Layered Silicate Composites Research Articles

Properties and Structure of the Friction surface of PTFE / Layered Silicate Composites

The wear of PTFE filled with layered silicates (LS) was investigated depending on the concentration and chemical nature of the fillers. The influence of these factors on the tribotechnical characteristics and the structure of the surface layers of composites is shown. Using SEM methods, it has been established that the introduction of LS contributes to the formation of a protective layer on the friction surface consisting of worn PTFE particles and a filler. The thickness of the layer does not depend on the concentration of LS, and the structure of the layer varies depending on the chemical composition of the fillers. It is shown that the formation of a protective layer occurs by means of worn particles clustering, uniformly covering the friction surface layer by layer.

Thermal and Morphological Properties of ABS/Muscovite Layered Silicate Composites

The present study investigated the effects of untreated (UM) and treated (TM) muscovite fillers on the morphological and thermal properties of acrylonitrile-butadiene-styrene (ABS) composites. The TM produced from a two-stage ion-exchange process and ABS composites were compounded using melt blending. ABS/muscovite layered silicate composites were characterized using Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) while the thermal properties was investigated through Thermogravimetric (TGA) analysis. It was found that ABS/TM recorded higher thermal properties when compared to neat ABS and ABS/UM. The FESEM images showed better dispersion of ABS/TM compared to ABS/UM. Finally, mixed morphology of intercalated-exfoliated structure of composites was proven by TEM analysis.

Mechanical Behaviour of Layered Silicate Composites from Nagavali River Clay

Abstract In the present study, clay is segregated, from both banks of Nagavali River flowing through the Srikakulam India at coordinates of 18.3°N 83.9°E. Effect of incorporation of clay into the epoxy polymer was investigated experimentally. Composites were manufactured by the conventional hand-layup process with the accumulation of the different weight ratio (10%, 20%, 30%, 40%, 50%, 60% and 80%) of clay to the Epoxy polymer. Clay obtained from both bank composites were compared. Various test was performed to analyse the mechanical behaviour of the composites. Manufacturing and testing of composites are done according to the ASTM standards.

Competitive interactions, structure and properties in polymer/layered silicate nanocomposites

Thermoplastic polymer/layered silicate composites were prepared from the same organophilized montmorillonite (OMMT) and four different matrices, polypropylene (PP), the blend of PP and a maleated polymer (MAPP), poly(lactic acid) (PLA) and polyamide (PA) in order to study the effect of their chemical structure and interactions on composite structure and properties. The components were homogenized by extrusion and then specimens were injection molded, which were then characterized by a variety of methods. The results showed that competitive interactions among silicate layers and between the silicate and the polymer determine the extent of exfoliation, and structure. The morphology of the composites is complicated, exfoliation is never complete, besides individual silicate layers, the composite can contain a silicate network, stacks of silicate platelets and larger particles in various amounts. Several local deformation processes can take place around the structural entities as well as in the matrix. Fracture and debonding are the main particle related processes, while cavitation takes place in the polymer, at least in PA and PLA. The macroscopic properties of layered silicate composites are determined by the extent of exfoliation and interfacial adhesion that decreases upon organophilization. Increased reinforcement and improved composite properties can be achieved only by the proper control of all interactions prevailing in the composite.

Effect of Surface Modification on Strain Rate Sensitivity of Polypropylene/Muscovite Layered Silicate Composites

Surface modification is one of the treatment methods that can be implemented to improve the strain rate sensitivity of composite materials. In this study, both untreated and treated polypropylene/muscovite layered silicate composites were tested under static and dynamic loading up to 1100 s-1 using the universal testing machine and the split Hopkinson pressure bar apparatus, respectively. Muscovite particles were treated with lithium nitrate and cetyltrimethylammonium bromide as a surfactant through ion exchange treatment. Results show that the treated polypropylene/muscovite specimens with fine state of dispersion level shows better rate of sensitivity as compared to untreated polypropylene/muscovite specimens under a wide range of strain rate investigated. Apart from that, the rate of sensitivity of both tested polypropylene/muscovite layered silicate composites also show great dependency on the strain rate sensitivity was steadily increased with increasing strain rate. Unfortunately, the thermal activation values show contrary trend. Key words: Ion exchange treatment; Strain rate sensitivity; Muscovite particles; Split Hopkinson pressure bar apparatus; Strain rates

Effect of Organic Modification on Dynamic Compression Properties of Polypropylene/Muscovite Layered Silicate Composites

In order to improve the mechanical properties of composite materials, one of the renowned techniques that can be applied is the filler modification. Still, no works were concern on this particular matter under dynamic standpoint. Therefore, in this study, both untreated and treated polypropylene/muscovite layered silicate composites were tested under static and dynamic loading up to 1100 s-1 using the universal testing machine (UTM) and the split Hopkinson pressure bar (SHPB) apparatus. Muscovite particles were treated with lithium nitrate and cetyltrimethylammonium bromide as a surfactant through surface modification. Results show that the treated polypropylene/muscovite samples with fine state of dispersion level shows superior mechanical performances as compared to untreated polypropylene/muscovite samples under an extensive range of strain rate investigated. Furthermore, the mechanical properties of both tested polypropylene/muscovite layered silicate composites also display great reliance on the strain rate applied where strength and stiffness properties were gradually increased with increasing strain rate. Key words: Organic modification; Strength and stiffness properties; Muscovite particles; Split Hopkinson pressure bar apparatus; Strain rates

Effect of ion exchange treatment on dynamic compression properties of polypropylene/muscovite-layered silicate composites

