Spatial distribution, abundance, and characterization of emerging plastic forms in binational coastal ecosystems.

In this study, the development of sustainable unsaturated polyester resin (UPR)-based composite materials with low thermal conductivity using waste chicken feather fibers (CFF) was aimed. To this end, by evaluating waste chicken feathers as a functional reinforcement material, the study seeks to both contribute to the recycling of environmental waste and to develop composite materials with low thermal conductivity. These composites offer significant advantages such as lightweight structure, low thermal conductivity, utilization of environmental waste, and sustainable material production. During the production process, five different mixtures were prepared with UPR/CFF ratios of 5∶95, 10∶90, 15∶85, 20∶80, and 25∶75 by volume. The produced composite specimens were comprehensively tested for their density, water absorption, porosity, ultrasonic pulse velocity (UPV), compressive strength, and thermal properties. In addition, the interfaces between UPR and CFF in the samples were examined using scanning electron microscopy (SEM). The experimental results revealed the effects of CFF content on the physical, mechanical, and thermal properties of the composites. It was observed that increasing the resin content led to higher density values, while water absorption and porosity values decreased. Thermal conductivity analysis indicated that samples with low resin content exhibited high insulation performance. Specifically, the thermal conductivity values of the samples with UPR/CFF ratios of 5∶95 and 10∶90 were below 0.1 W m−1K−1, classifying them as thermal insulation materials. UPV and compressive strength tests demonstrated that mechanical strength increased with higher UPR content; however, high CFF content negatively affected strength due to increased porosity. Through the applied experimental approach, the findings reveal that this waste material holds significant potential in terms of thermal insulation and provides a new perspective for sustainable material alternatives in the construction and insulation sectors.

Oxidative self-polymerization of conjugated biobased free fatty acids produces thick cross-linked polyester films with low surface instabilities

The use of textile fibre-reinforced composite materials for many alternative applications has significantly increased in the twenty-first century due to their lightweight nature and high strength-to-weight ratio. In this study, false banana fibres were used as reinforcement and unsaturated polyester resin as the matrix. The optimal ratio of fibre to matrix was established through an analysis of physico-mechanical parameters, including tensile, compressive, and flexural strengths, water absorption, and void fraction, utilising Design Expert software. Additionally, deformation, Von Mises stress, Von Mises strain, and velocity were analyzed using ANSYS simulation software. The composite exhibited water absorption of 1.5% over 24 to 48h, a void fraction of 1.02%, a tensile strength of 33.15MPa, a compressive strength of 29.69MPa, and a bending or flexural strength of 28.85MPa. Furthermore, the ANSYS results showed a maximum deformation of 0.60887mm, a maximum equivalent elastic strain of 0.0018815, a minimum value of 1.0375 × 10-10, a maximum equivalent stress of 22.27MPa, a minimum of 1.3877 × 10-5MPa, and a velocity streamline of 14.97m/s at 21rad/s. The simulated stresses were well below the material's measured strength limits, indicating a safe design under the analysed conditions.The weight of the developed composite blade was 31% lower than that of a conventional aluminum blade.

This study aimed to present a method for measuring the mechanical strength and electrical chargeretention properties of fibers containing nano-sized oxide particles, which have become widely usedin recent years, and to clarify the fundamental physical properties of these fibers. There have beenfew studies measuring the mechanical and electrical properties of composite fibers containing nanosizedoxide particles. Polyester fibers containing SiO2 and ZrO2 nanoparticles were fabricated usingindustrial techniques to clarify the effect of particle introduction on strength. Furthermore, theelectrostatic charge properties of fibers containing these particles, which act as insulators, weremeasured, revealing that mechanical strength and electrical charge retention properties are mutuallyexclusive parameters. Increasing the nanoparticle content decreased mechanical strength, butprolonged the charge half-life and improved electrostatic retention. Furthermore, it was shown thatthis phenomenon can be represented using an equivalent circuit model of a resistor and a capacitor.

