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Sum frequency generation vibrational spectroscopy (SFG) was applied to characterize the interfacial adhesion chemistry at several buried polymer interfaces in both model systems and blown multilayer films. Anhydride/acid modified polyolefins are used as tie layers to bond dissimilar polymers in multilayer barrier structures. In these films, the interfacial reactions between the barrier polymers, such as ethylene vinyl alcohol (EVOH) or nylon, and the grafted anhydrides/acids provide covalent linkages that enhance adhesion. However, the bonding strengths vary for different polymer–tie layer combinations. Here, using SFG, we aim to provide a systematic study on four common polymer–tie interfaces, including EVOH/polypropylene–tie, EVOH/polyethylene–tie, nylon/polypropylene–tie, and nylon/polyethylene–tie, to understand how the adhesion chemistry varies and its impact on the measured adhesion. Our SFG studies suggest that adhesion enhancement is driven by a combination of reaction kinetics and the interfacial enrichment of the anhydride/acid, resulting in stronger adhesion in the case of nylon. This observation matches well with the higher adhesion observed in the nylon/tie systems in both lap shear and peel test measurements. In addition, in the polypropylene–tie systems, grafted oligomers due to chain scission may migrate to the interface, affecting the adhesion. These by-products can react or interfere with the barrier–tie chemistry, resulting in reduced adhesion strength in the polypropylene–tie system. [ABSTRACT FROM AUTHOR]

Highlights Biodegradable biobased polymers are a promising solution to reduce the dependence on conventional plastics and minimize their environmental impact. This work evaluated the recycling capacity of a biodegradable polymer (MaterBi) and its composite with agave fibers. The materials were reprocessed by several cycles using compression molding. Service life simulation was performed using accelerated weathering. Samples from each reprocessing cycle were characterized in terms of melt flow index (MFI), color, porosity, water absorption, compostability, and mechanical and thermal properties. The MFI of MaterBi increased with each cycle, going from 3.5 to 95 g/10 min for the first to sixth cycles and from 2 to 117 g/10 min for the first and fourth cycles for the biocomposite. Reprocessing produced chain scission and modified the thermal and mechanical properties. MaterBi exhibited competitive mechanical properties compared to conventional polymers, even after four reprocessing cycles (tensile, flexural, and impact strengths of 27, 55 MPa, and 30 J/m). Besides potential cost reductions, the agave fiber addition positively affected the tensile and flexural modulus, which remained after the fourth cycle in 1100 and 2300 MPa. The results confirmed that MaterBi and its biocomposites can be recycled for several cycles, extending their useful life before final biodegradation. MaterBi (MB) and its agave fiber biocomposites are suitable for reprocessing. MB tensile and flexural properties remained stable after four reprocessing cycles. Agave fibers make MB more prone to weathering, impacting its properties. MB and its biocomposites degrade in water and compost conditions. [ABSTRACT FROM AUTHOR]

Polymer aging under environmental conditions causes deterioration of service properties. Understanding the aging behavior and mechanism is important not only for lifetime prediction, but also for material improvement and development. Therefore, comprehensive characterization of polymer materials during aging is crucial. In this review, various analytical methods for characterization of chemical changes, physical changes and service properties are introduced. Based on that, methods for stabilization evaluation and lifetime prediction, especially sensitive evaluation methods are reviewed. Chemical changes include molecular weight changes by chain scission and crosslinking, functional group changes on the surface and in the bulk, formation of free radicals, formation of small molecular species as the degradation products, and chemical distribution by heterogeneous aging and additives migration. Physical changes include crystallization changes (post- or chemi-crystallization) and morphology changes (cracking, debonding, etc.). Service property changes include deterioration of processability, mechanical properties, electrical properties and appearance. In the end, existing problems and future research perspective are proposed, including relationship between chemical/physical changes and service properties, introduction of modern mathematical and computer tools. [ABSTRACT FROM AUTHOR]

The need for eco‐friendly cooling materials and material recycling are two urgent challenges to address. In this paper, the role of the ground tyre rubber treatment (cryo‐grinding and devulcanization) is investigated on the tensile and elastocaloric properties of Natural rubber (NR)/ ground tyre rubber (GTR). The GTR particles that are sieved (<63µm) and devulcanized by microwave irradiation (1 min at 800Watts) exhibit a low network chain density (0.53 × 10−4 mol.cm−3) resulting from crosslinks breakage and rubber chains scission, as supported by FTIR showing a decrease of S─S, C─S, and C─C bonds. The NR/GTR blends show a high elastocaloric effect as compared to the pristine NR, which can be ascribed to the high content of carbon black in the GTR (52 wt.%) and also the high level of devulcanization of the GTR. NR/GTR blends reach a heating of +8 °C and a cooling of >−6 °C, resulting in a material's coefficient of performance COPmat = 2.8–3 compared to 2.6 for the pristine NR. The concomitant effect of cryogrinding and microwave devulcanization is proposed as a way to improve the tensile and elastocaloric properties of natural rubber/waste rubber blends for their possible integration into elastocaloric devices for heating/cooling applications. [ABSTRACT FROM AUTHOR]

Elastomers have diverse properties that make them suitable for use in many industrial applications. Natural Rubber, in particular, is an attractive elastomer due to its desirable mechanical properties as well as lightweight compared to metals. However, due to the natural rubber structure, these elastomers are susceptible to heat, oxidation, and chemical compounds, which limits their potential use. In this paper, in order to study the behavior of natural rubber under thermo-oxidative aging, experiments, including continuous stress relaxation, creep, and intermittent tensile tests, are carried out on the samples. Based on the experimental results and using dynamic-network model, a mechanical-chemical-diffusion model is proposed to predict the changes in natural rubber properties during thermo-oxidative aging considering the effect of the natural rubber curing system. In the chemical part of the model, the two main process of aging, including chain scission and crosslinking, are modeled by using two internal variables. The proposed model is implemented using the finite element method to simulate experimental tests for the model verification. The comparisons demonstrate the proposed model ability to accurately simulate the various loading states under thermo-oxidative aging of natural rubber. [ABSTRACT FROM AUTHOR]

An atomic‐level understanding of radiation‐induced damage in simple polymers like polyethylene is essential for determining how these chemical changes can alter the physical and mechanical properties of important technological materials such as plastics. Ensembles of quantum simulations of radiation damage in a polyethylene analog are performed using the Density Functional Tight Binding method to help bind its radiolysis and subsequent degradation as a function of radiation dose. Chemical degradation products are categorized with a graph theory approach, and occurrence rates of unsaturated carbon bond formation, crosslinking, cycle formation, chain scission reactions, and out‐gassing products are computed. Statistical correlations between product pairs show significant correlations between chain scission reactions, unsaturated carbon bond formation, and out‐gassing products, though these correlations decrease with increasing atom recoil energy. The results present relatively simple chemical descriptors as possible indications of network rearrangements in the middle range of excitation energies. Ultimately, the work provides a computational framework for determining the coupling between nonequilibrium chemistry in polymers and potential changes to macro‐scale properties that can aid in the interpretation of future radiation damage experiments on plastic materials. [ABSTRACT FROM AUTHOR]

