JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 45
·e53131
·
IF 3.057
Xinran Liu,Yu Wang,Yongyan Pang,Xia Dong,Dujin Wang
In this study, a fast and convenient method that can characterize the molecular weight (MW) and its distribution (PDI) of polyamide 1012 after the solid-state polymerization (SSP) was proposed with the rheological technique. Conventionally, polyamides have to be chemically modified to become soluble in an organic solvent suitable for the Gel Permeation Chromatography (GPC) measurement. Herein, to avoid the complex operation of chemical modification, the quantitative correlations between the rheological properties such as zero-shear viscosity, complex viscosity, the frequency and modulus at the crossover point between the storage and loss modulus curves, and the obtained MW and PDI were established. Thus, without chemical modifications, the characterization of PA1012 during SSP becomes convenient and time saving, which is more approach to the real “on-line” control of SSP. The lamellar thickening and SSP occur simultaneously above T g during SSP. Its influence on the final results of SSP was studied. Furthermore, the impact of crystallinity of the raw materials on the SSP behavior was also investigated. The higher crystallinity can lead to a decrease in the SSP rate and final molecular weight and molecular weight distribution.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
KEY ENGINEERING MATERIALS
·
2017
·
IF 0
Dong Han Li,Ming Yi Liao
Preparation of telechelic hydroxyl low molecular weight fluoropolymers by reduction reaction was presented. The telechelic carboxyl low molecular weight fluoropolymers were chosen as raw materials which were prepared by oxidative degradation method. The molecular weights of telechelic carboxyl low molecular weight fluoropolymers were about 3700. Then, using lithium aluminum hydride reacted with carboxyl groups to prepare the telechelic hydroxyl low molecular weight fluoropolymers. The effects of reaction temperatures, reaction times, contents of solvent and lithium aluminum hydride were investigated in detail. The structures, Mn and dynamic viscosity of low molecular weight fluoropolymers were analyzed by FTIR, 1H-NMR, GPC and viscometer respectively. Finally telechelic hydroxyl low molecular weight fluoropolymers were prepared. The conversion rate of that reduction reaction was about 95%. The product was a viscous fluid with a dynamic viscosity of 48Pa·s at 50°C.
研究领域:
材料化学
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高分子化学
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产品关联
DOI
Innovative Food Science & Emerging Technologies
·
2025
·
IF 6.8
Yu-Cheng Yang,Shu-Hao Cheng,Yi-Xiong Zhang,Jie Mao,Bing-De Zheng,Na Zhang,Ya-Yan Huang,Xue-Qin Zhang,Jing Ye,Mei-Tian Xiao
To effectively prepare value-added low molecular weight chitosan with improved molecular weight uniformity, a novel high-gravity reactor—the Rotating Foam Stirrer Reactor (RFSR)—is proposed to enhance the chemical degradation process of chitosan. The study reveals that the combined H₂O₂-Vc degradant significantly increases degradation efficiency compared to H₂O₂ or Vc alone, attributed to synergistic effects in hydroxyl radical production. Specifically, the degradation efficiency of the H₂O₂-Vc combination increased by 56.41 % and 32.88 %, respectively, within 5 min. Increased rotational speed improves degradation efficiency and narrows the molecular weight distribution, particularly at higher chitosan concentrations. The weight-average molecular weight rapidly decreases within the first 30 min and then stabilizes, while maintaining a more uniform distribution. Positioning the degradant feed at the stirrer's outer edge further enhances degradation. The RFSR outperforms traditional reactors, producing chitosan with lower molecular weight and better uniformity. Additionally, a predictive correlation for the reaction rate constant, incorporating mass transfer effects, shows good agreement with experimental results, with an error margin of approximately ±20 %, supporting large-scale industrial applications in polysaccharide degradation.
