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  1. Article ; Online: Flame Retardancy, Thermal and Mechanical Properties of Novel Intumescent Flame Retardant/MXene/Poly(Vinyl Alcohol) Nanocomposites

    Xiaofei Yan / Jie Fang / Jianjun Gu / Chenkai Zhu / Dongming Qi

    Nanomaterials, Vol 12, Iss 477, p

    2022  Volume 477

    Abstract: Poly(vinylphosphonic acid) (PVPA) and polyethylenepolyamine (PEPA) are used as novel intumescent flame retardants to improve the properties of MXene (2D Ti 3 C 2 T x )/poly(vinyl alcohol) (PVA) nanocomposites. We investigated the flame-retardant ... ...

    Abstract Poly(vinylphosphonic acid) (PVPA) and polyethylenepolyamine (PEPA) are used as novel intumescent flame retardants to improve the properties of MXene (2D Ti 3 C 2 T x )/poly(vinyl alcohol) (PVA) nanocomposites. We investigated the flame-retardant properties, thermal stability, and mechanical properties of MXene/PVA nanocomposites. The results show that MXene was homogeneously dispersed in the PVA matrix containing PVPA and PEPA. PVPA and PEPA effectively improved the flame-retardant properties of MXene/PVA nanocomposites and they did not obviously change the thermal degradation of the MXene/PVA nanocomposites. Moreover, MXene improved the thermal stability of the PVA matrix. The elongation at break of MXene/PVA nanocomposites reached its maximum when the MXene mass fraction was 1.0 wt.%, regardless of whether PVPA and PEPA were present in the PVA matrix, whereas the tensile strength and Young’s modulus of MXene/PVA nanocomposites increased with the increase in MXene content in the PVA matrix.
    Keywords flame-retardant properties ; MXene/PVA nanocomposites ; poly(vinylphosphonic acid) ; polyethylenepolyamine ; Chemistry ; QD1-999
    Subject code 660
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Biodegradable-Glass-Fiber Reinforced Hydrogel Composite with Enhanced Mechanical Performance and Cell Proliferation for Potential Cartilage Repair

    Chenkai Zhu / Changyong Huang / Wuxiang Zhang / Xilun Ding / Yang Yang

    International Journal of Molecular Sciences, Vol 23, Iss 15, p

    2022  Volume 8717

    Abstract: Polyvinyl alcohol (PVA) hydrogels are promising implants due to the similarity of their low-friction behavior to that of cartilage tissue, and also due to their non-cytotoxicity. However, their poor mechanical resistance and insufficient durability ... ...

    Abstract Polyvinyl alcohol (PVA) hydrogels are promising implants due to the similarity of their low-friction behavior to that of cartilage tissue, and also due to their non-cytotoxicity. However, their poor mechanical resistance and insufficient durability restricts their application in this area. With the development of biodegradable glass fibers (BGF), which show desirable mechanical performance and bioactivity for orthopedic engineering, we designed a novel PVA hydrogel composite reinforced with biodegradable glass fibers, intended for use in artificial cartilage repair with its excellent cytocompatibility and long-term mechanical stability. Using structure characterization and thermal properties analysis, we found hydrogen bonding occurred among PVA molecular networks as well as in the PVA–BGF interface, which explained the increase in crystallinity and glass transition temperature, and was the reason for the improved mechanical performance and better anti-fatigue behavior of the composites in comparison with PVA. The compressive strength and modulus for the PBGF-15 composite reached 3.05 and 3.97 MPa, respectively, equaling the mechanical properties of human articular cartilage. Moreover, the increase in BGF content was found to support the proliferation of chondrocytes in vitro, whilst the PVA hydrogel matrix was able to control the ion concentration by adjusting the ions released from the BGF. Therefore, this novel biodegradable-glass-fiber-reinforced hydrogel composite possesses excellent properties for cartilage repair with potential in medical application.
    Keywords biodegradable glass fiber ; poly(vinyl alcohol) hydrogel ; composites ; mechanical performance ; degradation behavior ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 621
    Language English
    Publishing date 2022-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Investigation of Fire Protection Performance and Mechanical Properties of Thin-Ply Bio-Epoxy Composites

    Xiaoye Cong / Pooria Khalili / Chenkai Zhu / Saihua Li / Jingjing Li / Chris Rudd / Xiaoling Liu

    Polymers, Vol 13, Iss 5, p

    2021  Volume 731

    Abstract: Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flame-retardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant ... ...

