Nanofillers In Polymer Matrix Research Articles

Graphene Base Nanocomposites: An overview

Abstract Polymer base nanocomposites are in great demand on commercial and scientific basis owing to their improved properties as compared to neat polymers. It is expected that the mechanical properties of the nanocomposites will rise, if nano-fillers having high aspect ratio are either exfoliated or well-dispersed in polymer matrix. Graphene is structurally similar to layered silicates and chemically comparable to CNTs and thus, it acts as exceptional nanofiller in polymer matrix. In recent years, the performance of the nanocomposites is found to improve by embedding graphene into it. The present review deals with the chemistry that occurs between the graphene and polymer matrix so that the resultant nanocomposites possess improved mechanical and electrical properties.

Formation of polypropylene/functional graphene oxide nanocomposites with Different FGs loading in elongation flow condition

Aggregation of nanofiller in polymer matrix is the key barrier to enhance the mechanical and thermal properties of polymer nanocomposites. Here, we report a novel vane mixer based on elongation flow processing, which is facial to achieve the homogeneous dispersion of functional graphene oxide sheets (FGs) in isotactic polypropylene (iPP). Scanning electron microscopy reveals that FGs in iPP matrix are fully exfoliated and uniformly dispersed. The crystallization behavior, mechanical properties and thermal stability of the nanocomposites with different FGs loadings are investigated by differential scanning calorimetry, dynamic thermomechanical analysis, and thermogravimetric analysis, respectively. The results illustrate that the mechanical and thermal stability of the iPP/FGs composites has enhancement obviously at low FGs loadings. POLYM. ENG. SCI., 59:830–837, 2019. © 2018 Society of Plastics Engineers

Enhancement of β-phase of P(VDF-TrFE)60/40 by BaTiO3 nanofiller

ABSTRACTPolymer nanocomposite thin film of β-phase P(VDF-TrFE) with 4 wt. % BaTiO3 was prepared by solution grown technique. The structural and surface morphology was investigated by Atomic force microscopy (AFM), X-ray diffraction, Fourier transform infrared spectroscopy (FTIR). AFM result shows the significant change in the surface topography of nanocomposite samples. XRD and FTIR spectra reveal the β-phase enhances due to incorporation of BaTiO3 nanofiller in polymer matrix. The enhancement of β-phase of P(VDF-TrFE) is corresponding to improvement of ferroelectric properties using BaTiO3 as a nanofiller.

Comparative Tribological and Mechanical Property Analysis of Nano-Silica and Nano-Rubber Reinforced Epoxy Composites

Nano-filler reinforced epoxy composites has been investigated in this study subjected to various mechanical and pin-on-disk tribological tests. Two different types of nano-filler were used namely, rigid nano-silica (SiO2) particles and soft nano-rubber particles. Incorporation of nano-filler in polymer matrix enhance mechanical properties. In addition, tribological response of composites are also better compared to neat epoxy polymer. However, the effect of nano-silica addition is much more pronounced than that of nano-rubber due to the high rigidity of nano-silica reinforced epoxy composite. This was mainly attributed to transfer film layer (TFL) formation. The TFL was further investigated by electron microscope and nanoindentor. The best set of tribological properties was achieved at 8 wt. % nano-silica addition. This was due to better reinforcement dispersion and continuous transfer film layer formation which eventually control the overall friction and wear mechanism.

Effects of Surface-Modified Alkyl Chain Length of Silica Fillers on the Rheological and Thermal Mechanical Properties of Underfill

Due to the increased packaging density as well as the size reduction of the gap between the chip and the substrate in modern flip-chip technology, there is an increasing demand for the use of nanosized silica particles as fillers into underfill to further improve its comprehensive performance. However, silica nanoparticles (SNPs) cannot uniformly disperse into the polymer matrix and usually cause some negative issues, such as a dramatic increase in viscosity and a significant decrease in the glass transition temperature as a result of their excessive surface energy and surface hydrophilic silanol groups. Surface modification with alkyl chains is an effective way to facilitate a uniform dispersion of nanofillers in polymer matrix since suitable repulsive forces can optimize spacing among nanoparticles by decreasing interactions between nanoparticles and changing the surface property of nanoparticles from hydrophilic to hydrophobic. In this paper, SNPs surface-modified by alkyl groups of different lengths were prepared and used as fillers to study the role of the surface alkyl chain length in the rheological and thermal–mechanical properties of underfill nanocomposites. It was found that surface alkyl chains could improve the dispersion of SNPs in epoxy matrix, and thus contributed to decrease the viscosity and enhance the glass transition temperature of underfill nanocomposites. With an increase in the surface alkyl chain length, the viscosity of underfill nanocomposites increased and the glass transition temperature shifted to a higher temperature. This paper sets the way toward the choice of an alkyl chain of proper length as filler surface functional group to improve the comprehensive performance of underfill.

