Polymer Bulletin最新文献

Fireproof sealant is a common sealing material and has a wide range of applications, which has the dual performance of sealing and fireproof. To figure out its thermal degradation behavior, the thermogravimetric experiments combined with Fourier transform infrared technology were conducted at multiple heating rates. The results showed that the pyrolysis process could be separated into three stages and the explicit reaction equations were revealed corresponding to each stage: First, ammonium polyphosphate decomposed to produce a large amount of inorganic acid, along with a small amount of ammonia and water. Then, a large amount of ammonia gas was produced from melamine decomposition, and the substrate including acrylic resin began to react. Furthermore, the remaining base materials and intermediate carbonized materials continued to be decomposed to produce large amounts of carbon dioxide, water and residue. The experimental results indicated that the various components of fireproof sealant could cooperate closely and played a synergistic role in flame retardant, which could be an important reference value for guiding the improvement of fire sealing materials.

The development of composite materials with fewer interface problems always helps to obtaining good properties. Two types of insulating biopolymers (7% w/w) were incorporated into a conductive matrix (polyaniline) during polymerization. The synthesis method, inspired by the synthesis of polyaniline and the coating of chitosan for the development of flexible electrodes, produces thermosets that are more thermally stable than the matrix until 350 °C. While one (gum) reduces the electrical conductivity, the other (lignin) increases the basic value of the raw material (~ 0.72 S Cm^–1) by a factor of 10. The physicochemical and morphological analyses show the formation of the polymer on the surface of the biopolymer with the appearance of new chemical bonds by interactions between hydroxyls of the biopolymer and the nitrogen of amine function from the polyaniline.

Modification of polyester (poly(ethylene terephthalate)) fabric by grafting with poly(methacrylic acid) was studied. The objective was to improve the hydrophilicity of polyester and, hence, its water uptake. The modified polyester fabrics were characterized by gravimetric method, Fourier transform infrared, dynamic mechanical analysis, and scanning electron microscopy. It was found that grafting of methacrylic acid onto polyester fabrics could be effected by radical reaction using benzoyl peroxide as radical initiator. Swelling of polyester fabric with benzyl alcohol was also found to be necessary for grafting to occur. The parameters which affected the modification reaction were initiator concentration, monomer to fabric ratio, reaction temperature, and reaction time. In addition, it was shown that the percentage uptake of moisture of the modified fabric (1–4.6%) increased with increase in the extent of grafting (5–32%). The modified fabric tended to be stiffer than the unmodified fabric, but they could be softened by controlled treatment with aqueous solution of sodium hydroxide. The stability of the modified polyester fabric, however, was found to decrease with increase in the extent of modification (high monomer to fabric ratio) and increasing concentration of sodium hydroxide solution. Thus, careful control of sodium hydroxide treatment process was necessary to prevent deterioration of the modified polyester fabric.

The furan/maleimide Diels–Alder (DA) reaction has been exploited to construct thermally reversible macromolecular structures, such as linear or cross-linked polycondensates, or to cross-link linear polymers, using the free end-type or pending furan and maleimide moieties as the diene and dienophile reagents. Here we report a different approach for the synthesis of homopolymers based on a diol, in which the DA adduct formed by the furan and the maleimide sits within the diol monomer structure. The OH end groups of the diol were used for the synthesis of a polyester and a polyurethane using conventional polycondensation methods and to study their retro DA (rDA) depolymerization through the thermal decomposition of their inner DA adducts. The relevant contribution of this study was however the possibility of synthesizing a copolymer by heating these two polymers together to induce their rDA deconstruction and then lowering the temperature in order to allow the ensuing fragments to recombine statistically by successive DA couplings, thus building the corresponding ester-urethane copolymer. ¹H NMR spectroscopy and DSC analysis were employed to confirm the success of this promising approach.

