科创中国

Viscoelastic models were employed to analyze the mechanical properties of novel regenerated cellulose fiber from NaOH complex solution. The stress-strain curves of the dry and wet fiber were fitted. The models were composed of a Maxwell element, linear spring and non-linear spring. The tested results indicate that the regenerated cellulose fibers exhibit better tensile properties in dry and wet condition than those of viscose rayon. It can be explained by the high molecular weight of novel regenerated cellulose fiber (-1.1×10⁵), compared to that of viscose rayon (-5×10 ⁴), as well as high degree of crystallinity (60-65% to 30-40%).

Shuai Zhanq;Wen Cong Wang;F. A.Xue Li;建勇 俞

Cellulose Chemistry and Technology

2013-5

The durability of the notch and un-notch composites is mainly affected by environmental ageing, the condition of mechanical loading and mechanical ageing. Due to the dissimilarity of two components of fibre mat-reinforced thermosetting composites (e.g. fibre and resin), thermal stress and strain can be generated and raised by moisture, temperature variation, thermal ageing and mechanical ageing in any working environment. This study aims at investigating the effect of thermal ageing fatigue and mechanical ageing fatigue on the mechanical durability and notch sensitivity properties of glass fibre mat unsaturated polyester resin composites and kenaf fibre mat/unsaturated polyester composites. Tensile tests of smooth and notched specimens, low cycle tensile fatigue tests, dynamic mechanical analysis, stress distribution by point-stress failure criteria and notch sensitivity analysis were performed to both types of the specimens. Both composites were previously taken under up to 100 number of freeze-thaw ageing cycles (from −25 to + 58℃). It is found that the tensile modulus and un-notched strength of kenaf fibre mat/unsaturated polyester were decreased by 30 and 27%, respectively, which was more severe than that of glass fibre mat/unsaturated polyester composites. After the thermal ageing, notch (open hole) did not diminish the strength property of kenaf fibre mat/unsaturated polyester, and there was an absolute increase of characteristic distance (d₀) which indicates the lower notch sensitivity of kenaf fibre mat/unsaturated polyester. Although glass fibre mat/unsaturated polyester had superior mechanical properties, after thermal ageing, while kenaf fibre mat/unsaturated polyester presented stable low cycle fatigue property, better energy absorption and notch sensitivity properties.

Md Sohag Miah;建勇 俞;Yuqiu Yang;Hafeezullah Memon;Muhammad A. Rashid

Journal of Industrial Textiles

2019

Due to their exceptional flexibility and transparency, CVD graphene films have been regarded as an ideal replacement of indium tin oxide for transparent electrodes, especially in applications where electronic devices may be subjected to large tensile strain. However, the search for a desirable combination of stretchability and electrochemical performance of such devices remains a huge challenge. Here, we demonstrate the implementation of a laminated ultrathin CVD graphene film as a stretchable and transparent electrode for supercapacitors. Transferred and buckled on PDMS substrates by a prestraininig-then-buckling strategy, the four-layer graphene film maintained its outstanding quality, as evidenced by Raman spectra. Optical transmittance of up to 72.9% at a wavelength of 550 nm and stretchability of 40% were achieved. As the tensile strain increased up to 40%, the specific capacitance showed no degradation and even increased slightly. Furthermore, the supercapacitor demonstrated excellent frequency capability with small time constants under stretching.

Ping Xu;Junmo Kang;Jae Boong Choi;Jonghwan Suhr;建勇 俞;Faxue Li;Joon Hyung Byun;Byung Sun Kim;Tsu Wei Chou

ACS Nano

2014-9-23

Creating a practical and energy-efficient method with high efficacy to separate oil-water mixtures, especially those stabilized by surfactants, has proven to be extremely challenging. To overcome this challenge, a novel and scalable strategy was developed for the synthesis of superhydrophilic and prewetted oleophobic nanofibrous membranes by the facile combination of in situ cross-linked polyethylene glycol diacrylate nanofibers supported on polyacrylonitrile/polyethylene glycol nanofibrous (x-PEGDA@PG NF) membranes. The as-prepared x-PEGDA@PG NF membranes have shown superhydrophilicity with ultralow time of wetting and promising oleophobicity to achieve effective separation for both immiscible oil-water mixtures and oil-in-water microemulsions solely driven by gravity. These new membranes having a good mechanical strength of 14 MPa and mean pore sizes between 1.5 and 2.6 μm have shown a very high flux rate of 10975 L m^-2 h^-1 with extremely high separation efficiency (the residual oil content in filtrate is 26 ppm). More importantly, the membranes exhibit high separation capacity, which can separate 10 L of an oil-water mixture continuously without a decline in flux, and excellent antifouling properties for long term use, thus making them important candidates for treating wastewater produced in industry and daily life. Such membranes are also ideal for high viscosity oil purification such as purification of crude oil. 2014 This journal is

Aikifa Raza;彬 丁;Ghazala Zainab;Mohamed El-Newehy;Salem S. Al-Deyab;建勇 俞

Journal of Materials Chemistry A

2014-7-14

Cellulose nanowhiskers is a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Here, for the first time, a novel controllable fabrication of cellulose nanowhiskers from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization is reported. The versatile jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and high crystallinity (69.72%), contains C6 carboxylate groups converted from C6 primary hydroxyls, which would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, pharmaceutical and optical industries as additives.

