Copolymerization Reaction Research Articles

Study on the factors influencing the thermal runaway hazards of styrene-acrylonitrile bulk copolymerization

The styrene-acrylonitrile bulk copolymerization reaction has a high risk of thermal runaway, but the factors influencing the thermal hazards of the reaction have not been adequately investigated. In this paper, the effects of different factors on the thermal runaway behavior of the styrene-acrylonitrile copolymerization are investigated using a combination of simulation and calorimetric testing. The simulation results indicate that increasing the proportion of styrene in the monomer feed significantly delays the onset of thermal runaway. The calorimetric results show that for di-tert-butyl peroxide (DTBP), azodiisobutyronitrile (AIBN) and tert-butyl peroxy benzoate (TBPB) initiators as examples, the TBPB-initiated copolymerization is found to have the maximum temperature-rising rate and pressure-rising rate. Under adiabatic runaway, the temperature and pressure change significantly with increasing TBPB concentration, indicating a great potential risk of thermal runaway. Calculation of kinetic parameters based on calorimetric data reveals thermal runaway mechanism.

Multi-functional Gleditsia sinensis galactomannan-based hydrogel with highly stretchable, adhesive, and antibacterial properties as wound dressing for accelerating wound healing

Design and development of a multifunctional wound dressing with self-healing, adhesive, and antibacterial properties to attain optimal wound closure efficiency are highly desirable in clinical applications. Nevertheless, conventional hydrogels face significant barriers in their mechanical strength, adhesive performance, and antibacterial properties. Herein, a tough hydrogel based on aldehyde-grafted galactomannan was synthesized through radical copolymerization and Schiff base reaction, incorporating hyaluronic acid, acrylamide, and the zwitterionic monomer to create a multi-crosslinked structure. The multiple crosslink structure pattern consisting of multiple hydrogen bonding, ionic interactions, reversible Schiff bases bonds, and molecular chain entanglement endowed this hydrogel with multiple functionalities, including high tensile strength (25 kPa), tensile strain (2200 %), toughness (391.59 kJ/m3), and Young's modulus (9.77 kPa). The presence of catechol groups and zwitterionic groups endow hydrogels with outstanding adhesion strength (42.21 kPa), which satisfied the adhesive demand for the ample motion of specific areas. The zwitterionic monomer provided long-lasting antibacterial properties and promoted migration and growth of negatively charged cells, capable of establishing efficient antibacterial barriers and serving as wound dressing. The in vivo and vitro experiments manifested that the optimized hydrogel demonstrated an inconspicuous inflammatory response, facilitating rapid healing of full-thickness skin wound in rat models. Therefore, this work provides a promising strategy and an ideal candidate for wound healing dressings in treating infected skin wounds.

The advancement of EVA polymerization kinetics and development of high-performance EVOH polymerization process

Ethylene-vinyl alcohol copolymer (EVOH) is a material with excellent barrier properties, produced via the radical copolymerization of ethylene and vinyl acetate in solution, followed by alcoholysis in methanol with NaOH as a catalyst. It is widely used in packaging and medical materials. However, balancing the barrier properties and processability remains challenging. Currently, multi-scale research methods using density functional theory (DFT) to explore polymerization mechanisms and obtain kinetic data, combined with process simulation methods to develop high-performance EVOH polymerization process, are gaining attention. Therefore, this study employs DFT and transition state theory (TST) methods to study the kinetics of chain growth and chain transfer reactions of radicals at first, yielding the average chain growth and chain transfer rate constants for copolymerization reactions. Then, based on these rate constants, process simulations were used to model the ethylene–vinyl acetate solution copolymerization reactor, developing polymerization process for EVOH with high barrier properties as well as EVOH with both high barrier properties and good processability. These findings provide suggestions and guidance for EVOH production and application.