This review’s main focus is highlighting and recognizing the significant scientific advances of smart expandable lost circulation material, i.e., shape memory polymers (SMPs) composites as loss circulation material (LCM) for drilling applications as innovative and futuristic materials. This review highlights and explains ways of producing new smart materials for LCM, which can be programmed by its SMP cycle. It briefly describes loss circulation further on loss circulation material and its classification. Only very few SMPs used as LCM, like shape memory polyurethane, thermoset shape memory polymer, shape memory epoxy, etc., either used as Grout, mixed with xanthan gum, or medium-size particles combined with base fluid, while the next section focuses on shape memory polymer as loss circulation material with the shape memory effect and programming over treating wide fractures. The last section consists of conclusion, prospects, and recommendations.

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This study focuses on the creation of high degree biocomposite with the utilization of renewable resources, including cardanol oil, palm kernel fiber and chitosan biopolymer. The principal aim of this research was to achieve high degree ratio of biocomposite for safe and eco-friendly application. The chitosan biopolymer was extracted from marine waste sea urchin spikes via deproteination. The biocomposites were prepared via hand layup technique following testing via ASTM standards. According to results, among the composites fabricated, PC5 exhibits exceptional mechanical strength with tensile strength of 88.2 MPa, flexural strength of 133.35 MPa and impact energy of 3.92 J. Therefore, PC6 composite performs better wear resistance with reduced coefficient of friction of 0.399 and Sp. wear rate of 0.01 mm³/Nm, respectively. And also, PC6 provides good thermal resistance with initial decomposition temperature of 345 °C. Similar to mechanical properties, in fatigue behavior also PC5 exhibits high fatigue life cycle counts with 19,647 for 25% UTS, 18,799 for 50% UTS and 17,571 for 75% UTS. The obtained results show that the inclusion of palm kernel fiber and chitosan significantly enhances the mechanical properties, wear and thermal resistance of the composites, while the cardinal oil binder ensures proper adhesion. However, thermal aging conditions were implemented to assess the material’s ability to withstand harsh environmental factors. Notably, among the composite materials tested, the designations with chitin (such as PC4, PC5, and PC6) exhibited lesser susceptibility to the effects of thermal aging. This resilience is attributed to the presence of NH₂ functional groups within chitin, which play a role in reducing the impact of thermal aging. These discoveries highlight the promising qualities of the developed polyester biocomposites, suggesting their suitability for a wide array of industrial applications requiring materials capable of enduring high-temperature environments such as automotive door panels, structural, space, defense and sports applications.

This present study investigates an eco-friendly electromagnetic interference (EMI) shielding material developed using cellulosic fiber and apple peel extracted biocarbon for safe electronic applications. The primary aim is to study how the biomass derived biocarbon influences in the wave shielding phenomenon. The fiber and filler both used from waste biomass which promotes circular economy and amine functionalization on both fiber and filler brings the novelty to this research. Further, the prepared composite under hand layup process is further assessed as per ASTM standards. Results revealed that due to the addition of surface modified cellulosic fiber and even dispersion of biochar particle into composite enhance mechanical, dielectric, EMI shielding effectiveness of the composite material. Thus, when compared to the plain vinyl ester resin (V), the amine functionalized cellulosic fiber reinforced composite material (V0) shows improved tensile, flexural and impact strength of 125 MPa, 151 MPa, and 4.1 J respectively. Further, the addition of biochar particle of 3 vol.% into the composite (V2) shows improved hydrophobicity behavior of 107° contact angle and the composite V2 further enhanced the tensile, flexural, impact strength of the composite of 145 MPa, 189 MPa, 5.1 J respectively. Moreover, the increase in biochar of 5 vol.% in to the composite (V3) shows effective dielectric loss of 0.28 in E band and 0.45 in J band. Furthermore, the composite under (V2) of 40 vol.% fiber, and 3 vol.% biochar shows maximum EMI shielding effectiveness of 8 dB in E band and 40 dB in J band, when compared to the 40 vol.% of fiber reinforced composite (V0) of EMI shielding effectiveness 9 dB in E band and 55 dB in J band respectively. Thus, this effective EMI shielding effectiveness, dielectric strength and load carrying capacity, impact strength and cost effective, light weight nature makes the composite material to be utilized in high signal protection applications, sensor, navigational devices, and various electric and electronic gadgets, etc.

