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1.
Ahmad Danial Azzahari Rosiyah Yahya Aziz Hassan Md. Rezaul Karim Sheikh 《Fibers and Polymers》2012,13(5):555-563
The new copolymers from different feed compositions of glycidyl methacrylate (GMA) and tetrahydrofurfuryl acrylate (THFA) were synthesized using free radical polymerization in toluene at 70±1 °C using benzoyl peroxide (BPO) as initiator. The polymers were characterized by 1H NMR, 13C NMR and FTIR spectroscopic techniques. The polydispersities of the copolymers suggest a strong tendency for chain termination by disproportionation. The glass transition temperature of the copolymers increases with increase in GMA content. The thermal stability of the copolymers increases with increase in THFA content. The copolymer compositions were determined using 1H NMR analysis. Reactivity ratios for GMA and THFA as determined by the Mao-Huglin method were r1=0.379 and r2=0.266. The results showed that all these copolymerizations are strictly linear systems describable by the Mayo-Lewis equation based on the terminal model and that accurate reactivity ratio data can be obtained. 相似文献
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3.
A novel charring agent poly(pentaerythritol spirocyclic phosphorusoxy spirocyclic diethanolamine borate) (PPSPSDB) was synthesized successfully with diethanolamine borate (DEAB) and spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC), which was combined with ammonium polyphosphate (APP) to endow linear low-density polyethylene (LLDPE) with flame retardance. The structure of PPSPSDB was characterized by FTIR and 1H-NMR. The study of thermal stability of various LLDPE composites showed that PPSPSDB/APP system could effectively improve the thermal degradation and thermal-oxidative stability of the char residues, and PE3 containing 30 wt% APP/ PPSPSDB with a 2 weight ratio left the highest amount of char residue at 800 oC. The results of flammability revealed that PE3 had the best combination property; the limited oxygen index value was 29.6, and vertical burning reached UL-94 V-0 rating, and the tensile strength and notched impact strength were 11.853 MPa and 28.8 kJ/m2 respectively. The investigation of structure and morphology of char residue indicated that the compact foaming char layer, as a good barrier against the transmission of heat and volatiles, was formed for PE3 during combustion. 相似文献
4.
N,N-Diethyl-m-toluamide (DEET) is widely used as an insect-repellent. Sulfonamides are an important class of anti-bacterial drugs. In order to combine the strength of anti-bacterial activities of sulfonamides and insect-repellent property of DEET, three azo reactive dyes were designed and synthesized. To do this, the diazoniom salts of sulfonamides viz. 4-amino-N-(4-methyl-2-pyrimidinyl) benzene sulfonamide, 4-amino-N-(4-dimethyl-2-pyrimidinyl) benzene sulfonamide and 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzene sulfonamide were prepared using HCl and NaNO2. The resulting diazoniom salts were then coupled to the coupling component containing N,N-diethyl-m-toluamide to produce the novel dyes. The synthesized dyes were filtered off and then purified. To investigate and analyze the dyes, analytical methods such as 1H-NMR, FTIR, UV-visible spectroscopy, and elemental analysis were used. Consequently, the anti-bacterial activities of dyes were measured with E. coli and P. aeruginosa as a Gram-negative strain and S. aureus and S. mutans as a Gram-positive strain according to MIC method. The insect-repellent efficacy of the dyes was studied using standard methods for Anophle mosquito repellent. The results confirmed anti-bacterial and insect-repellent activity of the dyes. 相似文献
5.
In this study, poly[2-(N, N-dimethyl amino)ethyl methacrylate] (PDMAEMA) was prepared by bulk polymerization using AIBN as an initiator. Aqueous PDMAEMA
solution was then purified by hollow fiber ultrafiltration membrane technology to remove oligomers. PDMAEMA/polysulfone (PSF)
positively charged nanofiltration (NF) membrane was developed by interfacial polymerization by using PSF ultrafiltration membrane
as the substrate, PDMAEMA aqueous solution as the coating solution and p-xylylene dichloride dissolved in n-heptane as the organic crosslinker. Effects of substrate material, concentration of monomer,
pH value of PDMAEMA, coating time and crosslinking time were then carefully examined on the separation properties of the prepared
NF membrane. Data suggested that the rejection rate of the composite NF membrane to 1 g/l of MgSO4 was around 86.7 %, and the water flux was about 18.4 L·m−2·h−1. Therefore, the developed NF membrane is suitable for rejection and desalination of alkaline dyes. 相似文献
6.