Humidity sensing has become an essential part of the process industry and the likewise essential device for domestic appliances. Humidity sensors are classified into capacitive and resistive based on their operating principles, capacitance-based humidity sensors dominate the market for their ease of use, simplicity of working, and reduced cost. In this investigation, a series of carbon fiber reinforced epoxy composites has been developed for use as a dielectric material in capacitance-based humidity sensors due to their low-cost, ease of fabrication coupled with excellent mechanical and electrical properties. The major limitation of carbon fiber-reinforced composites is their susceptibility to delamination, loss of stiffness, and overall failure of the fiber structures. To overcome these limitations, cross-linking and structural modification of the laminates was accomplished by gamma (γ) radiation exposure at dose levels of 1000 and 3000 kGy. γ-radiation exposure increases the volume resistivity and decreases the AC conductivity at higher frequencies due to reduction in free volume and hindered charge carrier transport. Radiation exposure increases the capacitance at 1000 kGy of γ-radiation by 6–32 times, and up to 5 times at 3000 kGy over the values non-irradiated laminate in the frequency range of 100–1000 Hz. The increase in capacitance due to radiation exposure is attributed to increase in dipoles resulting from orientation polarization, and chain scission. Higher sensitivity of 500 pF/%RH in achieved in laminate exposed to 1000 kGy, and 380 pF/%RH in laminate exposed to 3000 kGy over 200 pF/%RH of the base laminate. γ-radiation exposure does not alter the response time and it ranges from 60 to 65 s and the hysteresis is not affected by γ-radiation. Long term drift in capacitance is minimal and is unaffected by γ-radiation. [ABSTRACT FROM AUTHOR]

Polyolefins have a multitude of uses across packaging, automotive and construction sectors. Their resistance to degradation during reprocessing enables recyclability, but variability in recycled polymer feedstocks renders it difficult to assure their manufacturing suitability. The lack of quality control methods has disabled circular economy pathways; product failure is costly, wasteful and time-intensive. Using rheology-simulated and extrusion-based recycling experiments, we explore the degradation pathways of high-density polyethylene (HDPE). Chain scission dominates during the initial degradation of HDPE, and increasing exposure to O2 shifts the dominant mechanism to long-chain branching. Importantly, extending this method to post-consumer recyclate (PCR), the results show potential as a methodology to assess recyclate quality to enable a circular plastics economy. In this study, we establish the validity of this rheology simulation to define a characteristic degradation parameter, relating it to the structural evolution under different environments defined for virgin HDPE and post-consumer recyclate (PCR). Polyolefins are used across packaging, automotive and construction but variability in recycled polymer feedstocks renders it difficult to assure a consistent manufacturing quality. Here, the authors use rheology-simulated and extrusion-based recycling experiments to explore the degradation pathways of high-density polyethylene and present a rheology-based method to assess the quality of the recycled material. [ABSTRACT FROM AUTHOR]

This study investigates the impact of aging in methyl diethanolamine (MDEA) solution on cured rubber compounds comprising ethylene‐propylene‐diene monomer rubber (EPDM), butyl rubber (IIR), and blends, utilizing nano (nZnO) and conventional (ZnO) zinc oxides as curing activators. The analysis reveals that MDEA solution induces degradation in the rubber matrix by grafting amine and amide groups onto the rubber backbone, particularly affecting unsaturated units in diene monomers in EPDM and isoprene units in IIR. The Fourier‐transform infrared (FTIR) analysis validated the addition of these functional groups. Aging contributed to the formation of a thin rubber layer covering carbon black particles, likely due to un‐crosslinking and rubber chain scission, resulting in changes in bound rubber as observed in scanning electron microscopy (SEM) images. Tensile strength and elongation at break typically decreased with aging, with EPDM compounds exhibiting the highest initial tensile strength and IIR compounds demonstrating superior initial elongation. Hardness remains largely unaffected by aging. This study showed the detrimental effects of MDEA exposure on rubber compounds, emphasizing the critical importance of material selection and property tailoring for specific applications in MDEA‐rich environments, such as gas refineries. [ABSTRACT FROM AUTHOR]

The effect of added microalgae biomass to styrene–butadiene–styrene triblock composites (SBS) loaded with Chlorella vulgaris and Arthrospira platensis biomass was evaluated by nonisothermal chemiluminescence (CL), infrared spectroscopy, and differential scanning calorimetry (DSC) analysis. The high biomass content of up to 20% for Chlorella vulgaris and 30% for Arthrospira platensis create appropriate conditions for the propagation of oxidation, which is a convenient manner applicable to the degrading digestion of polymer matrix. The chemiluminescence spectra on these ecological formulations indicate the contribution of additives to the optimization of polymer waste disintegration. The degrading activities of the studied microalgal biomass added to the polymer matrix are influenced not only by concentration and source but also by the temperature evolution, which determines the proper thermal regime of material decay. The thermal aging of SBS/microalgal composites progresses peculiarly under the action of various pro-oxidant components. The amplitudes of oxidative conversion of SBS support are discussed with values of main kinetic parameters, onset, and intermediate oxidation temperatures. Although the addition of biomass to the polymer matrix introduces various transformations that affect its thermal behavior, the combined CL and DSC studies indicate that these changes ultimately enhance the polymer's stabilization. The control SBS composite was the most stable, likely due to its homogeneous structure compared to the heterogeneous mixture in the microalgae SBS composites. Prolonged heating at elevated temperatures (80 °C and 120 °C) can lead to thermal aging and degradation of the polymer matrix, causing changes such as chain scission or cross-linking, which alter the material's thermal properties. [ABSTRACT FROM AUTHOR]

Data on irradiation of poly(L-lactide) (PLLA) based active packaging is still limited. Therefore, effect of γ-irradiation on neat PLLA and active packaging with oligohexamethylene guanidine hydrochloride (OHMG·HCl) has been studied. Combined use of irradiation and active packaging technology is promising approach to maintain food safety and prolong shelf life. It has been found that regardless of the OHMG·HCl content PLLA undergoes chain scission during irradiation and this process becomes less pronounced at doses higher than 50 kGy. Slight racemization of PLLA during exposure has been observed using polarimetry and 13C NMR spectroscopy. Mechanical properties of films have been examined. Biocide addition led to a 30% decrease in films elongation at break. Irradiation either caused elongation decrease. Dose of 50 kGy and higher made PLLA active films brittle. Multiple melting behavior of irradiated PLLA has been analyzed by differential scanning calorimetry. Fraction of crystals with higher melting temperature rose with dose. Possible reason for this phenomenon is formation of α′ form with less ordered chain packaging that recrystallizes during heating. The biocide addition has not affected this process. Furthermore, in vitro antimicrobial test has shown efficacy of films with 2 wt.% of OHMG·HCl against gram-negative, gram-positive bacteria and fungi. [ABSTRACT FROM AUTHOR]

