Iranian Polymer Journal最新文献

Vegetable oils have gained popularity now-a-days as renewable resources due to their accessibility, affordability, non-toxicity and biodegradability. Globally, scientists have been making efforts to lessen dependency on feed stocks derived from petroleum-based resources. Dehydrated castor oil (DCO) being bio-based, non-edible, quick-drying compared to castor oil, imparting flexibility and excellent color retention was used as the main source of raw material in this work. Present study aims at single-step synthesis of dehydrated castor oil fatty amide (DFAm) by reacting dehydrated castor oil (DCO) with diethanolamine (DEA) avoiding the methyl ester synthesis step. The product obtained was then purified and characterized chemically and analytically. Further, DFAm was modified successfully to its hydroxyl-terminated fatty ester amide (DFEAm) derivative using sebacic acid (SA) and tris-2-hydroxyethyl isocyanurate (THEIC). THEIC, being heterocyclic in nature and imparting excellent thermal and chemical resistance, makes it suitable and novel to be used in coating applications. DFEAm was then successfully cured with various isocyanate adducts on mild steel substrates. Commercially available hydroxyl-terminated short oil alkyd was selected for comparative study under simultaneous conditions. These polyurethane coatings were evaluated as per ASTM standards for their optical, mechanical, chemical, thermal and anti-corrosive properties. DFEAm PU coatings exhibited comparable mechanical and inferior chemical properties but superior thermal and anti-corrosion properties than that of the commercial PU coatings.

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The production of nanofibers holds significant importance in both laboratory-based research and industrial applications. This study employed multiple spinnerets in the process of electrospinning to produce polyvinylidene fluoride (PVDF) nanofibers, which exhibited a desirable characteristic of being both thin and uniform. The spinning performance of multiple jet electrospinning was done. In addition, an examination was conducted to assess the impact of antistatic non-woven support materials on the fiber morphology of PVDF electrospun nanofibers. The morphology and β-phase (beta phase) of the electrospun nanofibers were analyzed using characterization techniques, such as scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The findings of the study indicate that the selection of antistatic non-woven support material had a notable impact on fiber morphology. Upon the utilization of various suitable substrate materials, polyethylene terephthalate (PET) contributed to the successful formation of well-structured and consistent nanofibers with a lesser diameter of 173 ± 38 nm, 92.8% β-fraction and a surface area of 12.99 m²/g. The laminating temperature and density of the fiber decreased the porosity and air permeability by 50%. The excellent flux recovery of 400 L/(m² h) on the nanofibers laminated at 130 °C of pore size of 0.54 µm even after dried and stored for 48 h at room temperature. A finite-element analysis (FEA) was conducted on computer-aided design (CAD) fiber structure, and results showed that at low pressure of 0.01 N, a max of 130.29 MPa stress was generated on fibers.

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VHB 4910/05 polymeric foam tape manufactured by 3M conglomerate is widely acknowledged as a dielectric elastomer with exceptional electromechanical actuation performance than its counterparts. However, actuation in VHB elastomers is well-known to be enhanced by cross-linkers and plasticizers, the impacts of particulate fillers on their structure, properties, and performance are yet to be recognized. This work addresses the influences of barium titanate (BT) and Ketjenblack (KB) dispersed trimethylolpropane trimethacrylate (TMPTMA) as fillers on the behavior of VHB 4910 elastomer for the planar actuators. The elastomer composites are prepared by swelling and then thermochemical curing of the samples in BT and KB dispersed TMPTMA. The incorporation of fillers in the elastomer matrix is confirmed by comparing optical micrographs, swelling degree, cross-link density, molecular bonds, optical bandgap, and opto-dielectric characteristics. Thus, the dielectric and mechanical behavior and electromechanical actuation performance of the filler-reinforced elastomer are discussed. Improved dielectric constant and specifically reduced elastic modulus are witnessed due to the gelation of TMPTMA leading to a new range of actuation in VHB 4910 elastomer. The areal actuation in elastomer comprising BT, KB and BT-KB particle dispersed TMPTMA is estimated at about 180%, 150% and 165%, respectively. The low electric field requirement is noticed for BT-containing elastomer composite. This work scopes the use of swelling techniques to modify microporous elastomers with particulate fillers towards soft actuators, sensors, and energy generators.

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A continuous extrusion foaming process was performed on poly(lactic acid) (PLA) in the presence of different chemical foaming agents (CFAs) and a chain extender additive using different extruder barrel and die temperature profiles. Chemical reactions, which are involved in the extrusion foaming process of PLA, are intensely investigated to control the reactive extrusion process and tailor the foam final properties. A set of experiments was designed using the response surface methodology to evaluate the effects of material and processing parameters and optimize the PLA foam property. The results showed that the maximum void fraction, i.e. 0.55, was obtained by exothermic CFA at higher extruder temperatures. In contrast to the exothermic CFA, the addition of endothermic CFAs did not result in lightweight biodegradable foams. The void fractions of these extruded foams were less than 0.05. The presence of water molecules as a by-product of the decomposition reaction and also relatively lower decomposition temperatures of the endothermic CFAs have been considered as the main reasons. Among the variables studied, the CFA type had the strongest impact on the foam properties. In the second step, the barrel and die temperatures were adjusted accordingly.

