Advances in Polymer Technology最新文献

In this work, the impact of using grafted hair as reinforcing agent for making composites has been studied and compared with composites using virgin hair. For this purpose, the composites have been prepared via compression molding using a thermoplastic resin, poly(methyl methacrylate) (PMMA), as matrix, and virgin or grafted human hair (HH), HH_act-g-PMMA_1.75, and HH_act-g-PMMA_2, with 56% and 78% of grafting percentages, respectively, were taken as reinforcement material, and their properties have been compared. The hair weight fractions in composites were varied from 15% to 60%. The SEM micrographs of the fractured surface of the tensile specimen of virgin HH-reinforced PMMA composites show hair pullouts. In contrast, in graft copolymer-reinforced PMMA composites, failure mainly occurs at the hair and not at the hair–matrix interface, showing better adhesion. This was supported by AFM images in which a decrease in surface roughness for grafted hair-reinforced composites was observed. The PMMA composites with grafted hairs showed improved mechanical properties than PMMA in contrast to composites with virgin hairs in which there was loss of tensile strength. On addition of 15% of HH_act-g-PMMA_1.75, the tensile strength raised by 21.86%, while in the case of HHact-g-PMMA_2 graft copolymer, the tensile strength was increased by 87.44% w.r.t virgin HH. The hair content up to 45% showed improvement in mechanical properties; however, further increase in hair content leads to a decrease in the mechanical strength. Dynamic analysis also showed an increase in storage (E′) and loss modulus (E′′), enhanced with the increase in hair concentration and reached the maximum for the 55:45::PMMA:hair ratio. The increase in E′ and E′′ was more when grafted hairs were used as the reinforcing agents. As compared to composites with virgin HH, an increase of 57–98% for E′ and 46–80% for E′′ was observed for composites with HH_act-g-PMMA_1.75. Similarly, for HH_act-g-PMMA_2 hairs, an increase of 49–102% in E′ and 45–98% for E′′ was observed. The present work thus shows that the use of grafted hairs results in the enhancement of adhesion of hair and matrix resulting in the improved properties.

Polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) blends with no compatibilizers have been manufactured commercially and widely used for many applications for many years. Although most studies have shown that compatibilizers can improve the product performance of PC/ABS alloys, there are still different scholars who have demonstrated that compatibilizers do not have the expected effect. This study investigated the effects of various types of compatibilizers on properties such as the impact strength of PC/ABS alloys. To make rubber particles better mixed and achieve fine dispersion, a closed torque rheometer was used to make PC/ABS alloys. To avoid the influence of flow orientation on rubber particle dispersion during injection molding, test specimens were prepared using the mold pressing method. PC-rich alloys with no compatibilizer show the best performance in all trial samples. Maleic anhydride grafted ABS (ABS-g-MAH), synthesized by emulsion polymerization, could not enhance properties significantly as a compatibilizer. Methyl methacrylate–butadiene–styrene (MBS), which has the same rubber content as ABS powder, could not improve performance either. Sufficient rubbers well-dispersed in styrene/acrylonitrile (SAN) and PC content are key factors in influencing the performance in PC-rich blends.

Crosslinking agarose with bisoxiranes and epihalohydrins has been explored for years and is widely applied in the manufacturing of chromatography beads as industrial standard. Nevertheless, the effect on the molecular structure of agarose and the resulting consequences when used as chromatographic adsorber are poorly investigated. Agarose beads modified with 1,4-butanediol diglycidyl ether (BDDE) and epichlorohydrin (ECH), respectively, were characterized regarding their pore size and diffusion coefficients. Modification with BDDE led to reduced pore sizes, whereas no influence could be observed when using ECH. After functionalization as cation exchanger, BDDE- and ECH-modified beads were analyzed among others regarding their binding capacity of lysozyme and γ-globulin. Therefore, the hypothesis of crosslinking-induced diffusion limitation, especially with BDDE, could be further strengthened. Finally, the data were described by calculating the static binding capacity and diffusion coefficient using a cubic grid model and Ogston model, respectively. Overall, those simplified models describe the data quite accurate, whereas the deviation of the model from the static binding capacity is 4% ± 17%, from the diffusion coefficient of the BDDE- or ECH-modified beads 1% ± 16% and from the effective diffusion coefficient of the further sulfonated and column packed beads 11% ± 27%.