Bassam A. Sweileh Fawwaz I. Khalili Imad Hamadneh Ammar H. Al-Dujaili 《Fibers and Polymers》2016,17(2):166-173
Diamino derivatives of thiadiazole namely, 2,5-diamino-1,3,4-thiadiazole and 3,5-diamino-1,2,4-thiadiazole were synthesized and characterized. Polyamides were synthesized by condensation of the two diamino derivatives with diacide chlorides. The structures of polyamides were verified by elemental analysis, FTIR, 1H-NMR, 13C-NMR and mass spectroscopy. The polyamides possess good solubility in aprotic organic solvents such as DMF, DMAC, DMSO and NMP at room temperature. Intrinsic viscosity measurements indicate that the polyamides synthesized have moderate molecular weights. The thermal stability of these polyamides in nitrogen atmosphere is relatively good, especially for those polyamides containing phenylene ring in the backbone. Compared to the structurally related Kevlar aramide, using 2,5-diamino-1,3,4-thiadiazole and 3,5-diamino-1,2,4-thiadiazole instead of p-phenylene diamine results in reducing the melting points of polyamides to below 350 °C. 相似文献
7.
Seung Woo Hu Hee Soo Myung Jong Seok Bae Eui Sang Yoo Seung Soon Im 《Fibers and Polymers》2000,1(2):76-82
A series of random copolyesters having various compositions were synthesized by bulk copolymerization of bishydroxyethyl terephthalate
(BHET) with 1,4-cyclohexane dimethanol (CHDM) or dimethyl isophthalate (DMI). CHDM and DMI content was less than 10 wt%. For
the synthesized copolyesters, isothermal crystallization rate, melting behavior, and equilibrium temperature were investigated
by calorimetry and by Avrami and Hoffman-Weeks equation. Crystalline lattice and morphology were studied by WAXD and SEM.
Regardless of the composition, the value of the Avrami exponent was about 3, which indicates that crystallization mechanism
of the copolyester was similar to those of PET homopolymer. Incoporation of CHDM or DMI units in PET backbone decreased the
crystallization rate of the copolyesters. Surface free energy of copolyesters was evaluated using the newly proposed equation.
The value of surface free energy was about 189×10−6 J2/m4 regardless of comonomer contents. This result is in good agreement with that of PET homopolymer. 相似文献
8.
An efficient and environmentally friendly method for the synthesis of cellulose carbamate from a mixture of cellulose pulp or the activated cellulose pulp and urea was presented in this paper. Cellulose carbamate with a nitrogen content of 1.21 % and 3.29 % were successfully synthesized via esterification reaction in the high-boiling aprotic and polar N-methyl-2-pyrrolidone solvents (hereinafter NMP). The structures of cellulose carbamate were characterized by Fourier transform infrared spectroscopy (FTIR), Kjeldahl analysis, thermo-gravimetric analysis, scanning electron microscopy (SEM), X-ray diffractometry (XRD), and 13C-solid-state NMR. The results showed that some functional groups of the alkali cellulose were substituted by amino in the high-boiling aprotic and polar solvents, then the cellulose carbamate was prepared with the reduced crystallinity and thermal decomposition temperature. In addition, the product was prepared with uniform substitution and distribution of carbamate group in the cellulose chain, which guaranteed its good solubility in aqueous alkali as well as its spinnability to produce fiber. 相似文献
9.
