In last two decades, acid doped polybenzimidazole as polymer electrolyte membrane (PEM) has been widely recognized and envisioned as "ideal" proton conducting materials for application in high ...temperature PEM fuel cell (HT-PEMFC). The majority of research and developmental work is mainly focused on poly (2,2´-m-phenylene-5,5´-bibenzimidazole), However, it is neither easy-processed nor inexpensive component of the respective family. On the other hand, among the various members belonging to benzimidazole family, poly (2,5-benzimidazole) is unique because it possesses a cost-attractive, single-step synthesis process, high extent of doping as well as good chemical and thermal stability. In the recent years this material has proved its potency in the earlier research. Thus this review puts special emphasis on poly (2,5-benzimidazole) and epitomizes the on-going breath-taking progress and achievements on the fabrication of poly (2,5-benzimidazole) based membranes. The write-up describes the effect of blending, cross-linking, ionic liquids and incorporation organic/inorganic nano-fillers. In addition, incorporating other protonic dopants such as heteropoly acids into the chain of poly (2,5-benzimidazole) molecular skeleton is also overviewed. Moreover, the critical interpretation of different causes responsible for earlier degradation and their effect towards the fabrication of high temperature membrane electrode assembly are visualized herein.
Highlights
Current developments and existing challenges of ABPBI in PEMFC have been reviewed.
PEM Modification and addition of protonic dopants has been discussed.
Proton migration, permeability, stability and reliability are thoroughly illustrated.
Different ABPBI-based membranes and their performance are comparatively analyzed.
•Using castor oil as a renewable raw material.•Synthesis of castor oil-based polyurethane prepolymers (COPUP) with different NCO/OH molar ratio.•Bio-based COPUP had good thermal and mechanical ...properties.
The use of new materials from natural origin in the synthesis of urethane-derived polymers is recently drawing eminent care from social, environmental and also economic viewpoints. In this work, NCO-terminated castor oil-based polyurethane prepolymer (COPUP) is synthesized through the reaction between the isophorone diisocyanate (IPDI) and castor oil (CO) with a variable ratio of the isocyanate (NCO) and hydroxyl (OH) groups (0.5:1; 1:1; 1.5:1; 2:1) analyzed by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy. Furthermore, the polyurethane prepolymers synthesized from IPDI played a significant role of inter-mixing between the soft polyether segments and the hard urethane groups, as shown by the analysis of hydrogen bonding in FT-IR deconvolution. A detailed study of the relationship between structure–property of cured prepolymers was carried out. As a result, COPUP obtained from biomass-derived polyols may enhance a promising alternative to the use of other petrochemicals in the paving industry.
•Major areas of research on mobile phone recycling from 1999 to 2015 were reviewed.•Material recovery has been the largest area of research in mobile phone recycling.•The methods and analytical ...techniques used by researchers have been discussed.•The number of articles based on year, topics and location are shown graphically.
There is an enormous growth in mobile phone consumption worldwide which leads to generation of a large volume of mobile phone waste every year. The aim of this review is to give an insight on the articles on mobile phone waste management and recycling, published in scientific journals, major proceedings and books from 1999 to 2015. The major areas of research have been identified and discussed based on available literature in each research topic. It was observed that most of these articles were published during the recent years, with the number of articles increasing yearly. Material recovery and review on management options of waste are found to be the leading topics in this area. Researchers have proved that economically viable refurbishing or recycling of such waste is possible in an environmentally friendly manner. However, the literatures indicate that without proper consumer awareness, a recycling system cannot perform to its maximum efficiency. The methodologies followed and analytical techniques employed by the researchers to attain their objectives have been discussed. The graphical representations of available literature on current topic with respect to year of publication, topics and location have also been explored.
