JOURNAL OF APPLIED POLYMER SCIENCE
·
2014
·Vol. 132
·期 7
·
IF 1.64
Pan Dongdong,Tian Hengshui
Soluble and thermally stable polycarbonate polyurethane elastomers were synthesized through a solvent-free and nonisocyanate melt transesterification process. The conditions of this process were studied, and the optimum conditions were as follows: the catalyst dibutyltin oxide dosage was 0.125 wt %, the raw material molar ( n ) ratio of dimethyl 1,6-hexamethylene dicarbamate (HDC) to poly(carbonate macrodiol) (PCDL) was n (HDC)/ n (PCDL) = 1:0.99, the reactants were prepolymerized under 100°C for 1 h and then under 185°C and a high vacuum for 4 h. Three different PCDLs were selected to participate in the reaction under the conditions mentioned previously, and their structures were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The products obtained from this process were still stable under 280°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41377.
研究领域:
高分子化学
·
生物材料
·
聚合物科学
·
材料化学
·
医用高分子
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 138
·期 39
·51010
·
IF 3.125
Yue Yin,Jian Yang,Linghui Meng
Poly(butylene succinate) (PBS) refers to a high-performance biodegradable polymer employed to substitute petroleum polymers that cause environmental issues. However, PBS exhibits the defect of flowing above the melting point and rapid dripping for its poor melt strength. Accordingly, this study proposed a novel method to fabricate PBS vitrimer by exploiting reactive extrusion technology to mix diepoxide with PBS and then by employing zinc acetate as a catalyst to crosslink the PBS. Therefore, after the reaction extrusion blending, the blend still has a lower viscosity and high processing performance; in the subsequent curing process, the polymer undergoes a transesterification reaction and the viscosity increases. Via transesterification to form a cross-linked network, the storage modulus, and loss modulus of PBS vitrimer at 140°C reach 55,800% and 3500% of pure PBS, respectively. At this time, the crystallinity of PBS vitrimer is still as high as 56.9% (The crystallinity of pure PBS is 47.4%). And the shape stability of PBS at high temperatures was significantly improved. Moreover, PBS vitrimer could still be reshaped after the cross-linking process. This study proposed a facile method to produce PBS materials exhibiting high thermal shape stability.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Mingjie Chen,Rui-Min Li,Troy Runge,Jin Feng,Jing Feng,Songnan Hu,Qing-Shan Shi
Cellulose acetate is one of the oldest synthetic thermoplastic polymers and has various applications including usage as films, fibers, and membrane products. Traditionally, cellulose acetate is prepared by reacting cellulose with acetic anhydride in acetic acid using sulfuric acid as a catalyst. This process suffers from extensive depolymerization of the cellulose molecules and corrosion of the equipment from the use of the acidic solvent and catalyst. Herein we present an acid-free cellulose acetylation process using vinyl acetate as both the reactant and reaction medium and 1-ethyl-3-methylimidazolium acetate as the catalyst. The obtained cellulose acetate was confirmed by FTIR, NMR, and XRD studies. Additionally, the reaction kinetics, mechanism of the process, and properties of the obtained cellulose acetate were studied. Cellulose triacetate was obtained by our process within 2 h at 90 °C. The reaction kinetics was described with the classical pseudo-first-order rate expression of heterogeneous cellulose acetylation. The reaction mechanism was shown to be a peel-off mechanism similar to that of cellulose acetylation by the traditional acetic acid process. The molecular weight of the cellulose acetate produced by this new process was significantly higher than that from the traditional acetic acid process because of the absence of strong acids, which can depolymerize cellulose. In summary, we describe a new acid-free process to produce cellulose acetate that limits cellulose depolymerization and avoids the use of corrosive chemicals.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2019
·
IF 6.044
Xueqin Zhang,Naiyu Xiao,Mingjie Chen,Yi Wei,Chuanfu Liu
An alternative transesterification with vinyl laurate (VL) was applied for chemical modification of hemicelluloses (HC) to prepare functional packaging films. Successful transesterification was confirmed by FT-IR and NMR. Semitransparent laurated HC (LHs) films were prepared by solvent casting method. SEM indicated the ordered honeycomb-patterned surface and the dense cross section of LHs films. The LHs films exhibited excellent hydrophobicity with water contact angle about 120° and the enhanced mechanical properties with tensile strength and elongation at break as 33.94 ± 3.09 MPa and 22.41 ± 2.87%, respectively. The water vapor permeability (WVP) and oxygen permeability (OP) values of LHs films ranged from 1.59 ± 0.07 to 2.23 ± 0.11 (10 −10 ·g/m·s·Pa) and 1.21 ± 0.04 to 4.24 ± 0.30 (cm 3 · μ m/m 2 ·d·kPa), respectively. Moreover, the films had acceptable antioxidant activity. In terms of these properties, the shelf life of green chilies could be largely extended to 15 days after packing with LHs films.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING & TECHNOLOGY
·
2014
·Vol. 37
·期 2
·283-292
·
IF 2.175
Bin Ye,Fengxian Qiu,Chuanjia Sun,Yihuai Li,Dongya Yang
A novel heterogeneous base catalyst for biodiesel production was prepared from the support of alumina/silica loaded with potassium sodium tartrate by a one-step sol-gel process and the optimal conditions were investigated. Microwave-assisted transesterification of soybean oil was carried out for the production of biodiesel. The catalysts were characterized by FT-IR, TG-DSC, SEM, TEM, EDX, XRD, and the Hammett indicator. The effects of the molar ratio of methanol to oil, reaction temperature, and amount of catalyst on the biodiesel yield were determined. The prepared heterogeneous catalyst could be easily separated from the reaction system with high efficiency and its constant activity maintained after application for four cycles.
