Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 12

年份

2023 2

2022 2

2018 2

2016 1

2014 1

2011 2

2008 1

展开︾

关键词

共混膜 1

油水分离 1

浸没沉淀 1

聚(乙烯-乙烯醇) 1

聚乙烯吡咯烷酮 1

展开︾

检索范围：

排序：展示方式：

Oil bleed from elastomeric thermal silicone conductive pads

Yuqi Chen,Yakai Feng,Jingqi Zhao,Jingbo Shen,Menghuang Feng

《化学科学与工程前沿（英文）》 2016年第10卷第4期页码 509-516 doi: 10.1007/s11705-016-1586-y

摘要： Oil bleed is a serious problem in elastomeric thermal silicone conductive pads. The components of the oil bleed and the effect of the silicone chemical parameters on the amount of oil bleed have been determined. The main components of oil bleeds are the uncrosslinked silicones in the cured resins, which include the unreacted silicone materials and the macromolecular substances produced by the hydrosilylation reaction. Cured resins with a high crosslinking density and a high molecular weight of vinyl silicone residues had a lower amount of oil bleed. In addition, a low Si-H content also reduced the amount of oil bleed.

关键词： oil bleed crosslinking density molecular weight vinyl silicones hydrosilicones

HTML PDF 收藏

Insight of chemical environmental risk and its management from the vinyl chloride accident

《环境科学与工程前沿（英文）》 2023年第17卷第4期 doi: 10.1007/s11783-023-1652-x

摘要： The combustion of vinyl chloride (VC) after the train derailment accident in Ohio, USA in February, 2023 has caused widespread concern around the world. This paper tried to analyze several issues concerning the accident, including the appropriateness of the VC combustion in the emergency response in this accident, the meanings of so-called “controlled combustion”, the potential environmental risks caused by VC and combustion by-products, and follow-up work. In our view, this accident had surely caused environmental and health risks to some extent. Hence, a comprehensive environmental risk assessment is necessary, and then the site with risk should be comprehensively remediated, hazardous waste should be harmlessly treated as soon as possible. Finally, this accident suggests that further efforts should be taken to bridge the gap between chemical safety management and their environmental risk management.

关键词： Vinyl chloride Combustion Chemical safety management Environmental risk Emerging contaminants

HTML PDF 收藏

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1484-1502 doi: 10.1007/s11705-023-2331-y

摘要： Various hydrophilic poly(ethylene-co-vinyl alcohol) (EVOH) were used herein to precisely control the structure and hydrodynamic properties of polysulfone (PSF) membranes. Particularly, to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol (VOH: 73%, 68%, 56%), the non-solvent-induced phase separation (NIPS) technique was used. Polyethylene glycol was used as a compatibilizer and as a porogen in N,N-dimethylacetamide. Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism. The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism. Accordingly, the addition of EVOH led to an increase in the rheology of the dopes. The resulting membranes exhibited a microporous structure, while the finger-like structures became more evident with increasing VOH content. The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics. Interestingly, the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^–2·h^–1·bar^–1, which was higher than that of pure PSF membranes (171 L·m^–2·h^–1·bar^–1). In addition, PSF/EVOH32 rejected bovine serum albumin at a high rate (> 90%) and achieved a significant restoration of permeability. Finally, from the thermodynamic and hydrodynamic results, valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

关键词： polysulfone blend modification ultrafiltration membrane formation hydrodynamics poly(ethylene-co-vinyl alcohol) copolymer

HTML PDF 收藏

Molecular diffusion in ternary poly(vinyl alcohol) solutions

《化学科学与工程前沿（英文）》 2022年第16卷第6期页码 1003-1016 doi: 10.1007/s11705-021-2121-3

摘要： The diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering. We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species. The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration, but significantly slows down the diffusion of rhodamine B above 3.9% (w/v) due to a dominating steric inhibition effect. Furthermore, introducing surfactants (cationic/nonionic/anionic) to the system results in a decreased diffusion coefficient of the molecular probe. In solutions containing nonionic surfactant, this can be explained by an increased crowding effect. For ternary poly(vinyl alcohol) solutions containing cationic or anionic surfactant, surfactant–polymer and surfactant–rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffusivity of rhodamine B. The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds, and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

关键词： fluorescence correlation spectroscopy poly(vinyl alcohol) anomalous diffusion crowding effects dynamic light scattering binding effects rhodamine B

HTML PDF 收藏

Progress on cleaner production of vinyl chloride monomers over non-mercury catalysts

