To tackle dye‐related water pollution, developing cost‐effective adsorbents with high efficiency in removing residual dyes from wastewater is of vital importance. Herein, magnetic composite hydrogels designed for dye adsorption and recyclability is synthesized by combining polyvinyl alcohol (PVA), xanthan gum (XG), and iron (II, III) oxide (Fe 3 O 4 ) magnetic nanoparticles. The PVA/XG hydrogel matrix is fabricated via freeze–thaw technique, and the Fe 3 O 4 nanoparticles are generated in situ within the hydrogel network. The structural and functional characteristics of the PVA/XG/Fe 3 O 4 magnetic hydrogels are systematically investigated using swelling behavior, turbulence stability, thermogravimetric analysis, and scanning electron microscopy. The impacts of adsorbent dosage, initial concentration, and solution pH on adsorption properties are comprehensively evaluated. Furthermore, the adsorption mechanisms of congo red (CR) and methylene blue (MB) onto the hydrogel are elucidated via kinetics studies, isotherm modeling, thermodynamic analyses, and Fourier transform infrared characterization. The Langmuir adsorption isotherm models predicted maximum adsorption capacities of 364.70 and 409.19 mg g −1 for MB and CR, respectively. A novel PVA/XG/Fe 3 O 4 magnetic hydrogel is developed that addresses a critical challenge in water treatment: the cumbersome recovery of adsorbents. By integrating rapid magnetic separability with high adsorption capacity, this material provides an innovative and sustainable solution for environmental remediation.

Anthocyanins are widely explored for developing freshness indicators. However, their applications are often limited by low color sensitivity and inability to accurately identify the sub-fresh stage of foods. This study developed a novel smart packaging indicator using a Cu2+-complexed grape skin anthocyanin (GSA). The complexation significantly enhanced colorimetric accuracy within the critical pH 6-8 range, enabling distinct transitions from pink (pH = 6) to light purple (pH = 7) and deep purple (pH = 8). The indicator was fabricated by incorporating the Cu2+-GSA complex and tea polyphenol into an electrospun zein/pullulan-polyvinyl alcohol nanofiber membrane. When monitoring shrimp freshness at 4 degrees C, the indicator's color shift from purple to green accurately corresponded to the sub-fresh (TVB-N > 16.74 mg/100 g) and spoiled (TVB-N > 30 mg/100 g) stages, with RGB values falling below 73 and 55, respectively. The integrated tea polyphenol extended the shelf life of the shrimp by approximately one day. The indicator also effectively monitored poultry and beef spoilage, with an RGB threshold < 85 reliably signaling spoilage (TVB-N > 15 mg/100 g). The platform establishes a strong correlation between visual color parameters and key freshness indices, offering a reliable, real-time solution for monitoring protein-rich food quality.

The urgent necessity to create affordable adsorbents for the effective elimination of leftover contaminants from wastewater arises from the significant water pollution resulting from the excessive use of dyes. A novel chitosan (CS) /pullulan (PL) hydrogel, chemically cross-linked using polyethylene glycol diglycidyl ether (PEGDE), exhibited high swelling capacity, excellent mechanical stability, and superior adsorption performance. Adsorption tests indicated that CS/PL-2 hydrogel attained a 93.23

The integrity of polyethylene (PE) pipe joints is critical for ensuring the long-term reliability of pipeline systems. This study develops a method of using phased array ultrasonic testing (PAUT) technique to identify welding defects in the joints of PE pipes. PAUT allows signal focusing and steering at desired angles and can overcome the limitations of the conventional ultrasonic method. The research investigates how varying fusion times at a constant welding voltage of 39.5 V affect weld quality and mechanical performance of PE pipe joints. Key findings indicate that the heat-treated joints, placed in a drying oven, revealed clear melt fusion zone (MFZ) boundaries, with the distance from the melt zone to the heating wire closely matching the Eigen-line positions observed in the PAUT results. Cold-welded joints (100 s) exhibited narrow fusion zones (1.4 mm), while over-welded joints (300 s) showed excessively wide zones (5.2 mm). Outside the heat-affected MFZ could be considered another type of welding defect where crystallinity was significantly affected by welding time, decreasing from 67.53% to 57.26% in standard welding, from 61.4% to 55.59% in cold welding, and from 59.35% to 48.52% in over welding. In over-welded joints, excessive heating led to stress concentration, thermal oxidative degradation, chain scission, and the formation of blow hole defects that most severely impaired mechanical properties. Peel tests confirmed the mechanical integrity of standard-welded joints, with a maximum peeling force of 2828.52 N, compared to 1806.47 N in cold welding and 1360.76 N in over welding. SEM analysis revealed a uniform size and distribution of crazes in standard-welded joints, whereas defective joints exhibited irregular and sparsely distributed craze structures.