Blending polylactide (PLA) with poly(propylene carbonate) offers potential solution to mitigate the greenhouse effect due to PLA's lower carbon dioxide (CO2) emissions and its use of CO2 as a monomer in PPC synthesis. In this investigation, a series of PLA and PPC blends were prepared using the solvent casting method to address their respective weaknesses. The blends exhibited partial compatibility, as evidenced by a noticeable shift in the glass transition temperatures toward each other. Tensile testing revealed that the incorporation of PPC improved the elongation properties of PLA. The degradation characteristics of the blend films were evaluated based on changes in the monolayer's occupied area, the properties of the bulk film, and changes in surface morphology. Results indicated that PPC content accelerated hydrolytic degradation but slowed enzymatic degradation in the blends. Hydrolytic and enzymatic degradation significantly impacted the mechanical properties of PLA/PPC blends, prolonging the degradation process through chain scission. [ABSTRACT FROM AUTHOR]

Poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is well‐known to be miscible with polystyrene, but immiscible with styrene copolymers containing polar groups. Certain nitrated‐PPOs (NPPOs) were found to be miscible with copolymers of styrene/acrylonitrile (SANs), copolymers of styrene/maleic anhydride (SMAs), a terpolymer of α‐methylstyrene/styrene/acrylonitrile (α‐MS/S/AN), and a copolymer of o‐ and p‐chlorostyrene (PCS). Also, certain simultaneously nitrated‐ and chlorinated‐PPOs (NCPPOs) were found to be miscible with SANs, SMAs and PCS whereas immiscible with the α‐MS/S/AN. The miscibility was indicated by the presence of a single composition‐dependent glass‐transition temperature for a given blend across the entire range of blend compositions tested. The miscibility of the aforementioned NPPOs and NCPPOs blends with SAN1 and SMA1 is attributed to hydrogen bonding of hydroxy groups of NPPOs and NCPPOs with nitrile groups and carbonyl groups, respectively, based on the literature information. The hydroxy groups were generated during nitration and simultaneous nitration/chlorination of PPO as a result of nucleophilic chain scission. Miscible blends of ‐NPPO/SAN and ‐NPPO/SMA with ABS1 showed a substantially better balance of the following properties than a comparable immiscible‐NPPO/SAN blend and a ‐PPO/SAN blend with ABS1: notched Izod impact strength, tensile properties, heat distortion temperature and gasoline stress‐crack resistance. Highlights: Nitration and simultaneous nitration/chlorination of PPO generated hydroxyl end groups.Certain NPPOs and NCPPOs were miscible with SANs, SMAs and PCS.Miscibility indicated by a single composition dependent Tg for a given blend.Miscibility attributed to hydrogen bonding of respective functional groups.Impact‐modified miscible‐NPPO/SAN blends and ‐NPPO/SMA blends with ABS1 as impact modifier had good key properties. [ABSTRACT FROM AUTHOR]

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In this work, we study the combinational effects of UV irradiation, functionalized graphene (FG) sheets, and organic solvents on the crack evolution in PMMA/FG composites. The UV irradiation leads to the scission of polymer chains in the PMMA/FG composites with the FG sheets hindering the scission of polymer chains. The evolutions of surface cracks and the pre-formed crack in the PMMA/FG composites depend on the diffusion of organic solvents. The increase of Hansen solubility distance (HSD) with the solvent follows the order of cyclohexanol, 2EA, and 1-butanol sequence. The solvent with a smaller HSD diffuses faster in polymer, producing larger tensile stress to cause the nucleation and growth of cracks. The density of surface cracks and the length of the pre-formed crack decrease with increasing the FG fraction and HSD and increase with increasing the UV dose. The activation energy and heat of mixing for the growth of surface cracks increase with the FG fraction and HSD and decrease with increasing the UV dose. The activation energy for the growth of the pre-formed crack increases with increasing the FG fraction and HSD and decreases with increasing the UV dose. The activation energy for the inculcation period of the growth of the pre-formed crack has an opposite trend to the activation energy for the growth of the pre-formed crack versus the FG fraction, HSD, and UV dose. The experimental results show that the evolutions of surface cracks and the pre-formed crack follow the scaling law describing the diffusion of organic solvents in solids. [ABSTRACT FROM AUTHOR]

The effects of 1.75 MeV N5+ ion beam irradiation of varying ion fluences, ranging from 1 × 1012 to 3 × 1014 ions/cm2, on high-density polyethylene have been done to investigate the structural, optical and chemical properties using X-ray diffraction (XRD), UV–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopic techniques. XRD patterns show no significant change in crystallinity in irradiated polymer samples. The lattice plane and crystallite size of the irradiated polymer have not changed noticeably. More than 50% decrease in optical band gap were found for higher ion fluences of 3 × 1014 ions/cm2. UV–visible spectra show a red shift in absorption maxima due to the formation of extended conjugation. FTIR peaks 3646, 1707 and 2170 cm−1 in irradiated polymer were observed. The reaction mechanism chemistry of radiation-induced product formations, including chain scission, molecular crosslinking and hydroxyl, carbonyl and alkyne functional groups have been discussed. [ABSTRACT FROM AUTHOR]

Electron beam (EB) treatment of a high vinyl styrene-butadiene-styrene (SBS) block copolymer was accomplished by exposing the polymer to high-energy electrons generated from an electron accelerator. This resulted in the formation of free radicals of carbon on the polybutadiene units in the backbone of the elastomer and subsequent radical coupling to produce cross-links. In the process, some unavoidable chain scission (CS) also occurred. An attempt was made to mathematically trace the nature of the CS as a function of radiation dose with the aid of the experimentally determined cross-link density (CLD), tensile strength and tear strength, the latter three also obtained as functions of radiation dose. The radiation dose was varied from 12.5 to 300.0 kGy in multiples of 12.5 kGy. The novelty of the work was, in part to create a function that can be used to calculate chain-scission in dependence of EB radiation dose. It was found that a change in the ratio of CS to CLD occurred as a function of radiation dose over the previously calculated constant ratio, using the Charlesby-Pinner equation. [ABSTRACT FROM AUTHOR]

