Effect Of Nanoclay Fillers Research Articles

Effect of Nano-Clay Filler on the Thermal Breakdown Mechanism and Lifespan of Polypropylene Film Under AC Fields

The wide application of nanocomposites in the insulation system has greatly contributed to the performance improvement of power equipment. However, nano fillers are not omnipotent for improving the properties of composite dielectrics. In some situations, nano-modified materials are in fact a compromise of improving some performance features while sacrificing others. In this work, the breakdown characteristics and time-to-failure of polypropylene film with nano-clay fillers have been evaluated under combined thermal stress and AC electric fields. Experiments on plain polypropylene (PP) samples have also been carried out under the same test conditions as control. Test results indicated that the time-to-failure of the samples with nano-clay filler was shorter than those without nano filler, which is different from the previous experience. SEM and EDS analyses were conducted to study how the failure mechanism had taken place in both plain polypropylene and the nano-clay filled polypropylene. The failure phenomenon in these materials can be explained by molecular thermodynamics. The main reason for the premature thermal breakdown of PP nanocomposite is essentially due to the weak coupling between nano-clay filler and polymer matrix. Finally, suggestions are proposed for nano modification methods and lifespan prediction models of composite dielectrics.

Effect of nano-clay fillers on mechanical and morphological properties of Napier/epoxy Composites

The effect of nano clay filler on the mechanical and morphological properties of Napier/epoxy composites was investigated. Neat, 2 wt%, 3 wt%, 4 wt% and 5 wt% of Montmorillonite (MMT) nano clay filled Napier/epoxy composites were fabricated by vacuum infusion technique. These specimens were tested in the three points bending according to the ASTM D790. The flexural stress-strain curve, flexural strength, flexural modulus and strain to failure were then discovered based on the flexural test results. The results revealed that flexural strength and flexural modulus increased when a particular amount of nano clay was added to the epoxy matrix. 3 wt% of nano clay filler yielded the highest flexural strength with an improvement of 163% when compared to the neat Napier/epoxy composites. Moreover, a maximum of 180% increases in flexural modulus was registered at 5 wt% of nano clay filler. The enhanced properties of nano clay filled composites were highly achieved due to better dispersion and distribution of nano clay in the epoxy resin as well as an increase on the interfacial bonding. Using Scanning Electron Microscopy (SEM), morphological analysis was conducted to observe the fracture surfaces of the specimens after the flexural test. Overall, the presence of nano clay filler loading with a range of 3 wt% to 5 wt% in the Napier/epoxy composites shows the significant improvement in mechanical and morphological properties.

On the Processing and Properties of Clay/Polymer Nanocomposites CPNC

An experimental investigation followed by fundamental characterization and discussion on the effect of nanoclay filler on the mechanical and fracture properties of polymer matrix was carried out. The study was carried out on clay/polymer nanocomposite made of High Density polyethylene (HDPE M40060) produced by Saudi Arabian company SABIC and montimorillonite MMT nanoclay (Nanomer I.34TCN) produced by Nanocore, USA. MMT nanomer I.34TCN is surface modified with organic surfactant to facilitate the bonding between nanoclay and HDPE. Current clay/polymer nanocomposite CPNC was produced by special technique of mixing, processing and molding. Samples of nanoclay, HDPE and nanocomposite were characterized by XRD, SEM and EDAX for investigating the chistillanity, distribution, desperion, intercalation, exfoliation, homogenity and defects. These aspects govern CPNC processing and bond between nanoclay and HDPE which controls the mechanical and fracture properties. Sheets of the produced CPNC were prepared for mechanical and fracture testing. Mechanical properties such as tensile strength, yield stress and elongation were tested and compared for both of pure HDPE and CPNC using non standard test specimens of flat sheets for comparison purposes. Fracture mechanics tests for checking and comparing the critical stress intensity factor due to stress concentration at the crack tips for mode I crack (KIc) were carried out using precracked non standard flat sheet specimens subjected to uniaxial uniform tensile stresses. Furthermore, standard experimental tests were conducted for both of HDPE and CPNC for investigating standard mechanical properties aspects based on ASTM D 638 using standard dumbbell-shaped specimen while for investigating standard fracture toughness standard single edge notch specimens SENB subjected bending moment due to effect of 3-point load based on ASTM D 5045 were carried out. The results showed that procedures of mixing, processing technique could produce nanocomposite with enhanced mechanical and fracture properties.

