POSS/polypropylene hybrid nanocomposite monofilaments by reactive extrusion

The Allyl-heptaisobutyl-polyhedral oligomeric silsesquioxane (AHO-POSS) grafted polypropylene (PP) was prepared by reactive extrusion and by physical blending routes. The structure and properties of physically blended and reactively blended POSS/PP nanocomposites were investigated by FTIR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis, SEM, spherutlic growth and mechanical properties studies. Chemical bonding of POSS with PP in reactive extrusion was confirmed by FT-IR spectroscopy. DSC and TGA studies showed that the thermal stability of AHO-POSS/PP nanocomposite prepared by reactive extrusion improved significantly as compared to only physically blended nanocomposites. WAXD studies showed decrease in crystallinity of the AHO-POSS/PP nanocomposites prepared by reactive extrusion. SEM studies showed aggregation tendency in case of physically blended AHO-POSS/PP nanocomposites. Spherulite growth studies show reactive blending retards spherulite growth in PP polymer.     

Preparation and characterization of silk sericin/glycerol/graphene oxide nanocomposite film

Sericin (SS) is a protein that is secreted by silkworms, but it is usually discarded during the degumming process. To obtain and make use of the sericin, we prepared sericin/glycerol/graphene oxide nanocomposite film. The inherent brittleness of pure sericin film was improved by the addition of glycerol (Glc) as a plasticizer. To compensate for the reduced stiffness, we added graphene oxide (GO) into the SS/Glc film. At concentrations of up to 0.8 wt% relative to SS, GO dispersed evenly in the SS matrix without any agglomeration. The maximum tensile strength (9.5±0.7 MPa) and Young’s modulus (414.4±23.2 MPa) were obtained when the GO content was 0.8 wt% relative to SS. The elongation of SS/Glc/GO nanocomposite film also increased by approximately 40 % compared to SS/Glc film. The strong interfacial interaction between the SS and the GO was responsible for the increased stiffness. The increased elongation was due to the reduced crystallinity of the sericin matrix in the presence of GO.     

Preparation of bacterial cellulose/carbon nanotube nanocomposite for biological fuel cell

In this study, electrically conducting composite membranes were prepared by incorporating carboxylic multi-walled carbon nanotubes (c-MWCNTs) into Bacterial Cellulose (BC) pellicles. The biocathode and bioanode were prepared by a simple method of adsorption. An enzyme biological fuel cell (EBFC) composed of a biocathode and an enzymatic bioanode were developed and tested. The materials was characterised by field emission scanning electron microscope (FESEM), Fourier Transform Infrared (FTIR) Spectroscopy and Thermogravimetric analysis (TGA). The results showed that the presence of c-MWCNTs on BC was certified, on which c-MWCNTs loading was calculated as 30.02/100 g. The BC/c-MWCNTs/Lac composite membranes was characterized by cyclic voltammetry (CV). An EBFC was characterized by linear sweep voltammetry (LSV). The results showed EBFC exhibited excellent performance with the largest open circuit voltage (0.76 V) and a maximum power density value (55 uW/cm³). Additionally, the cell also exhibited acceptable stability over the recording of 30 days. BC was considered to be suitable for advanced applications such as an enzymatic carrier of biological fuel cells.     

Surface modification of microporous polypropylene membrane by UV-initiated grafting with poly(ethylene glycol) diacrylate

Poly(ethylene glycol) diacrylate (PEGDA) was grafted, through UV-initiated grafting, onto a microporous polypropylene (PP) membrane in order to develop a moisture-sensitive porous structure. Based on the concentration of the PEGDA grafting solution, as well as other variables, the pores of the membrane were filled to varying degrees with cross-linked PEGDA hydrogel, decreasing the pore sizes. This decrease in pore size was highly dependent on the grafting degree (weight add-on of the grafted polymer) that was dependent upon grafting conditions. Grafting with PEGDA resulted in a microporous polypropylene membrane with increased hydrophilicity and moisture-responsive pores. The functional membrane can be used in biological protective materials to limit the transport of liquid-borne pathogens while maintaining moisture transport properties.     