High Antimicrobial Electrotherapy and Wound Monitoring Hydrogel with Bimetal Phenolic Networks for Smart Healthcare

AbstractThe design and fabrication of novel soft bioelectronic materials for rapid wound healing and real‐time monitoring are critical for smart healthcare. However, developing such integrated multifunctional materials devices remains challenging due to fabrication dynamics and sensing interface issues. Herein, a novel strategy is presented for accelerating the kinetics of hydrogels integrating antimicrobial, electrotherapeutic, and wound monitoring functions via bimetallic phenolic networks. The Al3+ catalyzes the radical copolymerization reaction of acrylic acid, resulting in the gelation of the system within 10 s, and also catalyzes the redox reaction between silver and lignin, inducing the sustained release of catechol, which significantly enhances the hydrogel's antimicrobial activity and shortened the wound healing process. Meanwhile, the abundant non‐covalent interactions enhance the hydrogel's tissue adhesion, and mechanical properties (tensile strength 1.558 MPa and elongation 1563%). In addition, the bimetallic ions endow the hydrogels with excellent sensing properties. Under the synergy of electrical stimulation, the wound healing rate is accelerated. Notably, wound assessment can be performed by monitoring changes in electrical signals over the wound, which can assist physicians and patients in achieving intelligent wound management. This work provides new insights into the design and application of multifunctional smart bioelectronic materials.

Microblog‐Assisted Synthesis of Schiff Base Network Polymers for SO2/Epoxide Copolymerization and Thermal Degradation Kinetics of the Products

AbstractThis study successfully prepared three environmentally friendly Schiff base network (SNW) polymers, SNW‐1, SNW‐2, and SNW‐3, using melamine and aldehyde compounds as raw materials through a microwave‐assisted synthesis method. The SNW materials were applied to catalyze the copolymerization reaction of SO2 and epoxides. Through detailed analysis of the chemical structure and properties of SNW‐1, SNW‐2, and SNW‐3, their catalytic efficiency was thoroughly investigated. Three thermal degradation kinetic models, Flynn–Wall–Ozawa (FWO), Kissinger, and Coats–Redfern, were employed to calculate the kinetic parameters of the thermal degradation of poly(cyclohexene sulfite) (PCS). Potential thermal degradation mechanisms were speculated. Additionally, the Kissinger model accurately described the thermal degradation kinetics features of PCS. Based on experimental results and kinetic analysis, this paper elucidates the potential mechanism of the copolymerization reaction of SO2 and epoxides. The study indicates that microwave‐assisted synthesis exhibits convenience and high efficiency in preparing efficient catalysts, demonstrating significant potential across various application domains.

Study on interfacial tension, wettability and viscosity in different salinities of synthesized a new polymeric surfactant for improving oil recovery

Over 50% of the original oil in place (OOIP) is immobile or trapped in the reservoir. Therefore, today, more efficient methods have been introduced in the tertiary oil recovery sector as a scheme of enhanced oil recovery (EOR). Due to the decline of conventional hydrocarbon reserves, polymers are increasingly used in EOR methods, such as surfactant-polymer (SP) and alkaline-surfactant-polymer (ASP) flooding. SP flooding has a complex formulation and design, leading to undesirable phase separation if improperly mixed. Polymeric surfactants are a promising alternative to SP flooding. They consist of hydrophobic groups attached to hydrophilic polymers, which help to improve the mobility ratio and reduce interfacial tension (IFT). This paper examines the rheological and synthesis properties of a new polymeric surfactant produced through bond co-polymerization reaction using different hydrolyzed polyacrylamide (HPAM) ratios and a zwitterion hydrophobic group. The synthesized hydrophobically modified zwitterionic polyacrylamide (HMZPAM) was characterized by FTIR and HMNR analysis. HMZPAM performed better than other substances in IFT, viscosity, wettability, oil recovery, and resistance to different one and two-valence cations. The results indicate that HPAM reduced the IFT to 13.65, while HMZPAM reduced it to 0.441 mN/m. Wettability change evaluated on a rock carbonate/crude oil/HMZPAM system that changed the water-wet state of the primary oil-wet rock carbonate to strongly water-wet state as wettability change measurements showed a decrease in contact angle from 62.76 to 21.23 degree. Comparative studies on the effectiveness of HPAM and HMZPAM were also conducted according to the measurement of viscosity and shear rate in the presence of salt, which indicates the higher shear rate and viscosity of HMZPAM. Core flooding tests revealed that HMZPAM resulted in better additional recovery due to microscopic displacement, resulting in a total oil recovery of 84%, compared to 48% of residual oil saturation for HPAM. Also, salts decreased oil recovery in HPAM injection but increased oil recovery in HMZPAM injection.

