A Study of the Flexural Properties of PA12/Clay Nanocomposites (original) (raw)
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Effect of Clay Modification on the Mechanism of Local Deformations in PA6 Nanocomposites
Macromolecular Materials and Engineering, 2013
PA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties of the composites reveal that several micromechanical deformation processes occur in the PA/MMT composites. The matrix cavitates at relatively small stress. Processes related to non-exfoliated clay structural units are initiated at larger stresses. Sound is emitted mainly by the fracture of particles, but debonding may also occur. The plastic deformation of the matrix dominates at larger stresses and deformations. The various local deformations are independent of each other and composite properties are not determined by silicate related processes but by the deformation of the matrix.
Strain amplitude response and the microstructure of PA/clay nanocomposites
Polymer, 2005
Polyamide 6/clay nanocomposites (PAn, where n is the mass fraction of clay) with various clay loading were prepared by melt compounding in a twin screw extruder. Exfoliation of clay in a PA matrix was confirmed by X-ray diffraction. Strain amplitude response of PAn in both melt and solution states has been investigated. In the melt state, critical strain amplitude of PAn is sensitive to strain amplitude response and decrease logarithmically with increasing clay loading. The elastic moduli (G 0 ) of PAn are reversible under frequency loop sweeps. Comparisons of strain amplitude response in both melt and solution states have been conducted. Two different responses have been observed: strain thinning in the melt state and weak strain overshoot in the solution state. FTIR studies show that amide II band of PAn shifts toward high wavenumbers, but amide I band and N-H stretching vibration are independent of clay loading. We suggest that two types of strain amplitude response of PAn can be explained: strain thinning which is dominant in PAn caused by physical adsorption and entanglement of PA chains on nanoclays and weak strain overshoot caused by weak bonds between PA chains and nanoclays. q Polymer 46 (2005) 6429-6436 www.elsevier.com/locate/polymer 0032-3861/$ -see front matter q
Melt processing effects on the structure and mechanical properties of PA6/clay nanocomposites
Polymer Engineering and Science, 2006
Polyamide-6 nanocomposites were prepared using two organoclays, Cloisite 30B and Cloisite 15A, and Cloisite Na+, which is unmodified sodium montmorillonite (Na-MMT) clay. Nanocomposites were prepared using two twin-screw extrusion systems: System B employing conventional mixing and residence time conditions, while System A was modified to achieve longer residence time and higher mixing efficiency. The work considers the effects of mixing conditions, residence time, and interactions between the polymer and clay surface on the structure and mechanical properties of polyamide-6 (PA-6)/clay nanocomposites. Furthermore, a comparison was made between experimental data and the predictions of composite models usually employed to predict mechanical properties of nanocomposites. The melt processing of Cloisite 30B in System A produced the highest degrees of exfoliation and the largest enhancement of mechanical properties. The aspect ratios of the filler particles in the nanocomposites were estimated from TEM micrographs and from composite models. Yield stress data were employed to calculate the values of parameter B in Pukanszky's equation, which incorporates the effects of the interfacial interaction, interfacial strength, and specific surface area of the filler particles. POLYM. ENG. SCI. 46:1094–1103, 2006. © 2006 Society of Plastics Engineers
PP/clay nanocomposites: Effect of clay treatment on morphology and dynamic mechanical properties
Journal of Applied Polymer Science, 2001
The morphology and properties of polypropylene (PP)/clay nanocomposites are described. The melt intercalation of organophilic clay was carried out with a single-screw extruder. The effects of two kinds of treatments of clay are discussed. Maleic anhydride (MAH)-grafted PP was used as a compatibilizer. The expansion of the intergallery distance of the clay was governed by the interaction between the clay treatment and the compatibilizer. In one case, the composites exhibited significantly reduced intensities of diffraction peaks, suggesting partial exfoliation of the clay layers, whereas for the second clay sample, expansion of the gallery height was noted. The mechanical properties of the PP/clay composites showed significant enhancement in their mechanical and thermal properties. About a 35% increase in the tensile modulus and about a 10% increase in the tensile strength were observed. The thermal degradation temperature increased from 270 to about 400°C as a result of the incorporation of clay, and the extent depended on the dispersion of clay in the composite. The most interesting outcome of this study was the changes in morphology for PP/clay composites, which are reported here for the first time. An optical microscopic study revealed that the PP/clay composites could be crystallized at higher temperatures than pure PP and that the morphology was remarkably altered because of the presence of layers of clay. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1786–1792, 2001
Full-Text PDF Abstract Polypropylene/montmorillonite nanocomposite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nanocomposite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD) and transmission optical microscopy (TOM) techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of nanocomposite.
