Advances in Polymer Technology最新文献

Chicken eggshells (ESs) consist of 96%–97% calcium carbonate, while about 3%–4% consists of organic substances, mainly in the form of protein-based membranes and occluded organic matter. Recently, ESs have been studied as a filler in polymer composite materials, which represents an innovative solution to address ES valorization. In this study, thermal and chemical treatments were investigated for membrane removal since the membrane may alter various properties when the ES fillers are added to the composite material. A nanoindentation method was used to measure changes in the ES mechanical properties. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier-transform infrared (FT-IR) spectroscopy were used to characterize the ES membrane removal through chemical treatment. The results showed that even at a heating temperature of 100°C, the ES mechanical properties were negatively affected, while a low concentration of bleach solution (25% bleach solution and 10 min of holding time) was able to remove the membrane without reducing the ES mechanical properties. The chemical treatment method offers a means for ES membrane removal while conserving the quality of the mineral fraction (calcite; CaCO₃).

To achieve sustainable and energy-efficient CO₂ capture processes, it is imperative to develop membranes that possess both high CO₂ permeability and selectivity. One promising approach involves integrating high-aspect-ratio nanoscale fillers into polymer matrices. The high-aspect-ratio fillers increase surface area and improve interactions between polymer chains and gas molecules passing through the membrane. This study focuses on the integration of cellulose nanocrystals (CNCs) with an impressive aspect ratio of around 12 into rubbery polymers containing polyethylene oxide (PEO), namely PEBAX MH 1657 (poly[ether-block-amide] [PEBA]) and polyurethane (PU), to fabricate mixed-matrix membranes (MMMs). By exploiting the interfacial interactions between the polymer matrix and CNC nanofillers, combined with the surface functionalities of CNC nanofillers, the rapid and selective CO₂ transport is facilitated, even at low filler concentrations. This unique feature enables the development of thin-film composites (TFCs) with a selective layer around 1 μm. Notably, even at a filling ratio as low as 1 weight percent, the resulting membranes exhibit remarkable CO₂ permeability (>90 Barrer) and CO₂/N₂ selectivity (>70). These findings highlight the potential of integrating CNCs into rubbery polymers as a promising strategy for the design and fabrication of highly efficient CO₂ capture membranes.

Deep-sea equipment is generally made of lightweight and pressure-resistant materials in order to meet the requirements of the actual work. In order to explore marine resources better, it is necessary to research lightweight buoyancy materials for loading on mining equipment. These buoyancy materials contribute not only to providing adequate buoyancy to the mining equipment but also to reducing economic expenses. In this paper, hollow glass microspheres reinforced epoxy hollow spheres (HGMSs-EHSs) were prepared by the rolling ball method using expanded polystyrene (EPS), epoxy resin (EP), and HGMS as raw materials. Epoxy syntactic foam (ESF) was manufactured by blending EP, curing agent, HGMS, and HGMS-EHS with molding method. Basalt fiber (BF) reinforced ESF was fabricated by adding BFs to form a fiber network inside the syntactic foam. The results revealed that the density and compressive strength of ESF increased progressively with the number of HGMS-EHS layers. The density and compressive strength of ESF decreased prospectively with the increase of the stacking volume fraction of HGMS-EHS. The density and compressive strength of ESF increased gradually with the enlargement of the length and content of BF. In the range of influencing factors mentioned above, the density of ESF remains around 0.3 g/cm³, which has a low density. When the number of layers of HGMS-EHS was two, the stacking volume fraction was 90%, the length of BF was 12 mm, the content of BF was 4%, the density of BF-ESF was 0.316 g/cm³, and the compressive strength was 6.93 MPa. The compressive strength of prepared buoyancy material can meet the pressure resistance requirements for operations in waters of a certain depth. With a density of only 0.316 g/cm³, it provides sufficient buoyancy to balance the gravity of the equipment. Compared with the current study, in this paper, BFs were used as the reinforcing phase to prepare solid buoyancy foam with low density and high compressive strength. The experimental results demonstrate that this economical fiber material can effectively improve the compressive strength of buoyancy materials. This buoyancy material may be suitable for loading on small equipment for extracting marine resources. This work provides a reference for the preparation of low-density solid buoyancy materials.

