CHEMOSPHERE
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2023
·
IF 8.8
Kangkang Wang,Yuli Kou,Kefu Wang,Siqi Liang,Changyan Guo,Wei Wang,Yi Lu,Jide Wang
Microplastics (MPs) and dye pollutants are widespread in aquatic environments. Here, the adsorption characteristics of anionic dye methyl orange (MO) and cationic dye malachite green (MG) on polyamide 6 (PA6) and polyamide 66 (PA66) MPs were investigated, including kinetics, isotherm equilibrium and thermodynamics. The co-adsorption of MO and MG under different pH was also evaluated. The results reveal that the adsorption process of MO and MG is suitably expounded by a pseudo-second-order kinetic model. The process can be characterized by two stages: internal diffusion and external diffusion. The isothermal adsorption equilibrium of MO and MG can be effectively described using the Langmuir model, signifying monolayer adsorption. Furthermore, the thermodynamic results indicated that the adsorption was spontaneous with exothermic and endothermic properties, respectively. The results of binary systems reveal that MO dominates the adsorption at low pH (2–5), while MG dominates at high pH (8–10). Strong competitive adsorption was observed between MO and MG in neutral conditions (pH 6–8). The desorption experiments confirm that PA6 and PA66 could serve as potential carriers of MO and MG. The interaction between dyes and polyamide MPs is primarily mediated through hydrogen bonds and electrostatic attraction. The results reveal that PA6 formed more hydrogen bonds with the dyes, resulting in higher adsorption capacity than that of PA66. This difference can be attributed to the disparities in the synthesis process and polymerization method. Our study uncovered the adsorption mechanism of dye pollutants on PA6 and PA66, and provided a more comprehensive theoretical basis for the risk assessment concerning different types of polyamide MPs in aquatic environments.
研究领域:
环境科学
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化学
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产品关联
DOI
PubMed
高影响因子
Polymers
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2023
·Vol. 15
·期 13
·2812
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IF 5
Yingwei Zhang,Chunhua Wang,Yong Yi,Wenzhi Wang,Jun Yang
In order to adjust the properties of polyamide 6 (PA6) and expand its application, a new strategy of introducing an aromatic imide structure into the PA6 chain through the random copolymerization method is reported. The diimide diacid monomer was first synthesized by the dehydration and cyclization of pyromellitic dianhydride and 6-aminocaproic acid before it reacted with 1,6-hexamethylene diamine to form poly(amide imide) (PAI) salt, and finally synthesized PA6/PAI random copolymers containing an aromatic imide structure by the random copolymerization of ε-caprolactam and PAI salt. The introduction of an aromatic imide structural unit into the PA6 chain could have a great influence on its properties. As the content of PAI increases, the crystallinity (Xc) and melting temperature (Tm) of the PA6/PAI random copolymer gradually decrease, but its glass transition temperature (Tg) increases obviously. When the PAI content is 20 wt%, the copolymer PA6/PAI-20 has the best comprehensive performance and not only has high thermal stabilities but also excellent mechanical properties (high strength, high modulus, and good toughness) and dielectric properties (low dielectric constant and dielectric loss). Moreover, these properties are significantly superior to those of PA6. Such high-performance PA6 random copolymers can provide great promise for the wider applications of PA6 materials.Keywords:polyamide 6;poly(amide imide);random copolymerization
研究领域:
材料科学
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高分子化学
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DOI
PubMed
高影响因子
IRANIAN POLYMER JOURNAL
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2024
·
IF 2.4
Yang Yuhao,Pu Zejun,Meng Chihan,Zhong Jiachun,Pang Jiahong,Yang Kaijie,Yue Mengjie,Wu Fang
Semi-aromatic polyamides have excellent comprehensive properties and can effectively adjust thermodynamic properties through monomer composition and ratio to meet different application requirements. Therefore, in this study, two copolyamides (PA6T/66 and PA6T/610) were synthesized by one-pot method and their thermal and mechanical properties were subsequently analyzed and compared. Firstly, the chemical compositions and microstructures of the two copolyamides were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy ( 1 H NMR), wide-field X-ray diffraction (XRD) and polarized ophthalmic microscopy (POM), and the viscosities [η] of the specimens were tested. Secondly, the heat resistance of the two copolyamides was analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Subsequently, the mechanical strength of the two copolyamides was evaluated. The FTIR, NMR and XRD results show that the molecular structure and crystal morphology of the two copolyamides are highly similar, which may prove the success of the target products. The TG results show that the heat resistance of the two copolyamides is very good, with the extrapolated initial decomposition temperature above 430 °C, and PA6T/66 has better heat resistance. The DSC results show that PA6T/66 has a higher melting and glass transition temperature. The mechanical test results show that PA6T/66 has greater tensile and flexural strengths of 70 MPa and 110 MPa, respectively, while PA6T/610 has better impact toughness. The above comparative results can be extended to determine the differences in performance between long-chain and short-chain polyamides, which can provide a reference for future related research. Graphical abstract
