JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 56
·期 4
·3623-3637
·
IF 3.553
Ning Lijian,Yuan Li,Liang Guozheng,Gu Aijuan
It is still a great challenge to endow remoldable triple-shape memory thermosets (Rtri-SMTs) with high glass transition temperature ( T g ) and high mechanical properties. Herein, two Rtri-SMTs with high T g and high tensile properties, coded as BA1 and BA2, were developed through building unique dynamic crosslinked networks based on bismaleimide and novel bisallyl compounds with dynamic ester bonds (AEG1 and AEG2). The T g values of BA1 and BA2 resins are 143 °C and 203 °C, respectively, much higher than those of Rtri-SMTs reported so far (10–110 °C); meanwhile, BA resins exhibit high tensile strengths (BA1: 81 MPa; BA2: 84 MPa) and moduli (BA1: 2165 MPa; BA2: 3233 MPa), which are severally at least about 1.3–1.4 and 3.2–4.7 times of those Rtri-SMTs in the literature, respectively. Besides the superiorly high thermal and tensile properties, both BA resins are able to be remolded and reconfigured through the re-arrangement of crosslinked networks induced by dynamic exchange reaction of ester bonds. The mechanism behind these attractive properties of BA1 and BA2 resins is discussed. Graphical abstract Remoldable triple-shape memory thermosets with high glass transition temperature, high mechanical properties and good reconfigurability were developed.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
RENEWABLE ENERGY
·
2020
·
IF 6.274
Yujiao Zhang,Shengli Niu,Kuihua Han,Yingjie Li,Chunmei Lu
Calcium oxide is one of the most promising heterogeneous catalysts for biodiesel production . However, an inherent drawback of CaO is the leaching of active species into the reaction solution with the degraded reusability . To strengthen the stability, different supports are composited with the SrO–CaO oxide through the hydrothermal method and mass ratio of SrO to CaO are optimized to get the best outcome of the catalyst. Meanwhile, various characterization methods, including TG , XRD , SEM-EDX, CO 2 -TPD, XPS , ATR-FTIR and ICP-AES, are used to explore the physicochemical properties of catalysts. The 0.4-SrO-CaO-Al 2 O 3 catalyst shows the best catalytic capability in transesterification of palm oil with methanol to produce biodiesel , where the FAME yield of 98.16% is achieved with the molar ratio of methanol to oil of 18:1 and catalyst concentration of 7.5 wt% at 65 °C for 3 h. Besides, ascribed to the greatly reduced leaching out of the active species , this catalyst presents the satisfying reusability and the FAME yield is slightly decreased to 92.61% for the fifth reused cycle. Therefore, this modification method for SrO–CaO–Al 2 O 3 is feasible for enhancing the catalytic stability in transesterification .
研究领域:
催化化学
·
可再生能源
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2020
·Vol. 11
·期 34
·5512-5525
·
IF 5.342
Ming Zhang,Yifei Tu,Zibo Zhou,Guozhang Wu
The exo-hydroxyl group (exo-OH) on isosorbide (ISB) has long been asserted as a highly reactive moiety compared with the endo-hydroxyl group (endo-OH). In this study, calculations based on density functional theory and experiments without adding catalysts reveal that endo-OH has strong nucleophilic ability, and in the case of transesterification with diphenyl carbonate, the nucleophilic attack surmounts steric hindrance in rendering endo-OH more reactive than exo-OH. The kinetics of transesterification with different catalysts is investigated to determine the catalytic reactivity and molecular structure evolution. The results show that preferential activation of exo-OH moieties can be achieved either by reducing the coordination ability of catalytic cations (lg β1) or by enhancing the alkalinity of catalytic anions. Despite the low reactivity of exo-OH on ISB monomers, terminal exo-OH on carbonate oligomers exhibits higher reactivity than terminal endo-OH, justifying the experimental fact that ISB-based polycarbonates (ISB-PCs) are mostly terminated by endo-OH. Balancing the reactivity between endo-OH and exo-OH can be promoted by increasing the reaction temperature, thus accelerating transesterification to a high equilibrium constant. These findings help to clarify the mechanism of ISB transesterification and provide new strategies for the synthesis of high-molecular-weight ISB-PCs.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
AICHE JOURNAL
·
2026
·
IF 4.4
Jingwen Qiu,Zixuan Huang,Xin Wei,Zhendong Pan,Zhihong Ma,Weizhen Sun,Zhenhao Xi,Shimei Xu,Ling Zhao,Weizhong Zheng
