Omid Zabihi

Bio: Omid Zabihi is an academic researcher from Deakin University. The author has contributed to research in topics: Epoxy & Diglycidyl ether. The author has an hindex of 23, co-authored 46 publications receiving 1344 citations. Previous affiliations of Omid Zabihi include Islamic Azad University, Science and Research Branch, Tehran & University of Mazandaran.

A technical review on epoxy-clay nanocomposites: Structure, properties, and their applications in fiber reinforced composites

Abstract: The review presents a survey of the literature on structure–property relationships in epoxy-clay nanocomposites. Herein, various pivotal parameters affecting structures and properties of the nanocomposites including various types of modification as well as a vast range of available dispersion techniques were discussed. Opportunities and challenges in regards to potential applications of nanoclay in multi-scale composites have been also addressed. The multi-scale composites containing nanoclays have been reviewed in terms of mechanical properties in both out-of-plane and in-plane directions, and compared with those containing carbon based nanofillers. In this regards, the improving mechanisms in mechanical properties of both epoxy-clay nanocomposites and nanoclay filled fiber reinforced composites were also discussed.

The Effects of UV Light on the Chemical and Mechanical Properties of a Transparent Epoxy-Diamine System in the Presence of an Organic UV Absorber

Abstract: Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV) damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degradation. In this present study, the effects of UV light on the chemical, mechanical and physical properties of cured epoxy structure, as well as the effect of an organic UV absorber, Tinuvin 1130, on the epoxy properties were investigated. Chemical changes in a cured epoxy system as a result of the presence and absence of Tinuvin 1130 were determined using Fourier transform infrared spectroscopy (FT-IR) analyses. The effect of Tinuvin 1130 on the surface morphology of the epoxy systems was also investigated by scanning electron microscopy (SEM) imaging. Additionally, the glass transition temperatures (Tg) before and during UV radiation were measured. After an 800 h UV radiation, mechanical test results revealed that the lack of the UV absorber can lead to a ~30% reduction in tensile strength. However, in the presence of Tinuvin 1130, the tensile strength was reduced only by ~11%. It was hypothesized that the use of Tinuvin 1130, as an organic UV absorber in the epoxy-amine system, could decrease the undesirable effects, arising from exposure to UV light.

A renewable bio-based epoxy resin with improved mechanical performance that can compete with DGEBA

Abstract: The aim of this study is to find a suitable substitution for diglycidyl ether bisphenol A (DGEBA) to avoid the devastating side effects of bisphenol A. Vanillin, an aromatic compound, was used as a renewable material to synthesize a bio-based epoxy resin. The structure of the vanillin-based epoxy resin was confirmed by Fourier transform infrared spectroscopy (FT-IR) analysis. The major drawback of bio-based epoxy resins is their poor mechanical properties preventing them from competing with petroleum based epoxy resins such as DGEBA. Herein, a prepared calcium nitrate solution as an inorganic accelerator was used to accelerate the curing reaction of bio-based epoxy resin which reduced curing times as well as improving significantly the mechanical properties e.g., tensile strength, pull-off strength, and Izod impact strength. Differential scanning calorimetry (DSC) analysis was used to investigate the curing process and thermal properties of the vanillin-based epoxy resin with and without inorganic accelerators and also DGEBA without accelerators. The results showed that in the presence of 2 wt% inorganic accelerator, the initial onset curing temperature of vanillin-based epoxy resin was reduced from 60.1 °C to 8.5 °C, while the initial onset curing temperature of DGEBA was 55.8 °C. In addition, tensile strength and Izod impact strength of the vanillin-based epoxy system in the presence of inorganic accelerators increased in comparison to the DGEBA system. Moreover, in order to study the effect of inorganic accelerators on the toughness of the synthesized vanillin-based epoxy resin, fracture surfaces from Izod impact strength tests were observed using scanning electron microscopy (SEM) which confirmed improving mechanical properties.

Introduction to Spectroscopy

Abstract: Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

Numerical methods for engineers

Abstract: The fifth edition of "Numerical Methods for Engineers" continues its tradition of excellence. Instructors love this text because it is a comprehensive text that is easy to teach from. Students love it because it is written for them--with great pedagogy and clear explanations and examples throughout. The text features a broad array of applications, including all engineering disciplines. The revision retains the successful pedagogy of the prior editions. Chapra and Canale's unique approach opens each part of the text with sections called Motivation, Mathematical Background, and Orientation, preparing the student for what is to come in a motivating and engaging manner. Each part closes with an Epilogue containing sections called Trade-Offs, Important Relationships and Formulas, and Advanced Methods and Additional References. Much more than a summary, the Epilogue deepens understanding of what has been learned and provides a peek into more advanced methods. Approximately 80% of the end-of-chapter problems are revised or new to this edition. The expanded breadth of engineering disciplines covered is especially evident in the problems, which now cover such areas as biotechnology and biomedical engineering. Users will find use of software packages, specifically MATLAB and Excel with VBA. This includes material on developing MATLAB m-files and VBA macros.

Carbon fiber reinforced metal matrix composites: Fabrication processes and properties

Abstract: This paper reviews the research and development works conducted over the past few decades on carbon fiber reinforced metal matrix composites (CFR-MMC). The structure and composition of carbon fiber and its bonding to metal matrix have an impact on the properties of the resulting CFR-MMC remarkably. The research efforts on process optimization and utilizing of carbon fibers are discussed in this review. The effect of carbon fiber on structural, physical and mechanical properties of metal matrix composite are studied as well. This review also provide an overview of the research to date on various fabrication methods that is used for production of CFR-MMC.