This work presents a novel semiempirical mathematical approach consisting of a coupled thermo-kinetic model as valuable tool for predicting the polymeric fraction profile of membranes synthesized by nonsolvent induced phase separation (NIPS). Equilibrium binodal curves (BCs) of the system component were incorporated to the Fick’s diffusive kinetic model allowing a satisfactory prediction of the tendency to develop symmetric or asymmetric porous membrane morphologies, as well as a fair quantification of average porous fraction profiles. The model was validated using two different ternary systems: (i) polycaprolactone (PCL)/N-methylpyrrolidone (NMP)/water (W) characteristic of instantaneous demixing (asymmetric finger-like porous cross-section morphology); and (ii) PCL/NMP/isopropanol (IPA) characteristic of delayed demixing (symmetric sponge-like cross-section morphology). The loading of graphene oxide (GO) in the quaternary system PCL/GO/NMP/IPA also gave rise to a sponge-like porosity, characteristic of delayed demixing systems, which was reasonably predicted by the coupled thermo-kinetic model developed in this study. In addition, a computational scanning electron microscopy (SEM) image processing methodology was developed to validate the thermo-kinetic model, resulting in an advantageous tool for that purpose. Overall, this work reveals the usefulness of the new thermo-kinetic mathematical approach as a facile computational tool for membrane manufacturers and researchers for a preliminary discrimination of component combinations in quaternary polymer/nanofiller/solvent/nonsolvent NIPS systems.

In this study, we investigated the process of obtaining dialdehyde carboxymethylcellulose (DCMC) with a high molecular mass and aldehyde content (AC) through periodate oxidation under microwave irradiation. We examined the effects of periodate oxidation time, sodium periodate (NaIO₄) concentration, and pH value of the solution under microwave treatment on the molecular mass, aldehyde group content, and yield of DCMC. Optimal conditions for the periodate oxidation reaction under microwave irradiation (microwave power level set at 10% or 70 W) were identified as follows: a reaction time of 10 min, oxidant concentration of 2.5% (with a molar ratio of carboxymethylcellulose to NaIO₄ of 1:1), and pH of 3.5. Under these conditions, the oxidation degree of DCMC obtained by microwave treatment was 82%, with a molecular mass of 141 kDa, a polydispersity of 1.4%, and a product yield of 70%. The obtained samples were analyzed using a variety of methods including chemical analysis, FTIR spectroscopy, thermogravimetric analysis, atomic force microscope (AFM), and nuclear magnetic resonance (NMR) spectroscopy.

This article presents a review of achievements in the research aimed at improving the main building material—concrete—along with its physical, mechanical, and operational properties. As is well known, in the near future, the role of concrete will continue to be primary in the construction of buildings and structures due to increasing demand. However, despite its advantages, this important building material is not without flaws. In particular, due to its porosity, concrete is highly permeable to liquids, making it insufficiently resistant to frost and corrosion and sometimes even brittle. At the same time, concrete mixtures used in modern construction must meet requirements such as good adhesive properties, improved waterproofing, high workability, retention of rheological characteristics over time, and the potential for increased strength. Today, the use of polymer additives as modifiers to improving concrete is particularly relevant. The purpose of this review is to examine recent advances in understanding the impact of polymer additives of both inorganic and organic nature on improving concrete properties. Continued research in the field of polymer modifiers and exploration of new research opportunities are for engineering advancements and the development of modern materials.

With a deeper understanding of the aging process, injectable dermal fillers have revolutionized cosmetic dermatology and plastic surgery. These minimally invasive treatments address signs of aging, such as wrinkles, fine lines, and volume loss. The market for injectable dermal fillers expands yearly, with each product offering unique compositions that influence therapeutic outcomes, handling properties, and potential adverse effects. Fillers are generally classified into three major types: temporary, semi-permanent, and permanent. Temporary fillers, including hyaluronic acid (HA) and collagen (COL)-based options, provide reliable correction but typically have limited longevity. Semi-permanent and permanent fillers, made from synthetic materials like poly-L-lactic acid and polymethylmethacrylate (PMMA), offer extended durations of neocollagenesis. This review focuses specifically on COL-based fillers, discussing both FDA-approved products and those still in the research stage.

