Dissertation/Thesis Abstract

Improvement of Mechanical and Hydrophobic Properties of Nanotube Reinforced Glass-Fiber Composites
by Vedangi, Geetika Spandana, M.S., California State University, Long Beach, 2020, 67; 27736099
Abstract (Summary)

An exponential increase in the use of composite materials over the past 70 years makes them ideal materials to improve the scope for diverse industrial applications. Fiber-reinforced composites (FRCs) are one of the imperative materials and are used extensively in distinct engineering fields such as aerospace, automotive, sporting goods, greener energy and more. Among the fiber-reinforced composites, Glass Fiber Reinforced Composites (GFRCs) are finding increased applications due to their high strength to weight ratio. Thermosetting polyesters and vinyl esters are primarily used in fiber-reinforced plastics due to their low cost. Epoxies are one of the vital resins in the market, particularly used in structural and aerospace applications, as it can perform under various temperatures and conditions.

One of the major applications for GFRCs is in wind turbine structures, particularly the blade. For wind turbine applications, improving mechanical strength and wettability of the GFRC structures are highly desired properties. In order to improve the performance, there are

several trends that have emerged in the field of polymer matrix composites with emphasizing the weight reduction as a key factor. One of the interesting trends in the field is the use of nano-particle reinforcements. The advantages of nanocomposites are improved surface area to volume ratio by decreasing the reinforcement scale, which provides larger interphase regions and potential for reaction with the surrounding matrix material. Many additives have been used to improve the strength of the GFRPs like nano clays, metal powders such as titanium, silica, graphene nanoplatelets, carbon nanofibers, etc., out of which carbon nanotubes (CNTs) have been considered as a promising means of enhancing the properties of advanced polymer composites. Expected property enhancements include high strength and stiffness, improved toughness and shear strength.

In the experimental part of this research, several Out Of Autoclave (OOA) techniques have been deliberated such as brushed method, hand layup, resin transfer molding and vacuum-assisted resin transfer molding (VARTM). Analyzing the results, failure modes, rate of

distribution and dispersion of nanotubes, VARTM is preferred as the ideal choice for fabricating composites at room temperature. VARTM allows uniform distribution of resin and lower porosity, compared to hand layup and brushed method, hence this method was used for all experiments conducted. This study focused on the following:

a) Developing a process to enhance mechanical and hydrophobic properties of GFRPs by

adding nano-particles with an outcome of minimizing the processing time.

b) Developing mathematical models to show the effects of CNTs on the surface and

mechanical properties of enhanced GFRPs.

Through experimental analysis, the present study optimized the fabrication of GFRC by

reducing the pre-processing time. Results from mechanical and static contact angles indicate that

vinyl ester resins exhibit superior properties for tensile, flexural and hydrophobic properties over

epoxy. The addition of nanoparticles showed significant improvement in tensile and hydrophobic

properties for both the resin systems but has a trivial effect on the flexural strength of vinyl ester

and diverse effects on the flexural strength of epoxy.

Indexing (document details)
Advisor: Yoozbashizadeh, Mahdi
Commitee: Yavari, Parviz, Roy, Surajit
School: California State University, Long Beach
Department: Mechanical and Aerospace Engineering
School Location: United States -- California
Source: MAI 81/9(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Aerospace engineering, Mechanical engineering
Keywords: Glass-fiber composites, Hydrophobic, Improvement, Mechanical, Nanopaticles, Properties
Publication Number: 27736099
ISBN: 9781658443531
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