Polypropylene (PP)/sisal fiber (SiF)/cellulose nanocrystals (CNC) hybrid composites were prepared at a variable weight percentage of SiF/CNC loading (29:1, 27:3, 25:5, and 23:7) using melt-blending ...technique followed by injection molding. The dispersion of the CNCs and SiFs within the nonpolar PP matrix was enhanced by using maleic anhydride grafted PP (MAPP) as a compatibilizer. Furthermore, the mechanical properties like tensile, flexural, and impact properties of the hybrid composites were evaluated. High tensile strength and modulus of 47.02 MPa and 2820.26 MPa, respectively, were observed for the hybrid composite with the incorporation of SiF/CNC (27:3 wt%) in the presence of 5 wt% MAPP. Additionally, an increment of 30.87% and 14.81% was observed for corresponding flexural strength and modulus as compared to their counterparts without MAPP. The elastic moduli obtained experimentally were compared with the theoretical elastic moduli using Cox–Krenchel and Ouali model in combination with the Halpin–Tsai model. Surface morphology by field emission scanning electron microscopy observed that the CNCs and SiFs were well dispersed within the PP matrix in the presence of MAPP. Differential scanning calorimetry thermograms showed no measurable changes in the melting temperature (
T
m
) of PP in PP hybrid composites; however, an increment in the crystallization temperature (
T
c
) was observed. The thermogravimetric analysis confirmed the enhancement in the thermal stability of PP hybrid composites due to the synergistic effect of hybridization within the PP matrix. Partial substitution of CNCs along with SiFs within the matrix polymer shows an increment in the stiffness of the hybrid composites as evident by dynamic mechanical analysis.
Graphic abstract
•Examined structural and compositional analysis of data cables used in computers.•This study found Polyvinylchloride as the major polymeric material in data cables.•We focused on the mechanical ...recycling possibilities of Polyvinylchloride.•Previous and degradation after reprocessing considered with help of FTIR studies.
Cables and wires are the indispensable parts of electronic equipments for transmission of both information and electricity. Nowadays, data cables are widely used in the computer equipments for sending information and they become waste once its life cycle is completed. However, recycling of cables and wires are mainly concentrating into the recovery of metals such as aluminium and copper, rather than other polymer present. Polymeric materials from the waste data cables are often disposed into landfills or incinerated, since they have only lower value in recycling yard. From the data cables collected, it has been estimated that the major constituents are copper (58.3%), polyvinyl chloride (19.9%) and polyethylene (16%). Similarly, polycarbonate (2.9%), silicon rubber (1.6%), steel (1.4%) and other material (0.4%) such as cotton cord were also present as minor components. Out of these, polyvinyl chloride is the dominant polymer present in data cables. Hence, the present work investigates the reprocessability of the polyvinyl chloride recovered from the data cables and deals with issues such as premature degradation during life cycle, assessment of plasticizers and degradation after reprocessing. Torque measurement studies using torque rheometer revealed further mechanical recycling possibilites of the recovered polyvinyl chloride. Besides, the applicability of melt blending technique for processing recovered polyvinyl chloride can be found out by analysing thermal behaviour by using thermogravimetric analysis, differential scanning calorimetry and heat distortion temperature.
Polymer composites have been a material of choice for lightweight and durable applications in sectors ranging from automobile, packaging, structural components, and electronics to energy harvesting. ...Their versatility and ability to be tailored to application requirements have made them prospective alternatives for metal enclosures used in communication systems, power electronics, electric motors, and generators. The easy processing and high strength-to-weight ratio provide advantages over traditional materials that involve time- and-labor intensive processes. However, high thermal conductivity (TC) and electromagnetic interference (EMI) shielding are factors limiting their penetration into niche markets, and thus the development of alternatives with high TC and EMI shielding efficiency is critical. Thermally conductive polymer composites and EMI shielding effectiveness (SE) is a current issue in different applications including polymers providing light weight, corrosion resistance, and ease of processing as compared with metal. This paper focuses on improvements in the TC and shielding effectiveness of polymers by incorporating various fillers including carbon-based, mineral-based, and hybrid fillers. The paper reviews the current research worldwide regarding the enhancement of the TC and shielding effectiveness of polymer composites.