This study investigates the impact of addition of different weight percentages of tungsten disulphide (WS₂) lubricant on the thermal and mechanical properties of high density polyethylene (HDPE) hybrid composites reinforced with a multi-walled carbon nanotube (MWCNT). HDPE composites were fabricated using a twin-screw extruder process employed to add reinforcement and lubricants in different weight percentages (%, by weight). X-ray diffraction (XRD) patterns indicated the distribution and dispersion of filler materials in the HDPE matrix. The quality of the composite was investigated by measuring the mechanical properties such as impact strength, hardness, tensile strength, and flexural strength. Thermogravimetric analysis (TGA) was employed to examine the thermal stability of the composite material. Main decomposition temperatures were determined using derivative thermogravimetry (DTG) analysis. Thermal transitions and degree of crystallisation (X_c) of the polymeric materials used were investigated by using differential scanning calorimetry (DSC) technique. The lubricant was added in three varying amounts of 2%, 4% and 8% (by weight) whilst MWCNT was maintained at 1% (by weight). The experimental results revealed that the composite with 2% (by weight) of WS₂ provides better mechanical properties such as impact strength, flexural strength, tensile strength, and hardness. With an increase in lubricant percentage, agglomeration of particles is found to be dominant in the composite, and the composite with 4% (by weight) of WS₂ displays better thermal properties, as determined using TGA, DTG and DSC analytical techniques.

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Temperature-dependent storage modulus of polymer nanocomposites, blends and blend-based nanocomposites was studied using both analytical and experimental approaches. The analytical strategy comprised modeling the thermomechanical property of the systems based on parameters affecting the conversion degree of polymer chains in state-to-state transitions and mechanical characteristics of the polymer/polymer interface. Accordingly, percolation theory was developed to define the order of conversion rate and conversion degree of polymer chains considering the thermomechanical characteristics of the neat polymer matrix, behavior of nanoparticles in the system and formation of polymer/particle interphase region. The effect of interphase on a temperature-dependent conversion of polymer molecules was estimated based on De Gennes’s self-similar using the molecular characteristics of the adsorbed polymer chains and related scaling factor. To validate the model predictions, different neat, blend, nanocomposite and blend-based nanocomposite samples were prepared using high-density polyethylene, polyethylene terephthalate and hollow graphene oxide nanoparticles, where needed, and subjected to dynamic mechanical thermal analysis and other required tests. Besides providing acceptably accurate predictions in the case of all neat and nanocomposite samples, the model was proved to be independent of the system’s morphological variation.

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Particulate matter and volatile organic compounds pose severe threats to human health. Therefore, in this study samples of polypropylene/graphene oxide with varying compositions were prepared for to be tested in automotive sector. Graphene oxide was obtained through an electrochemical exfoliation of graphite recovered from exhausted batteries. The preparation of the composites was performed using graphene oxide at ratios of 0.3%, 0.7% and 1.0% (w/w), already diluted in a hyperdispersant agent. The composites were compared to both pure polypropylene and polypropylene/carbon black composites. The samples were characterized based on their melt flow index, thermal stability, crystallinity, flammability, and mechanical and rheological properties. The formulations containing graphene oxide obtained from the recycling of exhausted batteries exhibited superior thermal properties and melt flow index compared to pure polypropylene. In addition, the composites containing 0.7% of graphene oxide showed an increase in flow index compared to the composite containing carbon black. The rheological properties of samples containing graphene oxide had values closer to pure polypropylene compared to those containing only hyperdispersant or carbon black. The increase in the flow index of a composite containing graphene oxide can result in energy cost savings during processing. Polypropylene/graphene oxide composites present an interesting alternative by replacing carbon black with recycled graphene oxide, both in terms of costs and environmental impact, aligning with the principles of green chemistry.

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Surface modification of polysulfone (PSF) membrane bioreactor using hybrid halloysite nanotubes (HHNTs) and dendrimers was investigated for industrial wastewater treatment containing heavy metals. Petroleum wastewater was obtained from liquefied gas plant 1200 (NGL 1200) in Gachsaran, Iran. Polysulfone)PSF( membranes were fabricated using hybrid halloysite nanotubes and dendrimers at different concentrations of 0, 0.5, 1, and 2 wt% and identified with certain codes of PSF, HNT0.5, HNT1, and HNT2, respectively. The fabricated membranes were characterized by FTIR, AFM, EDX, SEM, and contact angle analyses. The contact angle decreased as a result of HNT loading in PSF membranes, which was due to the enhancement of the membrane hydrophobicity. The heavy metal rejection in the HNT1 membrane for Cu (II), Pb (II), Ni (II), and Zn (II) was 83.25%, 98.79%, 81.09%, and 85.98%, respectively. Also, the rejection of Ni (II) in PSF was 38.24% which showed a lower amount. Based on the results, the HNT1 membrane which was fabricated using 1 wt% of the hybrid halloysite nanotubes showed the best performance to heavy metals removal from industrial effluents.

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