Journal of Applied Research of Chemical -Polymer Engineering

Abstract Research subject: This study investigates the effect of poly(butyl acrylate) (PBA)-based polymeric plasticizers on the performance of poly(vinyl chloride) (PVC) films. The main objectives were the synthesis and evaluation of graft copolymer plasticizers, PVC-g-PBA, with varying PBA chain lengths, and the examination of their impact on the microstructure, mechanical properties, and stability of PVC films.
Research approach: PBA chains with different molar percentages (40–80%) were grafted onto PVC chains via atom transfer radical polymerization (ATRP). The microstructures of the synthesized copolymers were confirmed using Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). These copolymers were then used as plasticizers (at 22 wt%) in the preparation of PVC films. The mechanical properties (tensile strength and elongation at break), morphology (via wide-angle X-ray diffraction (WAXD)), plasticizer stability in the PVC matrix (extraction test), and thermomechanical behavior (via dynamic mechanical thermal analysis (DMTA)) were evaluated.
Main results: Increasing the molar percentage of PBA in the copolymers reduced the yield stress from 53 to 10 MPa, while significantly increasing the elongation at break from 9% to 162%, indicating enhanced flexibility of the PVC films. WAXD results revealed that at lower PBA contents (up to 63%), chain ordering improved, whereas higher PBA incorporation (73%) led to a notable reduction in crystallinity due to the amorphous nature of PBA. The extraction test confirmed the high stability of the synthesized plasticizers in the PVC matrix after 24 hours. DMTA analysis indicated shifts in the glass transition temperature between phases as the PBA content increased. Compared to the conventional plasticizer dioctyl phthalate (DOP), the synthesized plasticizers exhibited superior mechanical performance and are proposed as a highly stable alternative for PVC applications.

 

Abstract Research subject: The flare, as an integral part of petrochemical plants, not only ensures the safety of operations and personnel but is also a major source of pollutant emissions and volatile organic compounds. The gases directed to the flare often contain valuable components whose recovery can significantly enhance production, increase revenues, and reduce greenhouse gas emissions. Therefore, investigating the recovery of flare gases and their reuse in petrochemical processes is of considerable importance.
Research approach: In this study, aimed at recovering flare gases in the Zagros Petrochemical Complex, process simulation and energy–exergy analyses were performed. The proposed process consisted of a methane steam reformer operating at 1000 K and 101.3 kPa, a system of heat exchangers, a water–condensate separator, and a gas compression unit increasing the recovered gas pressure to 7600 kPa in accordance with the methanol synthesis reactor conditions. Furthermore, a sensitivity analysis was conducted to examine the effect of steam-to-carbon ratio and reformer feed temperature on the overall energy and exergy performance of the system.
Main results: The results indicated that the optimum steam-to-carbon ratio in the reformer was 13, at which all methane was converted into syngas. Increasing the feed temperature reduced reformer energy consumption, enhanced energy efficiency, and decreased exergy destruction. Exergy analysis showed that the reformer accounted for the highest share of exergy destruction (49.43%), while the water separator contributed none. The overall energy efficiency of the process was calculated as 56.43%, with 17 GJ of input energy utilized. The specific energy loss and exergy destruction per ton of recovered gas were 13.13 GJ and 2.62 GJ, respectively. Methanol synthesis unit simulation revealed that syngas recovery increased methanol production by 9.16%, equivalent to 462.39 tons per day. Finally, the evaluation confirmed that implementing flare gas recovery completely eliminated CO2 emissions from flaring, thereby reducing the CO2 footprint from this source to zero.

Abstract Research subject: This study employs a novel approach to the synthesis of liquid polysulfide. One of the drawbacks of synthesizing liquid polysulfide is the use of 1,2,3-trichloropropane (TCP) as a crosslinking agent, which poses significant toxicity and carcinogenic hazards. Glutaraldehyde (GLH) was utilized as a crosslinking agent in this study, as it is safer than TCP.
Research approach: Bis(2-chloroethyl) formal and sodium tetrasulfide (Na2S4) monomers were used in a surface suspension reaction to create liquid polysulfide, with glutaraldehyde (GLH) serving as a crosslinking agent. The organic monomer, bis(2-chloroethyl) formal, was also produced by reacting ethylene chlorohydrin with paraformaldehyde. The organic monomer's synthesis and purity were assessed using gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The produced liquid polysulfide was then subjected to FTIR, viscometry, T-peel, tensile, and hardness tests for analysis. This study examined the effect of GLH concentration on the flowability, mechanical, and adhesion properties of liquid polysulfide by varying its proportion in the polymer.
Main results: The viscosity of liquid polysulfide with 1.5 to 2 wt. % GLH (LP-3 and LP-4) was 6800 and 11000 mPa.s, respectively, surpassing that of samples with 0.5 to 1 wt. % GLH (LP-1 and LP-2), with viscosities of 3900 and 4100 mPa.s, respectively. Samples LP-3 and LP-4 exhibited superior tensile strength compared to samples LP-1 and LP-2. The adhesion to metal in samples LP-1 and LP-2 exceeded that of samples LP-3 and LP-4. The optimal GLH composition, based on tensile properties and hardness, lies between 1.5 and 2 wt.%. However, due to the elevated viscosity of liquid polysulfide containing 2 wt.% GLH (LP-4) and its inadequate fluidity at ambient temperature as a sealant, along with the lower adhesion of sample LP-4, samples LP-2 and LP-3 were identified as the most suitable compositions in terms of viscosity, hardness, tensile strength, and peel strength for formulating a reliable liquid polysulfide sealant.