Ehsan Zamani Hanieh Shaki Mehdi Rafizadeh Alireza Khosravi Milad Pilehkouhi 《Fibers and Polymers》2017,18(8):1431-1437
A novel self-colored polyethylene terephthalate (PET) was synthesized using a synthesized dye, 4-amino-N-propanoic acid-1,8-naphthalimide. For this purpose, the prepared naphthalimide dye was added upon the polycondensation step and then a self-colored PET was prepared by step-growth polymerization. The characterization of synthesized self-colored PET and naphthalimide dye were carried out using TLC, FTIR, 1HNMR, DSC, UV-visible and Fluorometery. Results indicated that, the novel fluorescent yellow-green PET with appropriate properties was obtained. The glass transition temperature of self-colored PET was 70 °C and it was measured by differential scanning calorimeter, which revealed that addition of dye to the chains of polymer did not affect the context of glass transition of polymer. UV-visible spectrum indicated that, 99 percent of dye was incorporated in polymer chains chemically. Furthermore, the intrinsic viscosity of self-colored PET was 0.556 dl/g and molecular weight of polymer was around 35000 (g/mol) and measured using the viscometer technique. 相似文献
10.
The present study explored the preparation of glass fiber-coir reinforced unsaturated polyester resin hybrid (GCU) composites with a novel Prepreg/Press fabrication process. Flexural, impact and thermal-mechanical properties of GCU composites were investigated. Coir reinforced unsaturated polyester resin (CU) composites was also prepared with the same process to explore the enhancement effect of glass fabric on the mechanical properties of coir-based composites. The effect of fabrication pressure on the mechanical properties of CU and GCU composites was examined. Micromorphology and interfacial reaction of the composites were analyzed. It is shown that GCU composites fabricated with the Prepreg/Press process have excellent flexural strength (185.0 MPa), MOE (18.3 GPa), and impact strength (67.2 kJ/m2). The mechanical properties of GCU composites increased with the increase of applied pressure up to 0.8 MPa in the Prepreg/Press process. However, further increase of applied pressure led to the decrease in mechanical properties. The addition of glass fabrics to GCU composites showed 419 % improvement in flexural strength, 708 % improvement in MOE and 562 % improvement in impact strength over coir-based composites. The micromorphology study proved that the poor interfacial bonding between coir and matrix led to the low mechanical properties of coir-based composites. 相似文献
11.
Shihang Fan Linbin Deng Hongli Yang Liang Zhang Xingchao Sun Jinglin Liu Jing Liu 《中国油料作物学报(英文)》2019,(2):65-74
Recently, a novel green fluorescent protein eYGFPuv has been identified in the marine organism Chiridius poppei which displays high fluorescence intensity and can be visible by eyes in dark. Although strong green fluorescence was achieved in transgenic petunia, 3 expression cassettes (about 8 kb) complicate its application. In this study, to confirm whether 1 expression cassette could be used as a transgenic marker in prokaryotes and eukaryotes, eYGFPuv was cloned into prokaryotic expression vector pET28α-eYGFPuv- His and plant binary expression vector 35S::eYGFPuv. Compared to EGFP, eYGFPuv protein exhibited stronger dazzling green fluorescence in E. coli under excited light at 365 nm and maintains steadily over a long period of time without degradation. When transiently expressed in tobacco leaves, eYGFPuv protein displayed strong green fluorescence. Moreover, the fluorescence of eYGFPuv protein also could be directly observed in living plant, and thus can be used easily as a marker to screen transformed lines in transgenic research. Overall, compared to previous studies on eYGFPuv tandem repeats, our data confirmed that single eYGFPuv sequence still possesses high fluorescence intensity and quenching resistance. Furthermore, because of small size of expression cassette,it is suitable for efficient transformation in both prokaryotic and eukaryotic organisms. 相似文献
12.
