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Study of Microstructure and Mechanical Properties of PA6/GF/GB Hybrid Composites

Alamshahi, Amin | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52087 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza
  7. Abstract:
  8. Polyamide 6 is one of the well-known and oldest engineering thermoplastics, which has many uses in the transportation, automotive, apparel and sports industries due to its high strength, high corrosion resistance and high service temperatures. Cite gears, radiator tank, cylinder head cap and fuel rails can be mentioned as Polyamide 6 applications in the automotive industry. Glass fibers are used as reinforcement in PA6 media in order to enhance mechanical properties like tensile and impact strength. Even though the glass fiber improves the mechanical properties of the components produced from fiber-reinforced composites, it increases the anisotropy properties of the material and making it difficult to process the due to its high aspect ratio. As a result, the components produced with polyamide 6 and glass fibers composite have surface quality issues and in some cases the waste of the production process is noticeable. It is experimentally verified that the usage of glass microspheres improves the processability and dimensional stability, in addition to increasing the surface quality and beauty of the final product.In the present study, polyamide 6, glass fibers and glass beads were employed to fabricate hybrid composites and produce the test specimens. The tensile and impact tests were performed to detect the mechanical properties changes, differential scanning calorimetry and x-ray diffraction tests to analyze microstructure changes, gloss meter to investigate the surface gloss index, and scanning electron microscopy and transmitted optical microscopy to study fracture behavior of samples in four-point bending condition.The results show that the addition of glass fibers and glass particles to polyamide 6 changes the microstructure which appears as change in the crystallinity of the material. Furthermore, the addition of glass beads in composite reinforced with gloss fibers enhances the surface gloss index of the specimens.The mechanical tests results indicate that glass fibers help to improve the tensile and impact properties of polyamide 6, while glass particles have a negative effect on mentioned properties. The microscopic studies of the fracture surface state that the presence of glass fibers in the polyamide 6 activates toughening mechanisms such as fiber pull-out, crack branching, and bridging. However, in the case of glass particles, deviation results from debonding ahead of crack tip due to interface strength
  9. Keywords:
  10. Hybrid Composite ; Polyamide 6 ; Glass Fibers ; Glass Beads ; Mechanical Properties

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