Maziyar Sabet

Effect of zinc borate on flammability/thermal properties of ethylene vinyl acetate filled with metal hydroxides

In this work, zinc borate was used as a flame retardant in ethylene vinyl acetate/magnesium hydroxide or aluminum hydroxide flame-retardant formulations. High content zinc borate leads to significant improvements of flame retardancy through limiting oxygen index, UL-94 and cone calorimeter experiments. The protective char formation revealed significant structural modifications due to the presence of zinc borate. It was demonstrated that during polymer heating, aluminum hydroxide and magnesium hydroxide decomposed to Al2O3 and MgO which resulted an increase in ignition time. Moreover, formation of Al2O3 or MgO in situ from aluminum hydroxide or magnesium hydroxide during polymer combustion is the first event. Concurrently, zinc borate degraded and formed a vitreous protective coating, which yielded the substrate with an efficient char which acted as a physical barrier and a glassy cage for better protection of polymer substrate.

Studies on the Stability of the Foamy Oil in Developing Heavy Oil Reservoirs

In the process of natural energy depletion, foamy oil is characterized of low production Gas Oil Ratio, high oil viscosity, high daily production rate and high primary recovery factor. The stability of the foam turns out to be the prevailing factor that governs the life of the ‘foamy oil’. To enumerate the main factors affecting the stability of the foam, a high-temperature–high-pressure visualized experiment model for foamy oil stability test was developed. A serial of experiments was conducted to evaluate the performance of the foam stability. The effects of oil viscosity, height of the oil column, dissolved gas content and dispersed gas were investigated and recorded. These experiments were conducted using a Hele-Shaw, a high pressure cell. The volume of foamy oil produced, either by a step reduction in pressure or by a gradual (linear) reduction in pressure, and its subsequent decay was observed, visually. The experimental results show that foamy oil stability increases with higher oil viscosity, higher oil column, higher dissolved gas content and higher pressure decline rate. Asphaltene content was not observed to increase the foamy oil stability significantly. The results also show that the foam quality of foamy oils is much lower than aqueous foams.

Mechanical and electrical properties of low density polyethylene filled with carbon nanotubes

Carbon nanotubes (CNTs) reveal outstanding electrical and mechanical properties in addition to nanometer scale diameter and high aspect ratio, consequently, making it an ideal reinforcing agent for high strength polymer composites. Low density polyethylene (LDPE)/CNT composites were prepared via melt compounding. Mechanical and electrical properties of (LDPE)/CNT composites with different CNT contents were studied in this research.

Electron-beam irradiation of low density polyethylene/ethylene vinyl acetate blends

Abstract In this work, the properties of electron-beam irradiated low density polyethylene (LDPE), ethylene vinyl acetate (EVA) and blends were investigated. EVA addition had an enhancement effect on crosslinking of irradiated LDPE/EVA blends. The measured gel content increase of the blends and the improvement of thermal elongation, tensile strength, elongation at break, thermal aging and heat deformation, have confirmed the positive effects of electron-beam irradiation on the blend properties. The crystallinity of the blends decreased with irradiation. The gel content and hot set tests showed that the degree of crosslinking in the amorphous regions was dependent on the dose and blend composition. Increasing the EVA content resulted in tighter network structures. A significant improvement in the tensile strength of the neat EVA samples was obtained upon electron-beam irradiation up to 210 kGy. The irradiated LDPE/EVA blends showed improved tensile strength and elongation at break, when compared to LDPE. The enhanced irradiation crosslinking of the LDPE/EVA blends was proportional to the good compatibility and the increasing degree of the amorphous region’s content of the LDPE/EVA blends. The possible degradation mechanism of LDPE/EVA blends was discussed quantitatively with a novel method step analysis process of irradiated LDPE/EVA blends in the thermal gravimetric analysis (TGA) technique. It was found, with measuring thermal conductivity (k) and specific heat capacity (Cp) of the blends, that the k values of the LDPE samples at a prescribed temperature range decreased with increasing irradiation. An increase in the crystallinity led to an increase in the k values and a decrease in the Cp values of the LDPE samples. Irradiation below 150 kGy decreased the Cp (at 40°C) and k in average values, whereas increasing the EVA made enhanced the Cp and k values of LDPE/EVA blends at each irradiation. The surface resistance and volume resistivity (VR) of the blends reached a maximum at a 170 kGy irradiation and 30 wt% of EVA. Increasing the amount of EVA contents resulted in enhancement of the dielectric loss factor for the irradiated blends.

The Effect of TMPTMA Addition on Electron- beam Irradiated LDPE, EVA and Blend Properties

Abstract In this work low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) were blended in the presence of trimethylol propane trimethylacrylate (TMPTMA) (0 to 6 phr). The resultant blends were irradiated with a 3 MeV electron-beam resulting in dosages of 0 to 240 kGy using a rhodotron accelerator system. The effect of radiation exposure on the LDPE/EVA/TMPTMA blend properties were investigated with respect to gel content, tensile strength and elongation up to breakage of the blends. The findings indicate that increasing EVA and TMPTMA content yield tighter network structures through enhanced blend crosslinking, which is a direct consequence of irradiation. For pure EVA significant tensile strength improvements are evident as irradiation increases up to 210 kGy. Irradiated blends exhibit improved tensile strength and elongation at breakage with respect to pure LDPE and EVA. Volume resistivity (VR) and dielectric constant (DC) of the blends were also studied as a function of EVA content, TMPTMA content and radiation dosage. Increasing EVA and TMPTMA content enhances DC and VR values, whereas, increasing irradiation dosage only effects VR values of the blends. The maximum VR value attained in this work corresponds to a radiation dosage of 170 kGy and a blend comprising of 30 wt% of EVA.

