Iranian Polymer Journal最新文献

This research aimed to showcase an economical and environmentally friendly approach to producing sandwich-structured composites from recycled plastics and krajood waste. The effects of the contents and particle sizes on mechanical and physical properties, including thermal conductivity and sound absorption coefficient, were investigated. The experimental results were analyzed using Analysis of Variance (ANOVA). The results confirmed that the isocyanate glue at 25% (by weight) and krajood fiber at 75% (by weight) at 40 mesh enhanced the flexural, compressive, and screw withdrawal properties the most. The increase in krajood fiber contents ranged from 75 to 85% (by weight) and increased the water absorption percentages. Core layer samples with high conductivity at 0.085 W/mK are considered suitable for building insulation applications, whereas sandwich composites at 0.189 W/mK are used for outdoor materials. In addition, the sound absorption coefficient and noise reduction coefficient were used to evaluate the application efficiency of sandwich-structured composite materials. The highest sound absorption coefficient and noise reduction coefficient were found using a sound frequency of 1000 Hz. The highest noise reduction coefficient value of 0.78 was found in the core layer sample, meaning that the sample absorbs 78% of sound and reflects the remaining 22% of sound waves back into a room. Thus, the outcomes of this study offer recommendations for the manufacture of sandwich composite materials from recycled polypropylene reinforced with krajood fiber in applications for construction and building products.

Patterned polyethylene films are mandatory products in the rubber tire industry. They are used as protective lining to prevent contamination of the rubber. This pattern geometry (2D and 3D) prevents the rubber from sticking to each other. The film is desired to be homogeneous, precise in thickness, and have sufficient mechanical strength. The speed and the temperature of the pattern-forming machine are among the factors that determine this relationship between the thickness of the film and its mechanical properties for sustainable quality production. In this study, the effect of the speed and the temperature of the pattern machine on the pattern thickness during the creation of the pyramid-shaped pattern applied on a 100 ± 5 µm thick polyethylene film were examined. Four different machine speeds (24, 26, 28, and 30 m/min) and three different temperatures (100, 110, and 120 °C) were studied as variables. The impact of parameters on film thicknesses and tensile properties was assessed. Film thickness varied from ~ 375 to ~ 340 µm at higher machine speed, strength-at-break values decreased from 28 to 22 MPa, and elongation values dropped from 575 to 437% with the increment in speed. On the other hand, at higher temperatures, thickness rose from ~ 360 to ~ 390 µm, and elongation values reduced from 440 to 410%. Within the scope of the experimental studies, it was observed that the film thickness changes and the mechanical properties can be controlled by changing the line speed or process temperature.

In recent years, there has been a growing emphasis on eco-friendly methods to protect plants from pathogens, aiming to enhance crop yields while minimizing pesticide use. In this context, we synthesized salicylic acid-encapsulated chitosan nanoparticles (SA-CNPs) and evaluated their effectiveness in safeguarding tomato plants against Fusarium wilt caused by Fusarium oxysporum f. sp. Lycopersici (FOL). SA-CNPs at concentrations of 0.01%, 0.05%, 0.1%, 0.15%, and 0.2% w/v were prepared using ionic gelation and characterized through scanning electron microscopy, zeta potential, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. The results revealed an average particle size ranging from 30 to 300 nm, with zeta potential values − 30 to − 53 mV, confirming exceptional stability. Encapsulation efficiency varied from 19 to 90%. In antifungal tests, 0.2% SA-CNPs exhibited 76% inhibition rate using a food poisoning technique. Topical application of SA-CNPs increased the activities of plant defence enzymes and antioxidant enzymes in tomato plants. In an in vitro study, the percent efficacy of disease control (PEDC) demonstrated that 0.1% and 0.15% SA-CNPs provided 50% and 45% efficacy, respectively, in controlling FOL infection in tomato plants. These findings confirm the efficacy of SA-CNPs in reducing Fusarium wilt by leveraging their antifungal properties and enhancing antioxidant and plant defence enzymes.