Filler treatment is one of the recognized methods that can be implemented to improve the mechanical properties of composite materials. However, no research has examined this particular issue from the dynamic perspective. Hence in this study, both untreated and treated polypropylene (PP)/muscovite (M)-layered silicate composites were tested under static and dynamic loadings of up to 1100 s−1, using a universal testing machine and split Hopkinson pressure bar apparatus, respectively. M particles were treated with lithium nitrate and cetyltrimethylammonium bromide as a surfactant, through an ion exchange treatment. This treatment process was successfully proven, using Fourier transform infrared, X-ray diffraction, and transmission electron microscopy analyses. Results show that the treated PP/M specimens with a fine state of dispersion level show better mechanical performances under a wide range of strain rates that were investigated, when compared with the untreated PP/M specimens. In addition, the mechanical properties of both the tested PP/M-layered silicate composites also show great dependency on the strain rate applied, where yield stress, compression modulus, ultimate compressive strength, and absorbed energy steadily increased when the strain rate was increased. However, the yield strain shows a contrary trend. Postdamage analyses were found to be consistent with the mechanical results for both tested specimens.

Thermal properties of polypropylene/muscovite layered silicate composites: effects of organic modifications and compatibilisers

Polymer-layered silicate nanocomposites containing polypropylene, compatibilisers, muscovite, and organomuscovite were prepared through the hot compression technique. Muscovite particles were initially treated with lithium nitrate, followed by cetyltrimethylammonium bromide, to obtain the organomuscovite through an ion-exchange treatment. Maleic anhydride and polyhedral oligomeric silsesquioxane were used as compatibilisers to modify the polypropylene/organomuscovite nanocomposite systems. The effectiveness of the ion-exchange treatment and the implementations of both compatibilisers were successfully proven using the Fourier transforms infrared, X-ray diffraction, as well as the transmission electron microscopy. The overall thermal properties of the polypropylene/muscovite layered silicate composites were investigated by applying both differential scanning calorimetry and thermogravimetric analysis. It was found that the polypropylene reinforced with organomuscovite recorded higher thermal properties in terms of crystallisation temperature and thermal stability than its counterpart; whereas, the melting temperature and the degree of crystallinity displayed an opposite trend. For the effect of the compatibiliser, it was found that compatibilised polypropylene/organomuscovite nanocomposites recorded higher values of decomposition and crystallisation temperatures than that of non-compatibilised polypropylene/organomuscovite nanocomposites. However, the melting temperature and the degree of crystallinity of compatibilised polypropylene/organomuscovite nanocomposites were slightly lower, as compared to non-compatibilised polypropylene/organomuscovite nanocomposites.

Antifungal activity of Ag-carrying polymer layered silicate composites in broth medium and solid state: effects of structural factors and silver loading

Antifungal activity of Ag-carrying polymer layered silicate composites in broth medium and solid state: effects of structural factors and silver loading

EMNC_60과 EMNC_65에 대한 열적, 기계적, 전기적 특성 연구

Department of Electrical Electronic Engineering, Joongbu University, Geumsan 312-702, Korea (Received August 13, 2012; Revised October 16, 2012; Accepted October 18, 2012)Abstract: In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical ,electrical properties much improved EMNC_60 compared with EMNC_65.Keywords: Electric fields dispersion, EMNC (epoxy/micro/nano mixture composites), High voltage heavy electric equipment, Epoxy resins

Morphology, X-ray Diffraction and Mechanical Properties of Resol-montmorillonite Clay Composites

Layered silicate composites having phenolic matrix were prepared by melt intercalation. The resole resin was synthesized and was characterized by FTIR spectroscopy. Method for making composites consisted of mechanically mixing the modified montmorillonite clay with phenol formaldehyde resin and curing the polymer to form a composite material, via intercalation of polymer in between the clay galleries. The objective was to investigate the effect of clay percentage on the behavior of composites samples. Composite samples with different clay percentages (0—4%) were compared with pristine resin sample. The morphology of the composites was examined by using scanning electron microscope (SEM) and interesting observation was made from tensile fractured sample because of formation of dendrites at 0.8 wt% clay. The crystalline and amorphous behavior was investigated by using X-ray diffraction method. The XRD pattern showed that there was a decrease in amorphous behavior with increasing filler content. Although exfoliation cannot be claimed, but improvement in mechanical properties confirm intercalation. Tensile and flexural modulus increased up to 84 and 46%, respectively, of the initial value with increase in filler content up to 0.8%, after which there was a downward trend due to possible agglomeration of clay particles.

Nanoclay and long‐fiber‐reinforced composites based on epoxy and phenolic resins

AbstractIn this study, high‐performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long‐fiber‐reinforced composites and polymer‐ layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Melt compounded epoxidized natural rubber/layered silicate nanocomposites: structure-properties relationships

Epoxidized natural rubber (ENR)-layered silicate composites were produced by melt compounding and sulfur curing. Pristine (sodium bentonite and sodium fluorohectorite) and organophilic modified silicates (organoclays with primary amine and quaternary ammonium modifications) were introduced in 10 parts per hundred rubber (phr) in the recipes and their effect on the curing and (thermo)mechanical properties determined. The dispersion state of the silicates was studied by X-ray diffraction and transmission electron microscopy. Fastest curing and best mechanical properties were found for the ENR containing the organoclay with primary amine modification. This organoclay was partly exfoliated, partly intercalated and partly confined (reaggregated). Due to the high shearing during compounding the pristine fluorohectorite was also intercalated by ENR. The complex dispersion state of the layered silicates was well reflected in the glass transition relaxation, which showed multiple peaks. Intercalation/exfoliation of the silicates were best displayed in stiffness- and strength-related mechanical parameters.