Iranian Polymer Journal最新文献

In recent decades, the growth of rubbers has made a huge impact on polymer research and innovation. In fact, the aging process is a well-known challenge in rubber materials, as it affects their properties and, in turn, their service life. This makes this research item particularly intriguing. As these materials have potential applications in various engineering fields, obviously it would be of great interest to understand their degradation under real-life conditions. In this context, considerable efforts have been made to study their multi-physical properties under synergistic aging environments (e.g., moisture, thermal, oxygen, aggressive fluids, hygrothermal, thermo-oxidative, photo-oxidative,…). The current review paper sheds light on the degradation mechanisms of polymer rubbers and aims to provide a detailed insight into potential strategies to improve their durability. Interestingly, an in-depth analysis of the synergistic aging effects on rubbers is provided, highlighting the resulting microstructural modifications and changes in physico-chemical and mechanical properties. Likewise, the predictive models used to estimate the service life of rubber materials, are assessed. More importantly, the future directions for improving the durability of polymeric rubbers are critically discussed, with a view to extending their service-life under optimum performances. Finally, a detailed overview of the emerging applications of rubbers is presented. This review is intended to provide new insights into the durability of rubber materials to stimulate new research. It seeks to compile and compare research conducted over the past two decades, establishing a reference framework for future investigations.

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A polymer matrix with a natural fiber combination is popular in automotive applications, such as cabinets, roofs, and door panels, due to its enhanced tensile strength, lightweight nature, cost-effectiveness, and ease of recycling. However, this composite faces challenges related to high moisture absorption, as hemicellulose limits the roughness of the fiber, and reduced load-bearing capacity influences the mechanical characteristics of the composite. Current research objectives are enriching the quality of fiber, reducing the moisture absorption behavior and enhancing the mechanical properties of polypropylene (PP) composite made with 15% (by wt) abaca natural fiber (ANF), which is treated with 5% sodium hydroxide chemical/amino silane and different weight percentages (1, 3 and 5% by wt) of nanosilicon carbide (SiC) particles via hand layup assisted hot compression mold technology with an applied force of 100 MPa. The influence of composite processing on microstructural behavior is analyzed using a high-resolution transmission electron microscope, which reveals that the fibers and nano-SiC are evenly distributed in the PP matrix with effective interfacial bonding. The PP-based hybrid nanocomposite, comprising 15% (by wt) ANF and 5% (by wt) nano-SiC, demonstrated optimal functional characteristics, including a reduced water absorption rate. Specifically, the PP/15% (by wt) ANF/5% (by wt) nano-SiC hybrid nanocomposite exhibited a maximum flexural strength of 87 MPa, a high tensile strength of 76 MPa, a slight improvement in impact strength (5.2 kJ/m²), reduced elongation (6.1%), high hardness (48 HV), and low moisture absorption (4.1%). These enhanced properties make the PP/15% (by wt) ANF/5% (by wt) nano-SiC hybrid nanocomposite a promising candidate for automotive door panel applications.

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Bio-based polyesters derived from renewable compounds that mimic poly(ethylene terephthalate) (PET) material malleability while reducing environmental impact are a growing area of interest. This study utilized lignin-derived methyl syringate to synthesize a novel aromatic monomer, 1,4-bis(2,6-dimethoxybenzyloxy)benzoate (M). Copolyesters (P1–P4) were prepared via melt polymerization using monomer M, hydroquinone bis(2-hydroxyethyl)ether (HQEE), and varying aliphatic diacids (succinic acid, adipic acid, 1,8-octanedioic acid, and 1,12-dodecanedioic acid) with Sb₂O₃ as the catalyst. The random copolyesters were confirmed through ¹H NMR analysis, with molecular weights (M_w) ranging from 42 to 50 kg/mol and polydispersity of 2.14–2.45. Thermal analysis revealed glass transition temperatures (T_g) of 54–88 °C and melting points (T_m) above 150 °C. Mechanical testing showed that P1, containing succinic acid, exhibited a tensile modulus of 1900 MPa and a yield strength of 87 MPa, closely resembling PET (2200 MPa, 69 MPa), highlighting its suitability for packaging applications. Degradation studies over 30 weeks revealed increasing biodegradation rates with longer aliphatic diacid spacers: P4 (4.6%), P3 (2.4%), P2 (1.4%), and P1 (1.1%). This trend is attributed to reduced aromatic content and increased chain flexibility, which enhance enzymatic hydrolysis. These results underscore the potential of these aliphatic–aromatic copolyesters, synthesized from renewable sources, to serve as environmentally friendly alternatives to conventional PET.

Additive manufacturing is one of the emerging technologies for the manufacturing industries such as automobile, construction, medical and food industries. It avoids error and unnecessary waste as an alternative way of creating complicated or complex design of parts. It also allows greater versatility in customization and development of parts. Fused filament fabrication (FFF), an extrusion-based and a cost-effective additive manufacturing technique is studied in the present work. This work focuses on investigating the sound effects of process parameters of build orientation, printing speed and layer thickness on tensile strength, flexural strength, hardness and impact energy of poly-ethylene-terephthalate-glycol (PETG) samples fabricated through a FFF printer. Using the Taguchi method, the experimental design for this research is developed and the samples are fabricated according to the ASTM standards. On-edge build orientation exhibits better mechanical properties rather than flat and upright orientations because of the anisotropic behavior of the FFF printed parts. The mechanical properties are majorly affected by the build orientation, while layer thickness and printing speed have shown a little effect. In addition, the optimal process parameters settings for multi-responses obtained from the Grey relational grade are the build orientation of on-edge, printing speed of 20 mm/s and layer thickness of 0.21 mm, respectively. Finally, water absorption impact is also studied and discussed.