In response to significant water pollution stemming from dyes, it is crucial to develop affordable adsorbents capable of effectively removing leftover contaminants from wastewater. A novel hydrogel, made from polyvinyl alcohol (PVA) and xanthan gum (XG), exhibiting notable swelling characteristics and adsorption abilities toward methylene blue (MB) and congo red (CR), was produced using freeze-thaw cycling and freeze-drying techniques. The stability against turbulence of the porous composite hydrogel improved from 65.73 % to 84.8 % with the incorporation of graphene oxide (GO) into the PVA/XG-based framework. We discussed and analyzed the impact of the adsorbent dosage, initial dye concentration, aqueous solution temperature, pH value, and contact time on the adsorption capacity of the prepared hydrogel. The maximum adsorption capabilities, derived from the Langmuir isotherm, were measured as 289.31 mg/g for MB and 255.06 mg/g for CR. The thermodynamic analysis indicated the spontaneous nature of the dye adsorption process conducted in this study. In conclusion, the results indicated that the synthesized hydrogel may act as a potent adsorbent for the removal of dyes from water-based solutions.

In this study, polysaccharide-based nanofibrous fast dissolving oral films (FDOFs) were developed using pullulan (PUL) and xanthan gum (XG) via electrospinning. The edible, continuous, and bead-free nanofibers with average diameters ranging from 181.17 nm to 260.84 nm were prepared. The morphological, thermal, mechanical, and water-soluble properties of the nanofibrous FDOFs were characterized. For prospective future applications of the developed PUL/XG FDOFs, a model nutrient of vitamin C (VC) was encapsulated into the FDOFs. The success of VC encapsulation was confirmed by Fourier transform infrared spectroscopy. The encapsulation efficiency of VC was above 85% by ultraviolet-visible spectrophotometer. The amorphous structure of PUL/XG in the nanofibers film was demonstrated by X-ray diffractometer. In addition, the edible FDOFs could dissolve in water within 3 s. The nanofibers film we prepared could be used as nutrient or drug carriers and edible packaging film.

In this work, porous poly (vinyl alcohol) (PVA) hydrogels with different pore sizes were fabricated using inorganic non-metallic porogens by an environmentally friendly method, providing a potential solution for the field of wastewater treatment. PVA hydrogels have gained much attention in the field of wastewater treatment due to their excellent adsorption performance and porous network structure. However, the employment of inorganic non-metallic salts as porogens for PVA hydrogels has received limited attention so far. In this study, porous PVA hydrogels were prepared by freeze-thawing and freeze-drying with sodium sulfate (Na2SO4) and calcium carbonate (CaCO3) as porogens. PVA-Na exhibited denser network structure with the concentration of Na2SO4 solution increased, and the tensile stress was enhanced by about 45 times. Meanwhile, the tensile stress of PVA-Ca was improved significantly from 0.06 to 1.67 MPa, and the network structure became looser after adding CaCO3. Moreover, a comprehensive investigation was conducted on the adsorption performance of porous PVA hydrogel for Congo red (CR). Finally, five adsorption models were fitted to investigate the adsorption mechanism of porous PVA hydrogels, in which the maximum adsorption capacity of CR by PVA-Na-0.5 was predicted to be 215 mg/g by the Langmuir isothermal model fitting.