PP/clay nanocomposite: optimization of mixing conditions with respect to mechanical properties
Polymer Bulletin, 2010
Polypropylene/clay nanocomposites were studied with focus on optimization of mixing conditions. Two different types of commercial nanofillers Dellite Ò were used (Dellite Ò 72T and Dellite Ò 67G). Effect of various concentrations of fillers on morphology and mechanical properties was investigated. Conditions of preparation were varied with respect to mixing time and speed of rotation of kneaders. Results of morphology study showed that nanocomposites contained agglomerates of nanofillers. The comparison of the filler types revealed that better dispersion and distribution was found for nanocomposites containing Dellite 72T which had also better tensile strength. Optimum mixing time was 30 min. 3D graphical analysis showed that the optimum speed of rotation was 60 rpm and with increasing clay content (2-10 wt%) the tensile strength increased.
Experimental and theoretical analyses of mechanical properties of PP/PLA/clay nanocomposites
Composites Part B: Engineering, 2015
Compatibilized and non-compatibilized blends of polypropylene (PP) and poly(lactic acid) (PLA) with various compositions containing nanoclay particles were prepared by one step melt compounding in a twin screw extruder. Two nanocomposite systems with different matrices i.e. PP-rich (75/25 composition) containing Cloisite 15A and PLA-rich (25/75 composition) containing Cloisite 30B were selected for investigation of effect of nanoclays and n-butyl acrylate glycidyl methacrylate ethylene terpolymers (PTW) as compatibilizer on mechanical properties of PP/PLA/clay nanocomposites. Tensile and impact properties of the nanocomposite systems were investigated and correlated with their microstructures. Tensile modulus and strength of the blends were increased while elongation at break decreased by increasing PLA content. There was an irregular relationship between impact strength of the blends and PLA content. Several proposed models for blends and nanocomposites were used for prediction of tensile modulus of the samples. Most of the proposed models for blends could predict the tensile modulus of the blends successfully at low content of PLA. Another notable point was that most of the micromechanical models for nanocomposites fitted well to experimental values at low content of the clays and showed deviations at high clay loadings.
Journal of Applied Polymer Science, 2012
Effects of processing sequence on the clay dispersion, phase morphology, and thermal and rheological properties of PA6-HDPE-clay nanocomposites are investigated in this study. It has been found that the processing sequence plays a key role in the clay dispersion and phase morphology of the PA6-HDPE-clay nanocomposites. When PA6 is extruded with clay first, either in the absence or presence of HDPE, a continuous PA6 phase domain forms with exfoliated clay platelets that seem to have strong interaction with the dispersed HDPE droplets, leading to a favorable phase morphology. When HDPE is extruded with clay in the first extrusion, nonpolar HDPE molecules are sheared into the clay interlayers and form HDPE intercalated clay, and the HDPE-clay aggregates do not have strong interactions with PA6 in the second extrusion, resulting in a phase morphology of large HDPE par-ticles of hundreds of microns in size dispersed in PA6 phase. The DSC results indicate strong interaction between the polymers and clay; in particular, it is shown there is stabilization of c-form crystals by the compatibilizer (PEMA). Rheological characterization indicates that the PA6-HDPEclay nanocomposites exhibit significantly high storage and complex viscosity in the entire frequency range, and the loss modulus of the nanocomposites that have an exfoliated clay dispersion is lower than that of PA6 at high frequency. The results of this study suggest two types of microstructures of the PA6-HDPE-clay nanocomposites are possible using different processing sequences. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: E714-E724, 2012
International Nano Letters, 2015
This paper presents a methodology for determination of the optimal material and processing parameters (i.e., nanoclay content, melt temperature, feeding rate, and screw speed) to maximize simultaneously tensile modulus and tensile strength of injection-molded PA-6/clay nanocomposites through coupling response surface method and genetic algorithm. The tensile tests on PA-6/clay nanocomposites are conducted to obtain tensile modulus and tensile strength values, and then analysis of variance is performed. The predicted models for tensile modulus and tensile strength are created by response surface method, and then the functions are optimized by a genetic algorithm code implemented in MATLAB. Acceptable agreement has been observed between the values of the process parameters predicted by the response surface method and genetic algorithm and those of the process parameters obtained through experimental measurements. This study shows that the response surface method coupled with the GA can be utilized effectively to find the optimum process variables in tensile test of PA-6/NC nanocomposites.