Properties of ethylene–vinyl acetate filled with metal hydroxide

In this study, the properties of ethylene–vinyl acetate (EVA) and EVA filled with aluminum (aluminum trihydrate; ATH) and magnesium hydroxide (MH) as halogen-free flame-retardant materials were studied. Scanning electron microscopic analysis revealed that MH in EVA matrix is platy in structure, considerably broad size distribution and well homogeneously distributed, whereas ATH particles are smaller and much more homogeneous in size. Addition of ATH or MH to EVA had an impressive affection on the thermal aging and flame tests but impaired the blend mechanical properties. This research explored that in comparison with ATH, addition of MH to EVA blends was more efficient and suitable in all mechanical, thermal, and flammability tests.

Electron Beam Irradiation of LDPE Filled with Calcium Carbonate and Metal Hydroxides

This article deals with the effect of electron beam irradiation and flame-retardant loading on the performances of LDPE-based formulations for wire and cable applications. In this study the influence of electron beam irradiation on different blends of low density polyethylene (LDPE) filled with aluminum trihydrate (ATH), magnesium hydroxide (MH), and calcium carbonate (CaCO3) were studied. The mechanical, thermal, and burning properties of the resulting polymer networks have been analyzed and discussed. Addition of all non-halogenated fillers to LDPE deteriorated the mechanical properties. Addition of MH to LDPE presented a significant increase on adhesion forces inside polymer matrices and acted more efficiently than similar ATH/LDPE and CaCO3/LDPE compounds. LDPE flame retardancy improved significantly by a carbonaceous, non-flammable coating formation with high plasticity of CaCO3 addition at high temperature. The resulting MH blends were more efficient thermally and burned more stably than similar ATH...

The Effect of Addition EVA and LDPE-g-MAH on Irradiated LDPE Filled with Metal Hydroxides

Electron beam irradiation efffects on polymer cross-linking used for wire and cable insulations are still being researched. This study showed that upon irradiation, ethylene vinyl acetate (EVA) and maleic anhydride grafted polyethylene (LDPE-g-MAH) addition as coupling agent to the LDPE/fillers, improved processing and mechanical properties of compounds at each irradiation dosage (0–110 kGy). A gradual increase in gel content (GC) and tensile strength (TS) with a concomitant decline in elongation at break (EB), hot set (HS) and densities of compounds were observed upon irradiation of the blends. Melt flow index test (MFI) results revealed that filler addition reduced compounds flowing and in consequence, caused difficult to process. The LDPE/EVA blends TS values decreased significantly with fillers addition (ATH, MH and ZB). Consequently, this study demonstrated that filler addition to irradiated low density polyethylene (LDPE) impaired processing and mechanical properties of compounds, whereas, LDPE-g-MAH (6–12 phr) and EVA (0–100 phr) addition to the compounds (1I–8I) improved the blends flowability and mechanical properties at each irradiation dose (0–110 kGy). Moreover, among additive fillers, MH content compounds presented the strongest adhesion forces with polymeric compounds compared with analog compounds content aluminum trihydrate (ATH) or zinc borate (ZB) at each irradiation dosage.

Calcium Stearate and Alumina Trihydrate Addition of Irradiated LDPE, EVA and Blends with Electron Beam

Irradiation effects on the properties of alumina trihydrate (ATH) / low-density polyethylene (LDPE)/ ethylene vinyl acetate (EVA) / calcium stearate (CS) have been studied and confirmed that EVA and CS addition to the polymeric blends have improved the mechanical properties. ATH addition increased the cross-linking density and improved the blend reinforcing factor but deteriorated the blend mechanical properties. CS addition made ease the ATH dispersion inside polymer matrix. CS addition optimum value in blends was 3 phr and CS addition above 3 phr value deteriorated the blends mechanical properties.

Electron beam irradiation of low-density polyethylene filled with metal hydroxides for wire and cable applications

The effects of electron beam irradiation for crosslinking of polymers used for wire and cable insulations are still being researched. In this research, the influence of electron beam irradiation on the different blends of low-density polyethylene (LDPE) filled with aluminum trihydrate and magnesium hydroxide (ATH, MH) were studied. It was revealed by melt flow index, tensile strength, and elongation at break tests that addition of MH to LDPE increases the adhesion forces inside polymer matrices more efficient than similar ATH/LDPE compounds. Field emission scanning electron microscopy test showed that MH is platy in structure and more homogenous mixed than ATH with LDPE. The results on thermogravimetric analysis and limiting oxygen index tests revealed that the thermal stability and incombustibility properties of MH blends are more efficient than similar ATH blends. Meanwhile, it was observed by smoke density test that MH blends produce the lowest smoke density compared with virgin LDPE and similar ATH blends. It was also observed that increasing irradiation by electron beam had impressive affections on the density, gel content, and mechanical properties for all the polymeric samples in this study.