Jinli ZHANG, Nan LIU, Wei LI, Bin DAI

《化学科学与工程前沿（英文）》 2011年第5卷第4期页码 514-520 doi: 10.1007/s11705-011-1114-z

摘要： Polyvinyl chloride (PVC) has become the third most used plastic after polyethylene and polypropylene and the worldwide demand continues to increase. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), which is manufactured industrially via the dehydrochlorination of dichloroethane or the hydrochlorination of acetylene. Currently PVC production through the acetylene hydrochlorination method accounts for about 70% of the total PVC production capacity in China. However, the industrial production of VCM utilizes a mercuric chloride catalyst to promote the reaction of acetylene and hydrogen chloride. During the hydrochlorination, the highly toxic mercuric chloride tends to sublime, resulting in the deactivation of the catalyst and also in severe environmental pollution problems. Hence, for China, it is necessary to explore environmental friendly non-mercury catalysts for acetylene hydrochlorination as well as high efficiency novel reactors, with the aim of sustainable PVC production via the acetylene-based method. This paper presents a review of non-mercury heterogeneous and homogeneous catalysts as well as reactor designs, and recommends future work for developing cleaner processes to produce VCM over non-mercury catalysts with high activity and long stability.

关键词： polyvinyl chloride vinyl chloride monomer acetylene hydrochlorination non-mercury catalysts green chemical process

HTML PDF 收藏

Toughening of vinyl ester resins by two-dimensional MXene nanosheets

《化学科学与工程前沿（英文）》页码 1651-1658 doi: 10.1007/s11705-022-2208-5

摘要： Two-dimensional nanosheets are highly effective tougheners for vinyl ester resins. The toughening effect is related to the high specific surface area and unique two-dimensional planar structure of the nanosheets. In this study, a coupling agent γ-(2,3-epoxypropoxy) propytrimethoxysilane (Kh-560) was used to modify MXene nanosheets (M-MXene) for use in toughening vinyl ester resin. The mechanical properties, including the tensile strength, flexural strength, Young’s modulus and elongation, of neat vinyl ester resin and vinyl ester resin modified with MXene and M-MXene were investigated. The results showed that modification significantly improved the mechanical properties of the vinyl ester resin. The tensile and flexural strengths of the MXene-nanosheet-modified vinyl ester resin were 27.20% and 25.32% higher, respectively, than those of the neat vinyl ester resin. The coupling agent improved the interfacial compatibility between the MXene nanosheets and vinyl ester resin, which resulted in the tensile and flexural strengths of the M-MXene-nanosheet-modified vinyl ester resin being 52.57% and 54.60% higher, respectively, than those of the neat vinyl ester resin for a loading quantity of nanosheets of only 0.04 wt %, which is economically viable. The main mechanisms by which the nanosheets toughen the resin are crack deflection and crack pinning.

关键词： MXene nanosheets 2D material vinyl ester resin modification coupling agent

HTML PDF 收藏

Kinetics of UV curable alkyl 3-mercaptopropionate-vinyl silizane

SONG Jiale, CHEN Lixin, WANG Yazhou, CHEN Weiwei, WANG Rumin

《化学科学与工程前沿（英文）》 2008年第2卷第4期页码 390-395 doi: 10.1007/s11705-008-0080-6

摘要： Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers, based on a step-growth radical polymerization mechanism, is a novel, rapid, inexpensive and simple technique for producing preceramic structures from liquid precursors. The kinetics of alkyl 3-mercptopropionate-vinyl silizane under UV irradiation is investigated by using real-time Fourier transform infrared (FT-IR) and photo-differential scanning calorimetry (photo-DSC). The experimental results show preliminarily that: (1) about 80% conversion of vinyl group has been achieved in the presence of a low concentration photoinitiator under UV irradiation; (2) by increasing the functionalities of the thiol group, the peak rate of copolymerization increases and the final conversion of the vinyl group decreases; (3) the copolymerization is primarily a bimolecular radical termination process; (4) the copolymerization is first-order, i.e., its rate is proportional to the vinyl group concentration and independent of the concentration of thiol group.

关键词： step-growth irradiation bimolecular preceramic concentration photoinitiator

HTML PDF 收藏

Carcinogens that induce the A:T>T:A nucleotide substitutions in the genome

null

《医学前沿（英文）》 2018年第12卷第2期页码 236-238 doi: 10.1007/s11684-017-0611-y

摘要：

Recently, Ng . reported that the A:T>T:A substitutions, proposed to be a signature of aristolochic acid (AA) exposure, were detected in 76/98 (78%) of patients with hepatocellular carcinoma (HCC) from the Taiwan Province of China, and 47% to 1.7% of HCCs from the Chinese mainland and other countries harbored the nucleotide changes. However, other carcinogens, e.g., tobacco carcinogens 4-aminobiphenyl and 1,3-butadiene, air toxic vinyl chloride and its reactive metabolites chloroethylene oxide, melphalan and chlorambucil, also cause this signature in the genome. Since tobacco smoke is a worldwide public health threat and vinyl chloride distributes globally and is an air pollutant in Taiwan Province, the estimation of the patients’ exposure history is the key to determine the “culprit” of the A:T>T:A mutations. Apparently, without estimation of the patients’ exposure history, the conclusion of Ng is unpersuasive and misleading.