Polybenzoxazole (PBO) paper, made of PBO chopped fibers and PBO fibrids, is used in many cutting-edge fields because of its excellent properties. The rigid molecular structure makes PBO only dissolved in strong acids such as fuming sulfuric acid and polyphosphoric acid at a very high temperature. Due to the harsh preparation conditions, it is not easy to industrialize PBO fibrids. Herein, a two-step method was used to prepare the PBO paper. Firstly, polyhydroxyamide (PHA) was synthesized in an organic solvent and used to prepare fibrids, and the PHA paper was then prepared using PHA fibrids with a traditional wet papermaking process, and the obtained PHA paper was further converted into PBO paper by thermal cyclization. The results show that the PHA fibrids have a high length–diameter ratio, film shape, and abundant hair structure, and the tensile index of the PHA base paper is as high as 123.3 N·m/g. After thermal cyclization, the structure and morphology of the paper have little change, and the mechanical properties of the paper have a certain loss. However, it is still much higher than that of PBO paper prepared directly from PBO fibrids and has excellent thermal stability, so it is suitable for preparing high-temperature-resistant paper-based composites.

The findings suggest that rolling is a potentially effective technique for commercial applications in industries requiring high-performance polymer films. The solid-state rolling process is well-established for semicrystalline and amorphous polymers, but its application to segmented, two-phase polymers like thermoplastic polyurethane (TPU) which features physically cross-linked systems and excellent physical and mechanical properties, remains underexplored. This study aims to investigate the rolling of TPU under various conditions to address viscous relaxation and achieve maximum thickness reduction, producing thin sheets. The rolling characteristics were assessed by measuring the thickness changes of rolled specimens of two TPUs with different hard phase fractions, alongside thermoset polyurethane (PUR) with chemical cross-linking for comparative analysis. The results showed that the TPUs exhibited little plastic deformation at room temperature. The cold rolling test, conducted at a rolling speed of 0.5 m min⁻¹ with a nominal reduction of 85%, indicated that the permanent reduction ratio was less than 35% for both TPUs. However, when the rolling speed was increased to 3 m min⁻¹, the permanent reduction ratio increased to 67% and 60% for TPU ShA90 and TPU ShA85, respectively. This result indicates that at high rolling speeds, the thermal condition tends to change from isotherm to adiabatic in the rolling test. The maximum reduction ratio of 70% was achieved at a nominal reduction of 85% for TPU ShA90 at higher rolling temperatures and speeds.

In recent years, the drive to adopt sustainable practices and develop eco-friendly processes and products has gained significant momentum in the global polymer industry. A key component of this shift is the increased use of recycled materials, which not only align with environmental goals, but also offer considerable economic advantages. Integrating post-consumer recyclates (PCRs) into manufacturing processes, particularly in injection moulding, holds great potential for reducing CO₂ emissions, decreasing reliance on virgin materials, mitigating waste and promoting a circular economy. Nevertheless, a switch to 100% recyclate has not yet been effective or economical in many areas of application, so mixtures of virgin and recyclate material represent a promising approach and must be analysed further. Therefore, this study examines the impact of different virgin/recyclate-mixture ratios on both injection moulding process stability and resulting part quality, focusing on high-density polyethylene (HDPE) and polypropylene (PP) blends. For this purpose, virgin/PCR mixtures are compounded, rheologically analysed using high-pressure capillary rheometry and processed via injection moulding. The process data are analysed, and the produced parts are mechanically and geometrically evaluated. The findings show that for PP, an increasing recyclate content results in a nearly linear improvement in tensile strength and modulus of elasticity without significantly affecting material viscosity, ensuring stable processing conditions. However, part warpage increases with higher recyclate content. In contrast, for HDPE, a higher recyclate content decreases the mixture viscosity, leading to decreased injection pressure and dosing torque during processing. Despite this, the tensile strength and modulus of elasticity improve, while part warpage decreases for HDPE. For both materials, though tensile strength and elasticity increase, higher recyclate contents negatively affect fracture behaviour, as evidenced by breakage patterns and strain at break. The study also demonstrates that the linear mixing rule can be applied to process parameters and part geometry characteristics for virgin/recyclate mixtures, facilitating the integration of recyclate content into product development.