研究领域:
生物化学
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材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2024
·Vol. 62
·期 13
·3038-3046
·
IF 3.9
Linzhi Xie,Yunfeng Zhou,Xiaoming Zhu,Geng Huang,Lifen Xiao,Wei Li
Ring opening metathesis polymerization (ROMP) is widely used to prepare functional materials with various topological structures. However, it is difficult to prepare polymers with ultra-high molecular weight (UHMW) directly. We found a new method to prepare UHMW polymers by combining ROMP and acyclic metathesis reaction. First, monomer NB-2OH was polymerized by ROMP with different feed ratio of NB-2OH/G3, and obtained well-defined polymers P(NB-2OH) n ( n = 50, 200, and 463). Then acyclic metathesis reaction was used to synthesize UHMW polymers. The results indicated that polymer P(NB-2OH) z with higher molecular weight ( M w = 6067.3 kg mol −1 ) and narrower distribution (PDI = 1.58) could be obtained at 80°C for 5 min, when P(NB-2OH) 463 was used as raw material with H 2 SO 4 /G3 = 10/1. Compared with polymer P(NB-2OH)1990 ( M w = 5343.1 kg mol −1 , PDI = 1.61) prepared by ROMP directly, the new method tremendously shortens reaction time, lowers the requirement for the purity of monomer and produces UHMW polymers with narrower distribution. The compositions of prepared polymers were also confirmed clearly by post-modification and 1 H NMR characterization. Graphical
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
MATERIALS RESEARCH INNOVATIONS
·
2025
·
IF 0
Yu Tian,Feiyao Huang,Di Zhu,Li Jiang,Qimin Jiang,Hongjun Yang,Wenyan Huang,Xiaoqiang Xue,Bibiao Jiang
The branched poly (2-hydroxyethyl methacrylate)(BPHEMA) was carried out using 2-methyl-n-[3-(methyl phenyl amino)-propyl]–acrylamide(MPAEMA, synthesised in laboratory) and benzoyl peroxide(BPO) as redox initiator by water/toluene inverse emulsion polymerisation. The weight-average molecular weight (Mw.MALLS), mean-square radius of gyration(Rg), intrinsic viscosity([η]), relative branching factor g and g’, and micro rheological properties of BPHEMA were measured by static and dynamic light scattering(DLS-SLS) and Ubbelohde viscometer. The results show that the BPHEMA was synthesised by inverse emulsion polymerisation at room temperature. The degree of branching increased with the increase of the content of reducing agent MPAEMA in the feed ratio, and the molecular weight was not affected significantly by the change of feed ratio. However, the molecular weight of linear poly (2-hydroxyethyl methacrylate) (LPHEMA) was significantly affected by the change of feed ratio.
研究领域:
高分子化学
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材料科学
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物理化学
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产品关联
DOI
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2017
·Vol. 55
·期 20
·3404-3412
·
IF 2.952
Yulong Jin,Ning Zhao,Ruihua Cheng,Xuelian He,Zhen Liu,Dalin Dong,Yuezhen Bin,Xiaowei Chen,Liangbin Li,Boping Liu
Bimodal ultra-high-molecular-weight polyethylene (UHMWPE)/high-density polyethylene (HDPE) in-reactor blends (IRBs) are produced by the bimetallic catalysts, which are synthesized through co-supporting silylchromate and vanadium-oxide-based catalysts on silica or alumina, zirconia and titania-modified silica. After support modification, the activities of the catalysts for ethylene polymerization are substantially enhanced. The IRBs produced by the modified catalysts also contain more UHMWPE and low-molecular-weight polyethylene (LMWPE) fractions, and have much broader molecular weight distribution (MWD). The homogeneous nature of the IRBs is preliminarily confirmed by the differential scanning calorimetry melting curves, showing unique melting peak in both nascent and recrystallized states. The rheological results reflect that the viscosity of the IRBs is reduced more or less when compared with UHMWPE. The distinct elastic dominance of the IRBs is also observed, implying the UHMWPE characteristics in the IRBs. In addition, the intimate mixing of the IRBs is further verified by the similar slopes of Han curves for the polyethylene (PE) samples. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3404–3412
研究领域:
高分子化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Bioactive Carbohydrates and Dietary Fibre
·
2021
·
IF 0
Dongmei Wu,Xiaoliang Zheng,Weiwei Hu,Kai Zhu,Chengxiao Yu,Qiaojun He,Robert J. Linhardt,Xingqian Ye,Shiguo Chen
Pectic oligosaccharides are viewed as excellent immunomodulator, but the specific molecular weight (M w ) range required for anti-inflammatory effects remains unclear. In this study, citrus pectins was depolymerized by the ultrasound/H2O2/Vc system and the pectic mixtures was separated through the superdex 30 chromatography column . Three highly purified pectin fractions (USP1, USP2, USP3) were obtained, with the M w of 2713 g/mol, 3683 g/mol, and 7469 g/mol. All of them were RG-I pectins and USP3 contained more arabinan sidechains than USP1 and USP2. In vitro anti-inflammation assays based on LPS-induced RAW264.7 macrophages indicated that these pectins could suppress the NO release, ROS production and down-regulated the level of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α in a M w -dependent manner. The inhibitory effects increased in the order of USP13KD should be effective as a prophylactic agent against inflammatory diseases in functional food.