关键词： genomic signature carcinogen aristolochic acid tobacco smoke vinyl chloride hepatocellular carcinoma

HTML PDF 收藏

Rheological behavior of PMVE-MA aqueous solution with metallic cations

Xiaoping DONG, Li LI, Jun XU, Xuhong GUO

《化学科学与工程前沿（英文）》 2011年第5卷第1期页码 126-130 doi: 10.1007/s11705-010-0548-z

摘要： The rheological properties of aqueous solutions of poly(methyl vinyl ether-co-maleic anhydride) (PMVE-MA) upon addition of metallic cations at different pH values were investigated. Sol-gel transition and shear-thickening phenomena at moderate shear rate were observed upon increasing the amount of metallic cations, especially for cupric cation. At certain molar ratio ( ) of added cupric cations to carboxyl groups in PMVE-MA, the system became gel-like, and the storage modulus (G′) and loss modulus (G′′) were parallel and exhibited a power-law dependence on the frequency, which is consistent with Winter’s hypothesis of determining the gel point of a crosslinking system. The shear-thickening behavior depends on , pH, metallic valence, and temperature.

关键词： poly(methyl vinyl ether-co-maleic anhydride) shear-thickening gel point rheology

HTML PDF 收藏

Influence of accelerated curing on the compressive strength of polymer-modified concrete

Izhar AHMAD; Kashif Ali KHAN; Tahir AHMAD; Muhammad ALAM; Muhammad Tariq BASHIR

《结构与土木工程前沿（英文）》 2022年第16卷第5期页码 589-599 doi: 10.1007/s11709-022-0789-1

摘要： In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction polymer-modified concrete linear regression fit early age strength ethylene vinyl acetate

HTML PDF 收藏

Metal cation removal by P(VC-r-AA) copolymer ultrafiltration membranes

Nachuan Wang, Jun Wang, Peng Zhang, Wenbin Wang, Chuangchao Sun, Ling Xiao, Chen Chen, Bin Zhao, Qingran Kong, Baoku Zhu

《化学科学与工程前沿（英文）》 2018年第12卷第2期页码 262-272 doi: 10.1007/s11705-017-1682-7

摘要： A series of amphiphilic copolymers containing poly(vinyl chloride-r-acrylic acid) (P(VC-r-AA) ) was synthesized and used to prepare membranes via a non-solvent induced phase separation method. The prepared membranes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and water contact angle and zeta potential measurements. The copolymer P(VC-r-AA) chains did not dissolved in a coagulation bath, indicating that the AA segments were completely retained within the membrane. Enriching degree of AA segments in surface layer was 2 for copolymer membrane. In addition, the introduction of AA segments made the membrane electronegative and hydrophilic so that the membrane was sensitive to the solution pH. The fouling resistance, adsorption of Cu(II), Cr(III) and Ce(IV) ions and the desorption properties of the membranes were also determined. The copolymer membranes exhibited good antifouling performance with a fouling reversibility of 92%. The membranes also had good adsorption capacities for Cu(II), Cr(III) and Ce(IV) ions. The optimal pH for Cu(II) adsorption was 6 and the copolymer membrane has potential applications for low concentration Cu(II) removal.

关键词： poly(vinyl chloride-r-acrylic acid) negatively charged PVC membrane anti-fouling heavy metal adsorption Cu(II) removal

HTML PDF 收藏

聚乙烯吡咯烷酮/聚(乙烯-乙烯醇)共混膜的制备及其油水分离性能

白云翔,吴国梁,张春芳,顾瑾,孙余凭

《中国工程科学》 2014年第16卷第7期页码 79-83

摘要：

将聚乙烯吡咯烷酮（PVP）与聚(乙烯-乙烯醇)（EVAL）共混，采用浸没沉淀法制备了PVP/EVAL共混膜，并用于油水乳液分离过程。通过全反射红外光谱、扫描电子显微镜、拉伸试验、接触角测试等对膜的组成、结构形态、机械性能、亲水性进行了表征，并研究了PVP添加量对共混膜油水分离性能的影响。结果表明：添加PVP能较显著地改变EVAL膜的结构，且共混膜的机械强度和亲水性得到明显改善，当PVP添加量为10 wt%（PVP在铸膜液中的质量分数）时，其拉伸强度和断裂伸长率分别为纯EVAL膜的1.88 倍和1.34 倍。当PVP 添加量为4 wt%时，油水分离稳定通量为纯EVAL 膜的1.81 倍，截留率为92.2 %，比纯EVAL 膜略高。PVP 添加量为10 wt%的PVP/EVAL 共混膜清洗后通量恢复率由纯EVAL 膜的51 %增至77.98 %。

关键词：聚乙烯吡咯烷酮聚(乙烯-乙烯醇) 共混膜油水分离浸没沉淀