High-performance polyimide nanofiber membranes prepared by electrospinning

2018 ◽  
Vol 31 (4) ◽  
pp. 438-448 ◽  
Author(s):  
Bo Yi ◽  
Yuntao Zhao ◽  
Enling Tian ◽  
Jing Li ◽  
Yiwei Ren
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Decomposition Temperature ◽  
Filtration Efficiency ◽  
Gas Filtration ◽  
Promising Candidate ◽  
Initial Decomposition Temperature ◽  
Hot Gas ◽  
Filtration Performance ◽  
Nanofiber Membranes

Polyimide (PI) nanofiber membranes were successfully prepared from a PI/N-methyl-2-pyrrolidone (NMP) solution via electrospinning. This technique simply and facilely produced efficient high-performance PI fibers. The morphology, surface wettability, thermal stability, mechanical properties, and filtration performance of the as-prepared PI nanofiber membranes were characterized in detail. The membranes exhibited smooth and hydrophobic surfaces. The nanofibers were well distributed in the membranes with fiber diameters in the range of 140–400 nm. All the PI nanofiber membranes showed excellent thermostability, and their initial decomposition temperature ( Td) and heat resistance temperature ( THRI) exceeded 544.4°C and 198.8°C, respectively. The PI nanofiber membranes also possessed reasonable mechanical properties with a tensile strength and a Young’s modulus reaching 10.5 and 927.6 MPa, respectively. Regarding the filtration performance, the developed nanofiber membranes achieved the best filtration efficiency of 90.4%. Such electrospun PI nanofiber membranes can be a promising candidate for hot gas filtration.

scholarly journals Grafting Cellulose Nanocrystals With Phosphazene-containing Compound for Simultaneously Enhancing the Flame Retardancy and Mechanical Properties of Polylactic Acid

2021 ◽  
Author(s):  
Yajun Chen ◽  
Jingxiu He ◽  
Zhe Sun ◽  
Bo Xu ◽  
Juan Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Flame Retardant ◽  
Cellulose Nanocrystals ◽  
High Performance ◽  
Decomposition Temperature ◽  
Limit Oxygen Index ◽  
Initial Decomposition Temperature ◽  
Flame Retardant Properties ◽  
Index Value

Abstract Cellulose nanocrystals (CNCs) have been used as bio-based carbon source in intumescent system. However, CNCs have the disadvantages of low onset decomposition temperature and decompose and carbonize during processing. We, herein, demonstrated the design of phosphazene-containing CNCs (P/N-CNCs) with great thermal stability and outstanding charring ability. The TGA results showed that the initial decomposition temperature of P/N-CNCs was increased from 202.4 ℃ to 272.2 ℃ (increased by 34.5%), and the residual char at 700 ℃ was increased from 24.9 wt% to 55.8 wt% compared with CNCs. Then, flame retardant PLA composites were prepared by blending PLA, P/N-CNCs with ammonium polyphosphate (APP), melamine (MPP), aluminum hypophosphite (AHP) and piperazine pyrophosphate (PPAP), respectively. The thermal stability, flame retardant properties and mechanical properties of PLA composites were investigated. The results showed that the flame retardant system constructed by 7 wt% APP and 3 wt% P/N-CNCs had the best effect in PLA. PLA/7APP/3P/N-CNCs had the highest limit oxygen index value (28.1%), the lowest peak heat release rate (266 kW/m2) and reached UL 94 V-0 rating. Moreover, the tensile strength, impact strength and elongation at break of PLA/7APP/3P/N-CNCs were increased by 7.3%, 18.6% and 29.4%, respectively, compared with these properties of PLA/7APP/ 3CNCs. This work provides a new idea for the design of CNCs with great thermal stability and outstanding charring ability, and offers a new method for the preparation of high-performance flame-retardant PLA composites.

Comb-like copolymer dispersant for PP/CaCO3 composites: effects of particle concentration on properties of composites

2017 ◽  
Vol 37 (6) ◽  
pp. 607-616 ◽  
Author(s):  
Xiwei Jing ◽  
Weiguang Gong ◽  
Zhongjun Feng ◽  
Xin Meng ◽  
Baicun Zheng
Keyword(s):  
Mechanical Properties ◽  
Flexural Modulus ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Decomposition Temperature ◽  
Initial Decomposition Temperature ◽  
Thermal Stabilities ◽  
Anchoring Group ◽  
Copolymer Poly ◽  
Properties Of Composites