A novel route for the production of polyacryloamidoxime nano-fibers is described. The innovative solution blowing spinning technique is used for the production of polyacryloamidoxime nano-fibers. The polyacryloamidoxime was prepared by the amidoximation of the acrylonitrile groups in a non-aqueous medium (DMF) using the least possible amount of hydroxylamine. A comparison study was performed to evaluate the effectiveness of the amidoximation reaction in aqueous or non-aqueous media. As the presented method is acquiring only 0.5 g/g hydroxylamine, at 50 °C for 7 h to achieve 63.1 % conversions, also solution blowing is an alternative technique for manufacturing of micro- and nano-fibers. The morphological structure, the chemical nature as well as the dyeability of the obtained fibers are illustrated. The obtained nano polyacryloamidoxime fibers show superior adsorption ability toward copper ions. Results showed that the present work presents a promising synthesis root for spinnable polyacryloamidoxime. 相似文献
13.
Jianjun Liu Yuxia Huang Yan Yuan Xiang Zhang Yanxiang Wang Chengguo Wang 《Fibers and Polymers》2014,15(8):1583-1588
Acrylonitrile-methyl itaconate (AN-MIA) copolymers were successfully prepared by free-radical solution copolymerization, and then were spun into precursors of carbon fibers by one-step wet-spun method in this study. Effect of methyl itaconate(MIA), itaconic acid (IA) and methyl acrylate (MA) on the characteristics of the copolymers and precursors were studied in contrast. The monomer reactivity ratios for AN/MIA system were determined by Kelen-Tudos (K-T) method with r 1=0.65, r 2=1.80. The viscosity test shows that using MIA as a co-monomer is an effective way to decrease the viscosity of PAN solution. During the spinning and stretching processes, polyacrylonitrile (PAN) copolymer with MIA as co-monomer can reach the higher total draw-ratio of 12.0 folds, while PAN copolymer with IA as co-monomer can reach only 8.5 folds. The fineness and elongation at-break of the PAN precursors with MIA as co-monomer improve, but the tenacity decreases. DSC test shows MIA is less effective in improving the thermal property than IA. 相似文献
14.
Nylon 4, which can be synthesized by anionic ring-opening polymerization, has good mechanical properties and a very high affinity for water owing to its high polarity. On the other hand, despite its high melting temperature, the polymer has not been commercialized because of its low thermal stability. In this study, copolymerization of 2-pyrrolidone (C4) with 2-piperidone (C5) was performed to reduce the melting temperature of Nylon 4 homopolymer. The copolymerization reaction was controlled by changing the comonomer content, catalyst content, temperature, initiator content, and reaction time. The Nylon copolymers were characterized by 1H-nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The hydrophilic properties of Nylon 4 and its copolymers were evaluated by surface free energy analysis and moisture regain measurement. The intrinsic viscosity and polymerization yield of Nylon 4 increased with increasing catalyst concentration until 5 mole% and decreased with further increases in catalyst loading. The proton NMR spectrum revealed the composition of the Nylon 4/5 copolymer to be 62.5 % C4 moiety at a 5:5 comonomer feed ratio. The melting temperature of the Nylon 4/5 copolymers decreased considerably according to the composition. The moisture regain of the Nylon 4/5 copolymer was higher than 6.4 % even at 77.3 % C4 in composition. 相似文献
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16.
Li Chang Xiaozhuan Zhang Xibao Shi Liang Zhao Xuanming Liu 《Fibers and Polymers》2014,15(10):2026-2031
A novel antibacterial fiber named MTPB-PANF was synthesized by chemical modification of polyacrylonitrile fiber (PANF). The PANF was firstly reacted with alkali solution to get Na-PANF with -COONa functional groups. Na-PANF was then reacted with different concentration of methyltriphenyl phosphonium bromide (MTPB) into flasks, and the whole system was immersed into a to and fro vibrator. During the synthesis process, this paper investigated on the initial concentration of MTPB, the contact time, the reaction temperature and the pH of the solution that may have effect on the properties of the final fiber. The properties of MTPB-PANF were discussed by fourier transform infrared spectroscopy (FTIR), thermo gravimetric analyzer (TGA), scanning electron microscope (SEM) and the stability of organophosphorus groups on MTPB-PANF examined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The antibacterial activity of MTPB-PANF was examined against pathogenic Escherichia coli and Staphylococci aureus by improved shake flask method in sterile saline and was evaluated by the viable cell counting method. The obtained results showed an excellent antibacterial activity of MTPB-PANF. And the antibacterial mechanism was discussed by the concentration of K+ released from cells after bacterial testing. 相似文献
17.
