Functionalization of segregated MWCNTS/AGNPS to reduce the percolation threshold of uhmwpe composite /
Alfeorina Alfred,
Functionalization of segregated MWCNTS/AGNPS to reduce the percolation threshold of uhmwpe composite / Alfeorina Alfred - xvii, 157 pages : illustrations (some color) ; 30 cm. + 1 CD-ROM
Faculty of Chemical and Process Engineering Technology
Thesis (Master of Science) -- Universiti Malaysia Pahang – 2025
Includes bibliographical references
Conductive polymer composites (CPCs) combine the flexibility and lightweight properties of polymers with the high electrical conductivity of fillers. However, achieving low percolation threshold—the transition from an insulator to a conductor—often requires high filler content, which increases costs and diminishes mechanical and thermal properties. This study explores the functionalization of multi-walled carbon nanotubes (MWCNTs) and silver nanoparticles (AgNPs) with ester and amide groups to enhance dispersion and interaction within an ultra-high molecular weight polyethylene (UHMWPE) matrix. The goal was to reduce the percolation threshold while improving thermal and mechanical properties at lower filler concentrations. Composites were fabricated using compression molding with unmodified (UMCNT) and modified (MOCNT) MWCNT filler loadings from 0.25 wt.% to 2.0 wt.% and hybrid filler ratios of MWCNT:AgNPs at 100:0, 75:25, 50:50, 25:75, and 0:100. Fourier Transform Infrared Spectroscopy (FTIR) confirmed successful surface modification of the fillers. Mechanical testing showed significant improvements: tensile strength, yield strength, and elongation at break increased by 8.90%, 3.69%, and 7.45%, respectively, for modified MWCNT (MOCNT/UHMWPE) composites compared to unmodified MWCNTs (UMCNTs/UHMWPE) at 0.50 wt.%. Hybrid composites demonstrated even better performance, with tensile strength, yield strength, and elongation at break increasing by 14.79%, 12.58%, and 4.45% compared to pure MOCNT composites, due to synergistic effects of MWCNTs and AgNPs. Morphological analysis using Scanning Electron Microscopy (SEM) revealed reduced agglomeration in MOCNT/UHMWPE composites compared to UMCNT/UHMWPE. Field Emission SEM and Energy Dispersive X-ray spectroscopy (FESEM-EDX) confirmed excellent filler dispersion, contributing to enhanced properties. The modified MWCNTs achieved a percolation threshold at 1.0 wt.% with a maximum electrical conductivity of 1.80 × 10⁻³ S/cm, compared to 2.40 × 10⁻⁴ S/cm for unmodified MWCNT composites. Hybrid composites further enhanced electrical performance, achieving 6.05 × 10⁻⁴ S/cm at a 25:75 MWCNT:AgNP ratio. Thermal analysis via Differential Scanning Calorimetry (DSC) revealed a 25.95% increase in crystallinity for MOCNT/UHMWPE composites compared to UMCNT/UHMWPE, with hybrid composites achieving up to 63.58% crystallinity at a 50:50 ratio. Thermogravimetric Analysis (TGA) indicated increased degradation temperatures, up to 484 °C for modified composites and 464 °C for hybrid composites at 50:50, signifying enhanced thermal stability. These findings demonstrate that functionalized MWCNTs and AgNPs as hybrid fillers effectively reduce material costs and improve the conductivity, mechanical strength, and thermal stability of CPCs, making them viable for advanced applications in electronics, sensors, and energy storage devices.
THE0010085 (Local)
Faculty of Chemical and Process Engineering Technology--Dissertations
Universities and colleges--Dissertations
Thesis--Dissertations
Functionalization of segregated MWCNTS/AGNPS to reduce the percolation threshold of uhmwpe composite / Alfeorina Alfred - xvii, 157 pages : illustrations (some color) ; 30 cm. + 1 CD-ROM
Faculty of Chemical and Process Engineering Technology
Thesis (Master of Science) -- Universiti Malaysia Pahang – 2025
Includes bibliographical references
Conductive polymer composites (CPCs) combine the flexibility and lightweight properties of polymers with the high electrical conductivity of fillers. However, achieving low percolation threshold—the transition from an insulator to a conductor—often requires high filler content, which increases costs and diminishes mechanical and thermal properties. This study explores the functionalization of multi-walled carbon nanotubes (MWCNTs) and silver nanoparticles (AgNPs) with ester and amide groups to enhance dispersion and interaction within an ultra-high molecular weight polyethylene (UHMWPE) matrix. The goal was to reduce the percolation threshold while improving thermal and mechanical properties at lower filler concentrations. Composites were fabricated using compression molding with unmodified (UMCNT) and modified (MOCNT) MWCNT filler loadings from 0.25 wt.% to 2.0 wt.% and hybrid filler ratios of MWCNT:AgNPs at 100:0, 75:25, 50:50, 25:75, and 0:100. Fourier Transform Infrared Spectroscopy (FTIR) confirmed successful surface modification of the fillers. Mechanical testing showed significant improvements: tensile strength, yield strength, and elongation at break increased by 8.90%, 3.69%, and 7.45%, respectively, for modified MWCNT (MOCNT/UHMWPE) composites compared to unmodified MWCNTs (UMCNTs/UHMWPE) at 0.50 wt.%. Hybrid composites demonstrated even better performance, with tensile strength, yield strength, and elongation at break increasing by 14.79%, 12.58%, and 4.45% compared to pure MOCNT composites, due to synergistic effects of MWCNTs and AgNPs. Morphological analysis using Scanning Electron Microscopy (SEM) revealed reduced agglomeration in MOCNT/UHMWPE composites compared to UMCNT/UHMWPE. Field Emission SEM and Energy Dispersive X-ray spectroscopy (FESEM-EDX) confirmed excellent filler dispersion, contributing to enhanced properties. The modified MWCNTs achieved a percolation threshold at 1.0 wt.% with a maximum electrical conductivity of 1.80 × 10⁻³ S/cm, compared to 2.40 × 10⁻⁴ S/cm for unmodified MWCNT composites. Hybrid composites further enhanced electrical performance, achieving 6.05 × 10⁻⁴ S/cm at a 25:75 MWCNT:AgNP ratio. Thermal analysis via Differential Scanning Calorimetry (DSC) revealed a 25.95% increase in crystallinity for MOCNT/UHMWPE composites compared to UMCNT/UHMWPE, with hybrid composites achieving up to 63.58% crystallinity at a 50:50 ratio. Thermogravimetric Analysis (TGA) indicated increased degradation temperatures, up to 484 °C for modified composites and 464 °C for hybrid composites at 50:50, signifying enhanced thermal stability. These findings demonstrate that functionalized MWCNTs and AgNPs as hybrid fillers effectively reduce material costs and improve the conductivity, mechanical strength, and thermal stability of CPCs, making them viable for advanced applications in electronics, sensors, and energy storage devices.
THE0010085 (Local)
Faculty of Chemical and Process Engineering Technology--Dissertations
Universities and colleges--Dissertations
Thesis--Dissertations