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In order to improve the compatibility between lignin fillers and polyurethane matrix, two different chemical strategies were used to modify the lignin macromolecules. Modified lignin was incorporated into vegetable oil-based polyurethanes to produce composites with high bio-content. Lignin modified with octadecyl isocyanante (lignin urethane) was found to be more compatible with the polyurethane matrix...
During the last few years, different kinds of autonomic and non-autonomic self-healing materials have been prepared using diverse techniques for a number of applications. The incorporation of suitable functionalities into these materials facilitates a healing mechanism that is triggered by damage/rupture as well as various chemistries. This article presents a detailed study of the self-healing properties...
A new norbornenyl-functionalized castor oil alcohol (NCA) was synthesized and ring-opening metathesis copolymerized separately with two norbornene-based cross-linking agents: dicyclopentadiene (DCPD) and a bifunctional norbornene crosslinker (CL). Isothermal differential scanning calorimetry (DSC) was used to examine the cure behavior of NCA/DCPD and NCA/CL resins, through which a reasonable cure...
Supercritical carbon dioxide was employed as the solvent for the functionalization of multi-walled carbon nanotubes (MWCNTs) with an epoxy-capped silane. The silanization protocol was found to be a suitable green alternative to traditional routes that rely on organic solvents for grafting nearly monolayers of silane molecules onto the nanotube surfaces. The addition of silanized MWCNTs to a model...
The creep behavior of a liquid crystalline epoxy resin (LCER) was investigated and compared with that of a non-LCER prepared from the same epoxy monomer. The experimental data was evaluated using Burgers' model to explain the reinforcing effect of the liquid crystalline (LC) phase. The long-term performance of the material was predicted using the time–temperature superposition principle. The results...
Multiwalled carbon nanotubes (MWCNTs) were functionalized with aminosilanes via an aqueous deposition route. The size and morphology of siloxane oligomers grafted to the MWCNTs was tuned by varying the silane functionality and concentration and their effect on the properties of a filled epoxy system was investigated. The siloxane structure was found to profoundly affect the thermo-mechanical behavior...
A variety of vegetable oil-based, waterborne polyurethane dispersions have been successfully synthesized from different vegetable oil polyols exhibiting almost constant hydroxyl functionalities of 2.7 OH groups per molecule. The vegetable oil polyols, which have been prepared from vegetable oils with different fatty acid compositions (peanut, corn, soybean, and linseed oil), range in residual degree...
A biphenyl based epoxy monomer, 4,4′-diglycidyloxybiphenyl (BP), was synthesized and cured with a tetra-functional amine, sulfanilamide (SAA), to obtain a liquid crystalline epoxy network. The curing behavior of BP with SAA was studied using differential scanning calorimetry, polarized optical microscopy, and parallel plate rheology. Macroscopic orientation of the liquid crystalline epoxy resins (LCERs)...
The increasing use of polymer matrix composites (PMCs) in structural applications created demand for advanced repair techniques to fix internal delaminations in PMCs. One of a variety of repair techniques is injection repair, which involves injecting a low viscosity resin directly into the damaged area and subsequently curing the resin to heal the damage. In this study, bisphenol E cyanate ester (BECy)...
An epoxy monomer of 4,4′-diglycidyloxybiphenyl (BP) was synthesized and cured with a tetra-functional amine, sulfanilamide (SAA), to produce novel liquid crystalline epoxy resins (LCERs). The thermal properties, liquid crystalline morphologies, and cure behavior of the monomer were studied using differential scanning calorimetry, wide angle X-ray diffraction, and polarized optical microscopy. The...
“Click” chemistry is a frequently used technique in polymer chemistry for coupling polymer end groups to construct novel copolymer architectures and as a step-growth polymerization technique. In this study, the bulk polymerization of a diyne and a bisazide were achieved through the copper-catalyzed alkyne-azide 1,3-cycloaddition (CuAAC) with different catalysts, including the homogeneous catalyst...
Fiberglass-reinforced polymer composites were investigated for potential use as structural dielectrics in multifunctional capacitors that require simultaneous excellent mechanical properties and good energy storage characteristics. Composites were fabricated employing poly(methyl methacrylate), PMMA, as the structural matrix. While barium titanate (BaTiO 3 ) nanopowder was added to the composites...
We describe the influence of calcium copper titanate (CCTO), and montmorillonite (MMT) on the thermo-mechanical and dielectric properties of poly(methyl methacrylate) PMMA-based composites prepared by an in-situ, thermally activated, radical polymerization for multifunctional structural capacitor applications. MMT was used for its ability to disperse and suspend the CCTO particles through the generation...
A unique rapid scanning rate differential scanning calorimeter is used to examine the differences in melt and cold crystallized poly (l-Lactide) (PLLA), a biodegradable semi-crystalline polymer. After isothermal melt and cold crystallization at various temperatures, both melt and cold crystallized PLLA are characterized by similar melting temperatures (T m ) and exhibit multiple melting behavior...
A norbornene-based cross-linker was synthesized and mixed at different loadings with two separate monomers for self-healing polymer applications: 5-ethylidene-2-norbornene (ENB) and endo-dicyclopentadiene (endo-DCPD). The monomer/cross-linker systems were polymerized by ring-opening metathesis polymerization (ROMP) with Grubbs' catalyst. The thermal–mechanical properties of the polymerized networks...
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