Waste polyesters pose a severe environmental challenge and require transformative upcycling strategies to achieve a circular plastic economy. Distinct from conventional methanolysis relying on stoichiometric external alcohols or water-triggered esterolysis, this study proposes a novel universal low-temperature transesterification strategy for the upcycling of diverse polyesters into high-value esters, using an internally driven self-sustained transesterification cycle where, triggered by trace alcohols, dimethyl carbonate (DMC) dynamically exchanges its alkoxy groups with diols released from the polyester backbone. Typically, polyethylene terephthalate (PET) can be efficiently transesterified into dimethyl terephthalate (DMT) and ethylene carbonate (EC), reaching peak yields of 96% and 86%, respectively, under mild conditions. The self-sustained transesterification strategy shows broad applicability to various types of polyesters, mixed textiles, post-consumer plastics, and can also be extended to polyester upcycling using other alcohols and alkylating agents, which significantly reduces energy consumption and carbon emissions compared to traditional alcoholysis-based systems, providing a scalable route for plastic circularity.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2026
·Vol. 33
·期 4
·163
·
IF 3.5
Wang Jing,Bai Wei,Wang Gongying,Li Chen,Wang Qingyin
Bisphenol-fluorene-type polycarbonate as a transparent thermoplastic resin, exhibits low birefringence due to the rigid fluorene. In this paper, a series of random co-polycarbonates (BPEF/BPA-PC) were prepared from bisphenol A(BPA), 9,9-bis[4-(2-hydroxyethoxy) phenyl] fluorene (BPEF) and diphenyl carbonate (DPC) using melt transesterification method by adjusting molar ratios of raw materials. The effects of catalyst dosage, polycondensation temperature and polycondensation time on the molecular weight of the products were systematically investigated, and the copolymer structures were characterized by FT-IR, 1 H NMR and 13 C NMR spectra tests; the thermal performance were determined by Differential Scanning Calorimeter (DSC) and thermogravimetric analysis. The molecular weights and their distributions( Đ ) were determined by Gel Permeation Chromatography. The results of GPC showed that the max M w of copolymers reached to 6.8*10 4 g/mol and Đ was 1.81. The maximal thermal decomposition temperature ( T d,5% ) of the co-polycarbonate reached to 359.3 °C. The refractive index of the materials was characterized using an Abbe refractometer and it showed refractive index (n d ) up to 1.640 under visible light. Mechanical property tests showed that the tensile strength of co-polycarbonate were significantly increased when the contents of BPEF was higher, reflecting the enhancement effect of fluorene unit on the rigidity of molecular chain.
✓ 已验证
DOI
高影响因子
PROCESS BIOCHEMISTRY
·
2024
·
IF 3.7
Wenjing Liu,Kexin Qiang,Peipei Ye,Xin Li,Xiaoman Zhao,Jianhan Hong,Yafeng Duan
Polyethylene terephthalate (PET) fabric was enzymatically modified with polyethylene glycol (PEG). Lipase from Aspergillus oryzae was used as a catalyst. The wetting behavior of the modified PET fabric was characterized by the water contact angle , water adsorption dynamics and moisture regain. The initial water contact angle of the modified fabric decreased from 129.3° to 74.9°. The water absorption dynamics results indicated that the equilibrium water absorption amount of the modified fabric was approximately 10 times greater than that of the untreated sample. The initial absorption rate ( V init ) of the modified fabric was almost 30 times higher than that of the untreated fabric. The moisture regain reached 3.52 % after modification. Scanning electron microscopy revealed granular and sheet coatings on the surface of the modified fabric. Chemical linkage of PEG onto the PET fibers was confirmed by attenuated total reflection–Fourier transform infrared spectroscopy. The modification had no significant effect on the thermal properties of the PET fabrics according to the thermogravimetric curve and differential scanning calorimetry results. The mechanical properties of the modified fabric were slightly improved. Therefore, in situ enzymatic transesterification between PET and PEG could be a potential novel modification approach for adding value to PET fiber textiles .
研究领域:
材料科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH INNOVATIONS
·
2023
·
IF 0
Yiye Song,Jikai Zhang,Hongjun Yang
Poly(ester-ether)s are biodegradable copolymers with excellent performance. These copolymers are used as scaffolds for tissue engineering and degradable materials in packaging. However, their synthesis procedures are generally tedious which restrict their widespread applications. Furthermore, the inadequate availability of their commercial monomers also hampers their production. Herein, we reported a facile strategy for the synthesis of linear and branched poly(ester-ether)s using a polyol and methyl acrylate (MA) as monomers. During the polymerisation, the vinyl bond of MA reacts with the hydroxyl groups of a polyol following an oxa-Michael polyaddition mechanism. Simultaneously, esterification takes place between the ester group of MA and polyol. As a result, poly(ester-ether)s were successfully synthesised by combining these two different types of reactions into one polymerisation system. The linear and branched structures of the products were confirmed by the nuclear magnetic resonance and triple-detector gel permeation chromatography. This work provides a facile strategy for the synthesis of poly(ester-ether)s from commercially available monomers.