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The single-step synthesis of hydroxyl functionalized cis-1,4-polyisoprene telechelic was carried out by metathesis degradation of natural rubber in the presence of initiator cis-but-2-ene-1,4-diol and the Grubbs second generation catalyst (GII). The synthesis of hydroxytelechelic-based polyisoprene was assured by using FTIR and NMR spectroscopic techniques. The molecular weights of the resulting products with different concentrations of chain transfer agents were elucidated by gel permeation chromatography (GPC). It was investigated that the feed ratio of cis-but-2-ene-1,4-diol (NR)_o/(G-II)_o/(CTA)_o from 100/1/1 to 100/1/5 led to producing the lowest molecular weight telechelic. The hydroxytelechelic polyisoprene was used to synthesize poly(ε-caprolactone)-block-poly(isoprene)-block-poly(ε-caprolactone) through ring-opening polymerization. The synthesized ABA triblock copolymer was assured by measuring the molecular weight by GPC and the chemical evaluation was carried out by ¹H NMR. The synthesized ABA triblock copolymer was attuned to form phase-separated epoxy thermosets followed by reaction-induced phase-separation mechanism (RIMPS). The morphological studies of epoxy thermosets were carried out by transmission electron microscopy. The transition temperatures of epoxy thermosets containing different contents of triblock copolymer were investigated by dynamic mechanical analysis. The fracture toughness of phase-separated epoxy thermosets was measured in terms of the critical stress field intensity factor (K_IC). The comparison was discussed with phase-separated nanostructured epoxy thermosets containing polyisoprene chain in the form of ABA triblock copolymer and with the samples containing only polyisoprene chain.

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Aluminum hydroxide, magnesium hydroxide, and expandable graphite are commonly used as non-halogenated flame retardants known for their effectiveness and environmental safety. In this study, nitrile butadiene rubber (NBR) composites were prepared using a two-roll mill, incorporating various ratios of these flame retardants. The properties of flame retardants were evaluated using “limiting oxygen index” (LOI), UL-94 vertical and horizontal burning tests, and thermogravimetric analysis (TGA). The research examined the combined effects of expandable graphite, aluminum hydroxide, and magnesium hydroxide on the flame resistance of NBR. Results showed that incorporating all three additives significantly enhanced flame retardancy, demonstrated by increased LOI values and decreased horizontal burning rates, compared to using each additive alone. Furthermore, surface modification of aluminum and magnesium hydroxides with Si-69 silane, in combination with expandable graphite, led to improved flame resistance, achieving a UL-94 V-0 rating and an LOI exceeding 30.7 at 25 phr expandable graphite. In addition to flame retardancy, the influence of these additives on the mechanical properties of NBR was also assessed. Findings revealed a progressive reduction in mechanical strength as the flame retardant loading increased. Nevertheless, the mechanical properties remained within acceptable ranges for practical applications, indicating that the composites possess a good balance between flame retardancy and mechanical performance.

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Molecularly imprinted polymers (MIPs) are synthetic polymers with predetermined selectivity toward a given analyte or a group of structurally related species due to the creation of highly specific sites formed during the synthesis. Levothyroxine (T4), a thyroid hormone, has numerous vital functions in the body and is usually found in a healthy adult at levels between 100 and 200 ng/dL. These low concentrations determine the chemical analysis since they make it difficult to find efficient methods for T4 detection and quantification. In the current work, nanostructured MIPs were synthesized from deposits of SiO₂ particles for the selective binding of T4. The colloidal deposits were fabricated by vertical lifting deposition and the MIPs were elaborated using acrylic acid as the functional monomer and ethylene glycol dimethacrylate as a crosslinking agent. The swelling capacity of hydrogel films was studied at different pH, their morphological and structural characterizations were performed by SEM and FTIR analyses, and their T4 adsorption capacity was evaluated through recognition and swelling studies. The optical properties of the developed materials were characterized recording their UV–visible reflectance spectra. The results showed that MIPs exhibited selectivity to the template if compared with similar molecules such as T3. After incubation, the reflectance spectra of the films showed a shift of the Bragg diffraction peak that correlated with the presence of T4. Owing to the optical response and the capability of binding T4 hormone, the materials elaborated in the current work will be applied in the development of fast response photonic sensors for the quantification of T4 in different matrices.

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This comprehensive assessment investigates the revolutionary potential and recent advances in additive manufacturing (AM), a rapidly evolving technology revolutionizing the industrial sector. The study focuses on AM’s ability to construct elaborate designs, complicated geometries that are not attainable with traditional production methods, and its environmental friendliness due to lower material waste. This paper provides a complete overview of the global landscape for advancing and using AM techniques. The review focuses on the technical elements of various 3D printing processes and their critical role in producing precise 3D printed structures in diverse industries. A brief introduction to polymer-based composites and their applications is given. Besides, it explores the available knowledge of AM and highlights the most relevant technologies used for the fabrication of polymer-based composites. The article is structured as follows: initially, the various AM technologies and their economic aspects are described, followed by recent developments in three-dimensional printing techniques. Furthermore it includes a classification of additive manufacturing techniques based on their raw materials and a discussion on new technologies, which are combinations of existing AM processes. This paper also focuses on the industrial application in the current scenario.