The heat aging resistance of a peroxide-cured silicone rubber (VMQ) in the temperature range from 75 to 225 °C was investigated. Activation energies for the degradation process were calculated in order to understand the durability and lifetime of the rubber. The hardness, tensile stress at 10% elongation, and chemical cross-link density measured by solvent swell and double-quantum nuclear magnetic resonance increase as a function of thermal aging. The increase is due to the prevalence of cross-linking reactions over chain scission events which was confirmed by FTIR analysis. The unaged monomodal cross-link distribution becomes more heterogeneous with heat aging as its distribution significantly widens toward higher cross-link densities. Calculated activation energies for the heat-induced degradation process were between 70 and 101 kJ/mol. Activation energies depended on the experimental test used to probe the system. The FTIR analysis confirmed the loss of –CH bonds and gain of Si–O–Si linkages during thermal aging. Oxidative products were extracted and characterized from the degraded VMQ. Aerobic and non-aerobic degradation mechanisms have been proposed to explain the presence of cross-linking and chain scission reactions. Given the lack of data change during low-temperature aging, the results are suitable for use to predict the performance of VMQ in applications between 100 and 225 °C. [ABSTRACT FROM AUTHOR]

Bioabsorbable poly(4‐hydroxybutyrate) (P4HB) electrospun membrane has been widely used in various biomedical applications due to its biocompatibility and unique mechanical properties. When commercialization is envisaged, a sterilization procedure aiming to prevent bacterial contamination of biomedical devices is indispensable. Herein, P4HB membranes were sterilized by using different sterilization techniques. It's observed that ethylene oxide (EO), ultraviolet radiation (UV), and electron beam (E‐beam) irradiation do not influence the morphology of fiber membranes. Analysis of the data revealed that E‐beam irradiation sterilization can induce chain scission of P4HB. The EO sterilization process can increase the melting point of P4HB electrospun membranes. None of the sterilization methods showed a significant effect on the hemocompatibility of the P4HB membranes. Furthermore, the cytocompatibility experiment indicated that none of the P4HB membranes had any toxic effects on L929 cells. Taken together, selecting a suitable sterilization method that effectively sterilizes and does less damage during the sterilization process is critical to P4HB membranes for biomedical application. [ABSTRACT FROM AUTHOR]

The effect of temperature (15, 20, 25, 30, and 35 °C) on the ultrasonic degradation of sodium poly(styrene sulfonate) polyelectrolyte (5.10−3 g/ml) in aqueous NaCl solutions (2.75 m) was investigated. Using the thousands of data obtained by an online viscometer monitoring technique, the degradation kinetics, and the effect of temperature on this process were analyzed in detail with 12 theoretical models reported in the literature. The Giz, OHM, and Tang-Goto models were found to give good results, and these models were selected to evaluate the effect of temperature on the ultrasonic polymer degradation. The degradation constant and the limiting molecular weight at which no polymer chain scission occurs were found to decrease with increasing temperature for all models. Furthermore, modeling was performed using popular machine learning algorithms, such as Multilayer Perceptron, Adaptive Neuro-Fuzzy Inference System, Long Short-Term Memory, Gradient Boosting Regression, Light Gradient Boosting Machine, eXtreme Gradient Boosting Regressor, CatBoost, and Random Forest. The best results were obtained with the Long Short-Term Memory, a deep learning approach. In addition, optimization techniques, such as Particle Swarm Optimization, Genetic Algorithm, Artificial Bee Colony, Clustering, and Global Optimization Method based on a parabolic approach, were used to determine the optimum molecular weight evolution and degradation temperature. [ABSTRACT FROM AUTHOR]

This study provides key insights into the extrusion of a post‐industrial feedstock primarily composed of polypropylene (PP) and reveals its influence on the property profile of the recyclate. The objective of this study was to gain a fundamental understanding of complex process‐property relationships. Therefore, a two‐part experimental design was established. The first part aimed to analyze the feedstock variability by investigating key material properties of recyclates produced under constant processing conditions. The second part aimed to systematically evaluate the effect of the screw speed, filtration setup, and degassing setup on the properties of the recyclates. An industrial‐scale recycling extrusion line was used. The material evaluation included melt mass‐flow rate (MFR), ash content, oxidation induction temperature, tensile and impact properties, degassing performance, and residual volatile organic compounds (VOCs). Higher melt temperatures led to chain scission of the PP fraction, resulting in increased MFR and higher material stiffness. Additionally, a finer filtration positively contributed to the enhanced material stiffness. Furthermore, the mechanical properties were also influenced by the levels of inorganic fillers in the material composition of the feedstock. Finally, the filtration setup had a greater impact on degassing performance and residual VOC levels than the degassing setup and screw speed. [ABSTRACT FROM AUTHOR]

The ultrasound (US)‐induced activation of mechanophores embedded in linear polymers (LPs) is the most widely employed technique to realize chemical function by polymer mechanochemistry. However, the commonly used US frequency in this context is around 20 kHz, producing strong inertial cavitation limiting biomedical applicability. Herein, 20 kHz US and 1.5 MHz high‐intensity focused US (HIFU) are investigated to drive disulfide mechanophore activation and mechanochemical polymer chain scission in network core‐structured star polymers (NCSPs). It is found that the efficiency of activating disulfide mechanophores in NCSPs using 1.5 MHz HIFU irradiation is similar to the efficiency achieved with 20 kHz sonication. This is quantified by 'turn on' sensor molecules leveraging the Michael addition of the mechanochemically generated thiol groups and subsequent retro Diels–Alder reaction to release a fluorophore. Moreover, the anticancer drug doxorubicin (Dox) covalently loaded into NCSPs is efficiently released by 1.5 MHz HIFU. Finally, an in vitro study of drug release from NCSPs is performed, demonstrating the potential of HIFU‐activated polymer mechanochemistry for sonopharmacology. [ABSTRACT FROM AUTHOR]

2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is one of the high-energy oxidants, but has limited application due to its high sensitivity. In this work, polyvinylidene fluoride (PVDF) was used as a co-oxidizer, which is expected to increase the safety of CL-20. One kind of novel graphene-based carbohydrazide complex (GCCo and GCNi) was employed to modify the properties of dual-oxidant CL-20@PVDF composites by the spray drying method and compared with traditional nanocarbon materials (CNTs and GO). The properties of these composites were investigated using the TGA/DSC technique and impact test. The results show that GCCo and GCNi could increase the activation energy (Ea) of CL-20@PVDF composites, and change the physical model of CL-20@PVDF, which followed the random chain scission model and then the first-order reaction model. In addition, these nanocarbon materials could reduce the impact sensitivity of CL-20@PVDF by their unique structure. Besides that, a dual-oxidant CL-20@PVDF system was used to improve the combustion property of Boron. GCCo and GCNi with the synergetic effect could increase the flame temperature and control the burn rate of CL-20@PVDF@B compared with CNTs and GO. The energetic nanocarbon catalyst-modified oxidant provides a facile method for stabilizing high-energy but sensitive materials to broaden their application. [ABSTRACT FROM AUTHOR]