Thermal and optical properties, and aggregated structure of poly(substituted methylene)s produced by radical polymerization of fumarates containing fluorine-substituted alkyl ester groups

Fluoropolymers have excellent heat, oxidation, and chemical resistances as well as low dielectric constant and dielectric loss, and are often used as highly functional optical polymer materials. In this study, we conducted the radical polymerization and copolymerization of asymmetric dialkyl fumarates, in which a bulky alkyl group is introduced into one ester group and a trifluoroethyl or hexafluoroisopropyl group is into another ester group. We successfully synthesized high-molecular-weight poly(dialkyl fumarate)s (PDRF) with a poly(substituted methylene) structure containing fluorine atoms in the side chain, and evaluated their structure and physical properties. First, the effect of fluorine substitution on the radical polymerization and copolymerization reactivity was examined. We also evaluated the thermal and optical properties of the fluorine-containing PDRFs and clarified the role of the fluorine substitution for increasing the β transition temperatures and reducing the refractive indices. Furthermore, the higher-order structure of the PDRFs in the solid state was analyzed by wide-angle X-ray scattering (WAXS) measurement in order to discuss the aggregation of the rigid PDRF chains and a possibility for the formation of a phase-separated microstructure by the fluorine-containing side chains.

Purification Processes for Generating Cationic Lignin-Acrylamide Polymers.

Purification is an essential step in many polymerization processes for fabricating highly pure polymers. This study considered various purification methods for purifying the product of lignin, acrylamide (AM), and diallyl dimethylammonium chloride (DADMAC) copolymerization reactions at a laboratory scale. The charge density, yield, molecular weight, and solubility analyses confirmed that ethanol extraction and membrane filtration were the most effective processes for producing lignin-p(AM)-p(DADMAC). The 1H NMR analysis revealed that the membrane dialysis effectively removed unreacted AM and DADMAC monomers from the reaction medium. The produced samples of the ethanol-extraction and dialysis processes had higher solubility and yield compared to the product of the acidification process. Thermogravimetric studies confirmed that the ethanol-extracted and dialyzed samples had a degradation temperature (220 °C) higher than that of the acidified samples (160 °C). The rheological studies confirmed that the viscosities of the polymer solutions were influenced more by the solubility than by the molecular weight of the generated polymers within the molecular weight range examined in this study. The flocculation studies confirmed that the ethanol-extracted and dialyzed polymers were more effective flocculants than the acidified samples for the particles of a kaolinite suspension. Based on the above results, membrane filtration with a larger pore size could be an environmentally friendly method for effectively purifying lignin-p(AM)-p(DADMAC).

Preparation of Consolidated Dust Suppression Materials Based on Pectin: Graft Modification Experiment and Reaction Mechanism.

