was 1 MPa, the dosage film was 163 g/m2, the secondary press time was 5 min, the secondary press pressure was 0.5 MPa, and the secondary press temperature was 25 °C. EVA plywood can be used in indoor environments.

Properties of Lightweight Controlled Low-Strength Materials Using Construction Waste and EPS for Oil and Gas Pipelines

Due to its particularity and importance, long-distance oil and gas pipelines need to be well protected from damage by backfill materials. In this study, construction waste and expanded polystyrene (EPS) were used to replace conventional fine aggregate, and ethylene vinyl acetate-resin (EVA) was used to modify the surface of EPS to prepare lightweight controlled low strength materials (CLSM). Lightweight CLSM was tested in mechanics and physics and its microstructure was studied using microscopic analysis methods. The results revealed that the surface modification of EPS by EVA could greatly improve the compatibility of EPS with inorganic cementitious materials and prepare CLSM with a fluidity greater than 200 mm. EPS and cement content in cementitious materials play an important role in the development of material strength. When the volume ratio of EPS to construction waste was 2, and the content of cement in the cementitious materials was 35%, CLSM’s unconfined compressive strength at 28 days was only 0.48 MPa. In order to obtain the lightweight CLSM that meets the mechanical properties, the EPS content should not be too large. It can be concluded from the microscopic analysis that the increase of EPS content will lead to poor pore uniformity of the specimen, forming a loose mesh structure of defects, which is not conducive to the development of strength. In this study, EPS and construction waste are used to provide a green idea for preparing lightweight controlled low strength materials, which provides a reference for the backfill protection of the material in oil and gas pipelines in the future.

Synthesis of nano-hybrid polymethacrylate-carbon dots as pour point depressant and combined with ethylene-vinyl acetate resin to improve the cold flow properties of diesel fuels

The application of nanoparticles in terms of improving the cold flow properties of diesel fuels attracted more and more attention, and the composite technology of pour point depressant could further improve the cold flow properties of diesel fuels. A new type of nano-hybrid pour point depressant (PPD) was created in this study by copolymerising surface-modified carbon dots with tetradecyl methacrylate, which demonstrated good cold flow properties for diesel fuels (ΔSP = 21 °C, ΔCFPP = 9 °C). Besides, the ethylene-vinyl acetate (EVA) resin was also tested as a novel class of PPD to improve the cold flow properties of diesel fuels and exhibited excellent effect (ΔCFPP = 13 °C) on reducing the cold filter plugging point of diesel fuels. Thus, the combined technology of these two type of PPDs was used to further improve the cold flow properties of diesel fuels. The results indicated that the composite PPDs showed a great decrease in both solid point and cold filter plugging point of diesel fuels at a dose of 1500 ppm (ΔSP = 30 °C, ΔCFPP = 20 °C), which indicates better performance than achieved by either of them alone. In addition, polynomial and quadratic function fitting models are established to describe how the two main factors affect the cold flow properties of diesel fuels, and the fitting effects are well. In the end, using a differential scanning calorimeter, polarised optical microscope and rheological analysis, the paraffin crystallisation and morphology of wax crystals for diesel fuels before and after treatment with PPDs were studied, and the mechanism of heterogeneous nucleation and crystallisation of paraffin induced by PPD was proposed to explain the effects of nano-hybrid PPD, EVA resin and combined PPDs.

Factors Affecting Thermal Shrinkage of Mouthguard Sheet during Thermoforming: Model Shape and Sheet Material Thickness

The effectiveness and safety of the mouthguard depend on the sheet material thickness. The thickness of the thermoformed mouthguard is affected by the model undercut and the thermal shrinkage that occurs when the extruded-molded sheet is reheated. The aim of this study was to clarify the influence of the undercut amount of the model and the thickness of the sheet material on the thermal shrinkage of the extruded sheet. The mouthguard sheet used ethylene-vinyl acetate resin with a thickness of 4.0 mm (4M) and 3.0 mm (3M) and was manufactured by extrusion molding. The working models were three hard gypsum models with the undercut amount on the labial side trimmed to 0? (U0), 10? (U10), and 20? (U20). Mouthguard thickness after vacuum formation was compared between the conditions formed so that the extrusion direction was vertical (condition V) or parallel (condition P) to the model midline. Differences in the reduction rate of the mouthguard thicknesses of the labial and buccal side depending on the sheet extrusion direction, model angle, and sheet material thickness were analyzed by three-way ANOVA and Bonferroni method. The reduction rate of the thickness in condition P was significantly greater than in condition V under all conditions except U0-4M on the labial side and U0-4M and U10-4M on the buccal side. In all models, the reduction rate of the thicknesses was significantly greater in 3M than in 4M in the same extrusion direction. In both 4M and 3M, the reduction rate of the thicknesses tended to increase as the amount of undercut increased in each extrusion direction. This study suggested that a model with a large amount of undercut on the labial side or a thin sheet had a significant effect on the thermal shrinkage of the mouthguard sheet during thermoforming, which leads to the thinning of the mouthguard.