Wind turbine generator output cables are subjected to alternating torsional loads during long-term operation, combined with electrothermal stress, which may lead to insulation failure and other serious issues. Currently, the electrothermal aging mechanism under torsional stress is not fully understood. This study explores the synergistic degradation mechanism of electrothermal aging and nonlinear torsion by constructing a multi-stress aging test platform in the laboratory environment. This study involved accelerated aging tests with thermal, electrothermal, and electrothermal–torsional alternating stresses. The aged cable samples were analyzed for their physical and chemical properties using differential scanning calorimetry and Fourier transform infrared spectroscopy, while dielectric spectroscopy and mechanical tests were employed to evaluate their dielectric and mechanical performance. The results indicate that torsional stress induces physical changes at the molecular level in the ethylene–propylene rubber (EPR), leading to reduced strength, hardening, and increased brittleness, resulting in decreased mechanical strength. In addition, torsional stress promotes oxidation reactions and chain scission processes in the insulation layer, reducing crystallinity and causing a decline in mechanical performance. Increased oxidation and chain scission reactions result in an increase in polar groups, leading to an increase in the dielectric loss factor of the EPR. The findings of this study provide valuable insights for the design, manufacturing, and operational monitoring of wind turbine generator output cables. [ABSTRACT FROM AUTHOR]

Poly (lactic acid) (PLA) has received considerable attention as a sustainable and biodegradable alternative to petroleum-based polymers in recent years. In general, the properties of PLA depend on its molecular chain structure, e.g., linear, branched, and aggregated structure, e.g., orthorhombic α-form and stereocomplex crystals. However, the evolution of hierarchical structure triggered by photo-oxidation degradation remain elusive for PLA. Herein, the accelerated photo-oxidation degradation behaviors of PLA samples with different thermal histories, including quenching (PLA-q), slow cooling (PLA-c), and annealing (PLA-a), were investigated by several characterization techniques. Compared to PLA-q and PLA-c, PLA-a exhibits relatively lower rates of molecular chain scission and oxygen-containing groups generation during the accelerated photo-oxidation process, suggesting that the increase in crystallinity contributes to suppressing the degradation of PLA. Changes in the molecular chain structure leads to the evolution of aggregation structure. The crystallinity of PLA samples, whether slowly cooled or annealed, increases with UV exposure time, which is attributed to the newly-formed crystals induced by chemi-crystallization. Unexpectedly, although PLA-a exhibits a slower photo-oxidation degradation rate than PLA-q and PLA-c, it undergoes embrittlement at an earlier stage. Morphological observations of photo-oxidized samples indicate that the degradation reaction of PLA-a occurs preferentially in the amorphous region, transforming the molecular chains into volatile products and eventually resulting in the embrittlement of PLA materials. This research sheds light on photo-oxidation degradation behaviors of PLA, and will serve as a valuable reference for investigating the degradation of other bio-based polymeric materials. [ABSTRACT FROM AUTHOR]

High‐performance fibers are known for their exceptional specific strength and resistance to various hazardous conditions, including fire. However, the long‐term performance of these fibers when exposed to convective heat has rarely been reported. This study investigated the accelerated thermal aging behavior of three high‐performance fabrics of different blends of inherently flame‐resistant high‐performance fibers: copolymer of aramids (Technora®)/polybenzoxazole (PBO); para‐aramid/meta‐aramid; and para‐aramid/polybenzimidazole (PBI). Fabric specimens were thermally aged for up to 1200 h at temperatures ranging from 90 to 320°C. While all three fabrics experienced losses in the breaking force, the Technora®/PBO fabric displayed the best strength retention, despite the complete disappearance of the Technora® fiber crystallinity after aging at 320°C for 1200 h. The para‐aramid/PBI blended fabric showed signs of competing aging processes at high temperatures. An increase in the fabrics' crystallinity and evidence of chain scission were observed after thermal aging. Additionally, degradation in the fabric's water‐repellent finish was observed. The findings of this study will contribute to the development of more durable and safer protective gear, particularly for high‐risk activities like firefighting. [ABSTRACT FROM AUTHOR]

Ageing of elastomeric materials in triboelectric nanogenerators (TENGs) often leads to compromised electrical performance and can greatly affect their real‐world application as next‐generation energy harvesters and self‐powered sensors. Herein, the ageing behavior of PDMS‐based TENGs is investigated by probing the dielectric and mechanical properties of the membrane materials. Over time, ageing of PDMS after 17 months is evinced by a decline by 71%, 68% and 52% in open‐circuit voltage, short‐circuit current and charge transfer, respectively, and an increase by 6.8 times in surface charge decay rate. The reduced electrical performance can be attributed to a decrease in work function, dielectric constant, surface adhesion and heterogeneity in stiffness, as well as an increase in loss tangent. The effect of chemical chain scission on the PDMS surface is confirmed through nearfield infrared nanospectroscopy. This study gives insights into the underlying mechanism behind the ageing of PDMS‐based TENGs, paving the way to future work for ameliorating these ageing‐related issues with the aim to ensure long‐term stability of practical triboelectric devices. [ABSTRACT FROM AUTHOR]

The evolution of plane-strain fracture toughness in highly cross-linked epoxies was assessed for different hygrothermal aging temperatures (25, 50, and 75°C) and durations (0–75 days). The absorption of water increased with hygrothermal aging, but at a diminishing rate and without saturating. A fraction of the absorbed water persisted despite prolonged drying. Thermogravimetric analysis revealed that the epoxy-decomposition temperature decreased with hygrothermal aging. 13C solid-state nuclear magnetic resonance spectroscopy indicated an increase in the de-shielding of carbon atoms in the vicinity of electronegative elements like oxygen with hygrothermal aging severity, indicating the development of intermolecular hydrogen bonding. X-ray photoelectron spectroscopy tracked the chemical bonding state of carbon by using a narrow scan on the C1s binding energy region. Upon hygrothermal aging, there was a decrease in C-C/C= C groups, indicating main chain scission through hydrolysis. A simultaneous increase in the C-O species indicates the formation of alcohols as hydrolysis reaction products. In this manner, retained water was involved in hydrogen bonding and chemical reactions with the epoxy. With increasing severity of hygrothermal aging, the fracture toughness decreased. This was consistent with fracture surface micrographs that showed a greater distance amongst crack stretch marks in specimens with less toughness. [ABSTRACT FROM AUTHOR]