Abstract A comb-like copolymer poly (styrene-co-maleic anhydride)-graft-poly (ε-caprolacton) (SMA-g-PCL, SP) with carboxyl group as an anchoring group and polycaprolactone as a solvent chain was used as an effective dispersant for CaCO3 in the polypropylene (PP) matrix. The effects of CaCO3 concentration on crystallization behaviors, mechanical properties, and thermal stabilities were studied systematically. The results revealed that the dispersion of CaCO3 in the PP matrix was markedly improved owing to the steric hindrance effect caused by PCL, and the SP-coated CaCO3 was a very effective nucleating agent for PP. Proper CaCO3 concentration corresponded to the improvement of crystallization temperature, crystallinity, and crystallization rate of PP. There was only a slight improvement in yield stress but great improvement in Young’s modulus, flexural modulus, and impact strength. However, the excessive CaCO3 filler deteriorated the mechanical properties. The good dispersion of SP-coated CaCO3 in the PP matrix also accounted for the improvement of thermal stability. The initial decomposition temperature of the PP/CaCO3 composite with 7.4 wt.% CaCO3 increased 35°C compared with neat PP.

Preparation and study of low-resistance polyacrylonitrile nano membranes for gas filtration

2016 ◽  
Vol 87 (2) ◽  
pp. 208-215 ◽  
Author(s):  
Li-Hua Lou ◽  
Xiao-Hong Qin ◽  
Hongnan Zhang
Keyword(s):  
Pressure Drop ◽  
Filtration Efficiency ◽  
Special Structure ◽  
Air Filtration ◽  
Gas Filtration ◽  
Low Resistance ◽  
Nanofiber Membranes ◽  
Nanofibrous Membranes ◽  
Bubble Template

In this paper, patterned nanofibrous membranes were fabricated for air filtration. Polyacrylonitrile was employed as the electrospinning material as its fluffy property and bulged bubble template served as collector to prepare the patterned membrane. With this special structure, the pressure drop significantly declined from 151.7 to 24.7 mmH2O, although the filtration efficiency of nanofiber membranes exhibited a slight decline from 99.94% to 96.33% compared to traditional electrospinning nanofibrous membranes. These sharp declines of the pressure drop while retaining the filtration efficiency imply that it could have more extensive applications.

scholarly journals A strategy for constructing highly efficient Co3O4-C@SiO2 nanofibers catalytic membrane for NOx-SCR and dust removal

2021 ◽  
Author(s):  
Huixian Zhou ◽  
Yutang Kang ◽  
Hui zhong ◽  
Bin Chen ◽  
Shuanglu Ma ◽  
...  
Keyword(s):  
High Performance ◽  
Gas Permeability ◽  
Catalytic Performance ◽  
Filtration Efficiency ◽  
Co3o4 Nanoparticles ◽  
Catalytic Membrane ◽  
Nh3 Scr ◽  
Nanofiber Membranes ◽  
And Performance

The strategy of constructing catalytic membrane has a significant influence on its structure and performance. In this work, Co3O4-Cx@SiO2 nanofiber membranes (NFMs) were fabricated by an in-situ growth–pyrolysis–oxidation strategy. The Co3O4-Cx catalyst derived from ZIF-67 was wrapped around nanofibers, which helps to maintain a stable membrane structure, then suppressing the reduction of gas permeability. Among the Co3O4-Cx catalyst, the carbon skeleton can prevent the agglomeration of Co3O4 nanoparticles, obtaining an ultra-fine Co3O4 nanoparticles with high dispersibility, redox property and surface area. The obtained Co3O4-C300@SiO2 NFM exhibits excellent filtration efficiency and low pressure drop for PM2.5 (99.99% and 55 Pa) and outstanding catalytic performance with T90 of 245 °C for NH3-SCR, which is 40.3% higher than that of Co3O4@SiO2 NFM. This work might provide a universal strategy for the preparation of catalytic membrane with high-performance.

scholarly journals Investigation of the Impact of Two Types of Epoxidized Vietnam Rubber Seed Oils on the Properties of Polylactic Acid

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Nguyen Thi Thuy ◽  
Pham Ngoc Lan
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Melt Flow Index ◽  
Acid Value ◽  
Decomposition Temperature ◽  
Flow Index ◽  
Seed Oils ◽  
Initial Decomposition Temperature ◽  
Rubber Seed ◽  
The Impact

