Rheological and Thermal Properties of Acrylonitrile-Acrylamide Copolymers: Influence of Polymerization Temperature

Wu Xueping,Lu Chunxiang,Wu Gangping,Zhang Rui,Ling Licheng The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.2

An attempt was made to correlate the polymerization temperature and rheological and thermal properties of acrylonitrile (AN)-acrylamide (AM) copolymers. The copolymers were synthesized at different polymerization temperature. The copolymer structure was characterized by gel permeation chromatography (GPC) and Infrared spectrum (IR). The rheological and thermal properties were investigated by a viscometer and differential scanning calorimeter-thermogrametric (DSC-TG) analysis, respectively. When the polymerization temperature increased from $41^{\circ}C\;to\;65^{\circ}C$, the molecular weight $(\bar{M}_w)$ of copolymers decreased from 1,090,000 to 250,000, while its conversion increased from $18\%\;to\;63\%$, and the polymer composition changed slightly. To meet the requirements of carbon fibers, the rheological and thermal properties of products were also investigated. It was found that the relationship between viscosity and $\bar{M}_w$ was nonlinear and the viscosity index (n) decreased from 3.13 to 2.69, when the solution temperature increased from $30^{\circ}C\;to\;65^{\circ}C$. This suggests the dependence of viscosity upon $\bar{M}_w$ is higher at lower solution temperature. According to the result of activation energy, the sensivity of viscosity to solution temperature is higher for AN-AM copolymers synthesized at higher polymerization temperature. The result of thermal analysis shows that the copolymers obtained at higher polymerization temperature are easier to cyclization evidenced from lower initiation temperature. The weight loss behavior changed irregularly with polymerization temperature due to irregular change of liberation heat.

Effects of In-Situ BaB6/Al Composite Inoculant on the Mechanical and Corrosion Behavior of Al–7Si–0.3Mg Alloy

Yingguang Liang,Chunxiang Cui,Hongtao Geng,Lu Liu,Sen Cui,Shichao Yang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

In this work, as an inoculant, in-situ BaB6/Al composites was fabricated and used to refine the α-Al dendrites and modify theeutectic Si of A356.2(Al–7Si–0.3Mg) alloy. BaB6/Al ingot and ribbon composites mainly contain two phases, α-Al and BaB6. In BaB6/Al ribbons, nano-size BaB6ceramic particles exist and disperse uniformly which help to better exert the inoculanteffect in A356.2 alloy. YS, UTS, EL and HV of B2 alloy are 36.3%, 18.3%, 46.4% and 20.8% higher than the base alloy (B0),respectively. The ductile fracture characteristics are more obvious. Moreover, B2 alloy shows the best corrosion resistance. Aland BaB6form a clear, stable and well matched interface, so BaB6particles can act as the heterogeneous nucleation of α-Aland refine the A356.2 alloy. Furthermore, the combined of free micro-alloying elements Ba and B in BaB6/Al compositespromote the twins formation, which change the eutectic Si to fine fibrous and granular shape.

Bioinspired Fabrication and Evaluation of Molecularly Imprinted Nanocomposite Membranes with Inorganic/Organic Multilevel Structure for the Selective Separation of Emodin

Chao Yu,Jian Lu,Qi Zhang,Hougang Fan,Minjia Meng,Shi Zhou,Yinhua Jiang,Yongsheng Yan,Yilin Wu,Chunxiang Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.2

High purity emodin is in great demand with the development of medical treatment. Molecularly imprinted membranes (MIMs) have gained wide attention for selective separation of emodin due to its preferable selectivity. In this work, we describe a simple two-step method for developing emodin-imprinted TiO2@CA (ETMIMs) and emodin-imprinted SiO2@CA (ESMIMs) based on organic–inorganic nanoparticle (SiO2/TiO2) modified cellulose acetate membranes at room temperature. SiO2/TiO2 is used to improve the structural stability and roughness of membranes, and dopamine is used as the functional monomer and crosslinker. Importantly, the as-prepared membranes not only exhibited enhanced rebinding capacity (ETMIMs = 30.73 mg g -1 and ESMIMs = 46.04 mg g -1) but also possessed superior rebinding selectivity (2.76 and 2.99 for physcion and 2.42 and 3.30 for aloe emodin onto ETMIMs and ESMIMs) as well as permselectivity (7.59 and 6.69 for physcion and 5.94 and 5.78 for aloe emodin onto ETMIMs and ESMIMs). The regeneration ability of ETMIMs and ESMIMs still maintained 90.4% and 89.2% of the original rebinding capacity after 10 cycling steps, respectively. The ETMIMs and ESMIMs obtained in this work show potential applications for selective separation and purification of emodin from analogs.