The influence of different overlay layers (ABS, PC, and PLA) is investigated on the photodegradation behavior of poly(lactic acid) (PLA)-containing samples in double injection molding, and PLA/PLA samples serve as the control group. In terms of microstructure, an analysis is conducted on the chemical structure, thermal performance, crystallinity, and molecular weight of the base layer of samples. The carbonyl index and molecular weight of the base layer of PLA/PLA samples decrease rapidly, and the trend of crystallinity change is also fast. Among them, the number of molecular chain scissions decreases to 0.61, and the crystallinity increases to a maximum of 17.93%, which indicates that the photodegradation degree of the base layer of PLA/PLA samples is greater than that of the other two samples. The microscopic surface morphology change of the base layer of three PLA-containing samples is analyzed. The base layer of PLA/PLA samples becomes rougher after 600 h of UV degradation. Meanwhile, compared with other PLA-containing samples, the percentage of tensile strength loss of PLA/PLA samples is higher, decreasing by 16.64%. In summary, using acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) materials as overlay layers for double injection molding can mitigate the photodegradation of the base layer of PLA-containing samples in double injection molding. [ABSTRACT FROM AUTHOR]

Manufacturing thin‐film components is crucial for achieving high‐efficiency and high‐power thermal batteries (TBs). However, developing binders with low‐gas production at the operating temperature range of TBs (400–550 °C) has proven to be a significant challenge. Here, we report the use of acrylic acid derivative terpolymer (LA136D) as a low‐volatile binder for thin‐film cathode fabrication and studied the chain scission and chemical bond‐breaking mechanisms in pyrolysis. It is shown LA136D defers to random‐chain scission and cross‐linking chain scission mechanisms, which gifts it with a low proportion of volatile products (ψ, ψ = 39.2 wt%) at even up to 550 °C, well below those of the conventional PVDF (77.6 wt%) and SBR (99.2 wt%) binders. Surprisingly, LA136D contributes to constructing a thermal shock‐resistant cathode due to the step‐by‐step bond‐breaking process. This is beneficial for the overall performance of TBs. In discharging test, the thin‐film cathodes exhibited a remarkable 440% reduction in polarization and 300% enhancement in the utilization efficiency of cathode materials, while with just a slight increase of 0.05 MPa in gas pressure compared with traditional "thick‐film" cathode. Our work highlights the potential of LA136D as a low‐volatile binder for thin‐film cathodes and shows the feasibility of manufacturing high‐efficiency and high‐power TBs through polymer molecule engineering. [ABSTRACT FROM AUTHOR]

The PVC-PVDF-GO nanocomposites thin films were prepared by solution casting method. A thin film of Polyvinyl chloride (PVC), Polyvinylidene fluoride (PVDF), PVC-PVDF-GO was uniformly irradiated with a carbon ion beam at 70 MeV over a surface of 1 cm2 in a vacuum of almost 5 × 10−7 torr with ion fluencies of 1 × 1012 and 2 × 1013 ions/cm2. Fourier transform infrared (FTIR) spectroscopy was observed to track changes in the β-content, represented as F(β)%, during the recrystallization of PVDF after irradiation. At ambient temperature, the variation of dielectric constant and dielectric loss has been studied for pristine and irradiated samples. Ion beam irradiation caused significant changes to the dielectric constant and dielectric loss. After irradiation, the dielectric constant (ϵ′) increases at lower fluence (1 × 1012 ions/cm2), but decreases at higher fluence (2 × 1013 ions/cm2) in comparison with the pristine polymer samples. In PVDF, free radicals are generated by chain scission and cross-linking. [ABSTRACT FROM AUTHOR]

Polymer blends based on plastic waste and natural biodegradable polymers is an interesting strategy in view of environmental and technical concerns. This article investigates the structure, thermal and physical properties of virgin and post‐industrial polymethyl methacrylate (PMMA) waste/pristine chitosan (Cs) bio‐blends. Waste PMMA was generated by an extrusion process for the manufacturing of sheets. The results of gel permeation chromatography analysis (GPC) show a slight decrease (about 8%) in the average molecular weight of PMMA after extrusion. Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR‐ATR) spectra do not reveal changes in the chemical structure of post‐industrial PMMA/Cs blends compared to virgin PMMA/Cs samples, indicating that chain scission reactions are the dominant degradation mechanism of PMMA during processing. Dynamic mechanical analysis (DMA) results reveal a single glass transition temperature (Tg) for the blends, implying miscibility of the components. Post‐industrial PMMA/Cs samples exhibit slightly lower values of Tg compared to virgin PMMA/Cs blends. The post‐industrial PMMA waste slightly reduces nano‐mechanical properties and thermal stability of the blends relative to those from virgin PMMA. In contrast, it increases the water uptake of the bio‐blends compared with virgin PMMA. Highlights: Chain scission is the dominant degradation mechanism of PMMA during extrusion.Miscibility between the homopolymers within the blends.PMMA waste slightly reduced the nano‐mechanical properties of the bio‐blends.Post‐industrial PMMA waste increased the water uptake of the bio‐blends.Possibility of using post‐industrial PMMA waste by blending with chitosan. [ABSTRACT FROM AUTHOR]

This article explores the synthesis and characterization of furan-based polyamides using a continuous flow system. The researchers successfully synthesized the polyamides without impurities and optimized the synthesis process by adjusting reaction conditions. The resulting polyamides exhibited amorphous characteristics and thermal stability comparable to petroleum-based polyamides. The authors also demonstrated the depolymerization of the polyamides back into their monomers using acid-catalyzed hydrolysis, suggesting that this approach has potential for industrial applications and offers a sustainable alternative to fossil-based polyamides. [Extracted from the article]

Microplastic pollution has become one of the most concerned focuses in the world. Among many treatment methods, photocatalysis is considered to be one of the most environmentally friendly methods. In this work, the photodegradation behavior of polyamide microplastics is studied by using polyamide 6 PA6) as model microplastics and FeCl 3 as catalyst. It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl 3 is irradiated in water. The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl 3 aqueous solution, indicating that it is promising to use this new method to solve the problem of PA6 type microplastics. In addition, the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS), which provides a new insight for the study of polymer degradation mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