To minimize the brittleness of polylactic acid (PLA), the epoxidized rubber seed oils (ERO) or epoxidized ester rubber seed oils (EERO) are blended with PLA. The mechanical properties of ERO bioblend are higher than that of EERO bioblend and significantly improved compared to that of the PLA sample. Elongation at break is increased by 9.1 times, and impact strength and tensile toughness improved by 139% and 1370%, respectively. The morphological study showed the microdroplets of epoxidized oils distributed in the ERO bioblend are much smaller than those in the EERO bioblend. This means that the ERO is better compatible with PLA, and both ERO and EERO are partially miscible with PLA. This compatibility is confirmed by the decrease in the glass transition temperature, T g , from 65.7 to 60.5°C. The TGA analysis shows a sharp increase in an initial decomposition temperature (from 261.8 to 311.9°C) meaning an improvement in thermal properties. The NMR analysis proves that the epoxidized vegetable oils are linked to PLA chains, so both the melt flow index and an acid value of ERO or EERO bioblend decrease while the thermal stability is improved. The NMR peak area of some signals shows that the ERO is more attached to PLA, proving better compatibility of ERO with PLA, resulting in higher mechanical properties of ERO bioblend. The plasticizing effect of plasticizers is not dependent on the oxygen-oxirane content of the epoxidized oil but is strongly influenced by the acid value. Overall results show that both ERO and EERO can be used as a biodegradable, renewable plasticizer to replace petroleum-based plasticizers for PLA. In addition, the successful modification of PLA by using ERO or EERO promotes the use of this polymer as a potential material for researchers working on PLA applications.

scholarly journals Flame Retardancy of Carbon Nanotubes Reinforced Carbon Fiber/Epoxy Resin Composites

2019 ◽  
Vol 9 (16) ◽  
pp. 3275 ◽  
Author(s):  
Guo-qiang Chai ◽  
Guo-qing Zhu ◽  
Yunji Gao ◽  
Jinju Zhou ◽  
Shuai Gao
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
High Performance ◽  
Decomposition Temperature ◽  
Cone Calorimetry ◽  
Initial Decomposition Temperature ◽  
Solution Blending

In order to study the effect of carbon nanotubes (CNTs) on the flame retardancy of carbon fiber (CF)/epoxy resin (EP) composites, CF/EP and CNTs/CF/EP composites were prepared by solution blending. The flame retardancy and thermal stability were studied by cone calorimetry and thermogravimetric analysis. It was found that CNTs and CF had a certain synergistic effect on improving flame retardancy and thermal stability of EP. The peak heat release rate of F7N7, which represents the EP composites with 0.7 wt % CF and 0.7 wt % CNTs, was minimal. The total smoke production of F5N5 which represents the EP composites with 0.5 wt % CF and 0.5 wt % CNTs was the smallest, which was decreased by 43.04% more than the EP. The initial decomposition temperature of F7N7 was about 14 °C higher than that of F7, and the mass loss at Tmax was greatly reduced. The apparent activation energy of F7N7 is 2.7 kJ·mol−1 more than EP. Finally, the tensile and flexural strength of the composites were also improved, so it could be applied to a high-performance matrix of CF/EP composites, which are usually used as the advanced composites in the aerospace field.

scholarly journals Cross-Linked Chitosan as an Eco-Friendly Binder for High-Performance Wood-Based Fiberboard

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Erzhuo Huang ◽  
Yanwei Cao ◽  
Xinpeng Duan ◽  
Yutao Yan ◽  
Zhe Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dimensional Stability ◽  
High Performance ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Modulus Of Rupture ◽  
Wood Fibers ◽  
Promising Candidate ◽  
Pressing Method ◽  
Optimum Modulus

High-performance wood-based fiberboards with high strength and dimensional stability were fabricated by hot-pressing method using 2,5-dimethoxy-2,5-dihydrofuran (DHF) cross-linked chitosan (CS) as an eco-friendly binder. The effects of cross-linked chitosan on the mechanical properties and dimensional stability of wood-based fiberboards were investigated. It is evident that cross-linked chitosan addition was effective in improving mechanical properties and dimensional stability of wood-based fiberboards. The prepared wood-based fiberboard bonded by DHF cross-linked CS displayed optimum modulus of rupture (MOR) of 42.1 MPa, modulus of elasticity (MOE) of 3986.0 MPa, internal bonding (IB) strength of 1.4 MPa, and thickness swelling (TS) value of 16.3%. The improvement of physical and mechanical properties of wood-based fiberboards could be attributed to the amide linkages and hydrogen bonds between wood fibers and cross-linked chitosan. The high-performance wood-based fiberboards fabricated in this study may be a promising candidate for eco-friendly wood-based composites.

scholarly journals Biodegradable and Reusable Cellulose-Based Nanofiber Membrane Preparation for Mask Filter by Electrospinning

