Epoxy Resins Part 1

chichi's version from 2018-02-28 17:44

Section 1

Question Answer
General categories of modifiers include....rubbers, thermoplastics, diluents, flame retardants, fillers, and pigments and dyes
Rubber additivesused o increase flexibility, fatigue resistance, crack resistance, and energy absorption (toughness) in epoxy resins
Most often used rubbers in epoxy compositesCTBNs
CTBNslong-chain polymers have terminal carboxyl groups that may be reacted with epoxy to decrease cross-link density and increase tensile elongation.
Applications of epoxy resinsadhesives, coatings, encapsulates, casting materials, potting compounds, and binders; often used in aerospace and recreational industries
The glass transition temperature of a cured epoxy resin is dependent upon...the molecular structure that develops in the matrix during cure
Characteristics that effect curingcross link density, stiffness of the polymer backbone, and intermolecular interactions
Tg is closely related to....cure temperature
Molecular structure and other characteristics of the cured product are equally dependent on...the base resin, the curing agent, and modifiers employed in the formulation

Section 2

Question Answer
EEWEpoxy equivalent weight
What is epoxy equivalent weight?the weight of the resin per epoxide group
Divinding the molecular weight of a resin by the number of epoxide groups per molecule can approximate...the equivalent weight of a resin
Diglycidyl ether of bisphenol-ADGEBA
What's the first commercial epoxy resin?DGEBA
What can generate high molecular weight resin variants?modifying the ratio of epichlorohydrin to bisphenol-A during production
What increases viscosity?growth in molecular weight
As cross-link density decreases...fracture toughness increases

Section 3

Question Answer
Room temperature curings agents include...aliphatic amines, polyamides, and amidoamines
Aliphatic aminesthe curatives most often paired with epoxy resins.
How is aliphatic amines used?in stoichiometric amounts after the functionality and cure mechanism of each component is understood
Commonly used primary amines are...DETA, TETA, TEPA, AND N-AEP
DETA, TETA, TEPA, N-AEPAmines that cure at room temperature

Section 4

Question Answer
Other aliphatic amines sometimes used as epoxy curatives are...MXDA, polymeric form of MXDS
MXDA and the polymeric form of MXDAcuratives that contain aromatic ring but react as aliphatic amines which gibes them cured properties closer to that of the aromatic amines
Polyetheraminesknown by the trade name Jeffamine, are an interesting class of curative that are available as difunctional or trifunctional liquids with low viscosity and vapor pressure
Examples of tertiary amines are...pyridine, triethylamine, and 2,4,6-tris(di-methylaminomethyl) phenol
Tertiary amines react bycatalytic anionic polymerization
Cycloaliphatic aminescharacterised by having at leat one amino group attached directly to a saturated ring
Examples of cycloaliphatic aminesIPDA and PACM
Polyamideslike polyamines, are classified as primary, secondary, or tertiary depending on the substituents on the amide group
Amidoaminescontain both amide and amine groups