By hydrothermal treatment, α-Fe2O3 with club and date pit-like structures were successfully prepared using amphiphilic diblock copolymer poly(styrene-b-acrylic
acid) (PS-b-PAA) micelle as soft template. The particles were characterized by fourier transform infrared (FTIR), powder X-ray
diffraction (XRD), scanning electron microscopy (SEM). The influence of factors on the morphologies of α-Fe2O3 particles, such as the compositions and concentration of copolymer, and existence of citric acid, has been discussed. 相似文献
18.
Ali NO Ibrahim ME Grant KM Mottram JC 《Pakistan journal of biological sciences: PJBS》2010,13(16):775-784
We are reporting here, the cloning and characterization of the first cyclin from Leishmania mexicana. We have identified a cyclin-like motif from the L. major genome sequencing project. A cyclin homologue was cloned and sequenced from L. mexicana genome and it showed 96.1% amino acid identity with the putative L. major cyclin. It has also sequence identity to mitotic cyclins from other organisms. Southern analysis showed that it is present as a single copy gene. CYCa has been over-expressed in E. coli as a histidine fusion and western blot has confirmed the immunoreactive property of the recombinant cyclin, which then used to reconstitute active recombinant L. mexicana CRK3. No phosphorylation of histone HI was detected by both wild type and mutated CRK3 on the activation assays suggesting that phosphorylation status and cyclin binding are important for reconstituting protein kinase activity. The results confirm that we have isolated a cyclin molecule from L. mexicana (LmCYCa) which may play an important role in the regulation of the parasite cell cycle. 相似文献
19.
The demand for diesel fuel far exceeds the current and future biodiesel production capabilities of the vegetable oil and animal fat industries. New oilseed crops that do not compete with traditional food crop are needed to meet existing energy demands. Hybrid hazelnut oil is just such an attractive raw material for production of biodiesel. Hazelnut oil was extracted from hybrid hazelnuts and the crude oil was refined. Hazelnut oil-based biodiesel was prepared via the transesterification of the refined hazelnut oil with excess methanol using an alkaline catalyst. The effects of reaction temperature, time and catalyst concentration on the yield of diesel were examined, and selected physical and chemical properties of the biodiesel were evaluated. The biodiesel yield increased with increasing temperature from 25 to 65 °C and with increasing catalyst concentration from 0.1 to 0.7 wt%. The increase in yield with reaction time was nonlinear and characterized by an initial faster rate, followed by a slow rate. Hazelnut oil-based biodiesel had an average viscosity of 8.82 cP at 25 °C, which was slightly higher than that of the commercial soy-based diesel (7.92 cP at 25 °C). An approximate 12 °C higher onset oxidative temperature and a 10 °C lower cloud point of hazelnut oil biodiesel than those of its commercial soy counterpart indicated a better oxidative stability and flowability at low temperature. The average heat of combustion of hazelnut oil biodiesel was 40.23 kJ/g, and accounted for approximately 88% of energy content of diesel fuel. The fatty acid composition of hazelnut oil-based biodiesel was the same as the nature oil. 相似文献
20.
The effect of main chain structure of anion-containing copolyesters on the properties of copolyester sizing agents was investigated.
The copolyesters were prepared by conventional two step polymerization technique from DMT, DMI, DMS, EG, and DEG. The copolyesters
synthesized were characterized by atomic absorption spectroscopy,1H-NMR Spectroscopy, GC, FTIR Spectroscopy, and DSC. The solubility decreased as the DMT content increased. The copolyesters
having DMT:DMI=1:1 showed the minimum viscosity. The effect of EG content on the solution stability was not clear and the
samples having high DMI content showed better solution stability. The water resistance was best when only DMI and EG were
used, while it was worst when DMT:DMI was 1:0. 相似文献