CEMENT & CONCRETE COMPOSITES
·
2022
·
IF 9.93
Linan Gu,Tiejun Liu,Kai Wu,Zhenghong Yang,Zhaoyin Wen,Zhenlei Zhang,Haoxin Li
It is still uncertain whether temperature exerts some influence on the water retention (WR) and bleeding of cement-based materials with viscosity-enhancing admixtures (VEAs). Thus, WR and bleeding of cement-based materials with selected VEAs, such as sodium polyacrylate (PANA), hydroxyethoxy methoxy cellulose (HEMC) and hydroxypropoxy methoxy cellulose (HPMC), were evaluated at 20, 30, 40, 50, and 60 °C, and experiments on the apparent viscosity , total organic carbon (TOC) content, hydrodynamic radius and thermogravimetry were carried out to explore the responsible mechanisms. The results show that VEAs enhance WR and reduce bleeding at room temperature to varying degrees. However, this improvement at higher temperature does not occur as at room temperature (20 °C). The decreased improvements in WR and bleeding at higher temperature are associated with the lowered apparent viscosity , TOC content, hydrodynamic radius and the increased cement hydration . Below 40 °C, the apparent viscosity, adsorption and hydrodynamic radius dominate the bleeding behaviour of mortars with HPMC and HEMC. However, accelerated cement hydration is mainly responsible for the behaviour when the temperature exceeds 40 °C.
研究领域:
土木工程
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Feng Gao,Ke Liu,Yongjun Wang,Junming Dai,Wenxing Chen,Wangyang Lu
Direct spinning of polyamide 6 (PA 6) fibers, traditionally impeded by the presence of approximately 10% residual monomer and oligomers in the polymerized form, has been made feasible through our innovative approach. Current extraction methods predominantly employ hot water to extract monomer and oligomers. However, this approach is characterized by time-consuming procedures, high energy consumption, and substantial water usage. Therefore, in this study, a straightforward falling-film devolatilization method is proposed to synchronize the liquid-phase viscosity enhancement and oligomer removal of PA 6. PA 6 industrial yarns were successfully produced using devolatilized PA 6 (D-PA 6) obtained by this method. The viscosities of D-PA 6 samples were increased from 2.5 and 2.8 to 2.8 and 3.4, their monomer contents were reduced to 0.26%, and their dimer and residual oligomer contents were reduced to 0.54 and 2.54%, respectively, with a lower removal of dimer and trimer. The process led to a wider molecular weight distribution, consistent with that typical of PA 6 spinning. The obtained PA 6 industrial yarn exhibited a high degree of crystallinity, and its orientation, thermal properties, and mechanical properties were comparable to those of conventional yarn. Although its dyeing ability was slightly compromised, this did not hinder the practical application of the PA 6 industrial yarn. The falling-film devolatilization process enables simultaneous viscosity enhancement and devolatilization without the need for hot-water extraction (24 h) and drying (24 h), drastically shortening the production time from more than 48 h to less than 10 h, thereby greatly reducing energy consumption and wastewater discharge. This study provides technical guidance for the sustainable industrial production of PA 6 industrial yarn by direct melt-spinning, which significantly reduces energy and environmental impacts while improving production efficiency.
研究领域:
材料科学
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纺织工程
·
化工
✓ 已验证
产品关联
DOI
高影响因子
CEMENT AND CONCRETE RESEARCH
·
2025
·
IF 13.1
Jing Qiao,Chunsheng Zhou,Jingjing Feng,Miao Miao,Yanliang Ji,Linan Gu
Limestone powder (LS) with large particle sizes is widely used, but its effect on water migration behavior remains unclear. This study investigates the influence of LS and viscosity-enhancing admixtures (VEAs) on the water migration behavior and water distribution in fresh cement paste using 1 H low-field nuclear magnetic resonance (LF-NMR). Results indicate that LS increases the size of water migration channels, accelerates the water migration rate, and raises the bleeding ratio, while VEAs substantially mitigate the effects of LS. Compared to polyacrylamide, cellulose ether significantly slows down the water migration rate before 40 min, thereby reducing the bleeding ratio. Additionally, relaxation times were found to decrease during bleeding and can reflect the sedimentation process. It is confirmed that the pore structure of fresh paste exhibits fractal characteristics, with the fractal dimension closely correlating with water migration rates. The underlying mechanisms and their implications on material behavior are thoroughly analyzed and discussed.
