Positronium probes free volume to identify para- and meta-aramid fibers and correlation with mechanical strength

Ramani, R.; Kotresh, T. M.; Shekar, R. Indu; Sanal, F.; Singh, Upendra; Renjith, R.; Amarendra, G.

doi:10.1016/j.polymer.2017.11.064

Cited by 23 publications

(29 citation statements)

References 61 publications

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“…The occurrence of a highly eminent peak located around the 18.2° region, is consistent with the high crystallinity of PTFE fibers [23]. The XRD pattern of the Nomex fibers displays two relatively lower intensity peaks at around 23.52° and 27.33° which is consistent with its reported values [24]. Compared to the virgin fabric, the intensity of the diffraction peaks for the LbL-6-fabric obviously reduced.…”

Section: Lbl Film Modified Hybrid Fabric (Lbl-fabric) Characterizationsupporting

confidence: 83%

“…In the Raman spectra of the virgin fabric (Fig. 2(a)), the weak peaks at 278 cm −1 and 1,304 cm −1 correspond to the different modes of the CF 2 groups [23], while the strongest peaks centered at 1,000 cm −1 , 1,250 cm −1 , 1,339 cm −1 , 1,542 cm −1 and 1,602 cm −1 correspond to the C-C bands in the aromatic rings of Nomex fibers [24]. The vibration at 1,649 cm −1 position is attributable to the band of C=O group in the main fiber structure of Nomex.…”

Section: Lbl Film Modified Hybrid Fabric (Lbl-fabric) Characterizationmentioning

confidence: 99%

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Fabrication of PTFE/Nomex fabric/phenolic composites using a layer-by-layer self-assembly method for tribology field application

et al. 2019

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Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties. Nevertheless, the poor interfacial strength between fibers and the resin matrix limits the performance of composites utilized as tribo-materials. To overcome this drawback, a mild layer-by-layer (LbL) self-assembly method was successfully used to construct hybrid fabric composites in the present work. In addition, this investigation addressed the effect of self-assembly cycles on the friction and wear behaviors of hybrid fabric composites under dry sliding condition. The results demonstrate that fabric composites with three or more self-assembly cycles have significantly enhanced surface activities and anti-wear performances. The results obtained in this work can provide guidance in the preparation of selflubricating liner composites and highlight how the LbL self-assembly techniques could influence the properties of hybrid fabric composites.

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Section: Lbl Film Modified Hybrid Fabric (Lbl-fabric) Characterizationsupporting

confidence: 83%

Section: Lbl Film Modified Hybrid Fabric (Lbl-fabric) Characterizationmentioning

confidence: 99%

Fabrication of PTFE/Nomex fabric/phenolic composites using a layer-by-layer self-assembly method for tribology field application

et al. 2019

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“…The weight degradation versus temperature was illustrated in Figure 3. The weight loss in initial stage from 30 to 120°C in the materials KF, KF@PAn, KF-H and KF-H@PAn was attributed to the release of moisture(Huanda Zheng, 2015; Ramani et al , 2018). There were almost no weight loss until 500°C for KF and KF-H, 400°C for KF@PAn and KF-H@PAn, indicating high thermal stability of KF, owing to their aromatic ring structure and conjugation of electrons(Ramani et al , 2018).…”

Section: Resultsmentioning

confidence: 99%

Polyaniline dispersed by Kevlar fiber for uptake of organic dye

Liu

Tian

et al. 2020

PRT

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Purpose This paper aims to focus on the preparation of Kevlar fiber (KF) and alkaline hydrolyzed KF (KF-H) to improve the dispersed condition of polyaniline (PAn), as the aggregation of PAn would lead to some adsorption sites buried. And then the materials were used to enrich anionic dye Congo red (CR) from aqueous solution. Design/methodology/approach The materials (KF@PAn and KF-H@PAn) were designed by means of “diffusion-interfacial-polymerization” under mild condition as high affinity due to the structural properties of PAn, KF and KF-H. The dispersed degree of PAn on the surface of KF and KF-H was validated according to adsorption efficiency for CR. Findings The content of PAn introduced was not beyond 20 wt.%, while adsorption capacity for CR was significantly enhanced by 4–8 times (on the basis of kinetic data) according to the calculation only by the content of PAn due to KF and alkaline hydrolyzed KF exhibited almost no adsorption for CR, indicating dispersed situation of PAn coating was greatly enhanced and more active sites exposed, which was favorable for the adsorption process. Presence of NaCl would exhibit a more or less positive effect on CR uptake, suggesting the materials could be used for high salt environment. Research limitations/implications The investigated means of dispersed degree of PAn on the surface of KF and KF-H are the further and future investigation. Practical implications This study will provide a method to improve the dispersed situation of PAn and a theoretical support to treat anionic dyes from aqueous solution especially for salt environment. Originality/value The results showed that the dispersed condition of PAn on the surface of KF and KF-H was greatly improved. According to the adsorption capacities for CR, it can be concluded that part of adsorption sites were buried due to the aggregation of PAn, and introduction of KF and KF-H, buried adsorption sites decreased greatly. This study will provide a method to decrease buried adsorption sites of PAn and a contribution for their convenient application in wastewater treatment especially for high salt environment.

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“…Additionally, the packing of the polymer chains has an influence on the properties of the polymer formed. In general, metaamides are less densely packed as compared to para-amides [33]. Therefore, we hypothesize that the polymer 3-MPD has the tendency to form a gel, whereas 3-PPD precipitates more quickly into a well-defined cross-linked film.…”

Section: The Effect Of Chemical Structure On the Reactivitymentioning

confidence: 95%

The use of a star-shaped trifunctional acyl chloride for the preparation of polyamide thin film composite membranes

Maaskant

Vogel

Dingemans

2018

Journal of Membrane Science

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A star-shaped trifunctional acyl chloride bearing ether linkages was synthesized as an alternative to the commonly used trimesoyl chloride (TMC) in the preparation of polyamide thin film composite membranes (TFC). Although this star-shaped acyl chloride has the same functionality as TMC, it is larger in size and its acyl chloride groups are less reactive due to the electron donating ether linkages. In this work, we prepared TFC membranes by the interfacial polymerization of both this star-shaped acyl chloride and TMC with either one of the two structural isomers: m-phenylenediamine (MPD) or p-phenylenediamine (PPD). No strong effect was observed of the substitution pattern of the aromatic diamine on the membrane formation with TMC, due to the high reactivity of the acyl chloride groups of TMC. In contrast, the use of this star-shaped acyl chloride results in significant differences in the properties of the formed TFC membrane depending on the use of MPD or PPD. Where TMC-MPD membranes are well-known for their excellent retention, we could not obtain defect-free membranes prepared from MPD and this star-shaped triacyl chloride ( < R 77% rose bengal). The use of PPD instead of MPD, however, did result in defect-free membranes ( > R 97% rose bengal ) with an acceptable clean water permeance (2.5 L m −2 h −1 bar −1 ).

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Positronium probes free volume to identify para- and meta-aramid fibers and correlation with mechanical strength

Cited by 23 publications

References 61 publications

Fabrication of PTFE/Nomex fabric/phenolic composites using a layer-by-layer self-assembly method for tribology field application

Fabrication of PTFE/Nomex fabric/phenolic composites using a layer-by-layer self-assembly method for tribology field application

Polyaniline dispersed by Kevlar fiber for uptake of organic dye

The use of a star-shaped trifunctional acyl chloride for the preparation of polyamide thin film composite membranes

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