• Assessment of water based cleaning systems applied on p(EA/MMA) and p(nBA/MMA) acrylic paints. • Comparison between two application methods: swab and PVA hydrogels. • Study of the mid-term effects of aqueous cleaning treatment on the surfaces of acrylic paints. • Identification of internal alterations of the paint binder (polymer chain scission) by means of TGA. • Correlation between internal (binder structure) and surface alterations caused by cleaning treatment. Acrylic paints became popular among artists in the late 50′s. Some of the main conservation issues of these paints are inherent to their composition characteristics, for instance, their high sensitivity to water and a wide range of polar solvents. This makes difficult to stablish an accurate and respectful cleaning treatment for this kind of artworks. As reported on previous studies, the application of pH and conductivity adjusted solutions using accurate methods, such as confined on chemical gels, improved this kind of procedures. The aim of this work is to extend a previous study where the effect of water based cleaning treatments was tested on Liquitex acrylic paint mock-ups, and deepen on evaluating the alterations both on the surface and in the bulk of the paint film. In this paper, six acrylic commercial paints of two widely used paint brands, Titan Arts – Acrílico extrafino (Spain) and Hyplar Acrylic Colors® (USA), were selected to compare the effect of the cleaning treatment on their surface and binder matrix. Samples were prepared using Mylar sheets and left to dry in a dark and dust-free environment for three years. Adjusted water solutions were applied both using cotton swab and cryogels for comparison. Paints were characterized using Fourier Transform Infrared spectroscopy (FT-IR), pyrolysis - gas chromatography - mass spectrometry (Py–GC–MS), Thermogravimetric Analysis (TGA) and Atomic Force Microscope (AFM). All the samples showed different reaction to cleaning according to their different composition. This study revealed that those paint films where most surface alterations are observed after cleaning, are not those that suffer greater changes in the binder matrix. Moreover, a set of samples was aged under accelerated conditions (solar radiation under controlled temperature and humidity). The accelerated ageing was carried out under isochronous sampling up to a maximum of 1426 h. This tests revealed certain degradation processes such as chain scission of the binder that coincide with those alterations observed in several mock-ups after application of the cleaning treatment. [ABSTRACT FROM AUTHOR]

In the present work, a combination of virgin polypropylene and E-glass fiber was subjected to ten (10) reprocessing cycles via extrusion and compression molding techniques to mimic recycling and its impacts on the bending properties of the composites. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM), and melt flow index (MFI). The results revealed a gradual depreciation in flexural properties after each reprocessing cycle. The XRD analysis indicated a substantial reduction of peak intensities, degrees of crystallinities, and average crystallite sizes, explaining the lowered flexural properties in addition to a possible reduction in glass fiber lengths (fiber attrition). Melt-processing behavior shows a progressive increase of MFI from 7 to 19.16 g/10 min, confirming the probable damage in molecular weight and loss of complex viscosity. Chemical and structural analysis showed no alteration in the polypropylene major functional groups. It is concluded that the reductions in molecular weight and composites' properties occurred due to chain scission from recycling effects; hence, glass fiber-reinforced polypropylene composites can be recycled only three (3) times unless it is refreshed by the addition of virgin parts to compensate for the lost property. [ABSTRACT FROM AUTHOR]

PVC items (38% carbon atoms w/w) are environmentally friendly as, unlike polyolefins (86% carbon atoms w/w), they are mainly based on chlorine, one of the most abundant elements on Earth and, so, less based on fossil resources. However, in the eco-design context, articles' durability plays a crucial role, contributing to the enhancement of their sustainability. In this framework, the research on additives capable of increasing the weatherability of outdoor articles is essential. The theory section of the paper reviews the mechanisms of weathering that lead to PVC degradation and undermine the durability of items such as window frames or roller shutters. The weathering of PVC items is a complex phenomenon, involving photo-chemical and secondary chemical reactions, that yields the formation of conjugated polyene sequences underskin in the absence of oxygen and carbonyls in the surface. Here, the chain scission of the polymer backbone occurs, bringing about the disintegration of the surface of the item and causing the typical discoloration called chalking, especially evident in dark-colored articles. In the experimental section of the paper, the effect of different acid scavengers on item weathering has been studied using a natural outdoor and two accelerated exposures with xenon-arc and Q-UV testing devices. Results confirm that some acid scavengers are efficient in preventing chalking, but some are ineffective or even detrimental. Thus, the PVC formulations of durable articles upon weathering still depend on a complex choice of the appropriate ingredients, and several outdoor and indoor accelerated-weathering tests are needed to predict the articles' lifetime. [ABSTRACT FROM AUTHOR]

Despite the current growing interest in rubber composites with natural organic fillers, there is a lack of kinetic analyses that describe the decomposition of these materials during pyrolysis. For this reason, the main objective of this study was the kinetic analysis and determination of formal kinetic parameters for the pyrolytic decomposition of NR–CEL composites with different cellulose content (0, 30, 45, and 55 phr). Thermogravimetric measurements were made at heating rates of 2, 4, 6, 8, 10, and 20 °C min–1 in the temperature range of 20–600 °C. First, Friedman and KAS model-free methods were applied. Therefore, model-based methods and the model-fitting procedure were used to find the optimal multi-step kinetic model. The proposed final model consists of two parallel processes, which are kinetically independent: A → B → C and D → E → F. For each step, a kinetic triplet was calculated: the apparent activation energy, the pre-exponential factor, and the kinetic parameters of the extended empirical Prout–Tompkins model. The master plots method was used to determine the kinetic decomposition mechanism of the individual steps. It was found that step A → B has the shape of an nth-order model, step B → C mainly follows the diffusion model, the mechanism of step D → E transfers from a random scission kinetics model to an nth-order model with an increasing amount of CEL, and step E → F obeys the chain scission mechanism. [ABSTRACT FROM AUTHOR]

We conducted a comprehensive investigation to understand the effects of sequential aging temperature profiles on Neoprene rubber, aiming to provide a clearer understanding of the purpose, methodology, findings, and implications of our work. Two sequential thermal aging conditions were applied to the Neoprene rubber samples in a controlled, moisture-free environment. The characterization of the aged samples included crosslinking density analysis using swelling tests, Differential Scanning Calorimetry (DSC), and uni-axial tensile tests. Our study focused on unraveling the changes in the physical and mechanical properties of the Neoprene matrix resulting from thermal aging. Notably, we found that the degradation of Neoprene was influenced by both the temperature and the order of the aging profiles. Higher temperatures led to increased cross-linking density and improved thermal stability, indicating a prevalence of oxidation cross-linking over chain scission. This led to the creation of a more compact network structure within the material. Moreover, we introduced the concept of damage capacity, which revealed that different mechanisms of damage affect the material's toughness with varying degrees of impact. This understanding emphasizes the limited capacity for damage and subsequent mechanisms' reliance on the remaining capacity. The significance of our work lies in shedding light on the interplay between thermal aging conditions and the behavior of Neoprene rubber. The findings provide valuable insights for material design and have implications for a range of applications. [ABSTRACT FROM AUTHOR]