The natural material pectin was used as the matrix to prepare a dust suppressant. The regression model in response to the grafting ratio was established, and the optimum modification scheme was determined. The amount of monomer, initiator, cross-linking agent, and reaction temperature was 3.20 g, 0.20 g, and 0.15 g and 92 °C, respectively. Through Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy tests, not only the formation of the product in graft copolymerization reaction was validated but also the wettability of pectin was significantly improved. The surface morphology of pectin before and after modification was observed by a scanning electron microscope. After graft copolymerization treatment, the surface of pectin presented a dense grid structure, which proved that the pectin-modified dust suppressant can play a crucial role in wetting and condensing coal dust. Contact angle tests were used to characterize the effect of pectin modification on the wettability of bituminous coal before and after modification. The results of contact angle tests showed that when the droplets just contacted the bituminous coal flakes, the contact angle of modified pectin droplets on the flakes was the smallest, and the value was 55.21°. Compared with pure water droplets and unmodified pectin droplets, it decreased by 21.66° and 18.50°. The modification reaction process and dust suppression mechanism were explained at the molecular level.

Manufacture of Solid Propellants Based on Renewable Succinic Acid Polyols

AbstractModern energy policies encourage the replacement of fossil fuels with a more sustainable type. Succinic acid is a promising renewable material that can react with ethylene glycol and 1,4‐butanediol in a two‐step polycondensation reaction to form hydroxylated polyesters. Copolymerization reactions were investigated to produce novel green binders for manufacture of solid propellants. The ester of the first step of polycondensation was used as a plasticizer in the propellant formulation. These products can be an alternative to binders of fossil sources, such as hydroxyl‐terminated polybutadiene (HTPB), frequently used as fuel of commercial propellants. Initially, analyses of Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography indicated the formation of polymeric products and adequate chain growth at reaction conditions. Then, the obtained copolymers were characterized by rheological analyses, which revealed that the processability of the copolymer materials was similar to that of the HTPB samples. Additionally, thermogravimetric analyses indicated that the copolymers presented good thermal stability below 200°C. Furthermore, differential scanning calorimetric (DSC) analyses indicated that the glass transition temperatures of the obtained copolymer samples ranged from −20 to −60°C, a suitable range for the intended use. Solid propellants were then prepared with solid loadings above 70 wt %, heat of combustion above 11,300 J g−1 and heat of explosion above 4,980 J g−1, which are compatible with values expected for solid propellants. Finally, oxygen balance calculations showed that the intrinsic oxygen content of the polyesters can allow the reduction of amounts of oxidizers in the final propellants.

Synthesis and properties of superhydrophobic monomer stearyl methacrylate-modified polyacrylate latex pressure sensitive adhesives

Hybrid surfactants of long carbon chain hydrophobic nonionic emulsifier N-390 and conventional anionic emulsifier CO-436 were utilized in this study to enable successful emulsion polymerization of super-hydrophobic monomer stearyl methacrylate (SMA) together with butyl acrylate (BA), acrylic acid (AA), and 2-hydroxyethyl acrylate (HEA). The influences of SMA on the resulting latex and film properties were thoroughly investigated. Both FTIR and 1H NMR were used to confirm the successful participation of SMA in the emulsion polymerization. The results indicated that with introduction of SMA, the roughness of the latex film increases, while the light transmission decreases. It was also found that with the addition of SMA, contact angle of the latex PSA film increased from 115.1° to 127.2°, while water absorption decreased from 5.76 to 2.89 wt%. DSC curves demonstrated that SMA has participated more in the homopolymerization reaction than in the copolymerization reaction. TGA results showed that the initial decomposition temperature (T5%) of the latex film was increased from 302.8 to 332.7 °C with the increase of SMA dosage from 0 to 20 wt%. Finally, adhesion properties results indicated that loop tack and 180° peel force of the PSA films were decreased from 11.51 to 1.88 N/25 mm and 6.36 to 3.44 N/25 mm, respectively, while shear strength was increased from 732 to 2865 min.

Development of Group IV Metal Complexes Bearing Thioether-Amido Ligands with Enhanced High-Temperature Catalytic Performance toward Olefin Copolymerization.

