POLYMER
·
2019
·
IF 3.771
Bing Zhang,Chunxiang Lu,Yaodong Liu,Pucha Zhou,Zhuang Yu,Shuxia Yuan
Combing the advantages of hollow fiber with mesopore, hollow-mesoporous fiber would enlarge the applications of hollow fiber in the areas dominating by macromolecules . In this paper, polyacrylonitrile (PAN)-based hollow-mesoporous fibers with various draw ratios were fabricated firstly by incorporating alkali lignin through one-step wet-spinning technique. The spinning dope becomes unstable with the increase of the storage time and the proper way is to spin with as-prepared solution. The hollowness of fibers at different draw ratios is nearly 45% and sponge-like structure exists in the wall. The pores existing in the wall are mainly mesopores and macropores, and the pore diameter increases as draw ratios is added. The mesopore ratio of all fibers is more than 17%. The tensile strength and modulus reach to 3.37 and 85.82 cN/dtex when draw ratios is 6, respectively. This work explains the relationships between structure and properties of hollow-mesoporous fiber with the increase of draw ratios, and offers a simple way to construct hollow-mesoporous fibers.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CELLULOSE
·
2022
·Vol. 29
·期 2
·751-762
·
IF 6.123
Cui Shiqiang,Zhang Yang,Liu Changjun,Lou Shanhao,Zhang Yue,Zhang Yumei,Wang Huaping
In order to research the multi-level structure of Lyocell fiber at different draw ratios and to reveal the limiting factors for preparing the high strength Lyocell fiber, the paper reports on the effect of draw ratio including low drawing (1–5), high drawing (6–11) and excessive drawing (12–20) on the multi-level structure and the mechanical properties of Lyocell fiber. The structure was determined by wide-angle X-ray diffraction, small-angle X-ray scattering and fibrillation test, and the result showed that, at low draw ratio stage, the breaking strength, yield strength and modulus of the fiber increased with the draw ratio owing to crystallinity as well as orientation increased while the micropore decreased, and there were almost no microfibrils on the fiber surface. At high draw ratio stage, the orientation of amorphous region increasing was the principal reason for the increase of fiber mechanical properties, and the micropores continued to decrease and a few short and thick microfibril was formed. At excessive draw ratio stage, the breaking strength remained constant mainly due to the basically unchanged crystallinity and orientation of the fibers, the yield strength and modulus decreased due to the slip of the highly crystallized and oriented elementary fibril. Meanwhile, the micropores still decreased and became more slender, the number of microfibrils increased and the microfibrils showed tenuous structure. It can be summarized that Lyocell fiber has the characteristics of multi-level structure, and the fundamental reason limiting the improvement of mechanical properties with draw ratio increasing is the slip of elementary fibril.
研究领域:
材料科学
·
纤维化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2023
·
IF 4.6
Zirui Wang,He Zhang,Junkan Yue,Man Chen,Xinda You,Runlai Li,Qiang Fu
Producing thinner polymer membranes has been a research hotspot to satisfy the increasing demand from diverse application scenarios in the industry. This work used biaxially stretching with an exceptionally high draw ratio near melting point to thin down the excessively petrolatum-swollen UHMWPE gel from millimeters to hundreds of nanometers. Of which the meso- and micro-structural evolution during stretching processing was systematically investigated, especially within the thickness range from microns to submicrons, threading through the micron-thickness boundary. These membranes consisted of oriented smooth fibrils without identifiable overgrowth lamellae but with two obvious melting points, being different from the conventional bead-fiber shape of the typical shish-kebab super-crystalline structures. Moreover, an ionic rejection phenomenon of submicron UHMWPE was observed, which was attributed to the surface potential that emerged when thinning down PE membrane below the threshold of 800 nm. It is the first report of emerging surface potential for the nonpolar neutral polymers as a function of reduced thickness within the submicron range. This work provides insight into the processing of submicron-thin polymer membranes, with the unique structure and properties distinguished from the bulk revealed and explained. These findings may also help the processing and structure-property analysis of submicron membranes of other polymer materials.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2023