Environmental factors such as ozone, temperature, humidity, and UV light can influence the adhesion performance of RFL-coated polyester (PET) tire cords to rubber. Here, the combined effects of ozone, UV irradiation, temperature, and rubber compound chemistry were investigated using H pull-out testing supported by ATR-FTIR, SEM/EDX, and wettability analyses. Mild heat–humidity conditioning (30 min) caused only limited adhesion loss; the maximum reduction was from an indexed value of 100 to 94.6 at 40 °C/80% RH. UV irradiation alone (254 nm) did not measurably reduce adhesion. In contrast, ozone + UV exposure caused pronounced degradation: the indexed H pull-out force decreased from 100 to 46 after 10 min and to 35 after 30 min (ozone concentrations ∼0.4 ppm and ∼1.2 ppm, respectively). Temperature strongly governed ozone sensitivity: under 0.2 ppm O3 (5 min), adhesion deterioration was most severe within a 150–200 °C window, followed by partial recovery above 200 °C up to 240 °C. Rubber compound formulation significantly affected retention under combined aging: relative to the HRH-free compound (22% adhesion drop), adding methylene donors improved performance, with HMT retaining 95%, and HMMM increasing the indexed force to 112% under ozone (∼1.2 ppm) + UV exposure. Surface analyses confirmed oxidation and heterogeneity in the RFL layer after ozone + UV: EDX showed oxygen increased from 20.02 at.% to 25.74 at.%; water contact angle decreased from 91.4° to 84.1°, while surface energy increased from 23.7 to 26.8 mN/m. Overall, the study identifies a critical thermal window for ozone-driven adhesion loss and demonstrates that formulation (notably HMMM) and UV-free environments can mitigate degradation.

Kinetics and Dynamics of Enzymatic Degradation of Synthetic Polyester (PET) in Batch and Continuous Reactors

This study aims to evaluate the effect of external physicochemical factors on the behaviour of hydrogels based on polyethylene glycol maleate (p-EGM) and to assess their potential applicability in sorption-active polymer matrices and biomedical hydrogel systems. This paper presents the results of an investigation into the physicochemical properties of polyethylene glycol maleate and acrylamide solutions in acrylic acid and their cured products. The degree of unsaturation of the initial unsaturated polyester was determined using the bromide–bromate method. The dynamic viscosity of the initial polymer–monomer mixtures was found to be in the range of 0.251–0.697 Pa·s, while the density of the solutions varied from 1.0554 to 1.0996 g/cm3. The density of the cured terpolymers was calculated by the hydrostatic method, and the calculated total volumetric shrinkage did not exceed 15 %. The composition of the obtained terpolymers was confirmed by HPLC analysis. The synthesized hydrogels exhibited a high swelling degree (up to 2898 %) and pronounced sensitivity to environmental pH (4–8) and temperature (35–39 °C), as established by gravimetric measurements. Structural identification was performed using IR and NMR spectroscopy, and the surface morphology was analyzed by SEM. It was demonstrated that an increased acrylic acid content leads to the formation of a more porous polymer network with enhanced water absorption, controllable permeability and structural stability, indicating potential biomedical applicability of the developed materials. Overall, the obtained results suggest that the synthesized hydrogels may be considered promising candidates for potential use in sorption-active polymer matrices and hydrogel-based wound dressing systems.