Large-scale synthesis of NbSe 2 nanosheets and their use as nanofillers for improving the tribological properties of epoxy coatings

Abstract The paper presents a facile and effective method to exfoliate bulk niobium diselenide (NbSe2) into nanosheets which were used as nanofillers to improve the tribological properties of epoxy coatings. X-ray diffraction (XRD) analysis indicates that the hexagonal crystal structure of NbSe2 nanosheet is preserved after ball milling. Transmission electron microscopy (TEM) and atomic force microscope (AFM) observations show that NbSe2 nanosheets were produced with sizes in hundreds of square nanometers and graphene-like structure. The tribological properties of NbSe2/epoxy composite coatings were systematically investigated and results show that they possess better friction-reducing and anti-wear performances due to the addition of NbSe2 nanosheets. It is demonstrated that the superior tribological properties is ascribed to a transfer film formed by NbSe2 nanosheets preventing a direct contact between steel ball and coating during the friction process. Furthermore, this work shows the potential applications of two-dimensional NbSe2 nanosheets as reinforcing nanofillers in polymer matrix.

3D stereolithography printing of graphene oxide reinforced complex architectures

Properties of polymer based nanocomposites reply on distribution, concentration, geometry and property of nanofillers in polymer matrix. Increasing the concentration of carbon based nanomaterials, such as CNTs, in polymer matrix often results in stronger but more brittle material. Here, we demonstrated the first three-dimensional (3D) printed graphene oxide complex structures by stereolithography with good combination of strength and ductility. With only 0.2% GOs, the tensile strength is increased by 62.2% and elongation increased by 12.8%. Transmission electron microscope results show that the GOs were randomly aligned in the cross section of polymer. We investigated the strengthening mechanism of the 3D printed structure in terms of tensile strength and Young’s modulus. It is found that an increase in ductility of the 3D printed nanocomposites is related to increase in crystallinity of GOs reinforced polymer. Compression test of 3D GOs structure reveals the metal-like failure model of GOs nanocomposites.

Carbon nanofillers incorporated electrically conducting poly ε-caprolactone nanocomposite films and their biocompatibility studies using MG-63 cell line

Poly e-caprolactone (PCL)-based nanocomposite films were prepared by solvent casting method with different electrically conducting carbon nanofillers like carbon nanofiber (CNF), nanographite and liquid exfoliated graphite. These nanocomposite films show remarkable increase in both surface and bulk electrical conductivity. Continuous network of nanofillers in polymer matrix was observed under high-resolution transmission electron microscopy (HRTEM). The spreading resistance images in AFM showed the presence of nanofillers on the nanocomposite films. These films reveal strong directional effect in electrical conductivity towards longitudinal direction than transverse. PCL film dispersed with 10 % (w/w) CNF showed an electrical conductivity of 19 S/m at longitudinal direction as compared to 1 S/m at transverse direction. This can be best explained with the arrangement of nanofillers along longitudinal direction during solution casting method which is evident from HRTEM images. The electrical conductivity of the nanocomposite films increased in the presence of phosphate buffer saline and simulated body fluid with time. MTT and nuclear staining experiments with osteoblast MG63 cells clearly demonstrated good biocompatibility of these materials. Among all the nanofillers, CNF looks most promising for biomedical applications of PCL-based conducting nanocomposites, as it shows high electrical conductivity and good cell proliferation.

The influence of carbon fillers on the thermal properties of polyurethane foam

The aim of this work was to investigate the influence of different types of carbon filler on the thermal stability and flammability of rigid polyurethane foams. As a filler, multi-walled carbon nanotubes and graphite fakes were used. Scanning electron microscopy was used to observe the structure of foam and dispersion of nanofiller in polymer matrix. Thermal stability of these composites was determined by thermogravimetry analysis. Test was carried out under both nitrogen and air atmosphere. The degradation products were evaluated by thermogravimetry (TG) combined with infrared spectroscopy (TG–IR) measurements. The activation energy was measured by the Flynn–Wall–Ozawa method from the TG curves. Flammability tests like limiting oxygen index and smoke density were also measured. No significant changes in the thermal stability of the composites were observed. The activation energy of sample containing carbon filler increased. Based on TG–IR, one can notice that there were no differences in the emitted volatile products during thermal degradation. Carbon filler enhanced fire retardancy of polyurethane foam; however, graphite gives better results.