The growing demand for high-performance, light materials in several tertiary industries is a leading factor propelling the current polymer market. The international UHMWPE market was estimated at USD 1.87 billion in 2023 and is projected to increase by 11.3% CAGR (Compound Annual Growth Rate) from 2024 to 2030 (Ultra-high Molecular Weight Polyethylene Market Report, 2030). The aerospace, defence, and medical sectors have been this market’s primary drivers. Ultra-high molecular weight polyethylene is an excellent polymer popularly used for its enhanced strength, exceptional wear resistance, and ability to support life processes without causing undesirable reactions. Nevertheless, conventional surface modification techniques mainly focus on improving specific properties for established applications. In this article, we have explored how UHMWPE nanocomposites loaded with different nanomaterials like carbon nanotubes, graphene oxides, hydroxyapatite, and metal alloys could be used to make high-performance products. This review advances the frontiers of knowledge by concentrating explicitly on three key application areas: defence, biomedical, and electromechanical. In the defence realm, these advancements could revolutionise ballistic protection equipment, paving the way for next-generation gear with superior capabilities. Within the biomedical sector, UHMWPE nanocomposites hold great promise for creating exceptional joint replacements that possess enhanced wear resistance and biocompatibility. Lastly, in the electromechanical domain, these composites offer the possibility of developing lightweight and high-performance tribological components, thereby driving advancements in diverse mechanical systems.

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Diblock copolymers consisting of higher hydrophobic styrene and hydrophilic N-hydroxyethylacrylamide (HEAAm) segments were successfully synthesized via direct two-step atom transfer radical polymerization. Polystyrene (PS) homopolymers were synthesized using methyl 4-(bromo-methyl) benzoate initiator in N,N′- dimethylformamide (DMF) in the presence of Cu(I)Br/pentamethyldiethylene tetramine (PMDETA) catalyst system at 90 and 110 °C in nitrogen atmosphere. PS was used as macro-initiator for the synthesis of PS-b-PHEAAm polymer. Block copolymerizations were carried out in pure DMF in the presence of the same catalyst system at 110 °C while argon was used for deoxygenation and inert environment. Block copolymer was purified through dialysis into deionized water using a dialysis tubing (MWCO 3500, cellulose membrane). The number average molecular weight of PS polymers (Mn = 2240, 3250 and 10,800 Da) was determined by size exclusion chromatography using tetrahydrofuran (THF) as eluent. The chemical structures, functional groups and actual compositions of copolymer were determined using instrumental data, c.f. elemental analysis, attenuated total reflectance infra-red and proton—nuclear magnetic resonance (¹H-NMR) spectroscopy analysis. Thermo-gravimetric analysis confirms that diblock copolymer has higher thermal stability than PS homopolymer. Co-solvent effect on particle formation was investigated by regulating dielectric constant. It is revealed that THF/DMF (9:1) provides susceptible environment for the formation of smallest size (13 ± 4 nm) particle. This synthetic route would establish a direct synthesis of diblock copolymer with antagonistic segments for advanced technological applications.

The single-sited metallocene catalyst has attracted significant attention due to its high activity and application in olefin polymerization industry. In this work, we introduced a strategy of in situ modification of metallocene catalyst with pyrene through π–π stacking to study the effect in olefin polymerization. After activated by MMAO, the pyrene-modified metallocene catalyst exhibited high activities (up to 1333 kg mol⁻¹ h⁻¹) in ethylene polymerization, which was 1.9 times higher than that of the pyrene free catalyst system. This could be because the electron-donating ability of cyclopentene to the transition metal was enhanced through π–π interaction of pyrene with cyclopentene. The copolymerization of ethylene and 1-hexene was also studied. The pyrene-modified metallocene catalyst system performs with higher activity in the copolymerization with a lower monomer incorporation ratio. Density functional theory (DFT) calculations indicated the formation of π–π interaction between the Zr center with pyrene molecule leading to the increase in steric hindrance and electron density.

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