研究领域:
食品科学
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生物化学
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免疫学
✓ 已验证
DOI
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2025
·
IF 8.5
Song Li,Xiaomao Peng,Zengbo Wang,Chunhua Chen,Xin Li,Qixing Nie,Xiaojun Huang,Shuigen Bian,Junyi Yin,Steve W. Cui,Huizi Tan,Shaoping Nie
Pectins, a complex class of polysaccharides, are prominently represented by HG-chains, which are both abundant and extensively studied. Bacteroides species exhibit a remarkable ability to metabolize plant- and animal-derived polysaccharides, including the degradation of HG-type pectins through polysaccharide utilization locus (PUL). However, the effects of structurally diverse HG-type pectins on PUL expression, metabolite production, and metabolic pathways of Bacteroides remain unclear. Addressing this, this study chose HG-type pectins with different molecular weights from citrus (CP) and pomelo (PP), identified Bacteroides species capable of utilizing these pectins, studied the resulting metabolites through non-targeted metabolomics coupled with short-chain fatty acids analysis, and examined the activation of PUL and metabolic pathways by transcriptomic studies. The results showed that Bacteroides thetaiotaomicron A4 and Bacteroides caccae K9 could utilize HG-type pectins with different molecular weights. The production of propionic acid by Bacteroides thetaiotaomicron A4 was significantly affected by the molecular weight of pectins. Utilizing CP, B. thetaiotaomicron A4 enriched metabolites such as carbohydrates, amino acids, peptides, amines, and significantly enhanced pathways such as sphingolipid metabolism and drug metabolism (other enzymes) through PUL75, PUL63, and PUL55. In contrast, when using PP, B. thetaiotaomicron A4 enriched similar metabolites and further upregulated pathways related to sphingolipid metabolism and pyrimidine metabolism. The molecular weight of HG-type pectins differentially affected the expression of carbohydrate-active enzymes and metabolic pathways, resulting in different metabolite profiles. This study aims to contribute to the understanding of structure-activity relationship between pectins and gut microbiota and to inform precision nutrition strategies.
研究领域:
微生物学
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营养学
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产品关联
DOI
PubMed
高影响因子
POLYMER INTERNATIONAL
·
2020
·Vol. 70
·期 2
·185-192
·
IF 2.574
Yuanyuan Hou,Fei Huang,Hui Yang,Hao Cong,Xi Zhang,Xiaoxu Xie,Haibo Yang,Qiuping Tong,Ning Luo,Ping Zhu,Jianzong Meng
Levansucrase (EC 2.4.1.10) catalyzes both levan polymerization and sucrose hydrolysis. Levan production by recombinant Bacillus subtilis levansucrase SacB-T305A was investigated. The maximum conversion yield (33.09%) of sucrose to levan and levan yield (115.8 g L –1 ) were obtained as 30% (wt/vol) and 40% (wt/vol) initial sucrose, respectively. Under highly acidic conditions (pH 3.5 and below), the polymerization not only shifted distinctly to high molecular weight levan but also enlarged the size of low molecular weight levan. In particular, the proportion of high molecular weight levan to total products increased to 9-fold at pH 3.5. The presence of Fe 2+ , Mg 2+ , Mn 2+ and Zn 2+ ions at common ion strength (5 mmol L –1 ) increased only the size of low molecular weight levan from about 20 kDa to about 35 kDa. Our findings provide a supplementary view about the mechanism of levan molecular weight distribution in enzymatic synthesis and offer a possibility for producing levan of different molecular weights by modulating enzymatic reaction conditions. © 2020 Society of Industrial Chemistry
研究领域:
生物化学
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工业微生物学
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DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2015
·
IF 5.33
Yongguang Yin,Mohai Shen,Zhiqiang Tan,Sujuan Yu,Jingfu Liu,Guibin Jiang
