Polymer Bulletin最新文献

Chlorobutyl rubber (CIIR) is a synthetic elastomer possessing rapid cure rate, vast compounding ability as well as stable crosslinks. This unique elastomer of the isobutylene isoprene rubber family exhibits excellent mechanical, thermal, gas barrier and viscoelastic properties that can be further improved by the incorporation of various kinds of nanofillers resulting in the formation of chlorobutyl rubber nanocomposites. Moreover, CIIR demonstrates remarkable compatibility with a variety of other elastomers, including natural rubber and ethylene propylene diene monomer (EPDM), enabling the development of blends that exhibit superior elastomeric and physical properties beyond those of the individual constituents. The features of CIIR blends can be altered further to exhibit multifunctionality by the strategic addition of nanostructured fillers such as carbon nanotubes, graphene, graphene oxide, carbon black, boron nitride, and their hybrid derivatives. This review presents a comprehensive exploration of fabrication of CIIR nanocomposites and CIIR blend nanocomposites by giving special emphasis to their property enhancements. Additionally, the review highlights the wide-ranging applications of CIIR blend nanocomposites in real world applications like oil-water separation, protective clothing, and high-efficiency gas barrier systems.

In this paper, we simultaneously improved the crystallinity, heat deflection temperature (HDT) and toughness of injection-molded poly(lactic acid) (PLA). We achieved this through the use of a nucleating agent (NA) and the impact modifier ethylene-vinyl acetate copolymer (EVA), and by in-mold crystallization (IMC) and post-production crystallization (PPC). The best results were achieved when 10 wt% EVA and 2 wt% NA were added to PLA, which was injection-molded into a cold mold and then annealed at 80 °C. In this case, the properties of the resulting PLA were very close to the properties of acrylonitrile-butadiene-styrene. In the case of IMC, the best results were obtained when PLA was modified with 20 wt% EVA and 2 wt% NA and crystallized in a mold at 90 °C. The main difference between the resulting properties of modified PLA subjected to IMC and PPC was in strain at break: 3.5% for IMC and 14.6% for PPC. As the PLA-based compounds were crystallized by IMC and PPC, this huge difference between the strain at break of the samples can be explained with the differences in the crystalline structures developing under different conditions (crystalline modifications, spherulite size, etc.).

Bio based materials are gaining interest in wide industrial sectors due to their lightweight, cost effective, easy degradable in nature. One such bio based material is polymer composite, which are having matrix and bio mass derived reinforcement material, numerous studies are underwent on this biocomposite material. The uniqueness of present study is to extraction of short fiber from ivy gourd stem and activated biocarbon from walnut shell, further the extracted short fiber is treated under alkali and vinyl silane solution, which improves the strength features. The composite are fabricated by hand layup method and testing are carried out by ASTM standard. The study result reported that composite C5 with 4 vol% of activated biocarbon, and 40 vol% of alkali silane modified short fiber shows improved tensile, flexural behavior, and impact energy of 148 MPa, 188 MPa, and 6.6 J respectively. Moreover, with increasing filler concentration of 8 vol% these mechanical features shows reduced strength features. However, the composite C6 at this 8 vol% of activated biocarbon shows enhanced hardness, thermal conductivity, contact angle behavior of 92 shore-d, 0.473 W/m-K, and 98° respectively. Similarly, the wear resistance features of the composite C6 are enhanced by providing reduced mass loss and coefficient of friction of 0.57 g and 0.25 when 8 vol% of fillers are reinforced along with fiber matrix. Thus, the study shows the composite with reinforcement of short fiber from ivy gourd stem and activated biocarbon from walnut shell are not only eco-friendly but also provide high strength properties, which could be applied in areas where better wear resistance, heat insulating, hydrophobic, and mechanical load bearing capacity are required.