Enhancing the hydrophobicity of chitosan through acylation enables the encapsulation of water-insoluble drugs within the polymeric carrier cores. In this study, hydrophobically modified chitosan was synthesized by reacting low-molecular-weight chitosan with acyl chloride (C18–C24) using an agitation method under mild conditions. The structure of acylated chitosan was analyzed using FTIR and ¹H-NMR spectroscopy. The degree of substitution (DS) varied between 56% and 69% for different long-chain N-acylated chitosan, with N-stearoyl chitosan (ChC18) exhibiting the highest DS. The incorporation of capecitabine (CAP) into extended acylated chitosan increased particle size and decreased zeta potential. N-lignoceroyl chitosan (ChC24) exhibited the highest zeta potential value of −27 mV for 0.2 mg of CAP, indicating that the most extended acyl group was the most stable in the suspension. Transmission electron microscope images revealed that all acylated chitosan particles were spherical, with sizes ranging from 100 to 200 nm, and existed as stand-alone entities, indicating excellent stability in suspension. The loading of CAP increased in particle size but did not alter particle shape, except for ChC24, which exhibited agglomeration. SEM images revealed that the individual arrangement of particles in CAP-ChC18 made it more stable than other acylated chitosan. In contrast, the formation of clusters in CAP-ChC24 can be attributed to strong hydrophobic interactions. X-ray photoelectron spectroscopy results show that there is no nitrogen atom in ChC18, which means that the acyl group is oriented inward and bound to the stearoyl group via van der Waals forces. At different drug weight-to-carrier ratios, the encapsulation efficiency (EE) of CAP with varying acyl group lengths ranged from 85% to 97%. The drug loading (DL) capacity and EE increased as the amount of drug in the carrier increased. However, the length of the acyl group did not significantly affect DL and EE, even when the carrier-to-drug ratio was consistently maintained. Sustained release was observed in CAP-loaded ChC24, indicating a significant influence of the extended chain on chitosan. Consequently, extended N-acylated chitosan possesses enormous potential as a drug delivery system for CAP.

Process parameter optimization and selection play a crucial role in additive manufacturing, particularly in determining the quality and characteristics of the final product. Among these parameters, the infill pattern holds significant importance as it directly influences the structural integrity, production time, and material usage efficiency of the printed object. This research focuses on identifying the most suitable 3D printing infill pattern process parameters for thermoplastic polyurethane (TPU) material, specifically for applications in pipeline construction. The criteria considered for process parameter selection include printing time, ultimate tensile strength, ultimate flexural strength, and surface defect minimization. Various infill patterns, including hexagonal, line, solid, triangle (35°), triangle (55°), and line patterns, are evaluated as alternatives. Utilizing the multi-criteria decision-making technique known as analytical hierarchy process (AHP), a systematic approach is employed to determine the optimal printing pattern. The findings of this study reveal that the hexagonal infill pattern outperforms other selected patterns in terms of meeting the criteria set forth for pipeline construction using TPU material. This research contributes to enhancing the efficiency and quality of additive manufacturing processes in pipeline applications, emphasizing the importance of informed parameter selection for achieving desired performance outcomes.

Since polymer nanocomposites provide a versatile method to improve safety and protection in various applications, they are essential in tackling the problem of microbial infections. These nanocomposites are designed to actively prevent the growth of bacteria by including antimicrobial agents such as functional groups or nanoparticles. In the present article, copper oxide nanoparticles were synthesized via the green method using the solution method. The grafting of N-ethyl piperazine (NEP) to polyvinyl chloride (PVC) polymer was carried out to obtain NEP–PVC polymer using solution polymerization technique and further reacted with CuO nanoparticles to obtain polymernanocomposite which was characterized using FTIR and ¹H-NMR, SEM, TEM, DLS, and XRD. The comparison in the antibacterial activity of nanocomposite and the synthesized polymer was carried out to determine its efficacy against Escherichia coli and Staphylococcus aureus using the spread plate method. Our findings indicate that NEP–PVC-based nanocomposite after incorporating copper oxide nanoparticles has enhanced the antibacterial properties over NEP–PVC polymer, henceforth a promising candidate to be used in medical devices, food packaging, and surface coatings.