研究领域:
材料科学
·
土木工程
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 138
·期 25
·50601
·
IF 3.125
Wenlong Qin,Ruixuan Li,Hanxi Li,Guanfeng Jiang,Guowei Qin,Yang Wang,Jiang Yang
A Fe 3 O 4 nonaparticles coated with acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid copolymer(Fe 3 O 4 -Polymer NPs) was synthesized by emulsion polymerization. The structure of Fe 3 O 4 -Polymer NPs was then characterized by infrared spectroscopy, thermo-gravimetric analysis, and scanning electron microscopy. Meanwhile, the rheological properties of Fe 3 O 4 -Polymer NPs solution were systematically studied. The results showed that when dosage of hydrophobic Fe 3 O 4 -Oleic NPs is 10%, the synthesized Fe 3 O 4 -Polymer NPs was with the best viscosity enhancement performance, and the maximum saturation magnetization could reach to 20.0 emu/g. The apparent viscosity value of 5000 mg/L magnetic nano-composite solution was 154.6 mPa·s at 30°C. It shows strong viscosity enhancement ability and good temperature performance. Hence, it has great application potential in well stimulation of medium and high temperature oil and gas reservoirs.
研究领域:
材料科学
·
石油工程
✓ 已验证
DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2024
·Vol. 26
·期 8
·1-17
·
IF 2.1
Hu Deng,Huaizhi Tao,Jiawei Ai,Jindong Chen,Djouonkep Lesly Dasilva Wandji
Recently, conventional viscosifiers exhibit limited effectiveness under deep formations due to their poor salt tolerance and low thermal resistance. To address the limitations, a thermo-responsive macromonomer (DAM) consisting of N,N-diethylacrylamide and N,N'-methylenebisacrylamide was copolymerized with 2-acrylamido-2-methylpropane sulfonate and chemically modified nano-silica (N-np) to obtain an effective thermo-thickening/Nano-SiO 2 polymer composite (N-DPAM) via in-situ polymerization under optimal conditions. The molecular structure of N-DPAM was analyzed by FTIR and 1 H NMR, while rheological and rheometric responses under high temperature, salt dosages, and shear resistance were investigated. The rheometric results demonstrated that DPAM exhibits a viscosity increase of 235% from 65 to 160 °C, but rapidly decreased at 180 °C, whereas N-DPAM displayed stabilized thickening responses of 218% above 160 °C due to intercalation and self-assembly of N-np within the polymer matrix as temperature increases. The viscosity retention rate (VRR) at a high shear rate of 1021 s −1 and 200 °C indicated that the solution viscosity of N-DPAM was observed at 55 mPa s, which is 13 times higher compared to DPAM solution at 4 mPa s. From the rheological results, the VRR of N-DPAM fluid observed at 68% was slightly lower than that of HE300 at 73%, a commercially available viscosity additive in a salt-free environment at 200 °C, but three times higher (63%) than HE300 (25%) in the salt-saturated environment (20% NaCl). Additionally, a study of N-DPAM fluid contaminated by shaly soil from Dagang Oilfield demonstrated excellent compatibility with a filtration control agent to control the viscosity and filtration volumes (< 10 mL) at 200 °C. Graphical Abstract
研究领域:
材料科学
·
石油工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Wei-An Huang,Rui Su,Jing-Wen Wang,Yu Fan,Lin Jiang,Xuan Li,Jie Cao
The development of carbon (CO 2 ) dioxidecapture, utilization, and storage methods is crucial to achieving carbon neutrality. The use of supercritical CO 2 (sc-CO 2 ) in enhanced oil recovery applications offers a promising carbon utilization route; however, its application in petroleum exploration and production is limited by its low viscosity. Here, a host–guest complex was synthesized based on acetylated-β-cyclodextrin (ACD) and polyphthalamide (PPA) to enhance the viscosity of sc-CO 2 , and various techniques were used to characterize its structure. The results showed that adding 2.0 wt% ACD-PPA/10 wt% ethanol at an ACD/PPA molar ratio of 1:3 increased the viscosity of sc-CO 2 to 4.36 mPa·s, an increase of ∼ 109 times compared with pure sc-CO 2 . The mechanism for viscosity enhancement involves the building of a large number of C O bonds between the ACD and CO 2 molecules, contributing to the polymer’s high solubility in sc-CO 2 . Meanwhile, a strong hydrogen bond network is formed between the hydroxyl groups of the PPA terminal groups. Hence, a supramolecular system is developed through interactions of the host and guest molecules, which dramatically improves the viscosity of sc-CO 2 . Increasing the viscosity of sc-CO 2 allows it to be used in underbalanced drilling, anhydrous fracturing, thick oil extraction, etc., as well as being valuable in the field of carbon capture and storage.
研究领域:
材料科学
·
化学工程
·
石油工程
·
碳捕集与利用
✓ 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）