Effects of Crosslinking and Silicone Coupling Agent on Properties of EVA Composite Hot Melt Adhesive.

In order to improve the bonding performance, EVA composite hot melt adhesives were prepared by introducing crosslinking agent and silane coupling agent in this paper. A binary EVA resin blend as the base resin with appropriate viscosity and tensile shear strength was selected as hot melt adhesive. The effects of crosslinking agent and silane coupling agent on the properties of ethylene/vinyl acetate (EVA) composite hot melt adhesive were studied. By investigating the preparation and curing conditions of hot melt adhesive and the properties of hot melt adhesive after the introduction of dicumyl peroxide (DCP), the optimum temperature and dosage of DCP and its influence on the properties were determined. It was found that the tensile shear strength of hot melt adhesive increased from 0.247 MPa to 0.726 MPa when 2 phr DCP and 5 phr KH570 were added at the same time. The tensile strength and tensile shear strength of hot melt adhesive are only slightly improved when silicone coupling agents with different functional groups are added to EVA composite hot melt adhesive. However, it was found that excessive silane coupling agent would significantly reduce the tensile strength and shear peel strength of the material.

Physical Properties of Polyethylene and Ethylene Vinyl Acetate Foam Mixtures

Previous studies on the physical properties of each Polyethylene (PE) or Ethylene Vinyl Acetate (EVA) foam have been widely reported. The current challenge is how to understand the combination of PE and EVA foam in order to obtain appropriate properties in various applications. Therefore, an experimental breakthrough in order to understand the physical mechanism on the PE:EVA mixed foam in order to maintain many appropriate properties due to their applications was studied. The physical properties of a combination of PE and EVA foam with Azodicarbonamide (ADC) as blowing agent and the addition of Zinc Oxide (ZnO) as accelerated agent in foaming process have been investigated in this study. The foams were prepared via two steps. Firstly, the various content of PE and EVA resins with combination of various content of ZnO and the addition of ADC, stearic acids and antioxidants were mixed by a single screw extrusion as the results of pellets. Furthermore, this intermediate product was pressed by compression moulding at the temperature of 175 °C and pressure of 30 bar for 5 minutes, then the pressure was released for the foaming process. The effect of the addition of ZnO were observed on the density and the mechanical properties of the foams. The density decreased with increasing of ZnO content up to 4 per hundred resin (phr) on the foam with PE content maximum of 20 phr. Interestingly the density of the foam increased with the addition of 6 phr of ZnO. Due to the increasing number of ZnO, we found the formation of foams completely. We observed the approval of the hardness, tensile and compression properties of each formulation, respectively. Furthermore, the morphology observation of the foams was conducted by scanning electron microscopy (SEM) to measure the size and homogeneous of the cells. We observed large size of cells at low density of foams, meanwhile uniform of cell was obtained at the high density of foams. Finally, the Fourier transform infrared (FTIR) spectroscopy confirmed that in general the intensity of the absorption peak at around 2216 cm-1 - 2223 cm-1 of each formulation decreased with the addition of ZnO up to 4 phr of ZnO and increased again at 6 phr of ZnO.

Nano‐silica modification of UV‐curable EVA resin for additive manufacturing

AbstractDue 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.

Ammonium Polyphosphate with High Specific Surface Area by Assembling Zeolite Imidazole Framework in EVA Resin: Significant Mechanical Properties, Migration Resistance, and Flame Retardancy.

A zeolite imidazole framework (ZIF-67) was assembled onto the surface of ammonium polyphosphate (APP) for preparing a series multifunctional flame-retardant APP-ZIFs. The assembly mechanism, chemical structure, chemical compositions, morphology, and specific surface area of APP-ZIFs were characterized. The typical APPZ1 and APPZ4 were selected as intumescent flame retardants with dipentaerythritol (DPER) because of their superior unit catalytic efficiency of cobalt by thermogravimetric analysis. APPZ1 and APPZ4 possessed 6.8 and 92.1 times the specific surface area of untreated APP, which could significantly enhance the interfacial interaction, mechanical properties, and migration resistance when using in ethylene-vinyl acetate (EVA). With 25% loading, 25% APPZ4/DPER achieved a limiting oxygen index value of 29.4% and a UL 94 V-0 rating, whereas 25% APP/DPER achieved a limiting oxygen index value of only 26.2% and a V-2 rating, respectively. The peak of the heat release rate, smoke production rate, and CO production rate respectively decreased by 34.7%, 39.0%, and 40.1%, while the char residue increased by 91.7%. These significant improvements were attributed to the catalytic graphitization by nano cobalt phosphate and the formation of a more protective char barrier comprised of graphite-like carbon.