✓ 已验证
DOI
Molecular Catalysis
·
2018
·
IF 0
Yanan Liang,Kunmei Su,Lei Cao,Zhenhuan Li
Lithium doped TiO 2 were prepared by simple impregnation, which was used as heterogeneous catalysts for the transesterification of DMC with BPA. The characterized results of FTIR, XRD, XPS, SEM, TEM and temperature programmed desorption of CO 2 (CO 2 -TPD) showed that the structure and performance of the catalysts were obviously influenced by the doping amount of Li + and calcining temperature. The optimum catalytic activity was obtained when the molar ratio of Ti/Li reached 6 and the calcination temperature came up to 400 ℃, which was due to Li + reaction with TiO 2 to form surface Ti-O-Li at 400 ℃ (Ti/Li-6-400). When the transesterification of DMC with BPA was carried out at 160–180 ℃ over Ti/Li-6-400, BPA conversion reached 46.67%, and the yields of one-methylcarbonate-ended-BPA (MmC(1)) and two-methylcarbonate-ended-BPA (DmC(1)) achieved 36.36% and 5.97%, respectively, and only 9.3% methylation selectivity was detected. In addition, the possible transesterification mechanism was provided.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
Journal of Cleaner Production
·
2024
·
IF 9.7
Zhengkun Hou,Xueli Geng,Qiuyan Ding,Hong Li,Yaocong Guo,Ting Qiu,Chen Yang,Qinglian Wang,Xin Gao
With the increasing demand of cyclohexanol in nylon industry, it is significant to develop a safe, green and economical process to produce cyclohexanol. For this purpose, a novel reactive distillation process through cyclohexyl acetate transesterification with methanol was proposed in this work. The NKC-9 catalyst was preferred to establish the reaction kinetic model based on pseudo-homogeneous model. Seven reactive distillation experiments with pilot-scale for cyclohexanol synthesis were explored to prove feasibility of reactive distillation processes and accuracy of model by comparing simulated results, which ensured the establishment of the process simulation. Furthermore, three reactive distillation processes of cyclohexanol production were designed and optimized by the sequential iterative algorithm based on minimum total annual cost. After optimization of pressure and recycled stream flow, a novel double column of reactive and pressure-swing hybrid distillation process showed the minimized total annual cost per ton product, which was 170.90 $/kg. Finally, total annual cost of transesterification, hydrolysis and hydrogenation processes were compared, and transesterification process demonstrated economic advantage. This work would provide a guidance for cyclohexanol green production by reactive distillation through cyclohexyl acetate transesterification, while a whole, economical and atomic economical reactive distillation process of cyclohexanol production could be established in the future.
研究领域:
化学工程
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2019
·
IF 4.63
Xin Yuan,Panliang Zhang,Weifeng Xu,Kewen Tang
This paper reports the kinetics resolution of ( R , S )-4-methoxymandelic acid (4-MMA) by lipase AK-catalyzed transesterification reaction, using vinyl acetate (VA) as acyl donor in methyl tert-butyl ether (MTBE). Considering the Ping-Pong bi-bi mechanism with 4-methoxymandelic acid inhibition, the kinetic model was established. Kinetic parameters were obtained by fitting time-concentration curves for different initial 4-methoxymandelic acid concentrations. The average relative error below 3.0% indicated that the model predictions were in good agreement with the experimental data. Furthermore, the kinetic model was employed to predict the effects of enzyme loading, initial vinyl acetate concentration and reaction time on enantiomeric excess (ee s ) and conversion of substrate (c), and to optimize the conditions. The excellent results with high conversion of 4-MMA (50.2%) and large enantiomeric excess of substrate (98.6%) were achieved under the optimal conditions.
研究领域:
生物化学
·
有机化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2018
·Vol. 66
·期 2
·164-170
·
IF 0.862
Pingbo Zhang,Mengnan Zhu,Mingming Fan,Pingping Jiang,Yuming Dong
Several rare earth-doped, calcium-based magnetic catalysts were prepared for the synthesis of glycerol carbonate. The basicity and basic strength analysis of the catalysts showed that the doping of rare earth improved the basicity of the catalysts, and the doping of lanthanum maximized it. In addition, with the doping of lanthanum, the particle size of the catalyst became smaller to promote the organic reactants near the active sites of catalysts, thereby effectively improving the performance. NiFe 2 O 4 @[CaO-La 2 O 3 ] shows better catalytic performance with 99.0% yield of glycerol carbonate compared to the other catalysts. The NiFe 2 O 4 @(CaO-La 2 O 3 ) could be reused in six cycles without significant loss in activity.
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
BULLETIN OF THE KOREAN CHEMICAL SOCIETY
·
2017
·Vol. 38
·期 3
·369-377
·
IF 0.602
Fei Shi,Guo Bing Li,Hong Liang Sun,Wang Feng Cai
The dihydric alcohol transesterification of 1,4-butanediol with methyl acetate catalyzed by the ion-exchange resin is researched. The chemical system involves two transesterification reactions in series, with 1,4-butanediol monoacetate as an intermediate product. The effects of the catalyst type, catalyst size, catalyst loading, stirrer speed, the initial reactant ratio, and the reactive temperature have been meticulously studied. The results show that this consecutive transesterification is exothermic and the experimental values of reaction enthalpy are −8.50 and −6.85 kJ/mol, which are in good agreement with the values computed from the standard formation enthalpy. Three kinetic models (PH, LH, and ER) are applied to correlate the experimental data, of which ER model gives the best result with the lowest mean relative error. The activation energies are calculated to be 38.53 and 51.06 kJ/mol by ER model, demonstrating that the overall reaction rates are controlled by the reaction on the catalyst surface.
研究领域:
化学工程
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）