Thermal Properties of Polypropylene/ Montmorillonite Nanocomposites

This research paper deals with the loading of different wt.% of Montmorillonite (MMT) thermal properties of polypropylene (PP). PP/MMT nanocomposites have been manufactured by melt blending method using maleic anhydride grafted polypropylene (MAH-g-PP) coupling agents. Melt blending was achieved by using twin screw extruder. The MAH-g-PP used as coupling agent and helped the good dispersion of the nanofiller in polymer matrix. The crystallization behavior of PP and its nanocomposites were studied by differential scanning calorimetry (DSC). DSC isothermal curves showed an increase in the crystallization temperature along with increasing degree of crystallinity.Thermogravimetric analysis (TGA) which indicated good thermal stability of PP matix in Na+-MMT nanocomposites.Dynamic mechanical analysis (DMA) indicated significant improvement in the storage modulus and loss modulus compared with neat PP.

Thermal Properties of Polypropylene/Montmorillonite Nanocomposites

This research paper deals with the loading of different wt.% of Montmorillonite (MMT) thermal properties of polypropylene (PP). PP/MMT nanocomposites have been manufactured by melt blending method using maleic anhydride grafted polypropylene (MAH-g-PP) coupling agents. Melt blending was achieved by using twin screw extruder. The MAH-g-PP used as coupling agent and helped the good dispersion of the nanofiller in polymer matrix. The crystallization behavior of PP and its nanocomposites were studied by differential scanning calorimetry (DSC). DSC isothermal curves showed an increase in the crystallization temperature along with increasing degree of crystallinity.Thermogravimetric analysis (TGA) which indicated good thermal stability of PP matix in Na+-MMT nanocomposites.Dynamic mechanical analysis (DMA) indicated significant improvement in the storage modulus and loss modulus compared with neat PP.

Characterization and the Pattern of Surfaces of Sealant with nano size Composite Materials

Nano composite sealant is low viscosity, room temperature cured, opaque and flowable nature. They have variety of uses such as potting, pressure sealant and shock resistant. Most important factor influencing use of fillers in polymer composites is their ability to effectively transfer the applied load in the matrix. The effective utilization of fillers in composites for structural applications depends strongly on the ability to disperse the nano fillers homogeneously in the matrix without damaging them. R-Belite supper epoxy adhesive (RBSEA) were formulated with different nano fillers (KCl, Al2O3, ZrO2, SiO2, ZrO2) at room temperature. The composite were prepared with the 0.02 to 0.10 weight ratios to promote the nucleation of the nanoparticles in the applied sealant. Two main problems which arise in improving the properties are poor dispersion of the fillers in the composite and weak bonding between nano fillers and the matrix. These problems are solved by mechanical and chemical means. It was observed that mechanical properties like tensile strength, elongation hardness etc and thermal properties were also improved with incorporation of nanofillers in the working applied polymer matrix. The dispersion of nano fillers in polymer matrix is studied by Scanning electron microscopy (SEM). The results confirm the presence of nanomaterial in RBSEA/fillers nanocomposites. SEM is also used to characterize the pattern of surfaces with nano size composite materials.

Polystyrene/MWCNT/Graphite Nanoplate Nanocomposites: Efficient Electromagnetic Interference Shielding Material through Graphite Nanoplate–MWCNT–Graphite Nanoplate Networking

Today, we stand at the edge of exploring carbon nanotube (CNT) and graphene based polymer nanocomposites as next generation multifunctional materials. However, irrespective of the methods of composite preparation, development of electrical conductivity with high electromagnetic interference (EMI) value at very low loading of CNT and (or) graphene is limited due to poor dispersion of these nanofillers in polymer matrix. Here, we demonstrate a novel technique that involves in-situ polymerization of styrene/multiwalled carbon nanotubes (MWCNTs) in the presence of suspension polymerized polystyrene (PS)/graphite nanoplate (GNP) microbeads, for the preparation of electrically conducting PS/MWCNT/GNP nanocomposites with very high (~20.2 dB) EMI shielding value at extremely low loading of MWCNTs (~2 wt %) and GNP (~1.5 wt %). Finally, through optimizing the ratio of PS-GNP bead and MWCNTs in the nanocomposites, an electrical conductivity of ~9.47 × 10(-3) S cm(-1) was achieved at GNP and MWCNTs loading of 0.29 and 0.3 wt %, respectively. The random distribution of the GNPs and MWCNTs with GNP-GNP interconnection through MWCNT in the PS matrix was the key factor in achieving high electrical conductivity and very high EMI shielding value at this low MWCNT and GNP loadings in PS/MWCNT/GNP nanocomposites. With this technique, the formation of continuous conductive network structure of CNT-GNP-CNT and the development of spatial arrangement for strong π-π interaction among the electron rich phenyl rings of PS, GNP, and MWCNT could be possible throughout the matrix phase in the nanocomposites, as evident from the field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies.

