Blends of ethylene–methyl acrylate–acrylic acid terpolymers with ethylene–acrylic acid copolymers: Mechanical and thermomechanical properties

The effect of methyl acrylate content in ethylene–methyl acrylate–acrylic acid (E–MA–AA) terpolymers and acrylic acid content in ethylene–acrylic acid (E–AA) copolymers was investigated in blends of these two materials. The E–MA–AA terpolymer with 8 mol % methyl acrylate was not miscible with any E–AA material no matter what the AA content, whereas the terpolymer with only about 2 mol % methyl acrylate was miscible, at least to some extent, with the E–AA copolymer at high acrylic acid contents. Evidence supporting this conclusion derived from gloss, differential scanning calorimetry testing, and dynamic mechanical measurements. For the E–AA polymer material with the highest acid content, there was a synergistic effect for some properties at low added amounts of E–MA–AA copolymer; the tensile strength and hardness were 10% higher than values for the E–AA copolymer, even though the E–AA copolymer was much stiffer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2216–2222, 2004     

Mesoporous water adsorbent material from poly high internal phase emulsion for agriculture application

Mesoporous water adsorbent materials were prepared by high internal phase emulsion (HIPE) technique: a technique which used aqueous phase (water phase) as a temporary template (in the form of droplets) and oil phase (polymer phase) as a continuous structure. This research describes the preparation of porous poly[S/ethylene glycol dimethylacrylate (EGDMA)]HIPE from styrene crosslinked with EGDMA. Effects of chemical composition on the pores of the mesoporous adsorbents were investigated. The EGDMA concentration was varied between 0 and 40% of oil phase by total volume to give polyHIPE with various amounts of hydroxyl groups. Effects of oil: aqueous phase ratio on mesoporous adsorbent polyHIPEs resulted in interconnected pores in their morphology. The EGDMA concentration also affected the obtained polyHIPE morphology. The water adsorption of poly(S/EGDMA)HIPE gave high water adsorption, up to 350% of dry weight. The obtained polyHIPE with large average pore size were also found to give high water adsorption capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45509.     

Synthesis and encapsulation of magnetite nanoparticles in PLGA: effect of amount of PLGA on characteristics of encapsulated nanoparticles

Oleic acid-coated superparamagnetic iron oxide nanoparticles (Fe₃O₄) encapsulated within poly(d,l-lactide-co-glycolide) (PLGA) particles were prepared by the w/o/w emulsion technique using poly(vinyl alcohol) as a dispersant. The concentration of PLGA in the oil phase was varied (5, 15, 30, 45, and 60?mg/ml) at constant magnetite concentration in the oil phase (5?mg/ml) to study the properties of composite Fe₃O₄–PLGA nanoparticles. Even though PLGA concentration varied widely in the oil phase, the weight percent of 7–16?nm diameter magnetite in the particles varied only from 56 to 62?% (23–28?vol.%). The obtained composite nanoparticles were essentially spherical with magnetite spatially uniformly dispersed in individual PLGA particles, as measured by transmission electron microscopy (TEM). Also, the magnetite concentration in each particle did not vary widely as determined qualitatively via microscopy. Hydrodynamic diameters of the composite nanoparticles as measured by dynamic light scattering increased by approximately 10?% with added magnetite, with a smaller relative increase in diameter measured by TEM. The zeta potential of the particles was about ?26?mV, independent of Fe₃O₄ loading. Relatively high saturation magnetizations (36–45?emu/g) were measured for these highly loaded particles, with the latter value only 7?emu/g lower than the value measured for the oleic acid-coated particles alone.     

Use of zinc‐neutralized ethylene/methacrylic acid copolymer ionomers as blend compatibilizers for nylon 6 and low‐density polyethylene

The effect of the composition on the morphologies and properties of uncompatibilized and compatibilized blends of nylon 6 and low‐density polyethylene were studied over a wide range of weight fractions. The uncompatibilized blends had substantially reduced mechanical properties after mixing, and this was almost certainly due to poor interfacial adhesion between the two polymers. The addition of a zinc‐neutralized poly(ethylene‐co‐methacrylic acid) ionomer (Surlyn® 9020) as a compatibilizer improved the mechanical properties in comparison with those of the material blended without the compatibilizer. The clearest evidence of this improvement came from dynamic mechanical studies; for selected blends with high polyethylene contents, the drop in the modulus corresponding to the transition of a solid to a melt occurred at higher temperatures with the added compatibilizer. This improvement in the properties was accompanied by a reduction in the dispersed‐phase size due to the interaction between the ionic part of the ionomer and the amide groups of nylon 6, especially when nylon 6 was the dispersed phase of the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 620–629, 2003     

Melt Rheology of Low-Density Polyethylene/Polyamide 6 using Ionomer as a Compatibilizer

Rheology of blends of polyamide 6 with low-density polyethylene compatibilized with sodium-, zinc-, and lithium-neutralized ethylene-methacrylic acid ionomers were investigated at 11, 33 and 55% neutralization of ionomer. Blends of polyamide 6 with low-density polyethylene without compatibilizer had lower shear viscosities than a mixing rule would predict. After adding compatibilizer, the shear viscosity of the blend is increased, presumably due to the formation of graft copolymer from the reaction of the primary amine with free acid groups. The increase of shear and elongational viscosity properties is less with EMAA than with the ionomers; which is consistent with mechanical property and dispersed phase size results presented in an earlier publication. For high polyamide 6 content blends, zinc-neutralized compatibilizers yielded the highest shear and elongational viscosities; while for low polyamide 6 contents, lithium-neutralized compatibilizers yielded the highest viscosities.     