Abstract Research subject: In this study, a conductive sensitive layer composed of polybenzimidazole (PBI) and carbon nanotubes (CNTs) was designed and fabricated via electrospinning for the detection of volatile organic compounds (VOCs)—(methanol, ethanol, isopropyl alcohol (IPA), acetone—and water vapor.
Research approach: This study employed an experimental approach. In the first stage, various processing parameters—such as flow rate, voltage, and needle-to-collector distance—were optimized to enable the fabrication of uniform fibers with nanometric diameters. Subsequently, the fibers were deposited onto an interdigitated gold-on-glass electrode (IDE) as the sensor base to form the sensitive layer of the sensor. Finally, the dynamic response of the fabricated sensor was evaluated using a custom-built measurement system developed by the research group.
Main results: Optimal electrospinning conditions were established at a flow rate of 0.5 cc h⁻¹, an applied voltage of 24 kV, and a nozzle-to-collector distance of 15 cm, enabling the production of uniform nanofibers, as confirmed by scanning electron microscopy (SEM). Brunauer–Emmett–Teller (BET) analysis revealed a fiber specific surface area corresponding to 18.23 m² g⁻¹. Dynamic sensing experiments demonstrated strong sensor responses toward alcohols and acetone, with response intensity correlating inversely with alcohol polarity from methanol to IPA. The sensors exhibited an exceptionally short response time (< 10 s), attributed to the nanofibrous architecture of the sensing layer, which promotes rapid vapor diffusion and access to active sites. Furthermore, the response trends and selectivity toward target vapors were analyzed in the context of thermodynamic parameters, including the Flory–Huggins interaction parameter.

Abstract Research subject: Polypropylene (PP) is a cost-effective, highly processable polymer; however, its intrinsic flammability limits its use in several industrial applications. Among flame-retardant strategies, intumescent systems are prominent, yet they typically require high loadings to be effective, which can reduce melt flow and mechanical properties. In this study, ammonium polyphosphate (APP) was employed as the primary flame retardant and zinc borate (ZnB) as a synergist to determine the optimal formulation and to evaluate their effects on the flammability, melt flow behavior, and mechanical properties of PP.
Research approach: PP compounds were prepared using a twin-screw extruder containing 20–30 wt% APP and 3 wt% ZnB. Test specimens were obtained by injection molding. UL-94 vertical flammability test, melt flow index (MFI), tensile testing, and impact resistance evaluations were conducted to analyze processing–performance interactions.
Main results: APP alone improved flame resistance, but, even at 30 wt%, was limited to a V-1 rating. Adding 3 wt% ZnB produced a suitable synergistic effect. Formulations containing 25 wt% APP and 3 wt% ZnB achieved a UL-94 V-0 rating, characterized by rapid self-extinguishing and reduced melt dripping, attributed to the formation of a dense char layer. The MFI of the compounds decreased at additive loadings above 25 wt%. While APP reduced the impact resistance of PP, incorporating ZnB into the formulation with 25 wt% APP improved impact strength by 12% and more than doubled the elongation at break, while maintaining a similar range of tensile strength. Overall, the APP/ZnB system in a PP matrix offers a favorable balance between flame retardancy and mechanical properties, making it a suitable option for both industrial and environmentally friendly applications.

 

Abstract Research subject: In this study, a heterojunction nanostructure composed of graphitic carbon nitride (g-C₃N₄) and copper oxide (CuO) was synthesized and investigated to evaluate its photocatalytic efficiency in degrading organic dyes (such as Rhodamine B) and potassium amyl xanthate (PAX) under visible light irradiation. The main objective was to enhance photocatalytic performance by combining these two semiconductors and studying various parameters, including calcination temperature.
Research approach: To synthesize the g-C₃N₄/CuO heterojunction nanostructure, the calcination method was employed. In this process, g-C₃N₄ was synthesized through the polymerization of urea at 550  °C. For fabricating the heterojunction nanocomposite, different amounts of CuO nanoparticles were mixed with urea and calcined at various temperatures for 4 hours in a furnace.
XRD analysis was used to identify the crystalline phases, UV-vis spectroscopy was performed to measure optical transmittance, and FE-SEM was applied to examine the surface morphology. The electron–hole recombination rate was studied using photoluminescence (PL) spectroscopy. Finally, the photocatalytic activity of the composites was evaluated by the degradation of Rhodamine B and  potassium amyl xanthate under visible light irradiation, and scavenger tests were conducted to identify the active species involved in the degradation process.
Main results: XRD analysis confirmed the successful formation of the g-C₃N₄/CuO heterojunction. UV-vis spectra showed that incorporating CuO into g-C₃N₄ decreased visible light transmittance compared to pure g-C₃N₄. FE-SEM images revealed morphological changes and a reduction in the thickness of g-C₃N₄ layers as a result of heterojunction formation, contributing to improved  photogenerated charge transfer. The g C₃N₄/CuO composite degraded 88% of potassium amyl xanthate within 180 minutes and 96% of Rhodamine B within 80 minutes, whereas pure g C₃N₄ achieved only 68% degradation of potassium amyl xanthate and 90% of Rhodamine B. Scavenger test results indicated that superoxide radicals (·O₂⁻) were the main active species in the photocatalytic degradation process. These findings demonstrate the enhanced performance of the g-C₃N₄/CuO nanocomposite in light absorption, charge separation, and efficient pollutant degradation, suggesting its potential as an effective photocatalyst for industrial wastewater treatment.