Modification of polyethylene-polypropylene fibers by emulsion and solvent radiation grafting systems for boron removal

Preparation of boron-selective adsorbent was carried out by radiation induced grafting of glycidyl methacrylate (GMA) onto polyethylene-coated polypropylene (PE-PP) nonwoven fabric in emulsion or solvent medium followed by immobilization of N-methyl-D-glucamine (NMDG). Adsorbent precursors with 180 % degree of grafting (DG) were obtained by applying reaction parameters comprising 20 kGy dose, 5 % monomer concentration and 1 h reaction time in emulsion compared to 30 kGy, 10 % and 3 h in solvent medium. A glucamine density of 2.2 mmol/g could be imparted to the obtained adsorbents. The emulsion-mediated grafting was found more efficient and economical for preparation of boron chelating adsorbents.     

Preparation and characterization of glass fiber-coir hybrid composites by a novel and facile Prepreg/Press process

The present study explored the preparation of glass fiber-coir reinforced unsaturated polyester resin hybrid (GCU) composites with a novel Prepreg/Press fabrication process. Flexural, impact and thermal-mechanical properties of GCU composites were investigated. Coir reinforced unsaturated polyester resin (CU) composites was also prepared with the same process to explore the enhancement effect of glass fabric on the mechanical properties of coir-based composites. The effect of fabrication pressure on the mechanical properties of CU and GCU composites was examined. Micromorphology and interfacial reaction of the composites were analyzed. It is shown that GCU composites fabricated with the Prepreg/Press process have excellent flexural strength (185.0 MPa), MOE (18.3 GPa), and impact strength (67.2 kJ/m²). The mechanical properties of GCU composites increased with the increase of applied pressure up to 0.8 MPa in the Prepreg/Press process. However, further increase of applied pressure led to the decrease in mechanical properties. The addition of glass fabrics to GCU composites showed 419 % improvement in flexural strength, 708 % improvement in MOE and 562 % improvement in impact strength over coir-based composites. The micromorphology study proved that the poor interfacial bonding between coir and matrix led to the low mechanical properties of coir-based composites.     

A study of mechanical behavior and morphology of carbon nanotube reinforced UHMWPE/Nylon 6 hybrid polymer nanocomposite fiber

We report a phenomenal increase in strength, modulus, and fracture strain of ultra high molecular weight polyethylene (UHMWPE) fiber by 103 %, 219 %, and 108 %, respectively through hybridizing this fiber with Nylon 6 as a minor phase and simultaneously reinforcing it with single-walled carbon nanotubes (SWCNTs). Loading of Nylon 6 and SWCNTs into UHMWPE was 20.0 wt% and 2.0 wt%, respectively. Hybridized fibers were processed using a solution spinning method coupled with melt mixing and extrusion. We claim that the enhancement in strain-to-failure of the nanocomposites is due to induced plasticity in the hybridized Nylon 6-UHMWPE polymers. The enhancement in strength and stiffness in the nanocomposites is attributed to the load sharing of the SWCNTs during deformation. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) studies showed that changes in percent crystallinity, rate of crystallization, crystallite size, alignment of nanotubes, sliding of polymer interfaces and strong adhesion of CNT/polymer blends were responsible for such enhancements.     

Preparation and characterization of porous carbon based nanocomposite for supercapacitor

Porous nanocomposites are prepared by electrospinning blended polyacrylonitrile, copper acetate and mutiwalled carbon nanotube in N, N-dimethylformamide. The electrospun nanofiber webs are oxidatively stabilized and then carbonized resulting in composite carbon nanofibers. The study reveals that composite nanofibers with relatively smooth surface morphology are successfully prepared. X-ray diffraction is used to confirm the presence of Cu in carbon nanofibers. The carbon nanofibers with CNTs have better thermal stability and higher electrical conductivity. The Brunauer-Emmett-Teller analysis reveals that C/Cu/CNTs nanocomposites with mesopores possess larger specific surface area and narrower pore size distribution than that of C/Cu nanofibers. The electrochemical properties are investigated by cyclic voltammetry and galvanostatic charge-discharge tests. The nanocomposite with 0.5 wt.% CNT loading exhibits an energy density of 2 Whkg^?1, power density of 1916 Wkg^?1, a specific capacitance of about 225 Fg^?1 at a current density of 2 Ag^?1 and its capacitance decreased to 78 % of its initial value after 3,000 cycles.     