Membranes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 23
Author(s):  
Jizhen Wang ◽  
Shaoyang Liu ◽  
Xu Yan ◽  
Zhan Jiang ◽  
Zijing Zhou ◽  
...  
Keyword(s):  
High Performance ◽  
Face Mask ◽  
Filtration Efficiency ◽  
Nanofiber Membrane ◽  
Filtration Performance ◽  
Filtration Membrane ◽  
Wide Range ◽  
Potential Applications ◽  
Filtration Material ◽  
Airborne Viruses

Environmentally friendly face masks with high filtration efficiency are in urgent need to fight against the COVID-19 pandemic, as well as other airborne viruses, bacteria and particulate matters. In this study, coaxial electrospinning was employed to fabricate a lithium chloride enhanced cellulose acetate/thermoplastic polyurethanes (CA/TPU-LiCl) face mask nanofiber filtration membrane, which was biodegradable and reusable. The analysis results show that the CA/TPU-LiCl membrane had an excellent filtration performance: when the filtration efficiency reached 99.8%, the pressure drop was only 52 Pa. The membrane also had an outstanding reusability. The filtration performance maintained at 98.2% after 10 test cycles, and an alcohol immersion disinfection treatment showed no effect on its filtration performance. In summary, the CA/TPU-LiCl nanofiber membrane made in this work is a promising biodegradable and reusable filtration material with a wide range of potential applications, including high-performance face mask.

scholarly journals Effects of Environmental Aging on The Durability of Wood-Flour Filled Recycled PET/PA6 Wood Plastic Composites

2021 ◽  
Author(s):  
Chin-Lung Chiang ◽  
Yi-Luen Li ◽  
Ming-Yuan Shen
Keyword(s):  
Mechanical Properties ◽  
Building Materials ◽  
Wood Flour ◽  
Creep Property ◽  
Decomposition Temperature ◽  
Accelerated Weathering ◽  
Initial Decomposition Temperature ◽  
Recycled Pet ◽  
Plastic Composite ◽  
Environmental Aging

Abstract Outdoor building materials made of wood require preservatives containing chromated copper arsenate and other carcinogenic substances but still are subject to decay, hence they need to be replaced every few years. Wood plastic composite (WPC) is a novel environmental-friendly composite of wood flour/fiber reinforced thermoplastic polymers (i.e. plastic). As WPC is made of plastic to evenly cover the wood flour, it has a lower moisture content than wood. In this study, maleic anhydride grafted polyolefin (POE-g-ma) and methyl metharylate-butadiene-styrene copolymer (MBS) were used as impact modifiers to prepare recycled WPCs (rWPCs) from recycled polyethylene terephthalate (rPET) and recycled polyamide 6 (rPA6) blends (PET/PA6). The thermal properties of the WPCs with different mixing ratio polymer blends of rPET to rPA6 (E60/A40, E50/A50, and E40/A60) were investigated, as well as their mechanical properties after accelerated weathering. Furthermore, the creep property of rWPC was also investigated under different applied loading and environmental aging conditions. The higher PET content resulted in lower flowability and a higher initial decomposition temperature, with the E60/A40 rWPC having better mechanical properties. During the 10-hour creep test, the rWPC strain changed significantly with environmental aging and higher loadings. In conclusion, the rWPC composed of 60:40 PET to PA6 is more suitable for outdoor building applications.

scholarly journals Self-Supporting Three-dimensional Electrospun Nanofibrous Membrane for Highly Efficient Air Filtration

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2567
Author(s):  
Gaofeng Zheng ◽  
Zungui Shao ◽  
Junyu Chen ◽  
Jiaxin Jiang ◽  
Ping Zhu ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Performance ◽  
Three Dimensional ◽  
Filtration Efficiency ◽  
Nanofibrous Membrane ◽  
Air Filtration ◽  
Fiber Morphology ◽  
Filtration Performance ◽  
Fibrous Filters ◽  
New Strategy

High-performance air filtration was the key to health protection from biological and ultrafine dust pollution. A self-supporting, three-dimensional (3D) nanofibrous membrane with curled pattern was electrospun for the filtration, of which the micro-fluffy structure displayed high-filtration efficiency and low-pressure drop. The flow field in the 3D filtration membrane was simulated to optimize the process parameters to increase the filtration performance. The qualification factor increased from 0.0274 Pa−1 to 0.0309 Pa−1 by 12.77% after the optimization of the electrospinning parameters. The best filtration efficiency and pressure drop were 93.6% and 89.0 Pa, separately. This work provides a new strategy to fabricate 3D structures through the construction of fiber morphology and promotes further improvement of air filtration performance of fibrous filters.

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