Maize starch is hydrolysed using H₂SO₄ and the effects of varying acid concentrations (1M, 2M, 3M and 3.16M) on the morphological, thermal and structural properties of hydrolysed starch are studied. With the increasing acid concentration used for hydrolysis, crystallinity, anisotropy in the shape and non-uniformity in the size of hydrolysed starch particles increases. However, thermal stability, amylose content, and average molecular weight decreases. Acid hydrolysis leads to the formation of hydroxyl group in the starch molecule. Hydrolysis increases the size range of starch particles, by creating small particles due to disintegration and larger particles due to agglomeration. Starch hydrolysed using 2M acid concentration shows quite different behaviour, where thermal stability remains same as native starch, crystallinity decreases, and highest number of hydroxyl groups are formed as compared to other acid concentrations. From this study it becomes evident that 2M acid concentration is best for hydrolysis of starch, as it leads to maximum functionalization. This study focuses on preparing functionalized starch having maximum functionality which is suitable as filler in making bio-composites.

Antibiotics are typically administered via direct injection into the body. However, maintaining a stable drug concentration is challenging, leading to reduced bioavailability and potential toxic side effects due to improper concentration control. To address this issue, this study designed a controlled antibiotic release system based on thiolated beta-cyclodextrin crosslinked complexes, using levofloxacin as a model drug. First, beta-cyclodextrin was thiolated and then crosslinked via click reactions between thiol and alkene groups. The resulting crosslinked beta-cyclodextrin efficiently encapsulated levofloxacin through its hydrophobic structure. This system is regulated by a specific physiological stimulus—glutathione (GSH)—which triggers the dynamic disulfide-thiol exchange, leading to the dissociation of the crosslinked structure of beta-cyclodextrin and the controlled release of levofloxacin, enabling on-demand drug delivery. The formation of crosslinked beta-cyclodextrin was characterized using NMR, FTIR, SEM and DLS. Drug release experiments demonstrated that the crosslinked beta-cyclodextrin exhibited excellent GSH-responsive release characteristics. Cytotoxicity assays confirmed the good biocompatibility of the system, while antibacterial tests further validated that GSH stimulation significantly enhanced the antibacterial efficacy of levofloxacin-loaded crosslinked beta-cyclodextrin. This study developed GSH-responsive crosslinked beta-cyclodextrin drug carrier, providing a novel strategy for the controlled release of antibiotics, with the potential to enhance therapeutic efficacy and achieve on-demand drug administration.

The increasing demand for sustainable materials has driven extensive research into renewable, sustainable, and biobased resins as alternatives to conventional petroleum-based resins. This review comprehensively explores the synthesis, properties, and applications of resins derived from renewable sources such as lignin, cardanol, eugenol, vanillin, and vegetable oils. This review critically consolidates recent advances in chemo-enzymatic epoxidation, process intensification strategies and green catalytic systems, where reported studies frequently achieve > 85–95% epoxidation conversion under milder reaction conditions and substantially reduced auxiliary chemical demand relative to conventional petrochemical routes. Furthermore, this review systematically links these technological developments with quantifiable sustainability assessment frameworks, including life cycle assessment (LCA), biogenic carbon accounting, carbon footprint. This work also identifies key research gaps, performance–sustainability trade-offs, and industrial translation barriers. The review therefore provides an evidence-grounded synthesis of current methodologies and outlines critical directions needed to advance scalable, low-carbon, renewable resin systems for polymer and coating applications.

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Curing is one of the critical steps for preparing polymer-derived SiCN ceramic fibers, as it prevents the deformation and melting of polysilazane (PSZ) precursor fibers under high temperatures. Therefore, the development of an efficient curing method is essential. In previous work, the pyrolysis behavior of iodine vapor cured PSZ fibers has been reported. This work focused on iodine vapor curing process of PSZ fibers. To reveal the iodine curing mechanism of the PSZ fibers, SEM, electronic single fiber strength meter, FT-IR, XPS, and TGA were utilized. The result showed that the Si-H and N-H bonds in the PSZ fibers reacted with iodine and oxygen to form N-I bonds, Si-O-Si, and Si-O-C bridge structures during the curing process, which contributed to the curing of PSZ fibers. The obtained SiCN fibers exhibited a deformed and hollow morphology, along with a relatively low tensile strength when PSZ fibers were exposed to iodine vapor and air for shorter durations (0.5 to 2 h). In contrast, the SiCN ceramic fibers demonstrated a dense structure when the curing time was extended to 3 h. The work provides a guide for the curing of polymer derived ceramic fibers, which is different from air curing or electron beam irradiation curing.