Preparation and properties of polypropylene nanocomposites reinforced with exfoliated graphene

We have prepared a series of polypropylene/exfoliated graphene (PP/EG) nanocomposite films via efficient meltcompounding and compression, and investigated their morphology, structures, thermal transition behavior, thermal stability, electrical and mechanical properties as a function of EG content. For the purpose, EG, which is composed of disordered graphene platelets as reinforcing nanoscale fillers, is prepared by the oxidation/exfoliation process of natural graphite flakes. SEM images and X-ray diffraction data confirm that the graphene platelets of EG are well dispersed in PP matrix for the nanocomposites with EG contents less than 1.0 wt%. It is found that thermo-oxidative degradation of PP/EG nanocomposites is noticeably retarded with the increasing of EG content. Electrical resistivity of the nanocomposite films was dramatically changed from ∼10¹⁶ to ∼10⁶ Ω·cm by forming electrical percolation threshold at an certain EG content between 1 and 3 wt%. Tensile drawing experiments demonstrate that yielding strength and initial modulus of PP/EG nanocomposite films are highly improved with the increment of EG content.     

Preparation and evaluation of antioxidant capacity of Jackfruit (Artocarpus heterophyllus Lam.) wine and its protective role against radiation induced DNA damage

Jackfruit is an underutilized edible fruit in the tropics and subtropics. The aim of this study was to produce wine from jackfruit pulp and to evaluate the total phenolic and flavonoid contents and antioxidant properties of the wine. The ability of scavenging free radicals was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant assay (FRAP), N, N-dimethyl-p-phenylendiamine (DMPD) and nitric oxide (NO) scavenging assays. Experimental results indicated that jackfruit wine was effective in DPPH radical scavenging (69.44 ± 0.34%), FRAP (0.358 optical density value, O.D.), DMPD (78.45 ± 0.05%) and NO (62.46 ± 0.45%) capacity. By the analysis of the high performance liquid chromatography coupled to diode array detector (HPLC-DAD), two phenolic compounds namely gallic acid and protocatechuic acid were identified. The jackfruit wine was also able to protect H₂O₂ + UV radiation and γ-radiation (100 Gy) induced DNA damage in pBR322 plasmid DNA. The antioxidant and DNA damage protecting properties of jackfruit wine confirmed health benefits when consumed and could become a valuable source of antioxidant rich neutraceuticals. Additionally, the wine could be a commercially valuable by-product for the jackfruit growers.     

Preparation of collagen fiber/CaCO3 hybrid materials and their applications in synthetic paper

The collagen fiber/CaCO₃ hybrid materials were successfully prepared via in situ organic-inorganic hybrid technique. The surface morphology, hybrid mechanism, thermal and hydrothermal stability of these materials were investigated, respectively. Scanning electron microscopy (SEM) analysis showed that the size scale and distribution of CaCO₃ particles in collagen fiber relied on the concentration of CaCl₂. When the CaCl₂ was at low concentration, for example 6 wt%, the in-situ produced CaCO₃ particles were distributed evenly around the collagen fiber, the particle size could be controlled in the range of 2–4 µm and no apparent coagulation of CaCO₃ particles was found. Fourier transform infrared spectroscopy (FTIR) study revealed the interactions between the collagen fiber and CaCO₃ particles. The water solubility test and TGA analysis indicated that the solubility of collagen fiber in hot water decreased significantly after hybridization with CaCO₃ particles, whereas, the decomposition temperature was improved with increasing of the production of CaCO₃ particles. Moreover, the hybrid materials were used in conjunction with polyurethane and CaCO₃ powder to fabricate a novel synthetic paper. The result showed that the synthetic paper had good writing and printing.     