The investigation of chain branching in polypropylene (PP) holds significant importance for comprehending the impact of structural modifications on the properties of PP. The utilization of ethylene‐octene copolymer (EOC) presents a valuable opportunity to examine the influence of branching density on the ability of electron beam irradiation or a chemical agent in a PP blend. The introducing long chain branches (LCB) into PP can enhance its mechanical properties, particularly impact strength. This characteristic is of particular significance in applications where the material is subjected to mechanical stress, such as automotive components or packaging materials. Blends of PP/EOC were produced using 20 and 30 wt% of EOC and 0.5 phr trimethylolpropane trimethacrylate (TMPTMA) monomer. To evaluate the efficiency of branching in both solid and molten states, irradiated samples and samples mixed with dicumyl peroxide (DCP) were selected. The rheological properties of the molten blends in shear and extensional modes were assessed, and their morphology was examined using scanning electron microscopy. The existence of LCB in all samples was confirmed through dynamic viscoelastic measurements. It was concluded that although the irradiation promoted chain scission within the backbone, which resulted in long chain branching, DCP created LCB on the backbone chains of PP through chemical reaction in the melt state. Additionally, the strain hardening constant (n) was calculated, and its value for the irradiated sample PP/EOC 80/20 was 0.19, whereas its value for this blend when employing DCP was 0.14. While the complex viscosity of irradiated blend (8764 Pa.s) was greater than that of melt state branched blend (8377 Pa.s) at 0.1 rad/s, in the higher frequencies it became smaller due to the more effective creation of long chain branches through peroxide grafting in the molten state. The results of the study verified the presence of LCB in the materials by observing longer relaxation time and strain hardening behavior. Highlights: The chain branching of PP/EOC blends was investigated in both the melt state and solid state through the presence of TMPTMA monomer.The effectiveness of TMPTMA monomer in grafting was mostly notable in the molten state.The steady state viscosity of LCB‐(PP/EOC) was higher in the presence of dicumyl peroxide compared to irradiated PP/EOC.The samples containing 80 wt% of PP exhibited longer side branches compared to the sample with 70 wt% of PP according to shear and extensional rheometry.The induced side chain branches resulting from irradiation and the use of dicumyl peroxide help increase the miscibility of the polymers to a similar extent. [ABSTRACT FROM AUTHOR]

The growing interest in functional materials has resulted in the emergence of smart polymers, demonstrating practical performance in various applications especially for biomedical purposes. The properties of functional polymers are mainly determined by the presence of functional groups that differ from those in the main chains. While some polymers are naturally active and considered functional, others require modification for enhanced impact and functionality. Many functional polymers typically have a linear backbone, but very recently the attention has been shifted towards those with specific topologies and architecture, for example, bottlebrushes, stars, dendritic polymers, and gels. Over the past few years, there has been a rising emphasis on integrating selective bonds into complex polymer structures to enhance chain scission in single macromolecules. This review captures the most recent and promising approaches to the design of non-linear functional polymers containing selective/cleavable bonds and discusses the potential of these materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Stabilisers are an integral part of a propellant composition. They are essential for ensuring the chemical stability of nitrate‐ester based propellants, preventing oxidation, chain scission and uncontrolled heat generation. Progress is being made, especially in Europe, with REACh legislation (1907/2006) to use more environmentally‐friendly compounds. New stabilisers with a greener environmental profile and producing less toxic daughter products have been investigated by several groups, and several compounds demonstrated even better performances – more chemical stability and therefore longer shelf lives than formulations with the currently‐used stabilisers. Additionally, the good efficiencies and lower toxicities of the daughter products of the "green" stabilisers are also evaluated. This paper is a continuation of our previous work and demonstrates that for industrially‐manufactured propellants, that the tests performed by four different entities validate the stability and compatibility of the propellants, investigated previously on a laboratory scale, providing the community with safer formulations for the environment and health. [ABSTRACT FROM AUTHOR]

Microplastics (MP) encompass not only plastic products but also paint particles. Marine microdebris, including MP, was retrieved from five sampling stations spanning Nagasaki-Goto island and was classified into six types, primarily consisting of MP (A), Si-based (B), and Cu-based (C) paint particles. Type-A particles, i.e., MP, were exceedingly small, with 74% of them having a long diameter of 25 µm or less. The vertical distribution of type C, containing cuprous oxide, exhibited no depth dependence, with its dominant size being less than 7 μm. It was considered that the presence of type C was associated with a natural phenomenon of MP loss. To clarify this, polypropylene (PP) samples containing cuprous oxide were prepared, and their accelerated degradation behavior was studied using a novel enhanced degradation method employing a sulfate ion radical as an initiator. Infrared spectroscopy revealed the formation of a copper soap compound in seawater. Scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis indicated that the chemical reactions between Cl− and cuprous oxide produced Cu+ ions. The acceleration of degradation induced by the copper soap formed was studied through the changes in the number of PP chain scissions, revealing that the presence of type-C accelerated MP degradation. [ABSTRACT FROM AUTHOR]

The properties of thin surface layers of polymer substrates should be investigated and controlled for their application in electroless deposition. In this paper, polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) substrates were modified by plasma treatment, ultraviolet (UV)/ozone treatment, or UV (254 nm) irradiation. The chemical and physical properties of the modified layer were studied by measuring contact angle and zeta potential, field-emission scanning electron microscope (FE-SEM) imaging, and infrared spectroscopy. The condition of the surface modification affected oxygenation of the polymer chains. The oxygenation formed hydrophilic surface functional groups and relatively polar low-molecular-weight fragments resulting from the scission of the polymer chains. The surface functional groups and the fragments governed the properties of the modified layer. Adhesive metal films were electrolessly deposited on the thinner modified layer having the hydrophilic functional groups. In contrast, the thicker modified layer containing the fragments decreased the adhesion of the metal films. For example, UV/ozone treatment of the PEN substrate formed the thicker modified layer, on which no adhesive metal films were deposited. These findings illustrate that optimizing the condition of the surface modification thoroughly is feasible to form the modified layer having the chemical and physical properties appropriate for depositing adhesive metal films. [ABSTRACT FROM AUTHOR]

Controlled thermal degradation of high-molecular-weight poly-3-hydroxybutyrate (PHB) was studied in dimethylformamide (DMF), bromoform, tetrabromoethane, and trichloropropane. Samples with molecular weights of 1.6 kDa and higher were obtained. PHB degradation in pure DMF and in trichloropropane resulted in the formation of C-terminal crotonic acid residues at the sites of polymer chain scission. In the case of bromoform and tetrabromoethane, 3-bromobutyric acid residues were formed (61–68% at 100 °C and 29–54% at 145 °C), along with crotonic acid residues. This indicates the possibility of halogen capture from solvent molecules at the moment of chain scission. Presumably, the reaction follows the E1 mechanism involving the formation of an intermediate carbocation. The results show the possibility of using thermochemical degradation of biodegradable polyesters in solutions for obtaining their oligomeric bromo-substituted derivatives. [ABSTRACT FROM AUTHOR]