New technologies in polymer synthesis and pipe extrusion equipment have led to the commercialization of high-performance, large-diameter, thick-wall high density polyethylene (HDPE) pipes. They have been used in the field of seawater transport and cooling to replace metal pipes, due to their advantages of high corrosion resistance and extensibility. Connection of HDPE pipe is important as it determines the safety of the entire piping system. Butt fusion welding is commonly used for HDPE pipe connection but may cause the formation of weak points in the welded joints, interfering the reliability of the pipeline system in the application of nuclear power plants. At present, there is a lack of research on evaluating the performance of welded joint for large-diameter thick-wall HDPE pipes made by butt fusion-welding. The purpose of this study is to investigate the influence of three different butt fusion-welding processes, i.e., single low pressure (SLP), single high pressure (SHP) and dual low pressure (DLP), by evaluating the performance of their welded joints, including characterizing tensile strength, extensibility, crystallinity and hardness. In specific, a thick-wall HDPE pipe with OD of 812.8mm and wall thickness of 74mm which is certified for nuclear safety class was used for study. Representative specimen from the outer, middle and inner part across the wall of the main pipe body and welded joints were taken for testing. Different test methods and specimens were designed to assess the feasibility of evaluating the welding performance from different welding process. The results showed that the mechanical properties of different locations of the welded joints were different, and the tensile strength and fracture energy of the middle part of the joint were lower than that of the inner and outer parts, which could be caused by the difference in the crystallinity and thickness of the melting zone influenced by welding processes, as can be seen from the analysis of DSC test and morphology observation. Hardness testing was conducted on the section of the welded joints, and it revealed that the micromechanical properties of the welded joints in the region of the heat-affected zone were enhanced significantly, which may be due to the annealing effect caused by welding process. In summary, The DLP process resulted in the best extensibility of the welded joints among three processes, suggesting that the joining pressure from welding process plays an important role in affecting the extensibility of the welded joints.

Strawberries are a kind of nutritious fruit but they are easily spoilt by mold. Therefore, it is significant to prolong the shelf life of strawberries for the avoidance of their numerous wastes. To achieve the aforementioned objective, in this paper, the edible and biodegradable natural polymers of gelatin/zein were used to prepare the antibacterial fiber films loaded with cinnamaldehyde by electrospinning method. The fibers prepared in this study were smooth and bead-free, with the average diameters ranging from 1.46 to 2.02 μm. The successful encapsulation of cinnamaldehyde in obtained fiber films was confirmed by Fourier transform infrared spectra. The prepared fiber films decomposing at about 230 °C were shown by thermogravimetric analysis curves, indicating their high thermal stability. The amorphous structure of the polymers in the produced fiber films was displayed by X-ray diffraction curves. Compared with the untreated strawberries, strawberries treated with fiber films encapsulated with 15 wt.% and 20 wt.% cinnamaldehyde showed the smallest changes in appearance, weight loss rate, hardness, pH, and total soluble solids at 6 d. The shelf life of strawberries was increased to 6 days by the fiber films containing 15 wt.% and 20 wt.% cinnamaldehyde. The fiber films prepared in this study were potentially expected to be used as edible antibacterial packaging films, nutrient and drug carriers.

Faced with extensive water pollution caused by dyes and heavy metals, it is imperative to create cost-effective adsorbents that can effectively eliminate residual pollutants in wastewater. The synthesis of polyvinyl alcohol/xanthan gum (PVA/XG) hydrogels involved a combination of freeze-thaw cycling technique and the adsorption characteristics and mechanisms of methylene blue (MB) and heavy metal ions Pb 2 + were investigated. In comparison to pure PVA hydrogels, the swelling behavior of PVA/XG3 hydrogel exhibited a 185 % increase in swelling rate. The adsorption test results suggested that PVA/XG3 hydrogel was effective in absorbing MB (27.39 mg/g) and Pb 2 + (17.07 mg/g) from a 50 mg/L pollutant solution. The adsorption process of MB and Pb 2 + by PVA/XG3 hydrogel followed Langmuir adsorption isotherm and the QFO models, indicating a preference for homogeneous physical adsorption. Specifically, the Langmuir isothermal model predicted that the q max of MB and Pb 2 + by PVA/XG3 hydrogel were 94.47 and 58.50 mg/g, respectively. Therefore, this essay has created a cost-effective and environmentally friendly method for producing versatile PVA/XG hydrogels specifically intended for water treatment purposes.

通过熔融共混法在聚乙烯中加炭黑,模拟制备管道用聚乙烯/炭黑复合材料.采用了不同的焊接条件包括单程序焊接和多程序焊接进行复合材料的焊接,并对焊接性能、焊接管道的力学性能、结晶性能、微观形态进行了研究.结果表明,复合材料的制备工艺流程中挤出机的加工温度应避免超过240℃以上,且螺杆转速不超过40 r/min时能够有效避免管道制备过程产生炭黑分散不均匀以及气泡的缺陷;焊接过程中,单段式程序焊接过程中会出现实验末期温度急剧上升的情况,而多段式焊接程序能够使熔区温度保持在一个相对稳定的温度区间,对焊接试样进行拉伸剥离实验可知,多段式焊接程序的焊接性能要优于单段式焊接程序.

