Composites of thermoplastic polyurethane (TPU) and ultra-thin graphite (UTG) with concentrations ranging from 0.5 to 3 wt% were prepared using a solution compounding strategy. Substantial reinforcing effects with increased loadings are achieved. Compared to neat TPU, values for storage modulus and shear viscosity are enhanced by 300 % and 150 %, respectively, for UTG concentrations of 3 wt%. Additionally, an enhancement of thermal properties is accomplished. The crystallization temperature and thermal stability increased by 30 ºC and 10 ºC, respectively, compared to neat TPU. Controlling the oxidation degree, thus offers further possibilities to obtain composites with tailored properties. The presented approach is straightforward, leads to homogeneous TPU-UTG composites with improved materials properties and is especially suitable for commercial UTG materials and further up-scaled production.

Flour rice husk (FRH) was employed as a filler in block copolymer polypropylene (PPB) in order to prepare polymer-based reinforced composites. Four coupling agents were selected to modify the surface of the rice husk in the composite materials, including two types of functionalized polymers [PP homopolymer grafted with maleic anhydride (MA-PP) and an elastomer styrene-ethylenebutadiene-styrene triblock copolymer grafted with MA (MA-SEBS)] and two bifunctional organometallic coupling agents (silane and titanate with linear low-density polyethylene as a carrier). The influence of each type of coupling agent on the interfacial bonding strength was studied by dynamic mechanical analysis, scanning electronic microscopy, and rheological tests. The results showed that strong interactions were formed between the coupling agents and the filler surface. The addition of a coupling agent with an elastomeric carrier (MA-SEBS) increased the loss tangent and reduced the storage modulus of the composite. A similar but less intense effect was observed for the titanate coupling agent. However, an antagonistic performance was obtained when MA-PP and silane were employed as coupling agents. In addition, when the percentage of MA-SEBS was increased, the impact properties of FRH/PPB blends were improved and the strength was reduced.

Nanocomposites of polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) with multiwall carbon nanotubes (MWCNT) prepared by masterbatch dilution are investigated in this work. Melt compounding with twin screw extruder is followed by complete characterization of morphology, rheological‐, mechanical‐, and thermal‐properties of the nanocomposites. Light‐transmission‐ and scanning electron microscopy shows the preferential location of MWCNT in the PC. Nevertheless, relatively good dispersion in the whole matrix is achieved, what is corroborated with the specific mechanical energy. The study of viscoelastic properties of PC/ABS‐MWCNT shows the fluid–solid transition below 0.5 wt % MWCNT. Beyond this point the continuous nanofiller network is formed in the matrix promoting the reinforcement. Addition of 0.5 wt % MWCNT reduces ductility of PC/ABS and enhances Young's modulus by about 30% and yield stress by about 20%. Moreover, theoretical values of stiffness calculated within this work agree with the experimental data. Electrical conductivity, showing percolation at 2.0 wt % MWCNT, are influenced by processing temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40271.

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The influence of injection molding parameters on electrical properties and morphology of PC/ABS‐MWCNT nanocomposites is presented in this article. Investigation is based on the masterbatch of 5.0 wt % carbon nanotubes obtained by melt‐mixing. Further processing includes dilution of this nanocomposite to desired concentrations on twin‐screw extruder and injection molding or direct dilution of masterbatch in injection molding. Additionally, reprocessing of materials formed by compression and injection molding is presented along with the change in electrical conductivity. Morphology differs strongly between the two processing paths showing change in agglomeration behavior between nanotubes concentrations. Electrical properties show dependence on injection velocity and melt temperature in both applied processing paths. Moreover, electrical conductivity recovery is proved after injection and compression molding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2152–2158, 2013

In this work, nanocomposites of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) with various loads of multiwall carbon nanotubes (MWCNT) are investigated. Material is previously formed by masterbatch dilution approach and further processed by injection molding at various velocities. Microscopic characterization of nanocomposites morphology reveals stronger dependence of MWCNT dispersion on processing parameters at higher nanofiller load. Dispersion of carbon nanotubes at various distances from the injection gate is studied by Raman spectroscopy showing lower deviation at elevated injection velocity. Nanoindentation results that are in agreement with uniaxial tensile testing show a slight decrease of nanocomposites' mechanical performance at 3.0 wt % MWCNT in samples injected at reduced velocity. This is explained by the increase of agglomeration behavior at these conditions.

In this work, we present thermoplastic nanocomposites of polycarbonate (PC) matrix with hybrid nanofillers system formed by a melt-mixing approach. Various concentrations of multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GnP) were mixed in to PC and the melt was homogenized. The nanocomposites were compression molded and characterized by different techniques. Torque dependence on the nanofiller composition increased with the presence of carbon nanotubes. The synergy of carbon nanotubes and GnP showed exponential increase of thermal conductivity, which was compared to logarithmic increase for nanocomposite with no MWCNT. Decrease of Shore A hardness at elevated loads present for all investigated nanocomposites was correlated with the expected low homogeneity caused by a low shear during melt-mixing. Mathematical model was used to calculate elastic modulus from Shore A tests results. Vicat softening temperature (VST) showed opposite pattern for hybrid nanocomposites and for PC-MWCNT increasing in the latter case. Electrical conductivity boost was explained by the collective effect of high nanofiller loads and synergy of MWCNT and GnP.

Abstract. 4 wt% multiwalled carbon nanotubes (MWCNTs) were incorporated into a miscible blend of polyphenylenether/ polystyrene (PPE/PS) on a twin-screw extruder at a screw speed of 600 rpm. The masterbatch obtained was diluted at 400 and 600 rpm to obtain lower MWCNT loadings in PPE/PS. Electron microscopy & optical microscopy images show very good MWCNT dispersion even at high filler loadings of 4!wt%, but slightly larger agglomerate size fractions are observable at higher screw speeds. While MWCNT addition enhanced the thermal stability of PPE/PS, a small change in glass transition was observed on the composites at different filler concentrations compared to PPE/PS. The specific heat capacity at glass transition decreases considerably until 2!wt% MWCNT and levels down thereafter for both processing conditions pointing to enhanced filler-matrix interaction at lower loadings. Storage modulus of the nanocomposites was enhanced significantly on MWCNT incorporation with reinforcing effect dropping considerably as a function of temperature, especially at lower filler contents. The modulus and the tensile strength of PPE/PS were only marginally enhanced in spite of excellent MWCNT dispersion in the matrix. Electrical percolation occurs at 0.4!wt% MWCNT content, and the electrical conductivity of 0.5!wt% MWCNT reinforced PPE/PS was close to 12 orders in magnitude higher compared to PPE/PS.