The application of organic solvents and thermal process for eliminating EVA resin layer from waste photovoltaic modules

With rapidly increasing production and installation, recycling of PV modules has become the main issue. In this study, we developed the application to recover the tempered glass from panels and remove Ethylene-vinyl acetate (EVA) from PV cells. The processes divided into two parts, organic solvents soaking and thermal treatment. In the organic solvents process, this study soaked PV modules into organic solvents to dissolve EVA resin and recover tempered glass. In the thermal treatment, this study removed EVA resin remaining on the PV cell. This study can comprehensively recover tempered glass and remove 99.97% EVA resin from PV cell. Moreover, it can contribute to not only subsequent leaching processes but also the environment and humankind health.

Spray-Drying-Assisted Layer-by-Layer Assembly of Alginate, 3-Aminopropyltriethoxysilane, and Magnesium Hydroxide Flame Retardant and Its Catalytic Graphitization in Ethylene-Vinyl Acetate Resin.

Alginates (nickel alginate, NiA; copper alginate, CuA; zinc alginate, ZnA) and 3-aminopropyltriethoxysilane (APTES) were alternately deposited on a magnesium hydroxide (MH) surface by the spray-drying-assisted layer-by-layer assembly technique, fabricating some efficient and environmentally benign flame retardants (M-FR, including Ni-FR, Cu-FR, and Zn-FR). The morphology, chemical compositions, and structures of M-FR were investigated. With 50 wt % loading, compared with EVA28+MH, the peak heat release rate, smoke production rate, and CO production rate of EVA28+Ni-FR decreased by 50.78%, 61.76%, and 66.67%, respectively. The metals or metal oxide nanoparticles arising from alginates could catalyze the pyrolysis intermediates of EVA into graphene and amorphous carbon, which could bind the inorganic compounds (the decomposition products of MH and APTES) together and form some more protective barriers. For each M-FR, the flame retardant and smoke suppression efficiency were different, which were caused by the diverse carbonization and graphitization behaviors of three alginates. ZnA generated some ZnO aggregations and could not catalyze the graphitization of intermediates. For CuA, the catalytic graphitization was limited by the tightly binding graphene layer. As for NiA, the configuration of the Ni atom could not provide strong binding of Ni substrate and carbon. The liquid-like Ni nanoparticles could restructure and get out from firm graphene shells, so the catalytic graphitization of NiA was efficient and sustainable. This work displayed the catalytic graphitization mechanism of alginates while exploring a simple and novel strategy for fabricating efficient green flame retardants.

Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules

Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal.

An analytical approach for the non-invasive selection of consolidants in rubber artworks.

The effectiveness of five polymeric materials for the long-term conservation and restoration of rubber artworks was evaluated by accelerated photo-oxidative degradation studies. Two different ethylene vinyl-acetate resins, generally used in industry and uncommon in conservation field, a new water-based polyurethane, and two ethylene butyl-acrylate resins were assessed for the consolidation of rubber. By monitoring their degradation along time with LED imaging coupled to statistics and Fourier transform infrared spectroscopy (FTIR), the polymeric materials with the best properties that ensure the protection and security of the artwork were identified. The degradation was performed in solar box simulating the light exposure in a museum, under controlled temperature at no more than 35°C in order to exclude the thermal effects that could influence the ageing of polymers. The mechanical stress of the treated samples was also investigated. The spectroscopic analyses, the chromatic changes study, and the mechanical degradation were used as indicators of the consolidant stability, allowing the evaluation of the materials selected for the consolidation and conservation of rubber. The ethylene-vinyl acetate copolymers resulted the most stable and suitable for the conservation of rubber artworks. Lastly, the conservation treatment identified in this research was employed for the restoration of the contemporary artwork "Presagi di Birnam" made with bicycle inner tubes by the artist Carol Rama.

Layer-by-Layer Assembly of Multifunctional Flame Retardant Based on Brucite, 3-Aminopropyltriethoxysilane, and Alginate and Its Applications in Ethylene-Vinyl Acetate Resin.