The development of homogeneous metal catalysts with both high activity and exceptional thermal stability is crucial for the efficient synthesis of polyolefin elastomers (POEs) through solution-phase olefin polymerization. In this study, a series of Hf (Hf1-Hf5), Zr (Zr1), and Ti (Ti1) complexes featuring thioether-amido ligands were synthesized and carefully characterized using advanced techniques such as 1H and 13C NMR spectroscopy as well as single-crystal X-ray diffraction analysis for Hf4 and Hf5. The results revealed that the catalytic activity and 1-octene incorporation efficiency of these metal complexes followed the trend Hf > Zr > Ti, underscoring the significant impact of the metal center on catalytic performance. Furthermore, the choice of ligands was found to play a critical role in dictating the catalytic properties, with ligands bearing less steric hindrance on the sulfur atom proving to be more favorable for copolymerization reactions. Notably, the Hf complex Hf1, featuring a methyl group on the sulfur atom, displayed exceptional catalytic activity as high as 21,060 kg(polymer)·mol-1(Hf)·h-1 toward ethylene/1-octene copolymerization at 120 °C and produced POE with a high molecular weight (Mw = 6.3 × 104 g·mol-1), relatively narrow distribution (Đ = 2.4), and high incorporation of 1-octene (34.1 mol %). This study demonstrates the potential of tailored ligand design in developing efficient metal catalysts for the production of high-value-added POEs.

Simple/commercially‐available Lewis acid in anionic ring‐opening polymerization: powerful compounds with multiple applications in macromolecular engineering

Simple and commercially‐available Lewis acids (LA) are commonly used catalysts in anionic ring‐opening polymerization (AROP) reactions. In particular, for the AROP of epoxides, the addition of a Lewis acid allows the transition from a so‐called end‐chain mechanism to a monomer‐activated mechanism. The presence of the LA simultaneously leads to a decrease in the reactivity of active centers through the formation of a three‐species ate complex and to the activation of the monomer by LA coordination to the oxygen atom of the oxirane ring. These two effects result in both an increase in propagation kinetics and a decrease in transfer reactions, which has enabled the synthesis of high molecular weight polyethers. However, the impact of Lewis acids goes far beyond these classic effects. They have indeed enabled the polymerization of new functional monomers as well as the synthesis of heterotelechelic macromolecules. Also widely used as catalysts in copolymerization reactions (statistical, sequential, or alternating) Lewis acids can strongly influence the composition and sequence of monomer units in macromolecules. Finally, Lewis acids can also significantly influence the architecture of the obtained macromolecules. This review aims to list the various contributions of Lewis acids to macromolecular engineering and illustrate them with well‐chosen examples.

Creative synthesis of pH-dependent nanoporous pectic acid grafted with acrylamide and acrylic acid copolymer as an ultrasensitive and selective riboflavin electrochemical sensor in real samples

In current research, an innovative pectic acid was grafted with poly (acrylamide-co-acrylic acid) [PA-g-poly (AAm-co-AA)] nanoporous membrane using a free radical-mediated grafting copolymerization process. The optimized parameters for the grafting copolymerization reaction such as initiator concentration, monomer concentrations, polymerization reaction time, and temperature were studied. Additionally, the solid content, graft percentage, and conversion were calculated. The unique polymeric membrane was characterized using Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetry (TG), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) supported by energy dispersive X-ray spectroscopy (EDX). The formulated novel PA-g-poly (AAm-co-AA) had a nanoporous structure with a diameter of 113 nm. pH-dependent swelling and biodegradation measurements were also studied. The electrochemical characterizations of PA-g-poly (AAm-co-AA) were conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the screen-printed electrode (SPE) was modified with pure PA and the new generation of its grafted polymeric nanoparticles to detect and quantify the concentration of riboflavin (RF) in real samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode showed two linear concentration ranges from 0.01 - 2 nM and 2 – 90 nM with low detection limits (LODs) of 0.004 and 0.97 nM, respectively, demonstrating high sensitivity. Besides, the fabricated sensor exhibited more selectivity, simplicity, great reproducibility, repeatability, and good stability. Finally, the PA-g-poly (AAm-co-AA)-modified SPE based sensor was effectively used in real sample analysis of egg yolk, milk, and vitamin B2 drugs with good recovery rates.