Ultrafine Electrospun Polyamide‐6 Fibers: Effects of Solvent System and Emitting Electrode Polarity on Morphology and Average Fiber Diameter

Summary: In the present contribution, polyamide‐6 (PA‐6) solutions were prepared in various pure and mixed‐solvent systems and later electrospun with the polarity of the emitting electrode being either positive or negative. The PA‐6 concentration in the as‐prepared solutions was fixed at 32% w/v. Some of the solution properties, i.e., shear viscosity, surface tension, and conductivity, were measured. Irrespective of the polarity of the emitting electrode, only the electrospinning of PA‐6 solution in formic acid (85 wt.‐% aqueous solution) produced uniform electrospun fibers, while solutions of PA‐6 in m‐cresol or sulfuric acid (either 20 or 40 wt.‐% aqueous solution) did not. In the mixed‐solvent systems, formic acid (85 wt.‐% aqueous solution) was blended with m‐cresol, sulfuric acid (either 20 or 40 wt.‐% aqueous solution), acetic acid, or ethanol in the compositional range of 10–40 vol.‐% (based on the amount of the minor solvent). Generally, the average fiber diameter increased with increasing amount of the minor solvent or liquid. Interestingly, the diameters of the fibers obtained under the negative electrode polarity were larger than those obtained under the positive one.

Optical images of electrospun fibers from solutions of polyamide‐6 in a mixed solvent of 85 wt.‐% formic acid and 20 vol.‐% m‐cresol under positive (left) and negative (right) electrode polarity.     

Preparation and characterization of ultrafine electrospun polyacrylonitrile fibers and their subsequent pyrolysis to carbon fibers

The present contribution reports the fabrication and characterization of ultrafine polyacrylonitrile (PAN) fibers by electrospinning and further development of the as‐spun PAN fibers into ultrafine carbon fibers. The effects of solution conditions (i.e., solution concentration, viscosity, conductivity, and surface tension) and process parameters (i.e., applied electrostatic field strength, emitting electrode polarity, nozzle diameter, and take‐up speed of a rotating‐drum collector) on morphological appearance and average diameter of the as‐spun PAN fibers were investigated by optical scanning (OS) and scanning electron microscopy (SEM). The concentration, and hence the viscosity, of the spinning solutions significantly affected the morphology and diameters of the as‐spun PAN fibers. The applied electrostatic field strength and nozzle diameter slightly affected the diameters of the as‐spun fibers, while the emitting electrode polarity did not show any influence over the morphology and size of the as‐spun fibers. Utilization of the rotating‐drum collector enhanced the alignment of the as‐spun fibers. Within the investigated concentration range, the average diameter of the fibers ranged between 80 and 725 nm. Finally, heat treatment of the as‐spun fibers with their average diameter of about 450 nm was carried out at 230 and 1000 °C, respectively. Various characterization techniques revealed successful conversion into carbon fibers with an average diameter of about 250 nm. Copyright © 2006 Society of Chemical Industry     

The effect of zinc oxide addition on the compatibilization efficiency of maleic anhydride grafted high‐density polyethylene compatibilizer for high‐density polyethylene/polyamide 6 blends

A high‐density polyethylene with grafted maleic anhydride units has been investigated as a compatibilizer for high‐density polyethylene with polyamide 6. The material acts as an effective compatibilizer, causing a marked reduction in dispersed phase size as well as an increase in tensile strength and toughness. Compatibilizer also affects the glass‐transition temperature, crystallization kinetics, and amount of crystalline material for certain blend compositions. The addition of zinc cations, which are effective in increasing ethylene‐acid copolymer compatibilizer performance in low‐density polyethylene/polyamide blends, has little, if any, effect on compatibilizer performance in these high‐density polyethylene/polyamide blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3871–3881, 2007     

Melt-neutralization of maleic anhydride grafted on high-density polyethylene compatibilizer for polyamide-6/high-density polyethylene blend: effect of neutralization level on compatibility of the blend

Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.     

Improvement in the Efficiency and Capacity of Chopped Spring Onion Drying

ABSTRACT

Appropriate strategy for drying chopped spring onion with a batchwise flat bed was investigated. Both experimental and simulated results such as product quality, drying capacity and energy consumption were taken into consideration. For simulation work, equations of drying parameters such as specific heat, equilibrium moisture content and thin layer drying were first developed from the lab-scale experimental results. Then a mathematical model including shrinkage for a batchwix flat bed drying was developed. The model was lested with the results obtained from a food processing plant with an acceptable accuracy. Appropriate drying strategy war then investigated. The approximate conclusion was that the drying should be devided into 3 stages. In the 1^st stage, drying air temperature was 80°C, specific air flow rate was 33.9 m³/min -kg dry matter and drying time was 0.5 h. In the 2nd stage, drying air temperature and drying time were kept unchanged but specific air flow rate was decreased to 13.5 m³/min - kg dry matter. In the final stage, drying air temperature was decreased to 67°C, specific air flow rate was also decreased to 6.8 m³/min - kg dry matter and drying time was approximately 1.7 h. Following the suggested strategy, specific primary energy cornsumption was 6.2 MJ/kg H₂O, drying time was 2.7 h and product quality was maintained. It was proven that energy consumption was approximalcly 70% of that of the present practice in the plant.