An efficient and multifunctional brucite/3-aminopropyltriethoxysilane (APTES)/nickel alginate/APTES (B/A/Nia/A) hybrid flame retardant was fabricated via the layer-by-layer assembly technique with brucite, silane coupling agents, nickel chloride, and sodium alginate. The morphology, chemical composition, and structure of the hybrid flame retardant were characterized. The results confirmed the multilayer structure and indicated that the assembled driving forces were electrostatic interactions, dehydration condensation, hydrogen bonds, and coordination bonds. When used in ethylene-vinyl acetate (EVA) resin, the multifunctional flame retardant had better performance than brucite in improving the flame retardancy, smoke suppression, and mechanical properties. With 130 phr loading, the multifunctional flame retardant achieved a limiting oxygen index value of 32.3% and a UL 94 V-0 rating, whereas the brucite achieved only 31.1% and a V-2 rating, respectively. The peak heat release rate and total heat released decreased by 41.5% and 8.9%, respectively. The multifunctional flame retardant had an excellent performance in reducing the smoke, CO, and CO2 production rates. These improvements could be attributed to the catalyzing carbonization of nickel compounds and the formation of more protective char layers. Moreover, the elongation at break increased by 97.5%, which benefited from the improved compatibility and the sacrificial bonds in the nickel alginate. The mechanism of flame retardant, smoke suppression, and toughening is proposed.

Hydroxyl‐phosphazene‐wrapped carbon nanotubes and its application in ethylene‐vinyl acetate copolymer

ABSTRACTMultiwalled carbon nanotubes (MWNTs) are covalently grafted with hydroxyl modified phosphazene, which constitutes a novel flame retardant structure, and introduced into ethylene‐vinyl acetate (EVA) copolymer via melt blending. The structure and morphology of the phosphazene‐wrapped MWNTs are characterized using Fourier transform infrared spectroscopy and transmission electron microscopy. The grafted phosphazene introduces phosphorus‐ and nitrogen‐containing species onto the surface of MWNTs and thus improves thermal stability of EVA resin and the dispersion of MWNTs in EVA matrix. Thermogravimetric analysis and cone calorimeter analysis reveal that phosphazene and MWNTs produce a synergistic effect on the enhancement of the thermal stability and flame retardancy of EVA. Furthermore, SEM observation indicates that phosphazene accelerates the formation of char residue on the surface of MWNTs. The char residue fills the space in the network structure of MWNTs and glues the MWNTs together. The dense char/MWNTs layers constitute a heat and mass block and therefore a better flame retardancy is observed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4245–4254, 2013

Preparation and Measurement of Controlled‐Release SO2 Fungicide Active Packaging at Room Temperature

In this work, we prepared a novel, three‐layer‐structure packaging film for keeping fruit fresh with a controllable‐release amount of SO2 fungicide. The outer layer was composed of biaxially oriented polypropylene film. The middle layer, prepared by mixing polyurethane adhesive with sodium metabisulfite and calcium sulfite powder, was the generating layer for the SO2 fungicide. The inner layer consisted of a blended film of ethylene vinyl acetate (EVA) and low‐density polyethylene. The water vapour transmission rate and oxygen transmission rate of the composite films, as well as the release amounts of SO2 in all sealed packaging bags, were measured. Next, the controllable‐release mechanism of SO2 fungicide was investigated, of which a preliminary discussion is included. The results of this experiment showed that the release amounts of SO2 in packaging bags were controlled by the additional amount of EVA resin contained in the inner layers. The more EVA resin added to the inner layer, the more SO2 fungicide was produced. Inside the packaging, SO2 was released continuously for approximately 50 days at room temperature (25º ± 1°C). SO2 concentrations ranged from 10 to 40 ppm in the freshness‐preserving packaging bags, effectively retarding mould growth and keeping the fruits fresh. Copyright © 2012 John Wiley & Sons, Ltd.