Effects of Elevated Temperatures on the Compression Strength of Nanoclay Filled Unsaturated Polyester Resin

The paper describes the effects of the montmorillonite (MMT) fillers commonly known as nanoclay, on the compression properties of unsaturated polyester resins at different weight percentage of nanoclay. Modified resin specimens with 1, 3 and 5 wt. % of nanoclay contents were prepared and subjected to compressive tests according to ASTM D695. The static uniaxial compression testing were conducted at various temperatures ranging from room temperature (RT) to the temperature closer to its glass transition temperatureTgto study the effect of nanoclay fillers on the compressive stress-strain behaviour at high temperatures (room temperature, 35, 45, and 75°C). The mechanical properties of the nanomodified resin including the elastic modulus, maximum stress and failure strain were determined. The experimental results imply that adding these nanoclay fillers has enhanced the elastic modulus, compressive strength, and toughness without sacrificing the strain to failure and thermal stability of the unsaturated polyester. However it was found that generally, all specimens showed degradation in compressive strength with increases in temperatures.

Characterization of twin‐screw‐extruder‐compounded polycarbonate nanoclay composites

AbstractPolycarbonate nanocomposites were prepared by melt processing from two surface‐modified montmorillonite organoclays. The intercalation spacing and degree of the dispersion were characterized with wide‐angle X‐ray diffraction and transmission electron microscopy, respectively. The polycarbonate nancomposites showed rather good dispersion of nanoclay, with a mixture of exfoliated, intercalated, and confined morphology. The effect of nanoclay on the mechanical response of specimens subjected to tensile and impact loading was investigated. Results demonstrated that nanocomposites based on nanoclay possess increased Young's modulus and yield strength. However, their ductility upon tensile loading is significantly affected. A transition from ductile to brittle deformation occurs at studied clay loadings. Notched impact strength experiments supported this, showing that impact strength decreases significantly as nanoclay content increases from 1 to 5 wt%, regardless how the nanoclay surface was modified. Thermal analysis demonstrated that addition of nanoclay leads to decreased thermal stability of polycarbonate suggesting, enhanced dynamics of polymer chains. Finally, the tribological properties of selected specimens were evaluated using a pin‐on‐disc, and the effect of nanoclay fillers on tribological properties is discussed. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

Observation of two α-relaxation peaks in a nanoclay-filled epoxy compound

For over 10 years, the effect of nanosilicate layers on glass transition temperature of epoxy resins has been studied by various research groups. Unfortunately, there appears to be no consensus in the literature regarding the role of nanoclay addition on a-relaxation peak (Tg-peak) in montmorillonite (MMT)-filled epoxy compounds [1–8]. Several studies reported an increase in the overall glass transition temperature (Tg) of MMT-filled epoxies compared to the neat epoxy [1–3], while other studies claimed suppression of the Tg in these nanocomposites [4–6]. There are even some results indicating that the addition of nanoclay has no effect on a-relaxation peak of epoxy resins [7, 8]. Table 1 contains a description of the materials investigated in these studies. The following sections contain discussions of glass transition behavior in several types of nanoclay-filled epoxies. Messersmith and Giannelis [1] reported broadening of the tan d peak in the glass transition region and a slight increase in the Tg of mica-filled epoxy compound with the interlayer distances larger than 100 A. The glass transition temperature was characterized using a dynamic mechanical analyzer (DMA). The increase in Tg was attributed to the strong interactions between silicate platelets and epoxy network that restrict molecular motion of polymer segments near the silicate layer surface. Regarding the observations of Tg depression, several hypotheses have been proposed. Chen et al. [4] attributed this phenomenon to the presence of interphase region between the silicate layers where the surface modifiers of clay act as plasticizer in epoxy resin. They predicted the effective size of interphase region in the order of 50 A [4]. It was reported that the glass transition temperature decreased as the volume fraction of the interphase region inside the galleries increased by increasing the interlayer distance between silicate platelets [4]. However, Jackson and McKenna [9] found that confining organic liquids (1,2-diphenylbenzene and benzyl alcohol) in both surface treated and untreated nano-size pores resulted in similar Tg suppression. Becker et al. [5] believed that the presence of unreacted epoxy monomers leads to Tg depression in clay nanocomposites. Specifically, it was claimed that the drop in the Tg can be ascribed to the lower crosslink density of epoxy network between silicate layers, i.e. in the galleries [5]. The purpose of this letter is to report an observation on the effect of nanoclay fillers on the a-relaxation in an epoxy resin. This observation, which is a small portion of a more detailed study on MMT-filled epoxies, provides useful insight on glass transition processes in nanoclay-filled epoxy composites.