Epoxidation of Cardanol\u27s Terminal Double Bond.

In this investigation, the terminal double bonds of the side chain epoxidized cardanol glycidyl ether (SCECGE) molecule were further epoxidized in the presence of Oxone® (potassium peroxomonosulfate) and fluorinated acetone. Regular methods for the double bond epoxidation are not effective on the terminal double bonds because of their reduced electronegativity with respect to internal double bonds. The terminal double bond functionality of the SCECGE was epoxidized to nearly 70%, increasing the epoxy functionality of SCECGE from 2.45 to 2.65 epoxies/molecule as measured using proton magnetic nuclear resonance (1H-NMR). This modified material—side chain epoxidized cardanol glycidyl ether with terminal epoxies (TE-SCECGE)—was thermally cured with cycloaliphatic curing agent 4-4′-methylenebis(cyclohexanamine) (PACM) at stoichiometry, and the cured polymer properties, such as glass transition temperature (Tg) and tensile modulus, were compared with SCECGE resin cured with PACM. The Tg of the material was increased from 52 to 69 °C as obtained via a dynamic mechanical analysis (DMA) while the tensile modulus of the material increased from 0.88 to 1.24 GPa as a result of terminal double bond epoxidation. In addition to highlighting the effects of dangling side groups in an epoxy network, this modest increase in Tg and modulus could be sufficient to significantly expand the potential uses of amine-cured cardanol-based epoxies for fiber reinforced composite applications

Influence of Epoxidized Cardanol Functionality and Reactivity on Network Formation and Properties.

Cardanol is a renewable resource based on cashew nut shell liquid (CNSL), which consists of a phenol ring with a C15 long aliphatic side chain in the meta position with varying degrees of unsaturation. Cardanol glycidyl ether was chemically modified to form side-chain epoxidized cardanol glycidyl ether (SCECGE) with an average epoxy functionality of 2.45 per molecule and was cured with petroleum-based epoxy hardeners, 4-4\u27-methylenebis(cyclohexanamine) and diethylenetriamine, and a cardanol-based amine hardener. For comparison, cardanol-based diphenol diepoxy resin, NC514 (Cardolite), and a petroleum-based epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) were also evaluated. Chemical and thermomechanical analyses showed that for SCECGE resins, incomplete cure of the secondary epoxides led to reduced cross-link density, reduced thermal stability, and reduced elongation at break when compared with difunctional resins containing only primary epoxides. However, because of functionality greater than two, amine-cured SCECGE produced

The Effect of Side Chain Functionalization and Formulation of Cashew Nutshell Liquid (CNSL) on the Properties of Thermoset Networks

Cardanol which is the main component of the thermally treated cashew nutshell liquid (CNSL) is a versatile molecule with a C15 aliphatic side chain connected to a phenyl ring at the -meta position. The dual structure of cardanol which combines a rigid aromatic ring with a flexible and hydrophobic side chain with different degrees of unsaturation makes this molecule a suitable and sustainable candidate to utilize in top coat and primer formulations to improve corrosion performance. However, cardanol lacks reactive polymerizable functional groups on its structure and cardanol-derived networks possesses long dangling chains on their backbone which decrease the network performance regardless of their benefits. Thus, in this dissertation, the effect of cardanol's side chain functionalization on network properties and corrosion performance was explored. The unsaturation sites of the side chain of the mono-epoxy cardanol molecule, cardanol glycidyl ether (CGE), were epoxidized via peroxyacids to achieve secondary epoxies on the side chain and to connect the C15 chain of the cardanol into the polymer network. This side chain epoxidized CGE (SCECGE) epoxy resin was cross-linked with a range of amine curing agents. The lower reactivity of the secondary epoxies towards amines was demonstrated via a number of direct and indirect curing studies and a systematic methodology was developed to assess the extent of cure of secondary epoxies by using cardanol-derived model secondary epoxy. Structural characterization of SCECGE monomer also revealed the reduced reactivity of the terminal double bonds of the aliphatic chain towards epoxidation with respect to inner ones because of their reduced electronegativity. Thus, a useful methodology was developed to effectively epoxide the terminal double bonds of the SCECGE and to make a correlation between the degree of side chain functionalization and the network performance. SCECGE monomer was mixed with a bis-phenol A derived di-epoxy monomer (DGEBA, EPON 828) with changing weight rations and thermally cross-linked with a cycloaliphatic amine (PACM) to demonstrate the effect of side chain cross-linking on the water barrier and corrosion performance. Network properties and the coating performance of the DGEBA/SCECGE blends were evaluated and the results showed that; upon proper functionalization and careful formulation with DGEBA, cardanol based building blocks can meet significant requirements ofthermoset coatings while keeping satisfactory thermal and mechanical resistance for corrosion coating applications. The reactivity issue of the secondary epoxies was addressed via further reacting the epoxy moieties with methacrylic acid to fully react the side chain into the polymer network thus to improve the polymer performance and network properties. Due to the stearic limitations of the secondary epoxies; they are not able to fully react with amine hardeners. Replacing these secondary epoxies with methacrylate units and using the free radical polymerization mechanizm resulted in almost full cross-linking of the side chain in vinyl ester formulations. Finally, a useful hybrid molecule synthesized via the combination of cardanol and fatty acid based building blocks was incorporated with DGEBA-PACM system. This hybrid molecule demonstrated similar toughening effect to epoxidized soybean oil based tougheners while keeping the modulus significantly higher owing to its aromatic content.Ph.D., Chemical Engineering -- Drexel University, 201

Polybutylene Succinate (PBS) - Polycaprolactone (PCL) Blends Compatibilized with Poly(ethylene oxide)-block-poly( propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO) Copolymer for Biomaterial Applications

This study reports the preparation and characterization of Polybutylene Succinate (PBS)-Polycaprolactone (PCL) melt blends (10-40 wt.% PCL) in the presence of a compatibilizer, in order to explore their potential use as a biomaterial. The thermal transitions, as well as the crystallinity of the polymer blends were analyzed by Differential Scanning Calorimetry, the thermomechanical properties were analyzed via Dynamic Mechanical Analysis and phase morphologies were characterized by Scanning Electron Microscopy. Degradation profiles of the blends were analyzed in PBS buffer solution at pH 7.4 at 37 degrees C via pH measurements. Cytotoxicity of the PBS/PCL films were tested by MTS assay

Investigation of the effect of annealing on the structural, morphological and optical properties of RF sputtered WO3 nanostructure

In this study, we focused on examining the effect of annealing on the structural, morphological, and optical properties of the tungsten oxide (WO3) nanostructures. WO3 nanostructure deposited on n-type Si substrate using the radio frequency (RF) magnetron sputtering system. The WO3 nanostructure was divided into 6 parts. 5 samples except as-deposited samples were individually annealed at various temperatures ranging from 300 degrees C to 700 degrees C (by step 100 degrees C) in a conventional thermal annealing furnace (CTA) for 1 h. The stoichiometry of the asdeposited WO3 was determined by SEM-EDS and XPS measurements. Structural, morphological, and optic properties of the as-deposited and different annealed temperatures WO3 nanostructures were characterized by XRD, AFM, Uv-Vis and PL measurements. The effects of annealing on material analysis and properties were reported with a comparative study. It has been reported that the annealed WO3 nanostructure can be preferred as an effective material for device applications