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
LANGMUIR
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2023
·
IF 3.9
Ze-Lin Qiu,Wen-Han Yu,Wu-Shang Yang,Tong Sun,Zi-Hao Zhao,Qian-Wei Su,Bao-Ku Zhu
High-efficiency dye desalination is crucial in the textile industry, considering its importance for human health, safe aquatic ecological systems, and resource recovery. In order to solve the problem of effective separation of univalent salt and ionic dye under the condition of high salt, ionic hyperbranched poly(amido-amine) (HBPs) were synthesized based on a simple and scalable one-step polycondensation method and then incorporated into the polyamide (PA) selective layers to construct charged nanochannels through interfacial polymerization (IP) on the surface of a polyvinyl chloride ultrafiltration (PVC-UF) hollow fiber membrane. Both the internal nanopores of HBPs (internal nanochannels) and the interfacial voids between HBPs and the PA matrix (external nanochannels) can be regarded as a fast water molecule transport pathway, while the terminal ionic groups of ionic HBPs endow the nanochannels with charge characteristics for improving ionic dye/salt selectivities. The permeate fluxes and dye/salt selectivities of HBP-TAC/PIP (57.3 L m–2 h–1 and rhodamine B (RB)/NaCl selectivity of 224.0) and HBP-PS/PIP (63.7 L m–2 h–1 and lemon yellow (LY)/NaCl selectivity of 664.0) membranes under 0.4 MPa operation pressure are much higher than PIP-only and HBP-NH2/PIP membranes. At the same time, this project also studied the membrane desalination process in a simulated high-salinity dye/salt mixture system to provide a theoretical basis and technical support for the actual dye desalination process.
研究领域:
材料科学
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环境工程
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
GREEN CHEMISTRY
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2024
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IF 9.3
Ze-Yong Zhao,Ji Lan,Cong Deng,Yu-Zhong Wang
Polyamides (PAs) represent a class of polymers that are suitable for chemical recycling, where the amide group acts as a reactive site for degradation agents. However, the inherent stability of the amide group means that chemical recycling of PAs often necessitates stringent conditions, such as high temperatures and pressures, significantly hindering advancements in PA chemical recycling. Moreover, the effectiveness of chemically recycling polyamides into monomers or oligomers—essential components for subsequent polymer synthesis—has not been conclusively verified through comprehensive research. Here, we present the first demonstration of a method for the upcycling of PA6 into high-performance PA derivatives. In the proposed method, PA6 is fist degraded into oligomers with reactive end groups via glycolysis, with the reactivity of the resulting glycolysates subsequently verified. This oligomer acts as an intermediate in thermoplastic polyamide elastomer (TPAE) synthesis, facilitating direct integration with flexible polyethylene glycol oligomers into TPAE without requiring further degradation to monomers. The mechanical properties of the resultant TPAEs are commensurate with those previously reported for PA6-based TPAEs. By fine-tuning the reaction time and catalyst concentration, it is possible to control the molecular weight of the PA6 glycolysates, thus adjusting the TPAE’s mechanical properties. This study presents an innovative approach that seamlessly combines the degradation process of PA6 with the synthesis pathway of TPAE, thus achieving the cost-effective upcycling of PA6 into TPAE.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2022
·Vol. 139
·期 24
·52346
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IF 3.057
Yuhan Xu,Chenyu Zhao,Zhiyuan Guo,Wenjie Dong,Xiucai Liu,Weihong Guo
Polyamide is an engineering plastic, which has been widely used in industry and life. Polyamide 56, as a green and environmentally friendly bio-based product, is gradually replacing traditional petroleum-based products. However, in terms of auto parts, communication equipment, and mechanical products, a single polyamide monomer is difficult to meet the end-use standard. EPDM-g-MAH (ethylene propylene diene monomer grafted with maleic anhydride) is melt blended with bio-based polyamide 56 (PA56) in a twin-screw extruder to obtain polyamide elastomers with different formulations. Subsequently, its morphology and structure, thermodynamic properties, crystallinity, and mechanical properties were analyzed. The test results show that the composites containing 10% EPDM-g-MAH have better impact resistance and thermal properties in the range of adding 0‑20 wt% EPDM-g-MAH. In the fracture morphology analysis, it is found that the interface between the rubber phase and the polyamide phase fused well, and the elastomer showed the ductile fracture.
