Is epoxy crystalline or amorphous?
Epoxy resins are not crystalline either above or below their glass transition temperature because the high degrees of crosslinking inhibit any crystallization and are considered completely amorphous, but do have a three dimension structure.
Is cured epoxy crystalline?
Epoxy crystallization is more common in two-part systems (usually the resin side, labeled as Part A). But it can also occur in one-part heat cure epoxy. In rare cases, crystallization happens in curing agents too (usually labeled as Part B).
Will epoxy bond to cured polyester resin?
Polyester is an adequate adhesive but not as good as epoxy. While epoxy adheres tenaciously to cured polyester, the reverse is not true, so the bond between an epoxy repair and an overcoat of polyester gelcoat will not be strong. Use polyester for repairs that will be gelcoated.
What is the structure of epoxy resins?
Epoxy resins are formed from a long chain molecular structure similar to vinyl ester with reactive sites at either end. In the epoxy resin, however, epoxy groups instead of the ester groups form these reactive sites. The absence of ester groups means that the epoxy resin has particularly good water resistance.
Is resin a crystalline?
Epoxy resins, under certain conditions, can become solid or have a slush like appearance. This is called crystallization and it is where some component parts of the epoxy resin form a crystal like structure. But unlike water which melts at approximately 0°C the melting point of the Epoxy is 50°C.
Is epoxy a semi-crystalline?
The thermal conductivity of one epoxy resin reached 0.52 W/(m K), which is ∼2.5 times that of common polymers. These epoxy resins are shown to have a semicrystalline structure, and both the thermal conductivity and density of the four epoxy resins exhibited a positive correlation with crystallinity.
What causes resin to crystallize?
Epoxy resin crystallization can be caused by high purity resins, moisture, temperature changes, low viscosity resins or impure additives. In a clear resin, it could appear as tiny specks dispersed throughout, cloudiness or a complete solid. Eventually, this can lead to the entire contents turning solid.
Will polyester resin bond to cured polyester resin?
When a polyester boat is built, polyester gelcoat is first sprayed onto the mold surface. Applying gelcoat to a cured laminate relies on a mechanical bond. Because of the difference in curing chemistry, it is not possible to achieve a chemical bond between epoxy and polyester gelcoat.
Is Polyester a resin?
Polyester resins are synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Maleic Anhydride is a commonly used raw material with diacid functionality in unsaturated polyester resins. Polyesters are also used in anchor bolt adhesives though epoxy based materials are also used.
What are the applications of epoxy resin?
Epoxy has a wide range of applications, including metal coatings, use in electronics, electrical components, LEDs, high tension electrical insulators, paint brush manufacturing, fiber-reinforced plastic materials, and adhesives for structural and other purposes.
Is epoxy resin a polymer?
1 Introduction. Epoxy resin is a polymer also known as polyepoxides containing at least two and more epoxide groups per monomer which is also referred to as a glycidyl or oxirane groups.
Why choose epoxy for fiberglass repair?
Epoxy also provides a better moisture barrier than polyester resin. Our customers’ fiberglass repairs range from filling a minor screw hole to completely rebuilding the bottom of a boat that ran aground. In most cases, a final finish needs to be applied over the repair.
What is the difference between polyester resin and epoxy resin?
Polyester resin and epoxy resins differ in a number of ways. Polyester resin (often referred to as boat resin) is still used today to build most production fiberglass boats because it is the lowest cost option for new construction when combined with fiberglass reinforcements.
What kind of resin is used to repair a fiberglass boat?
Before WEST SYSTEM epoxy came on the polyester boat repair scene in the mid 1980’s, most fiberglass boats were repaired with polyester resin. The repairs were typically successful if done by an experienced repairer.
How can I vary the cure time of epoxy resin?
You cannot vary the cure time of epoxy resin. The hardener and the temperature determine epoxy resin’s cure time. A gallon of epoxy generally costs slightly more than polyester resin. They have hardly any odor. You don’t need a filter mask when working with epoxy. Epoxy is also non-flammable.