ABSTRACT To fabricate unsaturated polyester modified composite (UPMC) with excellent durability and fatigue properties for bridge paving layer, the multi‐objective optimization of mix proportion was implemented from multi‐scale detection. In this study, waterborne unsaturated polyester resin (WUP) was pre‐processed via phase inversion emulsification; the variation law on cracking resistance and chloride permeability was studied through combination of experimental analysis and level assessment; the attenuation law and mechanism of sulfate corrosion resistance were probed by analyzing the micro‐pore morphology and phases composition; the damnification and enhancement mechanism of fatigue properties were investigated utilizing fatigue‐life analysis and nano‐indentation characterization, herein fatigue‐life prediction as a function of stress levels and failure probability was completed based on multi‐parameter Weibull distribution. The proportional optimization design was conducted by utilizing hybrid multi‐index ellipsoidal gray‐target decision (HMEGD) model. The results demonstrated that WUP incorporation exerted a remarkable inhibiting effect on cracking behavior of UPMC at ultra‐early and curing period, manifesting as a reduction of crack area and quantity and a delay in crack initiation time; concurrently, chloride ion permeation and sulfate corrosion resistance could be enhanced by 8.92%–26.17% and 9.71%–23.28% due to the replenishment of interior micropore, the abatement of pore interconnectivity; the fatigue‐life at the stress‐level of 0.65–0.90 was prolonged by 18.23%–65.08% owing to the densification of internal micro‐defects and interface transition zone (ITZ). The established fatigue‐life equation at varying failure probabilities had a certain reliability for investigation of fatigue property. Based on the coordinative optimization of HMEGD model, the proportion of 3%–6% WUP was recommended for UPMC.

Objectives. The challenge of growing synthetic textile waste is a concern for sustainable development and needs addressing. Methods. This study develops protective gloves from recycled para-aramid fibres (RPA) with blends of cotton and polyester fibres (both virgin and recycled) to optimize protection and comfort. The impact of different blend ratios of fibres was studied for yarn properties along with comfort and protection of gloves through air permeability, cut, abrasion, tear and puncture resistance. Results. Higher content of RPA showed better strength; in contrast, substitution of cotton showed the opposite effect. In gloves, RPA–virgin polyester (60:40) had the best abrasion, cut, tear and puncture resistance at 500 cycles, 564 gf, 71 N and 87 N, with second-best air permeability. The sustainable alternative 60:40 RPA–recycled polyester (RP) gloves showed the best air permeability (2080 mm/s), with next-best abrasion, cut, tear and puncture resistance at 460 cycles, 555 gf, 70 N and 85 N. The worst characteristics were illustrated by a recycled cotton (RC) with RP blend. Statistical analysis by mixture regression models supported >95% of total variance for all results. Conclusion. These findings suggest parity of protection in recycled fibre and virgin fibre-derived safety gloves and manufactured sustainable protective gloves.

The transition to sustainable thermosetting resins is frequently hindered by the trade-off between high bio-based content and processability. This study reports a novel strategy in developing a highly bio-based, styrene-free unsaturated polyester resin (UPR) by leveraging maltodextrin-derived mixed esters dissolved in dimethyl itaconate (DMI). Unlike conventional polysaccharide-based systems that suffer from extreme viscosity, our functionalized prepolymer-DMI system achieves a low-viscosity curing solution without requiring petroleum-derived diluents such as styrene. Fourier-transform infrared spectroscopy confirmed the formation of a robust crosslinked network via the complete consumption of C=C bonds. Consequently, the cured resin exhibits exceptional thermal and mechanical performance, outperforming many existing bio-based analogs: a glass transition temperature (Tg) reaching 141 °C, a decomposition onset near 250 °C, and superior dimensional stability with a linear thermal expansion coefficient as low as 77 ppm/°C. Demonstrating a fully renewable, easy-to-process formulation with a flexural strength of 44 MPa, this work provides a design template for the next generation of high-performance, eco-friendly industrial thermosets.

Spin finishes play a critical role in the adhesion and stiffness of polyester (PET) cords in tire applications. This study examined the effects of finish type and amount. Two finishes were compared: neat oil (Finish A) and an oil-in-water emulsion (Finish B). Their influence on adhesion performance and the bending stiffness of PET cords was evaluated. The wettability of PET fibers treated with different finishes and concentrations was studied using the first dip activation solutions. The activation dip is essential to bond resorcinol-formaldehyde-latex (RFL) dip to the inert PET fibers. Therefore, it is crucial to understand how the finish affects the interaction between polyester fibers and the activation dip. The effect of finish type and amount was characterized through H-adhesion, strip adhesion, overcure adhesion, and stiffness measurements. SEM, EDX, and AFM analyses supported these results. PET fibers with emulsion-based finishes were wetted more effectively by the activation dip than those with neat finishes. Cords treated with emulsion-based finishes also showed more consistent adhesion performance, regardless of finish quantity. Overall, optimal adhesion was achieved when the finish on yarn (FOY) was minimized during yarn production.