Biomass-Based Synthesis of Green and Biodegradable Molecularly Imprinted Membranes for Selective Recognition and Separation of Tetracycline

Wendong Xing,Yilin Wu,Jian Lu,Xinyu Lin,Chao Yu,Zeqing Dong,Yongsheng Yan,Chunxiang Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.02

Aggravating environmental problems have driven the unprecedented development of sustainable materials. Treatments of environmental pollutants with biomass-based sustainable materials are catching attention of more researchers. In the present work, a biomass-based strategy was developed to prepare sustainable molecularly imprinted nanocomposite membranes (S-MINMs). Based on this strategy, biomass-activated carbon nanoparticles (ACNPs) as the porous filler were integrated into the porous cellulose acetate (CA)/chitosan (CS) hybrid membranes to synthesize renewable and easy degradable basal membranes. The specific recognition sites were fabricated from simple free radical polymerization method, and using methacrylic acid (MAA) and acrylamide (Am) as functional monomers, we obtain improved adsorption capacity on tetracycline (TC, template molecule). Performance of S-MINMs was evaluated by adsorption isotherm, adsorption kinetics, perm-selectivity, reusability and biodegradability. Results indicated that the as-prepared S-MINMs not only exhibited desirable biodegradability, but also possess superior adsorption and separation performance toward TC (15.99 mg g -1 for adsorption capacity and 4.91 for perms-selectivity factor). The method developed here shows great potential for development of sustainable membranes for selective separation of various pollutants.

Hair follicles transcriptome profiles in Bashang long-tailed chickens with different plumage colors

Xiaohui Liu,Rongyan Zhou,Yongdong Peng,Chuansheng Zhang,Lanhui Li,Chunxiang Lu,Xianglong Li 한국유전학회 2019 Genes & Genomics Vol.41 No.11

Despite the rich variety in plumage color found in nature, genetic studies on how hair follicles affect pigmentation are often limited to animals that have black and white pigment. To test how gene expression influences plumage color, transcriptomes of chicken hair follicles with white, black, hemp, reed catkins, silvery grey, and landscape plumage colors were generated using Illumina sequencing. We generated six RNA-Seq libraries with over 25 million paired-end clean reads per library with percentage of paired-end clean reads ranging from 96.73 to 96.98%. 78% of the reads mapped to the chicken genome, and approximately 70% of the reads were mapped to exons and 6% mapped to introns. Transcriptomes of hair follicles producing hemp and land plumage were similar, but these two showed moderate differences compared with gray and reed colored plumage. The black and white follicle transcriptomes were most divergent from the other colors. We identified several candidate genes, including GPNMB, PMEL, TYRP1, GPR143, OCA2, SOX10, SLC45A2, KRT75, and TYR . All of these genes are known to induce pigment formation in mice. White feathers result from the lack of pigment formation, and our results suggest that the white chickens due to the recessive insertion mutation of TYR . The formation of black area size and color depth may be due to the expression levels of GPNMB, PMEL, TYRP1, GPR143, OCA2, SOX10, SLC45A2, KRT75, and TYR . The GO analysis of the differentially expressed genes (DEGs) revealed that DEGs in our transcriptome analysis were enriched in cytoskeleton and cell structure related pathways. The black plumage transcriptome showed significant differences in melanogenesis, tyrosine metabolism, and riboflavin metabolism compared with transcriptomes of other plumage colors. The transcriptome profiles of the different chicken plumage colors provide a valuable resource to understand how gene expression influences plumage color, and will be an important resource for identifying candidate genes in breeding programs.