    Abstract Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flame-retardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant mats rely primarily on expandable graphite, mineral wool and glass fibre to generate a thermal barrier that releases incombustible gasses and protects the underlying material. A flame retardant (FR) mat is incorporated into the carbon fibre bio-based polymeric laminate and the relationship between the fire protection properties and mechanical properties is investigated. Hybrid composite laminates containing FR mats either at the exterior surfaces or embedded 2-plies deep have been tested by the limited oxygen index (LOI), vertical burning test and cone calorimetry. The addition of the surface or embedded E20MI flame retardant mats resulted in an improvement from a base line of 33.1% to 47.5% and 45.8%, respectively. All laminates passed the vertical burning test standard of FAR 25.853. Cone calorimeter data revealed an increase in the time to ignition (TTI) for the hybrid composites containing the FR mat, while the peak of heat release rate (PHRR) and total heat release (TTR) were greatly reduced. Furthermore, the maximum average rate of heat emission (MARHE) values indicated that both composites with flame retardant mats had achieved the requirements of EN 45545-2. However, the tensile strengths of laminates with surface or embedded flame-retardant mats were reduced from 1215.94 MPa to 885.92 MPa and 975.48 MPa, respectively. Similarly, the bending strength was reduced from 836.41 MPa to 767.03 MPa and 811.36 MPa, respectively.
    Keywords bio-based epoxy laminate ; thin-ply prepreg ; flame retardant mat ; mechanical properties ; fire protection performance ; Organic chemistry ; QD241-441
    Subject code 621
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    Kazi M. Zakir Hossain / Chenkai Zhu / Reda M. Felfel / Nusrat Sharmin / Ifty Ahmed

    Journal of Functional Biomaterials, Vol 6, Iss 3, Pp 564-

    2015  Volume 584

    Abstract: Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β- ... ...

    Abstract Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications.
    Keywords tubular scaffolds ; PLA fibre ; compressive modulus ; shape recovery ; cell proliferation ; Biotechnology ; TP248.13-248.65 ; Medicine (General) ; R5-920
    Subject code 500
    Language English
    Publishing date 2015-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of Fe2O3 addition

    Tan, Chao / Ifty Ahmed / Andrew J. Parsons / Nusrat Sharmin / Chenkai Zhu / Jinsong Liu / Chris D. Rudd / Xiaoling Liu

    Journal of materials science. 2017 June, v. 52, no. 12

    2017  

    Abstract: This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P₂O₅–5B₂O₃–5Na₂O–(29 − x)CaO–16MgO–(x)Fe₂O₃ and ... ...

    Abstract This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P₂O₅–5B₂O₃–5Na₂O–(29 − x)CaO–16MgO–(x)Fe₂O₃ and 45P₂O₅–5B₂O₃–5Na₂O–24CaO–(21 − x)MgO–(x)Fe₂O₃ where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q ² units with increasing Fe₂O₃ content. DSC analyses showed an increase in T g by ~5 °C with an increment of 3 mol% in Fe₂O₃ content. The thermal properties were also used to calculate processing window (i.e. T c,ₒₙₛ—T g) and another parameter, K gₗ, to determine the suitability for fibre drawing directly from melt, which equals (T c,ₒₙₛ—T g)/(T ₗ—T c,ₒₙₛ). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing Fe₂O₃ content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to Fe₂O₃ addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing Fe₂O₃ content.
    Keywords Fourier transform infrared spectroscopy ; X-ray diffraction ; depolymerization ; durability ; ferric oxide ; glass ; glass fibers ; magnesium oxide ; manufacturing ; melting ; phosphates ; thermal properties
    Language English
    Dates of publication 2017-06
    Size p. 7489-7502.
    Publishing place Springer US
    Document type Article
    ZDB-ID 2015305-3
    ISSN 1573-4803 ; 0022-2461
    ISSN (online) 1573-4803
    ISSN 0022-2461
    DOI 10.1007/s10853-017-0981-1
    Database NAL-Catalogue (AGRICOLA)

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