Xinwang Cao;彬 丁;建勇 俞;Salem S. Al-Deyab

Carbohydrate Polymers

2012-10-1

A facile, ultrasensitive, reproductive and selective sensor strip utilizing electrospun polyamide-6/nitrocellulose (PA-6/NC) nano-fibers/nets (NFN) membranes assemble bovine serum albumin decorated Au nanoparticles (BAu probe) for naked-eye colorimetric assay of Pb²⁺ has successfully prepared through dual-component alternate distribution multifluidic electrospinning technique. Benefiting from the extremely large specific surface areas and high porosity of NFN membranes, the stability of BAu probe dramatically increased and the strips presented a significant absorbance decreasing band at 546nm which induce the visual color changes from deep pink to white after incubated in Pb²⁺ liquor with a low detection limit of 0.2μM without any assistance of equipment. Upon exposure to a series of metal ions, only Pb²⁺ could induce a pink-to-white color change, which clearly exhibited that BAu probe immobilized PA-6/NC membranes could act as highly selective strips to detect Pb²⁺ with little interference from other metal ions. Additionally, the colorimetric responses are represented in visualized quantitative by calculated color difference from L^*a^*b^* coordinates which are presented with lightness and chrome values. Furthermore, the sensitivity of NFN membrane-based strips is much higher than that of film-based ones. The results indicate that this promising cost-effective sensing system could potentially allow for assaying of Pb²⁺ in human urine or blood as preliminary screening of lead poisoning.

Yan Li;Yang Si;Xueqin Wang;彬 丁;Gang Sun;Gang Zheng;Wenjing Luo;建勇 俞

Biosensors and Bioelectronics

2013-10-5

The separation and purification of chemical molecules from organic media under harsh chemical environments are of vital importance in the fields of water treatment, biomedical engineering, and organic recycling. Herein, we report the preparation of a flexible SiO₂/SnO₂ nanofibrous membrane (SiO₂/SnO₂ NFM) with high surface area and hierarchical porous structure by selecting poly(vinyl butyral) as pore-forming agent and embedding crystalline phase into amorphous matrix without using surfactant as sacrificial template. Benefiting from the uniform micropore size on the fibers and negatively charged properties, the membranes exhibit a precise selectivity toward molecules based on electrostatic interaction and size exclusion, which could separate organic molecule mixtures with the same electrostatic charges and different molecular sizes with a high efficiency of more than 97%. Furthermore, the highly tortuous open-porous structures and high porosity give rise to a high permeate flux of 288000 L m^-2 h^-1. In addition, the membrane also displays excellent stability and can be reused for ten consecutive filtration-regeneration cycles. The integration of high filtration efficiency, large permeate flux, good reutilization, and easy to industrialization provides the SiO₂/SnO₂ NFM for potential applications in practical molecular purification and separation science.

Haoru Shan;Xueqin Wang;Feihao Shi;Jianhua Yan;建勇 俞;彬 丁

ACS applied materials & interfaces

2017-6-7

Leitao Cao;Yuanyuan Wu;建勇 俞;彬 丁

2017

Flexible membranes created from porous carbon nanofibers (CNFs) hold great promise in the next generation wearable energy storage devices, but challenges still remain due to the poor mechanical properties of porous carbon nanofibers. Here, we report a facile strategy to fabricate elastic and hierarchical porous CNF membranes with NiFe₂O₄ nanocrystals embedded via multicomponent electrospinning and nano-doping methods. Benefiting from the scattering effect of NiFe₂O₄ nanocrystals and graphitized carbon layers for the condensed stress, the resultant CNF membranes exhibit an enhanced elasticity with a bending radius <12 μm, rapid recovery from the deformations, and a superior softness. Quantitative pore size distribution and fractal analysis reveal that the CNFs possessed tunable porous structures with a high surface area of 493 m² g^-1 and a pore volume of 0.31 cm³ g^-1. Benefiting from the robust mechanical stability, hierarchical porous structures and good electrochemical properties, the NiFe₂O₄ doped CNF membranes demonstrate a high electrical capacitance of 343 F g^-1, and good reversibility with a cycling efficiency of 97.4% even after 10 000 cycles. The successful synthesis of elastic porous CNF membranes also provided a versatile platform for the design and development of functional CNF based materials for various applications.

Jianlong Ge;Gang Fan;Yang Si;Jianxin He;Hak Yong Kim;彬 丁;Salem S. Al-Deyab;Mohamed El-Newehy;建勇 俞

Nanoscale

2016-1-28

Porous structure of fabric has a significant impact on the fabric functions such as air permeability, water transport and heat retention. In this article, six knitted fabrics with different blend ratio of cotton-like modified polyester fiber and cotton fiber were prepared. Pore sizes and its distribution of the fabrics were measured by CFP-1100-AI pore diameter tester. Porosity of the fabrics was obtained by three ways respectively, namely loop model method, image method and density method. The results show that the pore diameter of blended knitted fabrics presents an asymmetric distribution, that is, the smaller pores have a greater proportion to the total pores than larger pores. There exists an obvious diameter change in the pore size distribution which indicates the transition from intra-yarn pores to inter-yarn pores. Among the 3 test methods for porosity, the porosity obtained by the image method is much smaller than that of loop model method and density method, but its relationship to the fiber blending ratio is consistent with the variation law of fabric air permeability, which indicates intra-loop pores takes greater impact on air permeability of fabrics. The results of present study can play a theoretical guiding role in comfort property design and product development of cotton-like polyester fabrics.

Yun Feng Li;Li Qian Huang;建勇 俞

2013