Glycopolymers are essential biomaterials that include carbohydrate moieties in their polymer structure enabling specific interaction with cells, proteins, and microbes. The most recent advances in glycopolymer studies have shifted away from broad-based exploration synthesis toward one of controlled, mechanism-directed design with precisely defined molecular weight and sugar functionalities. The structural control facilitate multivalent binding to carbohydrate binding proteins enhancing the binding affinity and cell agglutination. Literature studies have shown that precision radical polymerisation can form chains with dispersities of less than 10% and highly predictable sugar loading during the formation of glycopolymer coatings on implantable biosensors. The article demonstrates that chain architecture modulation contributes to protein-polymer affinity with multivalent displays capable of eliciting binding affinities of up to 50-fold the affinities of monovalent analogues. The integration of bioactive carbohydrate motifs can be incorporated in a quicker manner by post-polymer modification strategies, specifically by copper-free click reactions, without damaging polymer integrity. This review summarizes recent advances in glycopolymer synthesis with focus on radical polymerization methods and post polymerization modifications that enable precise control of polymer architecture and functions. Such developments have resulted in tangible biomedical outcomes such as more tissue-compatible adhesives with greater wet-surface adhesion, glycopolymer scaffolds with high cell-binding affinity, and sensor interfaces with the ability to detect pathogen-associated lectins at clinically-relevant concentrations. The review indicates that molecular-level quantitative control is increasingly defining the next stage of glycopolymer use in diagnostics, as well as regenerative materials.

A convenient statistical approach is presented to derive the molecular parameters of hyperbranched polymers made by (:{text{A}text{B}}_{g}) monomers and (:{text{C}}_{f}) cores. Using statistical methods, explicit expressions for the average number of subchains with definite monomer sequences on the polymer skeleton are provided. General theoretical correlations between the subchains and molecular parameters, including the average molecular weight, the mean-square radius of gyration, and the particle scattering factor, are established. Utilizing the average number of subchains, explicit expressions for the molecular parameters of hyperbranched polymers are obtained. As an application, the characteristics of the average molecular weight, the z-average mean-square radius of gyration and the z-average particle scattering factor were examined under various conditions. The results demonstrate that related factors such as monomer mass, reactivity parameter, and functionality have significant impacts on the molecular and conformational characteristics of hyperbranched polymers.

Carbon nanotubes (CNTs), particularly when surface-functionalized, are highly effective reinforcements for natural rubber/ethylene-propylene-diene monomer (NR–EPDM) composites, enhancing both mechanical strength and swelling resistance. In this study, unmodified CNTs and CNTs functionalized with 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI) and bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) were incorporated into the NR–EPDM matrix at loadings up to 8 parts per hundred rubber (phr) using conventional melt mixing. The curing characteristics were analyzed using an oscillating disc rheometer, and detailed evaluations of mechanical, swelling, and compression properties were performed. Unmodified CNTs increased cure torque and reduced cure time, resulting in improvements in tensile strength, 100% modulus, and tear strength by 25%, 26%, and 22%, respectively, with optimum performance at 5 phr. However, higher filler loadings caused CNT agglomeration, which reduced the tensile strength and modulus. Composites containing BMI-functionalized CNTs exhibited superior reinforcement, achieving maximum increases of 39% in tensile strength and 44% in modulus at 5 phr, while tear strength improved by 29% compared to the unfilled blend. Composites reinforced with TESPT-functionalized CNTs showed the most significant enhancements, with tensile strength, modulus, and tear strength increasing by 52%, 56%, and 37%, respectively. These composites also displayed moderate reductions in elongation at break and rebound resilience. TESPT modification provided excellent swelling resistance, with peak performance observed at 5 phr, followed by a slight decline at higher filler concentrations due to filler clustering. Overall, TESPT-functionalized CNTs achieved better dispersion and stronger interfacial bonding within the NR–EPDM matrix, leading to remarkable improvements in mechanical integrity, crosslink density, and solvent resistance.