Effect of different initiators on the properties of diacetone acrylamide grafted starch-based adhesive

Environmentally friendly and non-toxic bio-based adhesives are emerging as the most promising substitutes for petroleum-based adhesives, attracting increasing attention. This work involved the synthesis of a starch-based adhesive for particleboards by grafting diacetone acrylamide (DAAM) onto starch. The graft polymerization was initiated using three different initiators: ammonium persulfate (APS), hydrogen peroxide (H2O2)/ammonium ferrous sulfate system, and ceric ammonium nitrate (CAN). A comparative study was conducted to assess the varying effects of these initiators. The results showed that in the graft copolymerization of starch with DAAM, different initiators produced different types of free radicals, and CAN initiation produced alkyl radicals and long-chain alkyl radicals with a peak total spin value of 3.96 × 1015, and thus had the highest grafting efficiency and grafting rate of 72.59 % and 16.75 %, respectively. From the comparison of the total number of spins, it can be seen that CAN is more targeted for starch initiation. In addition, characterization results from Fourier transform infrared spectroscopy and confocal Raman spectroscopy showed that DAAM underwent a graft copolymerization reaction with starch. Notably, the adhesive initiated by CAN demonstrated the highest water resistance and mechanical strength, with an absorption thickness expansion and static bending strength of 8.52 % and 10.56 MPa, respectively.

Synthesis and Evaluation of Trialkyl Ammonium Tetrakis(perfluorophenyl) Aluminate, a Highly Efficient Activator for High-Temperature Ethylene-α-Olefin Copolymerization Reactions

Synthesis and Evaluation of Trialkyl Ammonium Tetrakis(perfluorophenyl) Aluminate, a Highly Efficient Activator for High-Temperature Ethylene-α-Olefin Copolymerization Reactions

Detection of Sulfonamide Antibiotics Using an Elastic Hydrogel Microparticles-Based Optical Biosensor.

Sulfonamide antibiotics were the first synthetic antibiotics on the market and still have a broad field of application. Their extensive usage, wrong disposal, and limited degradation technologies in wastewater treatment plants lead to high concentrations in the environment, resulting in a negative impact on ecosystems and an acceleration of antibiotic resistance. Although lab-based analytical methods allow for sulfonamide detection, comprehensive monitoring is hampered by the nonavailability of on-site, inexpensive sensing technologies. In this work, we exploit functionalized elastic hydrogel microparticles and their ability to easily deform upon specific binding with enzyme-coated surfaces to establish the groundwork of a biosensing assay for the fast and straightforward detection of sulfonamide antibiotics. The detection assay is based on sulfamethoxazole-functionalized hydrogel microparticles as sensor probes and the biomimetic interaction of sulfonamide analytes with their natural target enzyme, dihydropteroate synthase (DHPS). DHPS from S. pneumoniae was recombinantly produced by E. coli and covalently coupled on a glass biochip using a reactive maleic anhydride copolymer coating. Monodisperse poly(ethylene glycol) hydrogel microparticles of 50 μm in diameter were synthesized within a microfluidic setup, followed by the oriented coupling of a sulfamethoxazole derivative to the microparticle surface. In proof-of-concept experiments, sulfamethoxazole, as the most used sulfonamide antibiotic in medical applications, was demonstrated to be specifically detectable above a concentration of 10 μM. With its straightforward detection principle, this assay has the potential to be used for point-of-use monitoring of sulfonamide antibiotic contaminants in the environment.