研究领域:
化学工程
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 7
·4408-4416
·
IF 4.036
Guanhao Liu,Jingyi Yang,Yibo Zhao,Xinru Xu
Novel modified MOF intercalated hydrotalcites was synthesized for catalyzing the conversion of glycerol into high value-added glycerol carbonate in this paper. [APmim]OH/ZIF-8 was prepared by encapsulating aminopropyl hydroxide imidazole ionic liquid in ZIF-8 and inserted in Ca–Mg–Al hydrotalcites with layered structures to prepare [APmim]OH/ZIF-8/LDH with strong basicity and high specific surface area. ZIF-8, [APmim]OH/ZIF-8 and [APmim]OH/ZIF-8/LDH were characterized by XRD, FT-IR, SEM and nitrogen adsorption–desorption. The results showed that the conversion rate of glycerol can reach 98.6% and the glycerol carbonate yield was 96.5% in the transesterification of glycerol with dimethyl carbonate catalyzed by [APmim]OH/ZIF-8/LDH when the molar ratio of DMC and glycerol was 3 : 1, the catalyst dosage was 3 wt%, the reaction temperature was 75 °C and the reaction time was 80 minutes. The glycerol conversion rate can still reach more than 90% after five reaction cycles.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FLUID PHASE EQUILIBRIA
·
2022
·
IF 2.745
Jingjun Liu,Dandan Pan,Qing Zhang,Yulei Guan,Bolun Yang
Phase splitting and merging exist in the glycerol transesterification with diethyl carbonate. This work measured the liquid-liquid equilibrium data for two ternary systems (glycerol – diethyl carbonate – glycerol carbonate/ethanol) and one quaternary system (glycerol – diethyl carbonate – glycerol carbonate – ethanol) involved in the glycerol transesterification at various temperatures (343.2 K, 363.2 K, 383.2 K, and 403.2 K) and 1.5 MPa. The equilibrium data were correlated using the NRTL as the activity coefficient model, and the corresponding binary interaction parameters were estimated and validated by checking the consistency of the Gibbs free energy and phase stability for all mixtures in both the immiscible and homogeneous regions. The NRTL model with the regressed parameters could tightly capture the phase equilibrium trends of the systems.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
DIAMOND AND RELATED MATERIALS
·
2023
·
IF 4.1
Yuan Xue,JinXia Wang,Hong Yuan,Hui Li
With the aim of preparing a sulfonic acid-type solid acid catalyst having a high density of acid sites and excellent stability, this work synthesized sulfonic acid bowl-shaped hydrothermal carbon microspheres (SA-OBHCs), using amine groups as the primary sulfonic acid bonding sites. This material was synthesized via a three-step functionalization process comprising the oxidation , amidation and sulfonation of BHCs. The extent to which chlorosulfonic acid reacted with amine groups in diethylenetriamine molecules on microsphere surfaces was also investigated using density functional theory calculations. These calculations showed that the substitution reaction of primary amines proceeded less readily than that of secondary amines but provided a more stable product. The surface acid d ensity of the SA-OBHCs was as high as 11.2 mmol·g −1 and the –SO 3 H groups on the SA-OBHCs were found to be thermally stable up to 200 °C. These SA-OBHCs were subsequently used to catalyze the synthesis of fatty acid methyl esters (FAMEs) from a waste frying oil model compound and methanol. Reactions performed using a methanol/oil molar ratio of 20:1 at 140 °C for 3 h gave a FAMEs yield of 93.4 %. After four reuses, an SA-OBHCs specimen provided a FAMEs yield of 77.5 %, demonstrating the significant stability of this material.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2022
·Vol. 98
·期 1
·66-76
·
IF 3.709
Yuan Xue,Xueling Zhao,Hong Yuan,Hui Li
Background An efficient sulfonic acid-type acid catalyst with high acid site density based on hydrothermal carbon microspheres (HCMs) has been developed. The reaction by which double bonds in the HCMs were oxidized to generate carboxyl groups was evaluated based on density functional theory calculations. Results Sulfonic acid-type HCMs (SHCMs) were prepared from HCMs through a three-step process comprising oxidation, amidation and sulfonation. An analysis of the oxidation process indicated that the formation of carboxyl groups involved the activation of O 2 molecules and C H bonds, the cleavage of CC bonds, the homolytic fission of peroxy acids and the coupling reactions of H • radicals. The formation of numerous carboxyl groups on the HCM surfaces was the key to obtaining SHCMs with a high acid density of 14.5 mmol g −1 . Conclusions The SHCMs obtained exhibited good catalytic performance during the transesterification of waste frying oil with methanol. Reactions performed using a methanol/oil molar ratio of 9:1 at 90 °C for 5 h gave a fatty acid methyl ester yield of 85.56%. © 2022 Society of Chemical Industry (SCI).