The aim of this work is a synthesis of suitable hydrogel to produce slow-release fertilizer using recycled cellulose which is obtained from waste paper. For this purpose, initially, we extracted alpha cellulose from waste paper and modified it to obtain carboxymethyl cellulose (CMC). Then, the CMC was converted to a suitable hydrogel through in situ graft copolymerization of acrylic acid and vinyl acetate in the presence of methylene bisacrylamide as a crosslinker. The various factors that affect hydrogel synthesis, such as the amounts of CMC, monomers, initiator, and crosslinker, were evaluated. In the optimized formulation, the weight ratio of monomers to CMC is 7, the molar ratio of monomers to each other is 1, and the crosslinker is used as 3 molar percent of monomers. The products were characterized using Fourier transform infrared, thermal gravimetric analysis, and scanning electron microscope analyses. The swelling behavior of the synthesized hydrogels was evaluated in different environments, such as distilled water, tap water, salt water, and different pH levels. The swelling ratio increases with an increase in pH level. Between the synthesized hydrogels, the best one was selected for slow-release fertilizer production and loaded with 20-20-20 fertilizer (NPK), and the release behavior was evaluated. In an alkaline pH, there was a long time for NPK release within a slow-release medium and even after 361 h, the release process was continued. Also, the performance of the fertilizer-loaded hydrogel in soil using water holding capacity and water retention ratio tests were evaluated.

Due to cross-linked structures, thermoset polymers cannot provide sufficient free volume for nanofillers to maneuver. Related composites are therefore governed by phase separation where filler-deficit regions become mechanical weakness. This work discovers that carbon nanotubes can be redispersed in thermoset polymer through heat treatments, thus, enhancing strength, thermal, and electrical conductivity of composites. Experiments carried out on a different thermoset matrix gives a similar trend where heating induced tube displacement is also verified by molecular dynamic simulations and piezo-resistivity tests.

To improve the electrical conductivity, mechanical properties, and antibacterial properties of conventional hydrogels while simplifying their preparation steps for better application in wearable, flexible sensors and biomimetic electronic skins. Polyvinyl alcohol (PVA) hydrogels were doped with an ionic liquid based on zinc chloride to synthesize improved hydrogels using the freeze-thawing method. It is found that the addition of ionic liquid based on zinc chloride to the hydrogel resulted in a significant increase in electrical conductivity. However, an excessive amount of these liquids led to a reduction in their mechanical properties. The results reveal that the balance between conductivity and mechanical properties can be achieved by controlling the concentration of the ionic liquid based on zinc chloride. The higher the ionic liquid concentration based on zinc chloride in the composite hydrogels, the better the conductivity performance. The addition of an ionic liquid based on zinc chloride resulted in a significant improvement in the conductivity performance of the hydrogels. Furthermore, excellent mechanical properties are maintained even at a mass ratio of 1 : 10 between ionic liquids based on zinc chloride and PVA hydrogels, and composite hydrogels exhibit excellent antibacterial properties.

This study aims to convert cotton-based post-consumer textile waste to biodegradable paper, which not only addresses the discarding of waste but also provides a second use of cotton. The post-consumer garment made with cotton was decolorized by stripping with concentrated NaOH and hydrose. Afterwards, it was chopped, ground, and treated with NaOH solutions. The paper was prepared through a wet-laid process by mixing carboxymethyl cellulose as a binder with chopped cotton textiles. To reduce water absorbency, the uncoated paper was coated with thermoplastic polyurethane (TPU) using heat pressing technique. The surface morphology and chemical structure of uncoated pristine paper, coated paper, and TPU films were conducted using SEM and FTIR studies. The tensile strength, contact angle, air permeability, and biodegradability tests were investigated according to the standard methods. The tensile properties of the papers were increased after TPU coating, accounting well around 28% compared to the uncoated pristine paper. The elongation at the break of the coated paper was at least 40% greater than the uncoated pristine paper. The coated paper displayed a higher water contact angle of 100°, even after 10 min. The lower air permeability was observed in the coated paper due to TPU film blocking the free spaces of the paper. The TPU-coated paper exhibited a weight loss of 48.1%–59.8% after 90 days, whereas the uncoated paper was 100% decomposed after 60 days. The burning of post-consumer cotton textile waste (PCCTW) paper generated ashes resembling those of burning paper, implying clean and environmental friendly biodegradation. The papers can replace the petroleum–plastic materials and serve as food and other packaging applications.