Microstructure and mechanical properties of polyurethane/nylon/montmorillonite nanocomposite

Nanocomposite of polyurethane (PU), Nylon66 (nylon), and montmorillonite (MMT) was prepared by a twin screw extruder, and the dispersion of MMT and the mechanical properties of the nanocomposite were analyzed. Dimethyl hydrogenated tallow 2-ethylhexyl ammonium modified Cloisite 25A (C25A) and methyl tallow bis-2-hydroxyethyl ammonium modified Cloisite 30B (C30B) were used as MMT. XRD and TEM analysis indicated that the continuous melt mixing by a twin screw extruder was effective in MMT dispersion. C30B having hydroxyl group on its surface has better dispersion than C25A in the PU/nylon matrix. Maximum stress and strain at break were the maximum at 1 wt% MMT regardless of matrix composition, and decreased at higher MMT content. Best MMT dispersion was also observed at 1 wt% MMT for the entire matrix composition. Aggregation of MMT occurred at MMT content higher than 1 wt%. Nylon addition also induced the aggregation of MMT because of the high polarity of nylon surface. Dispersion of MMT was very important in improving the mechanical properties of PU/nylon nanocomposite.     

Characterization of oil palm empty fruit bunch and glass fibre reinforced recycled polypropylene hybrid composites

The effects of hybridization of glass fibre on oil palm empty fruit bunch (EFB) and recycled polypropylene-based composites are described in this paper. The compounding process involved extrusion followed by injection moulding technique to prepare the samples for characterizations. Fibre loading were considered as 40 % of the total weight of the blends and EFB:glass fibre ratio was maintained as 30:70, 50:50, 70:30 and 90:10. Two types of coupling agents of maleic anhydride-grafted polypropylene such as polybond-3200 and fusabond P-613 of different molecular weight and maleic anhydride level were used to improve the interfacial adhesion between the fibres and the matrix. Composites were characterized by density, melt flow index, tensile, Izod impact and flexural testing. Morphological images of the fractured surfaces of the composites were examined by field-emission scanning electron microscopy. Samples were also characterized by thermal tests such as thermogravimetric analysis and differential scanning calorimetry to evaluate the thermal and crystalline properties, respectively. Optimization of hybridization of the fibres and effect of coupling agents were evaluated in terms of various properties of the samples. The composite prepared with EFB:glass fibre ratio of 70:30 showed better reinforcing properties than that of others.     

Structures and physical properties of graphene/PVDF nanocomposite films prepared by solution-mixing and melt-compression

We have manufactured poly(vinylidene fluoride) (PVDF)-based nanocomposite films with different graphene contents of 0.1～10.0 wt% by ultrasonicated solution-mixing and melt-compression. As a reinforcing nanofiller, graphene sheets are prepared by rapid thermal expansion of graphite oxide, which are from the oxidation of natural graphite flakes. Graphene sheets are characterized to be well exfoliated and dispersed in the nanocomposite films. X-ray diffraction data confirm that the α-phase crystals of PVDF are dominantly developed in the nanocomposite films during the meltcrystallization. DSC cooling thermograms show that the graphene sheets serve as nucleating agents for the PVDF α-form crystals. Thermal stability of the nanocomposite films under oxygen gas atmosphere is noticeably improved, specifically for the nanocomposite with 1.0 wt% graphene. Electrical volume resistivity of the nanocomposite films is substantially decreased from ～10¹⁴ to ～10⁶ W cm, especially at a critical graphene content between 1.0 and 3.0 wt%. In addition, mechanical storage modulus is highly improved with increasing the graphene content in the nanocomposite films. The increment of the storage modulus for the nanocomposite film at 30 °C with increasing the graphene content is analyzed by adopting the theoretical model proposed by Halpin and Tsai.     

Preparation and antibacterial properties of nanocomposite fibers made of polyamide 6 and silver-doped hydroxyapatite

Nanocomposite fibers of polyamide 6 (PA6) and hydroxyapatite (HA) were prepared and doped with silver to investigate antibacterial activities due to good potential for textile modification. Nano-sized HA could be synthesized using agarose and ethanol as thickener and washing medium, respectively. The PA6/HA nanocomposite fibers could be doped with silver by dipping the fibers having HA in aqueous AgNO₃ solution containing 300 ppm of Ag ion for 1 min utilizing HA as a carrier to load silver through ion-exchange mechanism. It was found that silver was successfully doped to PA6/HA nanocomposite fibers from the EDS spectra. The nanocomposite fibers containing 3.3 wt% of HA after silver doping demonstrated such excellent antibacterial activities against K. pneumonia and E. coli that they are expected to serve as functional antibacterial materials in various application fields.     

