Morphological and orientation studies of injection moulded nylon-6,6/Kevlar composites

Yu, Zhonghai; Aı̈t-Kadi, A.; Brisson, Josée

doi:10.1016/0032-3861(94)90340-9

Cited by 8 publications

(8 citation statements)

References 16 publications

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“…15 also shows that the Young modulus is larger when the injection speed is the largest due to higher polymer chain orientation and larger degree of nanotube alignment. Although the effect is not highly significant, it is different from what reported previously in the case of conventional injection molding of polymer/long fiber composites like Kevlar [49]. They found that lower injection speeds create a thicker solidified layer and result in a higher shear flow field at the solid-melt interface.…”

Section: Mechanical Propertiescontrasting

confidence: 54%

Flow induced orientation of multiwalled carbon nanotubes in polycarbonate nanocomposites: Rheology, conductivity and mechanical properties

Abbasi

Carreau

Derdouri

2010

Polymer

216

202

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Flow induced orientation of multiwalled carbon nanotubes inWe investigated the effect of flow field and deformation rate on the nanotube alignment and on the properties of PC/multiwalled carbon nanotube nanocomposites. Samples of various MWCNT loadings were prepared by diluting a commercial masterbatch containing 15 wt% nanotubes using optimized melt mixing conditions. Different processing conditions were then used to systematically change the degree of nanotube alignment, from random orientation to highly aligned. Morphological studies and Raman spectroscopy analysis revealed that the nanotubes are preferentially aligned in the flow direction, particularly at large injection or compression rates. Rheological measurements corresponding to high shear rate conditions showed drastic changes in the viscoelastic behavior. The complex viscosity significantly decreased and percolation threshold notably rose. High degrees of nanotube alignment also resulted in a significant increase in the electrical percolation threshold. The mechanical properties of the nanocomposites for different nanotube loadings were also shown to depend on the processing conditions, and somehow improved when the material was processed at higher rates. Finally, we used a power-law type equation to correlate the percolation behavior and the nanotube alignment. The estimated percolation threshold and the power index, q, significantly increase with the degree of nanotube alignment as determined by Raman analysis.

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Section: Mechanical Propertiescontrasting

confidence: 54%

Flow induced orientation of multiwalled carbon nanotubes in polycarbonate nanocomposites: Rheology, conductivity and mechanical properties

Abbasi

Carreau

Derdouri

2010

Polymer

216

202

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“…1. constituents show linear elastic behavior 2. the matrix is isotropic 3. fibers are transversely isotropic 4. fiber-matrix bond is perfect Assumption 2 excludes matrix orientation that may affect the tensile properties and any other load transferred from the matrix to the fiber [25].…”

Section: Micromechanical Modelmentioning

confidence: 99%

“…The concept of using empirical orientation factors leads to a great discrepancy between the significantly higher theoretical stress calculation for a composite system and the experimental results. Moreover, it is known that molecular orientation in the matrix is likely to be as important as fiber orientation in determining the modulus and strength contributions, and its effects may not be neglected [25].…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Modeling of Tensile Behavior of Short Fiber Composites

Meddad

Azaiez

Aı̈t-Kadi

et al. 2002

Journal of Composite Materials

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A simple micromechanical constitutive model is developed for short fiber reinforced composites (SFRC) undergoing damage. The model is based on the Carman and Reifsnider approach for the prediction of mechanical properties of discontinuous fiber reinforced composites. The composite is modeled by a distributed representative element composed of concentric circular cylinders using a general 3D configuration. The micromechanical model is used to evaluate the elastic properties of SFRC, by varying the orientation distribution of the fiber, the length distribution of the fiber and the fiber–fiber interaction phenomena. The composite is assumed to behave as linearly elastic in absence of any debonding of fiber from the matrix and in the fully debonded stage. The stress–strain behavior of molded composite materials and the debonding are modeled using the Hsueh model to estimate the debonding stress for misaligned fibers. A good agreement between calculated and experimental data was achieved.

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“…On the other hand, Kutty and coworkers 12 reported after melt compounding a noticeable fiber length reduction from 6 mm to 0.5-1.5 mm. The introduction of short Kevlar fibers in various polyamides (PA6, PA66 and PA11) was investigated by Yu et al [14][15][16] They showed the effect of stiffening, the crystallization dependence and the effect of the orientation in injection-molded composites containing up to 35% of Kevlar fibers. Several literature data from Bualaek-Limcharoen and coworkers 18,[20][21][22]26 evidenced the applications of aramid short fibers in styrene-ethylene-butylene-styrene (SEBS) and in other thermoplastic elastomers.…”

Section: Introductionmentioning

confidence: 99%

“…Following these considerations and the recent presentation of Ioffe, 40 it is evident the interest in improving the properties of thermosetting and thermoplastic materials by using short aramid fibers. Beside various polyamide-based composite systems 47,48 and the above-mentioned studies on PA6, PA66 and PA11 composites reinforced with short aramid fibers, [14][15][16][17] a rising interest has emerged in the preparation of PA12-based composites. In a recent work, we have successfully prepared and thermo-mechanically characterized PA12 composites reinforced with post-consumed PA66 fibers.…”

Section: Introductionmentioning

confidence: 99%

Effect of aramid regenerated fibers on thermo-mechanical behaviour of polyamide 12 composites

Dorigato

Fambri

2013

Journal of Reinforced Plastics and Composites

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Aramid regenerated short fibers, obtained from the production scrap of as-produced aramid yarns, were utilized as reinforcement in a commercial polyamide (PA12) at different contents, ranging from 10 wt% to 30 wt%, in order to evaluate the effect of the fiber loading on the mechanical and dynamic behaviour of the resulting materials. Differential scanning calorimetry tests revealed how the crystallinity slightly decreased with the fiber content, while quasi-static tensile tests evidenced that the introduction of aramid fibers provided an interesting stiffening effect on the resulting composites, proportionally to the filler content. On the other hand, the presence of agglomerated fibers led to an embrittlement of polyamide composites, with a progressive reduction of the deformation at break. Tensile dynamic tests confirmed the stabilizing effect provided by the recycled fibers, while the coefficient of linear thermal expansion was progressively reduced both under and above the glass transition temperature. Isothermal creep compliance of the material was substantially reduced upon fiber addition, especially at elevated testing temperatures. Accordingly, Vicat softening temperature was increased of 10-20 C in dependence on the fiber content. Also, the thermal degradation stability was slightly improved upon fiber addition. Morphological analysis on the cryofractured surfaces revealed a quite good fiber-matrix interfacial adhesion.

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Morphological and orientation studies of injection moulded nylon-6,6/Kevlar composites

Cited by 8 publications

References 16 publications

Flow induced orientation of multiwalled carbon nanotubes in polycarbonate nanocomposites: Rheology, conductivity and mechanical properties

Flow induced orientation of multiwalled carbon nanotubes in polycarbonate nanocomposites: Rheology, conductivity and mechanical properties

Micromechanical Modeling of Tensile Behavior of Short Fiber Composites

Effect of aramid regenerated fibers on thermo-mechanical behaviour of polyamide 12 composites

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