·
IF 11.2
Jianhua Huang,Gong Chen,Tianhang Han,Chenxin Yi,Yujia Zhang,Lang Ding,Tianshu Sun,Ting Jin,Shuai Zhou
Customizable structures and patterns are becoming powerful tools for biomimetic design and application of soft materials. The construction of long-range ordered self-wrinkled structures on multi-dimensional and complex-shaped surfaces with facile, fast and efficient strategies still faces serious challenges. During the stretch-recovery process, the carboxyl groups in the polyacrylamide/sodium alginate dual network gel form robust coordination with Fe 3+ to achieve a hard shell layer, resulting in a modulus mismatch between the inner soft layer and the outer hard layer, thereby forming a wrinkled surface. This flexible strategy allows simultaneous construction of complex topologies from 1D to 3D wits well-organized microstructure and controllable dimensions. The mechanism of the influence of ion treating time and pre-stretching ratio on wrinkle wavelength was explored in detail. The finite element simulations matched well with the experimental results. Due to the unique surface and dual crosslinking network, the self-wrinkled hydrogel maintains a high sensitivity of up to 67.47 kPa −1 in 1000 compression cycles. As a high-sensitivity pressure sensor integrated into the detection system, it can be efficiently applied to the contact dynamic tactile perception and monitoring of various movement behaviors of the human body.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Haiquan Zhang,Zijing Liu,Junping Mai,Ning Wang,Jie Zhong,Xianmin Mai,Nan Zhang
Super-elastic phase change materials (SPCMs), as brand-novel smart materials, have a wide range of potential applications in stress induction, thermal energy storage and temperature control. Polyacrylamide-based [email protected] _12h SPCMs with an ultimate tensile ratio greater than 500% were synthesized for the first time by a popular molecular self-assembly technology. In-situ polymerized polyacrylamide (PAM) builds a reversible deformable three-dimensional network, while the filled PEG2000 PCMs form hydrogen bonds with its amino group (–NH 2 ). 260% tensile ratio is impossible to cause obvious liquid leakage for the [email protected] form-stable phase change material, even exceeding the melting temperature of the PEG2000 PCM. Reversible PAM–NH 2 ⋯O–PEG hydrogen bond can also reduce the sensitivity of the polyacrylamide-based hydrophobically associated hydrogel (HAH) to air humidity fluctuations. Volumetric deformation ratio of the as-prepared PCM gel is close to zero during water vapour adsorption/desorption, which is much lower than that of the HAH without PEG2000 (20 vol%). Water molecules entering the self-prepared SPCMs are preferentially adsorbed by the PAM 3D architecture, which significantly improves the anti-interference ability of the PEG PCMs. The outstanding comprehensive performance makes the [email protected] SPCMs have great potential in the future.
研究领域:
材料科学
·
热能工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
NEW CARBON MATERIALS
·
2019
·
IF 1.387
Xiao-peng Li,Xi-dong Suo,Yao-dong Liu,Yong-hong Li
The use of gel spinning technology in the formation of polyacrylonitrile (PAN)-based carbon fibers has led to significant tensile property improvements. PAN, dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions were dry-jet spun, gelled in methanol at −20 and −50 °C for different times from 0 to 40 d, and vacuum-dried at 0 °C for 24 h to obtain PAN fibers that were drawn to a drawing ratio (DR) of 4 in a hot glycerin bath at 110 °C, and then to various DRs in a glycerin bath at 155 °C. The effects of gelation time on the microstructures, mechanical properties and cyclization reactions of the gel-spun PAN fibers were investigated. Results showed that the gelation time affected the gel structure and the maximum possible draw ratio. The gelation effects were significant in the first 5-10 d, and were more prominent for the DMSO system than the DMF system. The maximum possible draw ratio, strength and modulus, orientation and crystallinity of the PAN fibers increased with gelation time. The cyclization temperature decreased and the reaction enthalpy increased with gelation time in cyclization, indicating an improved chain orientation and crystallinity with gelation time. Gelation was an important step affecting the microstructures and properties of gel-spun PAN fibers for making high performance carbon fibers.
研究领域:
材料科学
·
高分子科学
·
纺织工程
✓ 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）