In order to overcome the environmental problems posed by traditional packaging materials and taking into account the degradation factors, a natural polypeptides-based nanofiber rich in different polyphenols was prepared by electrospinning technique and has been explored as an active food packaging material. The results showed that the introduction of polyphenols improved the hydrophobicity and oxidation resistance of the natural polypeptides based nanofabric. The antioxidant value was 82.5% after incorporation of 15% gallic acid, which was ten times more than that of the natural polypeptides-based nanofabrics without polyphenols. Through the packaging test of wrapped cherries, it was found that the nanofabric films greatly improved the preservation performance of cherries. Water loss, hardness and gas release were significantly enhanced when compared with those of unwrapped cherries. In this work, the zein/gelatin film with 15% gallic acid or 10% procyanidins polyphenols exhibited the best fresh-keeping performance and remarkable effect thus leading to potential application aspect.

Confronted with severe water contamination induced by organic pollutants, developing low-cost adsorbents with high removal efficiency is a crucial approach to addressing the issue of residual organic pollutants in wastewater. This study prepared polyvinyl alcohol/porous carbon (PVA/C) hydrogels using freeze-thaw cycles and freeze-drying processes. And the adsorption behaviors were investigated with organic pollutants including congo red (CR), ibuprofen and doxycycline hydrochloride (DOX). Compared with pure PVA hydrogels, tensile test showed that PVA/coconut shell carbon hydrogel with a mass ratio of 10:2 (PCS2) had an increase of 285.78% in tensile stress. Through the adsorption experiment, PCS2 hydrogel demonstrated a good adsorption capacity for CR (27.39 mg/g), ibuprofen (15.48 mg/g), and DOX (17.07 mg/g). Furthermore, the adsorption mechanism of three organic pollutants by PCS2 hydrogel consistent with quasi-first-order kinetic and Freundlich adsorption isotherm model, indicating its adsorption process was dominated by multilayer physical adsorption. Therefore, this paper built a green, convenient, and economic method to prepare environmentally friendly and multifunctional PVA hydrogels for water purification.

Although polyvinyl alcohol (PVA) membranes are commonly used for CO2 separation, there is still large development space in mechanical properties and high selectivity of the gas separation process. In this study, the gas separation performance and mechanical properties of the (PVA/Cu2+) substrate membranes were improved by introducing polyamidoamine (PAMAM). PAMAM had an important effect on the gas adsorption and separation performance of the membrane. In addition, the gas adsorption and separation properties of the PVA/Cu2+/PAMAM membrane (PPCm) were analyzed and studied when the inlet gas pressure and the species of mixed gases were variable. The results showed that the crystallinity and mechanical properties of the membrane with the PAMAM had been significantly improved. Young's modulus of PPCm with 30% PAMAM was 132% higher than that of the PVA/Cu2+ composite membrane without PAMAM. In addition, efficient separation efficiency and high selectivity of the gas separation process were observed. The separation factors of the PPCm for CO2/H-2 and CO2/N-2 were about three times higher than that of the PVA/Cu2+ substrate membranes. These results suggested that the introduction of PAMAM was promising for CO2 separation and permeance.

Although polyvinyl alcohol (PVA) membranes are commonly used for CO 2 separation, there is still large development space in mechanical properties and high selectivity of the gas separation process. In this study, the gas separation performance and mechanical properties of the (PVA/Cu 2+ ) substrate membranes were improved by introducing polyamidoamine (PAMAM). PAMAM had an important effect on the gas adsorption and separation performance of the membrane. In addition, the gas adsorption and separation properties of the PVA/Cu 2+ /PAMAM membrane (PPCm) were analyzed and studied when the inlet gas pressure and the species of mixed gases were variable. The results showed that the crystallinity and mechanical properties of the membrane with the PAMAM had been significantly improved. Young’s modulus of PPCm with 30% PAMAM was 132% higher than that of the PVA/Cu 2+ composite membrane without PAMAM. In addition, efficient separation efficiency and high selectivity of the gas separation process were observed. The separation factors of the PPCm for CO 2 /H 2 and CO 2 /N 2 were about three times higher than that of the PVA/Cu 2+ substrate membranes. These results suggested that the introduction of PAMAM was promising for CO 2 separation and permeance.