Functionalised SIS triblock copolymer elastomer and its nanocomposites: synthesis and characterisation

Polystyrene-block-polyisoprene-block-polystyrene (SIS) triblock copolymer was modified into an epoxidised version (ESIS) using performic acid. The ESIS was further acrylated to prepare the acrylated version (ASIS). The nanocomposites of each sample (SIS, ESIS and ASIS) were prepared using boehmite nanofiller via solution casting, which were characterised by Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). The TEM investigations revealed that the epoxidation of the diene block enhanced the dispersion of the nanofiller in polymer matrix, which may be attributed to the improved compatibility between alkybenzene sulphonic acid coated inorganic filler and polar modified middle block of the copolymer. The segregation of the nanoparticles towards the interface of different microscopically segregated polymer domains was observed in the acrylated block copolymer based nanocomposite implying the incomplete acrylation of the block copolymer, which might segregate from the bulk unmodified or partially modified polymer.

Effect of TiO2 nanoparticles on the long-term hydrolytic degradation behavior of PLA

The longer-than-one-year hydrolytic degradation of poly (lactic acid) (PLA)/TiO2 nanocomposites was investigated in phosphate buffer solution of pH 7.4 at 37 °C so as to elucidate the effect of nanofillers on the degradation characteristics of PLA. The temporal changes in appearance, water absorption, number-average molecular weight (Mn), glass transition temperature, melting temperature, and crystallinity of the samples were traced. The results showed that the heterogeneous degradation and bulk-erosion were general mechanisms for PLA and its TiO2 nanocomposites. The change in surface morphology and molecular weight after hydrolysis revealed that the hydrolysis of nanocomposites occurred at the interface of PLA matrix and nanofillers, and the degradation rate was accelerated by the addition of the TiO2 nanofillers. The dispersion of nanofillers in polymer matrix affected the water absorption and degradation rate. The rapid increase of crystallinity also affected the degradation rate of nanocomposites. The present study suggested that the hydrolyzability of PLA could be controlled by adding TiO2 nanoparticles.

Effect of Gum arabic on distribution behavior of nanocellulose fillers in starch film

Uniform distribution of nanofillers in polymer matrix is posing a major challenge in exploiting the full potential of nanomaterials. Various fillers are being evaluated to improve the performance of biopolymer films like starch. In this work, nanocellulose is used as fillers to increase the performance characteristics of starch film. Due to high surface energy and hydrophilic nature of nanocellulose, they tend to aggregate during the film forming process. To circumvent this problem, Gum arabic (GA) was added to distribute the nanocellulose uniformly. GA helps in reduction of surface energy (as analyzed by contact angle) and thus facilitates the uniform distribution of nanocellulose (as demonstrated through polarized light microscopy). Nanocellulose as filler improved the tensile strength of starch film by 2.5 times while that of uniformly distributed nanocellulose by 3.5 times. Moreover, while nanocellulose as such could reduce the water vapor permeability of starch film by 1.4 times, uniformly distributed nanocellulose reduced it by 2 times proving the importance of GA. Starch film filled with nanocellulose and GA will be a 100% biopolymer-based system having potential demand in eco-friendly applications.

Investigation of thermally stimulated charge relaxation mechanism in SiO2 filled polycarbonate nanocomposites

Abstract The thermally stimulated charge relaxation properties of polycarbonate (PC) filled with SiO2 nanofiller were studied by means of thermally stimulated discharge current (TSDC). The nanocomposite samples were further characterized by UV–vis spectroscopy, scanning electron microscopy, energy dispersive X-ray spectra, and differential scanning calorimetry (DSC) techniques to investigate the dispersion of nanofillers in polymer matrix and glass transition temperature. All pristine and nanocomposites samples of thickness about 25 μm were prepared using solution mixing method. The suitable weight percentage of SiO2 nanofillers has been chosen to prevent the nonuniform dispersion. TSDC measurement of PC (Pristine) and PC+ (7% SiO2) shows the single peak, while TSDC characteristic of other nanocomposites are showing two peaks. The higher temperature TSDC peak of pristine and nanocomposites samples is originated due to the charge relaxation from shallower and deeper trapping sites, however, low temperature...