研究领域:
催化化学
·
理论计算
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2023
·Vol. 13
·期 38
·26700-26708
·
IF 3.9
Zhenglong Zhao,Wenwang Wu,Lihua Jia,Xiangfeng Guo
The efficient sodium phosphate (Na3PO4) solid base catalysts were prepared and applied in the production of novel biodiesel: ethylene glycol monomethyl ether monolaurate (EGMEML) by transesterification. The calcined sodium phosphate catalysts (NaP-T) were characterized using thermogravimetry analysis (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and so on. The effects of calcination temperature of Na3PO4 and main reaction parameters such as molar ratio of ethylene glycol monomethyl ether (EGME) to methyl laurate (ML), dosage of catalyst, reaction time and temperature on the yield of EGMEML were examined. The results showed that the maximum yield of EGMEML could reach 90% under 120 °C within 4 h and 5 wt% of Na3PO4 calcined at 400°, and the catalysts displayed good stability and recovery. In addition, the kinetics of transesterification reaction was explored and the results showed that the transesterification reaction followed 1st order kinetics when a large excess of EGME was used, the activation energy (Ea) was found to be 40.2 kJ mol−1.
研究领域:
化学工程
·
可再生资源与环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2023
·
IF 5.9
Md Asraful Alam,Liya Deng,Ange Douglas Potchamyou Ngatcha,Aymard Didier Tamafo Fouegue,Jingcheng Wu,Shen Zhang,Anqi Zhao,Wenlong Xiong,Jingliang Xu
Traditional two steps biodiesel production process generally involves corrosive sulfuric acid in the transesterification step, which is not environmentally benign. In this work, a novel procedure was presented for the direct production of biodiesel using Lewis acid deep eutectic solvent (LADES) to avoid using sulfuric acid. Synergy between the Lewis site of the LADES catalyst and the Brønsted site from biomass pretreated by Brønsted acidic deep eutectic (BADES) has resulted in the development of a bifunctional medium considered to be appropriate for high biodiesel formation and increase the FAMEs weight. The mechanism of biodiesel formation was anticipated through the experimental and computational studies of Lewis and/or Brönsted acid sites in the reaction process. The potential interference factors of the extraction process such as time of reaction, temperature, LADES catalyst concentration in methanol, and solvent volume were further optimized experimentally, followed by the Box–Behnken method. The highest amount (39.86 mg/g) of fatty acid methyl esters (FAMEs) was obtained from Chlorella pyrenoidosa biomass at 120 °C for 90 min, 5 mL solvent volume, and 5% concentration of LADES (ChCl-CrCl 3 .6 H 2 O) catalyst in methanol. The predominant FAMEs were C16:0 (9.47 mg/g), C18:2 (12.42 mg/g), and C18:3 (8.68 mg/g), and obtained biodiesel qualities meet international standards. The recyclability of LADES was tested, and satisfactory results of FAME weight were observed up to three cycles, and the FTIR peaks of LADES catalyst after four cycles of reusing have shown the structure of DES remain stable. Despite the existence of sustainable, efficient, and less toxic ways for microalgae transesterification, further investigation is required to assess the scalability of these methods for large-scale use.
研究领域:
生物技术
·
能源科学
·
环境科学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
·
2014
·Vol. 16
·期 6
·3218-3223
·
IF 6.852
Dongling Xue,Ying Mu,Yu Mao,Tiankui Yang,Zhilong Xiu
The production of biodiesel from soybean oil and ethanol was investigated in switchable-polarity solvent (SPS) media of DBU and ethanol. The highest biodiesel yield catalyzed by DBU could reach 97.9% under optimized conditions, i.e. ethanol–oil molar ratio: 12 : 1, DBU–oil molar ratio: 2 : 1, reaction temperature: 70 °C, reaction time: 2 h. According to the kinetic analysis, the reaction order of oil was estimated to be 0.7, the apparent activation energy was 16.763 kJ mol−1, the pre-exponential factor was 561.31 mol0.3 mL−0.3 min−1 using the Arrhenius equation for the first time, which explains the high efficiency of the DBU catalyst. The DBU-catalyzed transesterification in the DBU–ethanol switchable-polarity solvent offered an interesting alternative, which would be used to simplify the transesterification and separation to a single step.
研究领域:
化学工程
·
能源科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）