Pusat Pengajian Kejuruteraan Mekanikal - Tesis

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    Bio-based and hybrid based polymer composites for enclosures of memory storage device application
    (2022-08-01)
    Janakiraman, Vishnu Chandar
    A large proportion of consumer electrical and electronic packaging applications were made up of thermoplastics. Casings or enclosures are generally used in circuit boards, and data storage which is made up of plastic to ensure the appliances are mobile, lightweight while being tough and durable and at the same time, the plastics used in these applications are very high and also not biodegradable. This research aims to reduce the usage of plastics in storage applications via two approaches, i.e., bio-based and hybrid-based polymer composites. In this work, pure polymer [polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), cellulose acetate (CA)] and its bio-based composite ((PLA/Aluminium oxide (Al2O3)/Boron Nitride (BN)), PLA/BN/Graphene tubes (GT), PHBV/Al2O3/BN, PHBV/BN/GT, CA/Al2O3/BN, CA/BN/GT) sheets with different concentration of hybrid filler [(Aluminium oxide (Al2O3)/Boron nitride (BN), BN/Graphene tubes (GT)] were fabricated. Similarly, pure thermoplastics (polyoxymethylene (POM), polypropylene(PP), polycarbonate (PC)) and its hybrid-based composite POM/PHBV/Al2O3/BN, POM/PHBV/BN/GT, PP/cellulose fiber (CF)/Al2O3/BN, PP/CF/BN/GT, PC/basalt fiber (BF)/Al2O3/BN, PC/BF/BN/GT) sheets with different concentration of hybrid fillers were fabricated using internal mixer equipment and compression molding method. The effect of fillers on the structural, optical, thermal, thermophysical, mechanical, surface, electrical properties of the pure polymer and its bio-based and hybrid-based polymer composite sheets were studied, compared, and suggested for electronic packaging applications. XRD results confirm the presence of polymers and fillers (ceramic, carbon, and natural) in the prepared bio-based and hybrid-based composites. The prepared bio-based (PLA/BN/GT, PHBV/BN/GT, CA/BN/GT) and hybrid-based (POM/PHBV/BN/GT, PP/CF/BN/GT, PC/BF/BN/GT) polymer composites exhibit high UV-VIS-NIR absorption, thermal conductivity (0.29 - 0.51 W/mK and 0.35 – 0.53 W/mK), flexural strength (34.2 – 66.4 MPa and 59.1 –74.8 MPa), flexural modulus (1088 – 3239 MPa and 1313 – 3424 MPa), storage modulus (726 – 2130 MPa and 1492 – 3132 MPa), scratch hardness (0.43 – 0.73 GPa and 0.44 – 1.19 GPa), and low CTE (17 - 42.9 µm/m ºC and 38.6 – 114 µm/m ºC), ESD (<10V to <100V and <10V) compared to composites with Al2O3/BN filler and pure polymer that may be due to the high thermal conductivity, mechanical strength and synergetic effect of BN and GT filler. As for dielectric permittivity, Al2O3/BN reinforced composites exhibit favourable dielectric constant (3.02 - 4.74 and 2.72 –3.37) and loss (< 0.02), whereas BN/GT reinforced polymer composites shows higher values at a lower frequency. Like bio-based, hybrid-based polymer composites also follows the same trend in dielectric permittivity. On comparing the bio-based composites, CA/BN/GT polymer composites are suitable for USB products with high storage capacity as per the obtained melting, glass transition temperature, CTE, ESD, mechanical, and scratch performance, whereas PLA/BN/GT and PHBV/BN/GT polymer composites are suitable for USB products with very low storage capacity and can ultimately reduce 98% of plastics. Similarly, the prepared hybrid-based polymer composites (POM/PHBV, PP/CF, PC/BF) with BN/GT filler are suitable for USB, SSD, and HDD products with both low and high capacity as per the obtained thermal, ESD, mechanical, and scratch performance and can ultimately reduce 15-40% of plastics in enclosure applications.