研究领域:
材料科学
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高分子化学
✓ 已验证
DOI
高影响因子
Membranes
·
2018
·Vol. 8
·期 4
·89
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IF 0
Qin Liu,Xing Wu,Kaisong Zhang
To improve the filtration performance and properties of organic solvent nanofiltration (OSN) membranes, we firstly introduce nanoporous silica (SiO2) particles into the polyamide (PA) active layer of polysulfone (PSf) membrane via an interfacial polymerization process. Results from the study revealed that introduction of SiO2influenced the properties of PSf/PA-SiO2composite membranes by changing the surface roughness and hydrophilicity. Moreover, results also indicated that nanoporous SiO2modified membranes showed an improved performance of alcohols solvent permeance. The PSf/PA-SiO2composite membrane modified by 0.025 wt % of SiO2reached a permeance of 3.29 L m−2h−1bar−1for methanol and 0.42 L m−2h−1bar−1for ethanol, which were 20.0% and 13.5% higher than the control PSf membrane (permeance of 2.74 L m−2h−1bar−1for methanol and 0.37 L m−2h−1bar−1for ethanol). Conclusively, we demonstrated that the increase of membrane hydrophilicity and roughness were major factors contributing to the improved alcohols solvent permeance of the membranes.Keywords:silica;polysulfone;composite membrane;polyamide
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
·
IF 4.9
Mengjie Huang,Mengjia Zhang,Xinyu Huan,Yuanyi Li,Wei Wei,Yong Zhang
Microplastics (MPs) commonly undergo aging in various environmental media, affecting both their environmental behavior and Trojan-horse effect for contaminants. However, the mechanisms underlying the different impact of various aging processes on the Trojan-horse effect of polyamide (PA) MPs towards metal oxyanions remain unclear. This study explored how chemical aging and UV irradiation impact the structural characteristics and Cr(VI) adsorption of PA MPs under various influencing factors. Results showed that both aging processes enhanced the negative surface charge, surface oxygen content, and roughness of PA MPs, with FTIR correlation spectroscopy confirming an increase in O-containing functional groups. Cr(VI) adsorption onto aged PA sharply increased by 17.4 % (14 days of UV irradiation), 39.4 % (42 days of UV irradiation), and 21.7 % (chemical aging) compared to original PA. Salinity and natural organic matter had adverse effects on Cr(VI) adsorption. Spectroscopic analyses highlighted the crucial role of hydrophilic amide groups in controlling Cr(VI) adsorption onto aged PA, involving hydrogen bonding, electrostatic interactions, and reduction. Aged PA exhibited higher adsorption capacities but also greater desorption under simulated seawater and intestinal fluid, suggesting increased migration potential for Cr(VI). This study provides helpful insights into assessing the environmental risk of co-existing PA MPs and metal oxyanions, particularly considering the effect of aging processes.
研究领域:
环境科学
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化学
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Bingbing Yuan,Pengfei Li,Honghong Sun,Shengchao Zhao,Peng Li,Haixiang Sun,Q. Jason Niu
Polyamide membranes based on trimesoyl chloride (TMC) have captured the majority of the market share for desalination in water treatment. The TMC based membrane is prone to form calcium bridges with the organic foulants due to the relatively strong deprotonation ability of the benzoic acid generated from the incomplete reaction of the acyl chloride monomers . The foulants are thus rapidly deposited on the surface of the TMC based membrane, which results in the deterioration of water production and decrease of membrane lifespan. Herein, we have fabricated a polyamide membrane based on novel trimesoyl-[4,4-dimethyl-5(4H)-azlactone] (TMDMA) monomer instead of TMC monomer. Since the carboxylic groups of the prepared TMDMA polyamide nanofilm are not directly connected to the phenyl ring, the acidity coefficient ( p K a ) value is higher and, consequently, deprotonation ability is expected to be weaker. To confirm this theory, we have conducted the fouling experiment on TMDMA based membrane using alginate as a model foulant and compared that with TMC based polyamide membranes. A lower flux decline (33%) and higher cleaning efficiency (90.72%) are observed for the TMDMA polyamide membrane, while the flux decline and cleaning efficiency for the TMC based polyamide membrane are 52% and 49.52% respectively. Furthermore, the average Ca 2+ density of the TMDMA polyamide membrane surface before and after cleaning are 81.52 mg m −2 and 21.61 mg m −2 respectively, which are lower than that of the TMC based polyamide membrane surface. Thus, it is clearly showing that the surface of the TMDMA polyamide membrane is not prone to form calcium bridges with foulants due to the weaker complexation between Ca 2+ and the carboxylic acid groups.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Separations
·
2023
·Vol. 10
·期 2
·123
·
IF 2.6
Zhou Cheng,Xuanhao Lin,Ming Wu,Guoping Lu,Yanru Hao,Cehui Mo,Qusheng Li,Jianfeng Wu,Jichun Wu,Bill X. Hu
Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using a combination of batch experiments, column experiments and numerical models. The results of scanning electron microscope (SEM) and Fourier transform infrared spectra (FTIR) show that the surface of PA particles is changed significantly after adsorption of BPA. The isothermal adsorption process of BPA can be simulated by the Langmuir model and the Freundlich model. Kinetic adsorption, on the other hand, can be fitted by a quasi-first-order adsorption model, and the adsorption results indicate that the maximum adsorption of BPA on PA reaches 13 mg·g−1. The results of the column experiments suggest that the mass recovery rate of BPA decreases with PA content, and increases with flow velocity, while initial concentration has no apparent influence on BPA transport. In addition, due to the hydrolysis of BPA, the mass recovery rate of BPA does not change with pH under conditions of pH < 10.2 and increases substantially to 94% when pH > 10.2. Moreover, Ca2+has a significant inhibitory effect on the transport of BPA, while Na+has no apparent influence on the transport of BPA. The transport process of BPA in porous media is simulated using a single-point kinetic model, and the fitted mathematical relationships for the variation of kinetic parameters with environmental factors are obtained by regression analysis.Keywords:bisphenol A;microplastics;adsorption;transport;polyamide;kinetic parameter
研究领域:
环境科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2023
·Vol. 15
·期 8
·1887
·
IF 5
Hui Fang,Guifeng Li,Kai Wang,Fangjuan Wu
This study investigates the effect of adding stearic acid (SA) on the thermal conductivity of polyamide 6 (PA6)/boron nitride (BN) composites. The composites were prepared by melt blending, and the mass ratio of PA6 to BN was fixed at 50:50. The results show that when the SA content is less than 5 phr, some SA is distributed at the interface between BN sheets and PA6, which improves the interface adhesion of the two phases. This improves the force transfer from the matrix to BN sheets, promoting the exfoliation and dispersion of BN sheets. However, when the SA content was greater than 5 phr, SA tends to aggregate and form separate domains rather than being dispersed at the interface between PA6 and BN. Additionally, the well-dispersed BN sheets act as a heterogeneous nucleation agent, significantly improving the crystallinity of the PA6 matrix. The combination of good interface adhesion, excellent orientation, and high crystallinity of the matrix leads to efficient phonon propagation, resulting in a significant improvement in the thermal conductivity of the composite. The highest thermal conductivity of the composite is achieved when the SA content is 5 phr, which is 3.59 W m−1K−1. The utilization of a composite material consisting of 5phr SA as the thermal interface material displays the highest thermal conductivity, and the composite also demonstrates satisfactory mechanical properties. This study proposes a promising strategy for the preparation of composites with high thermal conductivity.Keywords:thermal conductivity;polyamide;boron nitride;stearic acid
研究领域:
材料科学
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热管理技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Rongze Sun,Jianlong Dai,Danrong Cai,Wentao Yan,Yong Zhou,Congjie Gao
Xylose is a small organic molecule with great economic value in fine chemical production. High-quality xylose production requires removing salt from the feed solution, which is typically an expensive process. Polyamide nanofiltration membranes, characterized by their high rejection of salts (e.g., Na 2 SO 4 ) and low rejection of small organic molecules (such as xylose), are an effective separation technique. The present study proposes a CTAB-assisted shedding strategy toward polyamide oligomers to enhance the xylose/salt separation. When the membrane contacts CTAB solution at appropriate concentrations, CTAB aggregates adsorb onto the membrane surface due to electrostatic and hydrophobic interactions. The hydrophilic outer layer of these aggregates, attributed to the quaternary ammonium groups, facilitates the migration of polyamide oligomers into the solution, increasing membrane pore size and thereby decreasing xylose rejection. This mild process preserves the membrane structure and its strong negative charge, maintaining effective charge repulsion and ensuring high salt rejection. The increased pore size also enhances membrane flux. Results show that xylose rejection decreased from 44.2 % to 20.3 %, while Na 2 SO 4 rejection remained above 98 %. The separation factor increased by 117 %, and flux increased by 104 %. Investigation of the shedding mechanism revealed that the variation of membrane flux with CTAB concentration aligns with the S-shaped adsorption isotherm model of surfactants at the solid-liquid interface. This suggests that the adsorption form of CTAB on the membrane surface is the dominant factor influencing this process. This work shows the promising potential of polyamide nanofiltration membrane technique for the xylose purification and the proposed strategy in small organic molecule/salt separation.
研究领域:
化学工程
·
膜科学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）