Presence Of Nanoclay Particles Research Articles

Effect of electron beam irradiation on mechanical properties of unsaturated polyester/nanoclay composites reinforced with carbon and glass fibers

Following our previous work on morphology, corrosion resistance and thermal properties of unsaturated polyester (UP)/nanoclay composites, the effect of electron beam (EB) irradiation on mechanical properties of UP/nanoclay composites with various nanoclay contents is investigated in this work. Moreover, influence of EB irradiation with doses of 100, 500 and 1000 kGy on tensile properties and hardness of nanocomposite was examined. FTIR spectroscopy was employed to examine the effect of irradiation on chemical structure of polymer. EB irradiation up to 500 kGy led to the improvement of tensile strength and hardness of the samples. The best mechanical properties were observed for the nanocomposite with 1 wt.% nanoclay content. As the selected nanocomposite, UP/nanoclay(1 wt.%) composite was reinforced by carbon and glass fibers and the effect of EB irradiation on the mechanical properties of the prepared UP/nanoclay/fiber composites was studied. When compared to the fiber-reinforced UP without nanoclay, presence of nanoclay particles in UP/nanoclay/fiber composites resulted in the better mechanical properties and higher radiation resistance. Hence, the UP/nanoclay/fiber composite with proper amount of nanoclay has been shown to be a dependable choice for structural applications in which the material is exposed to ionizing radiations.

Curing kinetics of solid epoxy/DDM/nanoclay: Isoconversional models versus fitting model

The curing behavior and kinetics of epoxy nanocomposites based on solid epoxy, diaminodiphenyl methane (DDM) and nano organoclay were studied. The curing kinetics of epoxy nanocomposites was elucidated by non-isothermal differential scanning calorimetry. The fitting model was used to calculate the kinetic parameters. The kinetics of the curing reaction was also evaluated by two different isoconversional models. The kinetic parameters calculated from fitting model were almost the same for neat epoxy system and nanocomposite systems indicating that the curing kinetics was not affected by the presence of nanoclay particles. However, the isoconversional models showed that the incorporation of nanoclay particles into the epoxy/DDM system had a significant effect on the trend of activation energy during the curing process. Therefore, it can be concluded that using isoconversional models would be a preferred method to elaborate the effect of nanoparticles on the curing mechanism of nanocomposite systems.

Effect of Nanoclay on the Nonisothermal Crystallization of Poly(propylene) and its Blend with Poly[(butylene succinate)-co-adipate

The non-isothermal crystallization behaviour and kinetics of neat poly(propylene)(PP), PP/poly[(butylene succinate)-co-adipate] (PP/PBSA) blend and its composite with nanoclay was studied by differential scanning calorimetry at six different cooling rates. Various models, namely the Avrami, the Ozawa and the combined Avrami-Ozawa, were applied to understand the kinetics of the non-isothermal crystallization. All analyses revealed that the rate dependent crystal growth mechanism of neat PP changes after preparation of blend with PBSA and in presence of nanoclay particles in blend composite. Polarized optical microscopy was used to support this conclusion. The activation energy for the non-isothermal crystallization of neat PP, PP/PBSA blend and nanoclay modified PP/PBSA blend composite samples was evaluated by using Kissinger and Augis-Bennett methods. The results showed that the absolute value of the activation energy for the PP matrix crystallization was increased in the case of PP/PBSA blend and this value was dramatically increased in presence of nanoclay. This indicates the slower crystallization kinetics of the PP matrix in presence of nanoclay.

Morphological, thermal, rheological, and mechanical properties of polypropylene-nanoclay composites prepared from masterbatch in a twin screw extruder

A commercial homopolymer polypropylene was melt blended with commercial nanoclay masterbatch at different concentrations of nanoclay using twin screw extruder (TSE). The influence of three different concentrations (5, 10, and 15 wt%) of the nanoclay on the morphological, thermal, rheological, and mechanical properties was investigated. The morphology of the nanocomposites was characterized using Scanning Electron Microscope (SEM), whereas, the thermal behavior (e.g., melting and crystallization) was characterized using Differential Scanning Calorimetry (DSC). The melt rheology and dynamic mechanical properties were analyzed using a torsional rheometer. Additionally, the tensile properties were characterized as well. The morphological analysis showed that the nanoclay was well distributed in the PP matrix as indicated by the SEM micrographs. The DSC results showed that the presence of nanoclay in the PP matrix increased the degree of crystallinity of PP-nanoclay composites, which reached a maximum at 5 wt% of nanoclay concentration. However, the melting temperature of the PP-nanoclay composites was not affected by the presence of nanoclay particles. In addition, rheological analysis showed that the melt response gradually changed from pseudo-liquid like to pseudo-solid like as the nanoclay concentration increased. Moreover, the storage modulus (G′) increased by increasing nanoclay content. Furthermore, tensile test results showed that the addition of nanoclay leads to a significant enhancement in the mechanical properties of the PP nanocomposites.

Poly(vinyl acetate)/poly(vinyl alcohol)/montmorillonite nanocomposite microspheres prepared by suspension polymerization and saponification

Poly(vinyl acetate) (PVAc)–poly(vinyl alcohol)–montmorillonite (MMT) nanocomposite microspheres were prepared through suspension polymerization followed by the heterogeneous saponification. The effects of MMT on the polymerization rate and the saponification rate of PVAc were studied. It was found that the rate of polymerization decreased when MMT content was increased. However, the saponification rate of PVAc significantly increased in the presence of nanoclay particles. The XRD measurement illustrated that the clay particles are intercalated in the polymer matrix.

Nanostructured coatings of glass fibers: Improvement of alkali resistance and mechanical properties

Surface defects cause the measured tensile strength of glass and other brittle materials to be significantly lower than their theoretical values. Coatings can be used to “heal” surface flaws and modify surface properties. Here, we describe an online process by which a nanometer-scale hybrid coating layer based on styrene–butadiene copolymer with multi-walled carbon nanotubes (MWCNTs) and/or nanoclays, as a mechanical enhancement and environmental barrier layer, is applied to alkali-resistant glass (ARG) and E-glass fibers. Our data indicate that the nanostructured and functionalized traditional glass fibers show significant improvements in both mechanical properties and environmental corrosion resistance. With low fractions of nanotubes (0.2wt% in sizing), the strength of healed glass fiber increases by up to 70%. No apparent strength variation appears for nanoclay-coated fiber subjected to alkaline attack. The adsorption isotherms of moisture vapor on the fiber surface have been analyzed and an assessment of changes in the nanomechanical properties of the fiber surface is provided. It is shown that the sorption of moisture is reduced by the presence of nanoclay particles in the coating. We introduce a healing efficiency factor and conclude that the coating modulus, thickness and roughness are responsible for the mechanical improvement of fibers.