Abstract Unsaturated polyester is a polymer widely used as a composite matrix in engineering applications, including vehicles, ships, and other fields. However, this material has limited use because it is brittle and stiff, so it is easily cracked when impacted. Many studies have been conducted previously. In this study, the addition of Crude Palm Oil (CPO) to unsaturated polyester was expected to reduce its brittleness, as this material was previously brittle, thereby limiting its use. The use of CPO is beneficial because the CPO molecular chain can reduce interlocking between the polyester molecular chains. So that it can increase the fracture toughness of unsaturated polyester polymers, in this study, it was found that the addition of palm oil (CPO) with a mixture percentage of 30%wt CPO in unsaturated polyester polymers can significantly reduce the brittle properties of polyester with a fracture strength value of K1C 15,787 MPa.m0.5 higher than the fracture strength value of pure polyester which only has a fracture strength value of K1C of K1C 2,023 MPa.m0.5or a high of 780%.

Microplastics contamination in agricultural soils represents an emerging threat to soil health and ecosystem functioning. This study investigated the effects of polyester (PES) microplastic (MP) fibers on soil physical quality (SPQ) using indicators derived from soil water retention curve (SWRC) inflection point, based on Dexter's S-theory. Six soils with different textures were contaminated with PES fibers at concentrations of 0.25 %, 0.5 %, and 1 % (w/w) and incubated for about six months. Four SWRC models (van Genuchten with Mualem constraint, VGM; van Genuchten with Burdine constraint, VGB; van Genuchten unconstrained, VGN; and Kosugi, KSG) were fitted to experimental water retention data. The VGN and VGM models provided the best fitting accuracy across soil types. Overall, MP contamination altered key SPQ indicators determining: a decrement of the pressure head at inflection point (h*) and of effective porosity (Φ*), indicating larger modal pore diameters; an increment of the slope at inflection point (S*), suggesting enhanced soil aggregation. Effects were soil type and concentration dependent, with changes primarily occurring at 1 % MP concentration. Soils with moderate clay content (clay < 30 %) showed improved S* values, while clay rich soils showed minimal response. Capacitive indicators (air capacity and plant available water capacity) remained largely unaffected, suggesting preserved total porosity despite internal pore structure modifications. These findings demonstrate that PES MP fiber contamination can alter soil pore architecture and aggregation without substantially impacting bulk hydraulic properties, highlighting the complexity of MP-soil interactions and the value of inflection point indicators for detecting subtle changes in soil physical quality.

Molecular interactions and dynamics of microplastics in indoor dust with lung-inflammatory receptors: A study in academic settings.

Impact of cellulose digestion on the accuracy and reproducibility of microplastic and synthetic microfiber quantification.

A new bio-based unsaturated polyester resin was blended with a bio-based reactive diluent and evaluated. Furan-based monomers were selected as the main monomers in both the resin and the bio-based reactive diluent to enhance thermomechanical properties and address solubility issues typically seen in bio-based resins and diluents. The resin was synthesized from 2,5-furan dicarboxylic acid, isosorbide, and glycerol, and the resulting polymer intermediate was then end-capped with methacrylic anhydride to introduce reactive sites for cross-linking reaction. The resin was then mixed with either different percentages of bio-based reactive diluent (2,5-bis(hydroxy-methyl) furan methacrylate) or with styrene to study the thermomechanical and rheological behavior of obtained resins. FT-IR, 13 C-NMR, and 1 H-NMR were used to determine the chemical structure of the bio-based reactive diluent. The thermomechanical properties of resin containing bio-based reactive diluent or styrene are characterized and compared by DMA, TGA, and DSC. The synthesized resin had good solubility in the bio-based reactive diluent but not in the styrene. The different mixtures of resin and bio-based reactive diluent showed glass transition temperatures ranging from 166 °C to 174 °C, which was higher than the commercial fossil-based unsaturated polyester resin used as a reference in this study. With thermal and mechanical properties comparable to commercial petroleum-based thermosets, these bio-based resins are promising candidates for high-performance composites, coatings, and other thermoset-based applications.

