scholarly journals Effect of the catalyst system on the reactivity of a polyurethane resin system for RTM manufacturing of structural composites

2022 ◽  
Vol 16 (3) ◽  
pp. 234-247
Author(s):  
Oihane Echeverria-Altuna ◽  
Olatz Ollo ◽  
Tamara Calvo-Correas ◽  
Isabel Harismendy ◽  
Arantxa Eceiza
Keyword(s):  
Catalyst System ◽  
Resin System ◽  
Structural Composites ◽  
Polyurethane Resin

scholarly journals Material characterization of a pultrusion specific and highly reactive polyurethane resin system: Elastic modulus, rheology, and reaction kinetics

2021 ◽  
Vol 207 ◽  
pp. 108543 ◽  
Author(s):  
Onur Yuksel ◽  
Michael Sandberg ◽  
Ismet Baran ◽  
Nuri Ersoy ◽  
Jesper H. Hattel ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Reaction Kinetics ◽  
Material Characterization ◽  
Resin System ◽  
Polyurethane Resin

Organophosphorus-hydrazides as potential reactive flame retardants for epoxy

2019 ◽  
Vol 38 (1) ◽  
pp. 28-52 ◽  
Author(s):  
Alexander B Morgan ◽  
Vladimir Benin ◽  
Donald A Klosterman ◽  
Abdulhamid Bin Sulayman ◽  
Mustafa Mukhtar ◽  
...  
Keyword(s):  
Heat Release ◽  
Flame Retardant ◽  
Flame Retardants ◽  
Aliphatic Amine ◽  
Resin System ◽  
Total Heat Release ◽  
Structural Composites ◽  
Bisphenol F ◽  
Flaming Combustion ◽  
Novel Structures

For structural composites used in vehicles and aircraft, flame retardant chemistries which enhance char formation and reduce heat release are preferred. Phosphorus-based and phosphorus–nitrogen flame retardants for epoxies have been well studied to date, but phosphorus hydrazides have not been studied for their flame-retardant potential in epoxy. These hydrazides offer some novel structures and they can potentially offer a combination of vapor and condensed phase flame retardant action. A series of eight compounds were systematically investigated in this study as reactive flame retardants in a bisphenol F epoxy/aliphatic amine resin system at a level of 2.5 wt% phosphorus. Results suggest that the phosphorus hydrazides react with the epoxy during thermal decomposition, and they also release nitrogen during flaming combustion of the epoxy matrix. The observed reactions resulted in increased char yields and reduced total heat release, while simultaneously lowering heat of combustion and total smoke release.

Structure and Properties of UV-Curable Waterborne Polyurethane/Acrylate Composite Resin

2010 ◽  
Vol 177 ◽  
pp. 677-681 ◽  
Author(s):  
Zhen Wu ◽  
Qing Guo ◽  
Run Ping Jia ◽  
Fei Wei Liu
Keyword(s):  
Composite Resin ◽  
Waterborne Polyurethane ◽  
Resin System ◽  
Structure And Properties ◽  
Uv Curable ◽  
Comprehensive Properties ◽  
Polyurethane Acrylate ◽  
Polyurethane Resin ◽  
Waterborne Polyurethane Acrylate ◽  
Two Phases

UV-curable waterborne polyurethane/acrylate (WPUA) composite resin was prepared, and its properties were compared with those of waterborne polyurethane resin. Results showed that the particle size distribution of the compounding resin was broader, and the compatibility of two phases in resin system became better after adding the acrylate into polyurethane. Moreover, water and alcohol resistances, and mechanical properties of composite resin were superior to those of waterborne polyurethane resin. Comprehensive properties of resin film were the best when photoinitiator amount is 3% of resin.

scholarly journals Characterization of PAN based Carbon Tow for Structural Composites

2019 ◽  
Vol 8 (6) ◽  
pp. 2067-2071
Keyword(s):  
Tensile Strength ◽  
Composite Materials ◽  
Tensile Test ◽  
Tensile Properties ◽  
Tensile Failure ◽  
Resin System ◽  
Structural Composites ◽  
Liquid Resin ◽  
Epoxy Resin System

Fibers are load carrying component in a fiber reinforced polymer composite materials. Tensile properties of composite are affected by the properties of the fiber. Polyacrylonitrile (PAN) based carbon fibers are widely used as a reinforcement in composite materials because of its high tensile strength and tensile modulus. Stringent characterisation of PAN based carbon tow is paramount for the fabrication of high performance advanced composite products. This paper presents characterization of PAN based carbon tow for structural composites. The physical and chemical parameters of carbon tow namely tex, density, diameter of single fiber, sizing content and carbon content were characterized for carbon fiber. Tensile properties of PAN based carbon tow can be determined by mono filament test and liquid resin impregnated tow tensile test. In the present study, tensile strength and modulus of PAN based fiber was evaluated by mono filament test. It was observed that tensile failure load was varying from filament to filament for same lot of fiber in mono filament test. High scattering in tensile strength values of filaments was observed due to statically distributed surface flaws on the filaments. Coefficient of variance for tensile strength of filament by mono filament tensile test was varied from 12-25 % from one lot to other lot of carbon tow. Liquid resin impregnated tow tensile test was conducted with specified resin system with low temperature cure cycle, to get more consistent and more accurate values of fiber tensile strength, modulus and % strain. Carbon tow was characterized by laminate level mechanical properties namely NOL ring hoop tensile strength and ILSS with high temperature curing epoxy resin system, which is used for fabrication of actual structural composite product.