Ubiquitous natural organic matter (NOM) plays an important role in the aggregation state of engineered silver nanoparticles (AgNPs) in aquatic environment, which determines the transport, transformation, and toxicity of AgNPs. As various capping agents are used as coatings for nanoparticles and NOM are natural polymer mixture with wide molecular weight (MW) distribution, probing the particle coating-dependent interaction of MW fractionated natural organic matter (Mf-NOM) with various coatings is helpful for understanding the differential aggregation and transport behavior of engineered AgNPs as well as other metal nanoparticles. In this study, we investigated the role of pristine and Mf-NOM on the aggregation of AgNPs with Bare, citrate, and PVP coating (Bare-, Cit-, and PVP-AgNP) in mono- and divalent electrolyte solutions. We observed that the enhanced aggregation or dispersion of AgNPs in NOM solution highly depends on the coating of AgNPs. Pristine NOM inhibited the aggregation of Bare-AgNPs but enhanced the aggregation of PVP-AgNPs. In addition, Mf-NOM fractions have distinguishing roles on the aggregation and dispersion of AgNPs, which also highly depend on the AgNPs coating as well as the MW of Mf-NOM. Higher MW Mf-NOM (>100 kDa and 30–100 kDa) enhanced the aggregation of PVP-AgNPs in mono- and divalent electrolyte solutions, whereas lower MW Mf-NOM (10–30 kDa, 3–10 kDa and <3 kDa) inhibited the aggregation of PVP-AgNPs. However, all the Mf-NOM fractions inhibited the aggregation of Bare-AgNPs. For PVP- and Bare-AgNPs, the stability of AgNPs in electrolyte solution was significantly correlated to the MW of Mf-NOM. But for Cit-AgNPs, pristine NOM and Mf-NOM has minor influence on the stability of AgNPs. These findings about significantly different roles of Mf-NOM on aggregation of engineered AgNPs with various coating are important for better understanding of the transport and subsequent transformation of AgNPs in aquatic environment.
研究领域:
环境科学
·
纳米技术
·
化学
✓ 已验证
DOI
PubMed
高影响因子
CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Yu-Xiao Wang,Ting Zhang,Yue Xin,Xiao-Jun Huang,Jun-Yi Yin,Shao-Ping Nie
Agrocybe cylindracea is a common source of active polysaccharides, but their fine structures are not clearly elucidated. In the present study, four fractions were purified from the alkaline extract of A. cylindracea (JACP), and their chemical components and structures were compared by HPAEC-PAD, methylation combined with GC–MS, and 1D/2D NMR analysis. Results showed the purified fractions’ physicochemical properties, including monosaccharide compositions, molecular weights, viscosities and surface morphology considerably varied. JACP-30 was identified as a fucoglucogalactan with a α-(1 → 6)-galactopyranosyl as main chain. JACP-50p and JACP-80r were characterized as β-(1 → 6)-glucans with side chains composed of terminal and 3-substituted β-glucopyranosyl residues attached at O -3 for every three residues. Similarly, the backbone of JACP-80 was β-(1 → 6)-linked glucopyranosyl and β-(1 → 3,6)-linked glucopyranosyl residues at a ratio of 4:1. This work provides more information to the understanding of polysaccharides from A. cylindracea , further guiding its biological researches and developing the application in food and biomedicine industries.
研究领域:
食品科学
·
生物化学
·
药学
✓ 已验证
DOI
PubMed
高影响因子
MARINE CHEMISTRY
·
2019
·
IF 2.713
Yuxi Lu,Xuelu Gao,Chen-Tung Arthur Chen
In this study, a method was developed for the desalination and pre-concentration of three colloidal trace metals in seawater , namely Cd, Cu and Pb, using diethylammonium diethyldithiocarbamate and ammonium 1-pyrrolidine dithiocarbamate as chelates. Seawater samples were first treated with cross-flow ultrafiltration (CFUF) for the separation of the colloidal matter of different molecular weights , i.e. 1–3 kDa, 3–10 kDa and 10 kDa-0.22 μm. Then, after acid digestion , the organic chelates and the extracting agent chloroform were added at pH = 3.8. Finally, the organic phase was back extracted, and the target metals in all samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) with low detection limits in the range of 0.13–1.18 pmol L −1 . The extraction efficiencies for the three metals were in the range of 92.2%–100.3% with an enrichment factor of 40, and their mass recoveries in the studied colloidal fractions were in the range of 83.1%–103.5%. The developed method has been successfully applied for the analysis of seawater samples collected from the sites off the south coast of North Yellow Sea in Shandong Peninsula , China. For the first time, the distribution of colloidal Cd, Cu and Pb in different molecular weights in this area is reported. The results obtained from real samples demonstrate that the developed method is simple, efficient and convenient for routine analysis with low detection limit.
研究领域:
海洋化学
·
分析化学
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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）