ABSTRACT The ortho-unsaturated polyester resin (UPR01) composite laminate was synthesised using a precise resin formulation and fabricated through the hand lamination method, over a temperature range of 20°C to 45°C, utilising different concentrations of cobalt catalysts and inhibitor solutions and testing various physical characteristic features such as specific gravity, viscosity, volatile content, acid value, gel time, and peak exotherm temperature. The resin, formulated with components like propylene glycol, diethylene glycol, maleic anhydride, phthalic anhydride, and styrene monomer, exhibited optimal liquid properties and curing behaviour, and the composite laminate showed high tensile strength (308.39 N/mm2), flexural strength (282.51 N/mm2), and impact strength (278.01 KJ/m2), significantly resemblances with the industry standard materials results in advanced composite materials for the modern world.

The demand for sustainable materials has increased interest in natural fiber-reinforced composites as eco-friendly alternatives to synthetic counterparts. Among them, Agave sisalana (sisal) offers excellent mechanical properties and availability, but poor interfacial adhesion between untreated fibers and polymer matrices limits its reinforcing potential. This study investigates the effect of alkali treatment on the physicomechanical and interfacial adhesion of sisal fiber–reinforced unsaturated polyester composites. Sisal fibers were treated with 5% NaOH for 0, 2, and 4 h prior to composite fabrication. The 2-h treatment yielded the best performance, resulting in a tensile strength of 413.7 MPa, interfacial shear strength of 24.2 MPa, and composite tensile shear strength of approximately 35 MPa. FTIR analysis confirmed hemicellulose removal through the disappearance of the 1735 cm−1 carbonyl peak, while SEM images revealed a cleaner, rougher surface that enhanced matrix adhesion. However, excessive treatment (4 h) led to surface degradation and reduced performance. Overall, moderate alkali treatment significantly improves interfacial bonding and mechanical strength, making sisal fiber more suitable for polyester-based composite applications.

This study presents a comprehensive experimental investigation into the physical, mechanical, thermal, and acoustic properties of sustainable biocomposites reinforced with natural plant fibers. The composites were fabricated using two different polymer matrices—unsaturated polyester resin (UPR) and flame-retardant polyester (FRP) with varying fiber-to-resin ratios (70:30 to 40:60 wt. %). The results demonstrated that increasing the fiber content led to a decrease in composite density and compressive strength, alongside an increase in water absorption. UPR-based composites exhibited lower density and superior thermal insulation performance, with thermal conductivity values between 0.0503 and 0.0567 Wm −1 K −1 . FRP-based composites, while denser and exhibiting higher thermal conductivity (up to 0.0720 Wm −1 K −1 ), are advantageous for fire-resistance applications. Acoustic analysis revealed that samples with lower resin content and higher porosity achieved better sound absorption characteristics. Moreover, ultrasonic pulse velocity (UPV) tests and SEM analyses indicated a correlation between matrix continuity and mechanical integrity. Statistical analyses confirmed strong relationships between density, compressive strength, thermal conductivity, and water absorption. Overall, the findings suggest that natural fiber-reinforced biocomposites, especially those based on UPR, have strong potential for use as lightweight structural materials with added thermal and acoustic insulation benefits, while FRP-based alternatives offer enhanced performance in fire-sensitive environments. These results indicate that such composites are promising candidates for lightweight interior wall and ceiling panels, insulation boards, and other building components requiring combined structural, thermal, and acoustic performance.