采用黏合性聚烯烃AMDER与结晶改善型无规共聚聚丙烯(PP-RCT)熔融共混制备AMDER/PP-RCT增黏改性聚丙烯,增强PP-RCT与聚乙烯醇(PVA)的热熔黏合性.研究AMDER对PP-RCT的热性能、流动性、塑化性能、力学性能以及与聚乙烯醇热熔黏合性能的影响.研究表明,AMDER的引入有效降低了PP-RCT的塑化时间和平衡扭矩,促使PP-RCT的流动性增加,同时结晶温度与结晶度基本不变.将AMDER/PP-RCT增黏改性聚丙烯与甘油塑化PVA进行3层共挤,制备AMDER/PP-RCT与PVA的3层复合材料.通过剥离强度测试,在AMDER/PP-RCT增黏改性聚丙烯中AMDER质量分数增加至20％以及上时,AMDER/PP-RCT与PVA两相间的剥离强度显著增加,当AMDER质量分数量达到33％时,剥离强度达0.3 N/(15 mm).

In this work, red phosphorus (RP) grafted graphene oxide (GO) was generated inside polyimide foam (PIFs) matrices using a novel method. Definite chemical interaction between RP and GO was confirmed. The RP grafted GO (GO-RP) as a beneficial additive greatly improved the mechanical, thermal and flame resistance properties of the PIFs. Scanning electron microscopy (SEM) revealed the cell size of PIFs/GO-RP minished and homogenized when compared to the pristine PIF. The mean cell diameter decreased to 0.29 mm from 0.38 mm and the open cell content was reduced by 4%. The specific strength increased greatly after adding GO-RP, from 2.14 x 10(3) N.m/kg to 2.48 x 10(3) N.m/kg. Besides, the pyrolysis temperature of PIFs/GO-RP shifted to a higher value and the carbon residue increased at 800 degrees C, indicating excellent thermal properties. The flame resistance property of foams significantly enhanced while the peak heat release rate (PHRR) was reduced by 66% compared to that of the pristine foams. The craft of PIFs/GO-RP presented here has greatly provided an potential value in the design of materials.

Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to study the effect of talc on the crystallization properties and morphology of PVA/talc composite films from the perspective of heterogeneous nucleation effect. The Mo Zhishen equation and Avrami equation were used to study the crystallization kinetics behavior, and successive self-nucleation annealing (SSA) method was used to analyze the wafer thickness at various melting temperatures. PVA films were prepared by flow-casting method, and talc was added as inorganic nucleating agent to improve the crystallinity of PVA. The results show that the addition of talc to the PVA film promotes its crystallization, and as the content of the nucleating agent increases, the crystallinity tends to increase. Due to the increase of nucleation point, the proportion of thinner wafers increases, and the gap of wafer thickness becomes smaller, and the wafer thickness becomes uniform. These results show that talc regulates the crystallization of PVA, improves the crystallinity and crystallization rate of PVA. Talc has heterogeneous nucleation effect on PVA films.

Zein as a natural protein had been widely used in various fields due to its biodegradability and biocompatibility. However, its sensitivity to humidity and poor mechanical performance limited its application in practice. In this study, zein-based composite nanofibers loaded with curcumin were prepared by electrospinning assisted with polyvinyl alcohol (PVA). The filtration efficiency of the modified nanofibers to the particles with diameters larger than 0.5 μm was all above 98%. The loaded curcumin interacted with protein molecular chains to form a network structure within tightly connected nanofibers, which exhibited excellent moisture resistance and good adhesion to cellulose paper towels used as air filter substrates. Meanwhile, its tensile strength had also been enhanced vastly to 0.72 MPa compared with the initial tensile strength of 0.21 MPa. This study provides a new electrospinning strategy for the preparation of zein-based composite nanofibers that can be widely utilized in air filtration with high moisture resistance.

Slow crack growth (SCG) is the principal factor for determining the operating lifetime of polyethylene (PE) pipes. Exploring the relationship between the molecular structure and the strain hardening (SH) modulus is helpful to evaluate the SCG resistance of PE pipe materials accurately. This paper uses an efficient SH test method to study the SH modulus for four kinds of PE pipes. Meanwhile, the correlation between SH modulus and sample thickness, material crystallinity (Xc), comonomer type and content, weight‐average molecular weight, and molecular weight distribution has been established and investigated respectively. The results represent that the comonomer type and the Xc of PE materials played significant roles in the SH modulus. The SH modulus of ethylene‐hexene copolymer is 5–7 MPa higher than that of ethylene‐butene copolymer. The amount in the range of 1 × 103 to 1 × 105 of the molecular weight distribution of PE materials has a significant contribution to the establishment of the tie molecular network. In addition, the higher Xc and the thinner thickness were beneficial to obtain the higher measured SH modulus.