Determination of Reactivity Ratios of N-butyl Acrylate/methyl Methacrylate Copolymerization by NMR Spectroscopy

In this study, the reactivity ratios of n-butyl acrylate (BA) and methyl methacrylate (MMA) were investigated. The copolymerization reactions were performed in toluene at 70 oC, using azobisisobutyronitrile as the initiator. The composition of the initial monomer mixture and copolymers was easily determined with the help of proton nuclear magnetic resonance (1H-NMR) spectroscopy. The molar fractions of BA and MMA in the feed were varied to apply the linear methods of Fineman–Ross and Kelen - Tudos. The calculation gave the reactivity ratios and . The computed copolymer composition was relatively close to the real copolymers obtained, with a 5% deviation.

Increasing softening point of isotropic spinnable asphalt by two-step preparation from ethylene tar residue modified with bio tar residue

Carbon fiber prepared from asphalt may be a critical type of low-weight chemical material of excellent mechanical performances. Here, an isotropic spinnable asphalt (EBA) was prepared from ethylene tar residue (ETR) by a two-step method of bio tar residue (BTR) through co-polymerization-air blowing, and isotropic asphalt carbon fibers were prepared from the product asphalt. The main types of molecules contained in the two feedstocks were determined by 1H NMR and LDI-TOF MS analyses. The co-polymerization behavior and thermal stability of the asphalt blends were analyzed using polarized light microscopy and thermogravimetric analyzer, respectively. Finally, the morphology and mechanical properties of carbon fibers made from EBA were evaluated by scanning electron microscope and universal testing machine. The results show that BTR contains much more oxygen-containing functional groups and unique long-chain sawtooth molecular structure; the former can promote the reactivity of the co-polymerization reaction, and the latter can limit the formation of large-plane cyclic aromatic hydrocarbon polymers due to the spatial resistance effect to greatly reduce the content of the mesophase. The softening point of the product asphalt shows a tendency of increasing and then decreasing with the increase of the proportion of BTR in the raw material mixture, and a reaction mechanism based on linear and bulky molecules is proposed to explain it by analogy with the structure of macromolecules. Consequently, the EBA made from a mixture of ETR and BTR at ideal moderate proportions has excellent performance in terms of softening point and mesophase content than ETRO made from ETR alone, and the carbon fiber made has a high tensile strength of 1.82 GPa with an elastic modulus of 38.9 GPa, which has reached the level of high tensile strength carbon fiber. Therefore, the use of inexpensive renewable energy bio-asphalt in the modification of heavy oil to obtain high softening point isotropic asphalt for preparing isotropic carbon fiber with excellent properties is achievable.

Eco‐friendly synthesis of non‐isocyanate polyurea using PET and CO2 upcycling: A double green approach

AbstractFrom the perspective of sustainability, this research explored both the recycling of polyethylene terephthalate (PET) and the conversion of carbon dioxide (CO2) into polymer materials. To this end, a series of copolyurea specimens were synthesized through the polycondensation of carbon dioxide with hexamethylenediamine (HDA) and terephthalic dihydrazide (TDH), where TDH was derived from the chemical recycling of PET via the aminolysis method. FTIR spectroscopy, 1H NMR, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) characterized the products of PET recycling and synthesized copolyureas. Additionally, we sought to identify the optimal parameters for both the recycling and copolymerization processes. The results of identification analyses for both the recycling and copolymerization reactions confirmed the formation of the desired structures. An increase in the hard segment (TDH) led to discrepancies between the intended and actual monomer ratios in the synthesis, possibly due to dimethyl sulfoxide (DMSO) solubility issues or unreacted TDH. Furthermore, the TGA analysis indicated that the initial degradation temperature (Td,5%) of the copolymer increased with the proportion of aromatic rings in the hard segment, underscoring the complex interactions within the copolymer matrix affecting its thermal and structural properties. The DSC results revealed that for copolyureas with the formula HDAxTDH100–x (where x = 50, 60, 70, 80, 90), reducing the x fraction or increasing the TDH content lowered the melting temperature. Furthermore, at a high percentage of TDH, the melting point disappeared entirely due to the destruction of the crystalline structure, indicating a critical threshold where the copolymer transitions from a semi‐crystalline to an amorphous state.