Transmission electron microscopy of composite materials

1988 ◽  
Vol 46 ◽  
pp. 1012-1015
Author(s):  
K.P.D. Lagerlof
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Structural Defects ◽  
Structural Composites ◽  
Multiphase Materials ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Reinforced Fiber ◽  
Particulate Reinforced Composites ◽  
Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

Epoxy Resin Embedment

1968 ◽  
Vol 26 ◽  
pp. 100-101
Author(s):  
J. G. Adams ◽  
M. M. Campbell ◽  
H. Thomas ◽  
J. J. Ghldonl
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Epoxy Resin ◽  
Light Microscope ◽  
Epoxy Resins ◽  
Image Contrast ◽  
Tissue Preservation ◽  
Resin System ◽  
Excellent Quality

Since the introduction of epoxy resins as embedding material for electron microscopy, the list of new formulations and variations of widely accepted mixtures has grown rapidly. Described here is a resin system utilizing Maraglas 655, Dow D.E.R. 732, DDSA, and BDMA, which is a variation of the mixtures of Lockwood and Erlandson. In the development of the mixture, the Maraglas and the Dow resins were tested in 3 different volumetric proportions, 6:4, 7:3, and 8:2. Cutting qualities and characteristics of stability in the electron beam and image contrast were evaluated for these epoxy mixtures with anhydride (DDSA) to epoxy ratios of 0.4, 0.55, and 0.7. Each mixture was polymerized overnight at 60°C with 2% and 3% BDMA.Although the differences among the test resins were slight in terms of cutting ease, general tissue preservation, and stability in the beam, the 7:3 Maraglas to D.E.R. 732 ratio at an anhydride to epoxy ratio of 0.55 polymerized with 3% BDMA proved to be most consistent. The resulting plastic is relatively hard and somewhat brittle which necessitates trimming and facing the block slowly and cautiously to avoid chipping. Sections up to about 2 microns in thickness can be cut and stained with any of several light microscope stains and excellent quality light photomicrographs can be taken of such sections (Fig. 1).

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance

2019 ◽  
Author(s):  
Dennis Bücker ◽  
Annika Sickinger ◽  
Julian D. Ruiz Perez ◽  
Manuel Oestringer ◽  
Stefan Mecking ◽  
...  
Keyword(s):  
Chain Length ◽  
Length Distribution ◽  
Catalyst System ◽  
Chain Conformation ◽  
Controlled Polymerization ◽  
Chain Length Distribution ◽  
Electron Resonance ◽  
Double Electron ◽  
The Individual ◽  
Double Electron Electron Resonance

Synthetic polymers are mixtures of different length chains, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.

Mechanistic Insights into Fe Catalyzed α-C-H Oxidations of Tertiary Amines

2019 ◽  
Author(s):  
Christopher J. Legacy ◽  
Frederick T. Greenaway ◽  
Marion Emmert
Keyword(s):  
Free Radical ◽  
Catalytic Mechanism ◽  
Catalyst System ◽  
Oxidation Products ◽  
Tertiary Amines ◽  
Catalyst Activation ◽  
Rate Determining Step ◽  
Fe Catalyst ◽  
Ligand Coordination ◽  
Rate Kinetics

We report detailed mechanistic investigations of an iron-based catalyst system, which allows the α-C-H oxidation of a wide variety of amines, including acyclic tertiary aliphatic amines, to afford dealkylated or amide products. In contrast to other catalysts that affect α-C-H oxidations of tertiary amines, the system under investigation employs exclusively peroxy esters as oxidants. More common oxidants (e.g. tBuOOH) previously reported to affect amine oxidations via free radical pathways do not provide amine α-C-H oxidation products in combination with the herein described catalyst system. Motivated by this difference in reactivity to more common free radical systems, the investigations described herein employ initial rate kinetics, kinetic profiling, Eyring studies, kinetic isotope effect studies, Hammett studies, ligand coordination studies, and EPR studies to shed light on the Fe catalyst system. The obtained data suggest that the catalytic mechanism proceeds through C-H abstraction at a coordinated substrate molecule. This rate-determining step occurs either at an Fe(IV) oxo pathway or a 2-electron pathway at a Fe(II) intermediate with bound oxidant. We further show via kinetic profiling and EPR studies that catalyst activation follows a radical pathway, which is initiated by hydrolysis of PhCO3 tBu to tBuOOH in the reaction mixture. Overall, the obtained mechanistic data support a non-classical, Fe catalyzed pathway that requires substrate binding, thus inducing selectivity for α-C-H functionalization.<br>

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