Chemical modification of isotactic polypropylene by melt blending

The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of theb-PP was increased with increasing the initiator content. On the introduction of the alkylamine as the branching agents the MFI of theb-PP was increased, while that of theb-PP with the pentaerythritol triacrylate (PT) was decreased. It may be caused by the chain scission of thei-PP backbone due to the reduced thermal stability of thei-PP on the melt blending. The MFI of theb-PP without the antioxidant was increased due to the chain scission occurred during the melt processing, while on the introduction of the antioxidant, the MFI of theb-PP was decreased. The crystallization temperature of theb-PP was higher than that of PP, which was attributed to the branched chain structure. It was found that the PT was the most effective functional monomers for enhancing the melt properties of theb-PP.     

Effect of reinforcement and chemical treatment of fiber on The Properties of jute-coir fiber reinforced hybrid polypropylene composites

Present research investigates the mechanical properties of jute-coir fiber reinforced hybrid polypropylene (PP) composite with fiber loading variation and observes the effect of chemical treatment of fiber on property enhancement of the composites. Composites were manufactured using hot press machine at four levels of fiber loading (5, 10, 15 and 20 wt%). Fiber ratio’s were varied (jute:coir=1:1, 3:1 and 1:3) for 20 % fiber loaded composites. Both jute and coir fiber was treated using 5 % and 10 % NaOH solutions. Composites were also prepared using treated fiber with jute-coir fiber ratio of 3:1. Tensile, flexural, impact and hardness tests and Fourier transform infrared spectroscopic analysis were conducted for characterization of the composites. Tensile test of composite showed a decreasing trend of tensile strength and increasing trend of the Young’s modulus with increase in fiber loading. During flexural, impact and hardness tests, the flexural strength, flexural modulus, impact strength and hardness values were found to be increased with increase in fiber loading. All these properties enhanced with the enhancement of jute content except impact strength. 5 % NaOH treatment provided an improving trend of properties whereas, 10 % NaOH treatment showed the reverse one. The FTIR analysis of the composites indicated decrease of hemicelluloses and lignin content with alkali treatment.     

Investigation of mechanical properties of developed antimicrobial PPsuture/Ag nanocomposite

In order to prevent surgical complications due to microbial infections, we have developed polypropylene suture grafted with silver nanoparticles (PPsuture/Ag nanocomposite) by a simple immersion procedure. Physical and mechanical properties of developed suture are investigated. Suture surface characteristics are examined by scanning electron microscopy (SEM) imaging and atomic force microscopy (AFM). Silver content on suture surface was determined by Inductively coupled plasma atomic emission spectroscopy (ICP-AES). The mechanical properties of developed antibacterial PP suture/Ag were studied. We note that proposed silver coating method has not affected mechanical performances of suture. Antimicrobial performances of PP suture/Ag nanocomposites against S. aureus and E. coli colonies were also investigated.     

Electrospinning and microwave absorption of polyaniline/polyacrylonitrile/multiwalled carbon nanotubes nanocomposite fibers

Electrical conductive nanocomposite fibers were prepared with polyaniline (PANI), polyacrylonitrile (PAN) and multi-walled carbon nanotubes (MWCNTs) via electrospinning. The morphology and electrical conductivity of the PANI/PAN/MWCNTs nanocomposite fibers were characterized by scanning electron microscope (SEM) and Van De Pauw method. Electrical conductivity of nanocomposite fibers increased from 1.79 S·m^?1 to 7.97 S·m^?1 with increasing the MWCNTs content from 3.0 wt% to 7.0 wt%. Compared with PANI/PAN membranes, the mechanical property of PANI/PAN/MWCNTs nanocomposites fiber membranes decreased. The microwave absorption performance of composite films was analyzed using waveguide tube, which indicated that with the thickness increasing the value of R_L reduced from ?4.6 to ?5.9 dB.