A study of the recycling and stability of flexographic photopolymer plates

AbstractFlexographic photopolymer plates have a wide range of commercial applications despite the fact that recycling of such materials is difficult. In consequence, there is a large bulk of leftover material around the world. In this research, the photopolymer plate waste products, identified as styrene‐butadiene rubber (SBR)/polyester are blended into common polypropylene (PP) and ethylenevinylacetate (EVA) resins at different loading percentages. PP and EVA are used as the polymer matrix and the recovered styrene‐butadiene rubber (SBR) material as the filler. Evaluation of the mechanical, spectroscopic, thermal and chemical properties, as well as morphology, is done by means of scanning electron microscopy (SEM). Mechanical results show that elongation strongly depends on the matrix polymer: the greater the amount of solid‐sheet photopolymer (SSP), the smaller the elongation. No specific interactions were detected; however, thermal degradation and transitions were displaced, suggesting some miscibility. More homogeneity is seen for EVA blends, with no significant chemical attack detected. It is possible to reuse these recycled materials in blends with PP and EVA resins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Study of Relationship between Consumption of Potassium Permanganate and Total Organic Carbon on Plastic Kitchen Utensils, Food Packages and Toys

Consumption of potassium permanganate and total organic carbon (TOC) were investigated as indices of total organic matter migrated into water from plastic kitchen utensils, food packages and toys for children. The samples were soaked in water at 60 or 95 degrees C for 30 min for kitchen utensils and food packages, and at 40 degrees C for 30 min for toys and the eluates were examined, using the two indices. The quantitation limits were both 0.5 microg/mL. Among 97 kitchen utensils and food packages tested, consumption of potassium permanganate and TOC were 0.5-10.9 microg/mL and ND-18.9 microg/mL for polyvinyl chloride (PVC) tea-pot spouts and nylon kitchen utensils, respectively. Among 32 toys tested, the levels were 0.8-45.5 microg/mL and 0.5-8.9 microg/mL from PVC toys and block toys made by ethylene vinyl acetate resin. The levels for other samples were very low. There were large discrepancies between consumption of potassium permanganate and TOC for some PVC products and nylon kitchen utensils. The cause may be a marked difference of the oxidation decomposition rate by potassium permanganate, depending on the kind of organic matter that migrated from the plastics.

Flammability characteristics and flame retardant mechanism of phosphate-intercalated hydrotalcite in halogen-free flame retardant EVA blends

The flammability characteristics and flame retardant mechanism of phosphate-intercalated hydrotalcite (MgAl-PO 4) in the halogen-free flame retardant ethylene vinyl acetate (EVA) blends have been studied by X-ray diffraction (XRD), Fourier transfer infrared (FTIR) spectroscopy, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI) and UL-94 tests. The results show that the hydrotalcite MgAl-PO 4 intercalated by phosphate possesses the enhanced thermal stability and flame retardant properties compared with ordinary carbonate-intercalated hydrotalcite MgAl-CO 3 in the EVA blends. The CCT tests indicate that the heat release rate (HRR) and mass loss rate (MLR) values of the EVA/MgAl-PO 4 samples are much lower than those of the EVA/MgAl-CO 3 samples. The TGA data show that the thermal degradation rates of MgAl-PO 4 and EVA/MgAl-PO 4 samples are much slower and leave more charred residues than those of MgAl-CO 3 and its corresponding EVA blends. The LOI values of EVA/MgAl-PO 4 samples are 2% higher than those of the corresponding EVA/MgAl-CO 3 samples at the range of 40–60 wt% loadings, while the EVA sample with 55 wt% MgAl-PO 4 can reach the UL-94 V-1 rating. The dynamic FTIR spectra reveal that the flame retardant mechanism of MgAl-PO 4 can be ascribed to its catalysis degradation of the EVA resin, which promotes the formation of charred layers with the P–O–P and P–O–C complexes in the condensed phase. The SEM observations give further evidence of this mechanism that the compact charred layers formed from the EVA/MgAl-PO 4 sample effectively protect the underlying polymer from burning.

Processability, mechanical properties, and electrical conductivities of carbon black-filled ethylene-vinyl acetate copolymers

The objective of this study was to investigate the processability, mechanical properties, and electrical properties of carbon black-filled ethylene-vinyl acetate (EVA) copolymers with different melt flow indexes (MFIs) and vinyl acetate (VA) contents. The effects of carbon black on maximum temperature, equilibrium torque, equilibrium viscosity, and work energy were characterized in a Haake torque rheometer. These properties were found to increase with an increase in carbon black concentration. MFI was found to be the important factor in determining processing properties of the three different EVA resins. Mechanical properties, including tensile modulus, tensile strength at break, and elongation at break were evaluated and the results showed that tensile modulus was dominated by VA content. MFI was the primary factor influencing tensile strength and elongation at break. Volume and surface resistivity of blends were also studied. EVA with higher MFI and higher crystallinity provided a lower percolation concentration. Bound polymer could be used to explain the differences in viscosity and percolation between EVAs at different molecular weights. © 2000 John Wiley & Sons, Inc. Adv Polym Techn 19: 132–139, 2000