A novel Polyvinylidene fluoride/Ag decorated TiO2 (PVDF/Ag@TiO2) nanocomposite membrane was successfully prepared using APTES as a crosslinker via phase inversion technique. Synthesized Ag@TiO2 was ...characterized by Raman spectroscopy and XRD. Nanocomposite membranes were characterized by FTIR, SEM, AFM. Flux performance and flux recovery ratio of PVDF/Ag@TiO2 membranes revealed that the PVDF/Ag@TiO2 nanocomposite membrane exhibited a pure water flux up to 465.8 Lm−2h−1 which is three-fold higher than virgin membrane and a higher BSA rejection of 93.7% after rinsing with DI water followed by UV irradiation. Also, PVDF/Ag@TiO2 nanocomposite membrane shows a faster removal of E. coli. Overall, the incorporation of nanoparticles in the polymer matrix enhanced the antifouling and antibacterial properties of the nanocomposite membrane to a remarkable extent.
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•Nanocomposite membranes were prepared by entrapping of Ag@TiO2 nanoparticle within PVDF.•The resultant membrane exhibited significantly improved hydrophilicity and water permeability.•PVDF/Ag@TiO2 membrane has excellent antibacterial and antifouling properties.•Good self-cleaning performance of the membranes confirmed from flux recovery ratio.
The current research discusses the properties of an elastomeric heat‐shielding material, based on nano‐silica (NS) filled ethylene propylene diene monomer (EPDM) rubber/Kevlar fiber (KF) hybrid ...composites. The developed elastomeric insulating material consists of an aromatic polyamide fiber (KF) and silica nanoparticles. An in‐depth analysis of mechanical properties, density, coefficient of thermal expansion, thermal conductivity, thermogravimetric analysis, and heat release rate of the insulating materials ‐was performed. TEM micrograph represents an excellent distribution of nanoparticles in the EPDM matrix. The improvement in the mechanical and the flame retardancy of the NS filled EPDM/KF hybrid composite insulations is based on the fiber/matrix adhesion. Maleic anhydride grafting confers polarity to the nonpolar rubber matrix. The char residues of the insulations inspected by scanning electron microscopy and energy dispersive spectroscopy are depicting a rigid and rough surface by the optimal composites, which can aid in better insulation. The optimal formulation of the hybrid composites exhibited a 220% enhancement in char residue with improved thermal stability and mechanical properties.
The present article summarizes the development of polypropylene-bamboo/glass fiber reinforced hybrid composites (BGRP) using an intermeshing counter rotating twin screw extruder followed by injection ...molding. Maleic anhydride grafted polypropylene (MAPP) has been used as a coupling agent to improve the interfacial interaction between the fibers and matrix. The crystallization and melting behavior were investigated employing differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) indicates an increase in thermal stability of the matrix polymer with incorporation of bamboo and glass fibers, confirming the effect of hybridization and efficient fiber matrix interfacial adhesion. The dynamic mechanical analysis (DMA) showed an increase in storage modulus (
E′) indicating higher stiffness in case of hybrid composites as compared with untreated composites and virgin matrix. The rheological behavior of the hybrid composites has also been studied using time–temperature superposition (TTS) principle and corresponding viscoelastic master curves have been constructed.
Catastrophic breakdown that occurs during the flight of supersonic vehicles demands more focused research in the insulation of rocket engines. At present, optimization of polymeric ablatives as ...viable insulation for solid rocket motor casing has a prominent role in the successful mission of rockets. Among polymers, elastomer serves an imperative part. Comprehensive investigations were disclosed, especially in the elastomeric heat shielding materials with various reinforcing agents. In this paper, research progress of mostly used elastomers is reviewed, and a circumstantial understanding about the features of ablation and insulation has been validated.
