Synthetic resins are industrially produced resins, typically viscous substances that convert into rigid polymers by the process of curing. In order to undergo curing, resins typically contain reactive end groups,[2] such as acrylates or epoxides. Some synthetic resins have properties similar to natural plant resins, but many do not.[3]
Synthetic resins are of several classes. Some are manufactured by esterification of organic compounds. Some are thermosetting plastics in which the term "resin" is loosely applied to the reactant(s), the product, or both. "Resin" may be applied to one of two monomers in a copolymer, the other being called a "hardener", as in epoxy resins. For thermosetting plastics that require only one monomer, the monomer compound is the "resin". For example, liquid methyl methacrylate is often called the "resin" or "casting resin" while in the liquid state, before it polymerizes and "sets". After setting, the resulting poly(methyl methacrylate) (PMMA) is often renamed "acrylic glass" or "acrylic". (This is the same material called Plexiglas and Lucite).
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The classic variety is epoxy resin, manufactured through polymerization-polyaddition or polycondensation reactions, used as a thermoset polymer for adhesives and composites.[4] Epoxy resin is two times stronger than concrete, seamless, and waterproof.[citation needed] Accordingly, it has been mainly in use for industrial flooring purposes since the s. Since , however, epoxy and polyurethane resins are used in interiors as well, mainly in Western Europe.
Synthetic casting "resin" for embedding display objects in Plexiglas/Lucite (PMMA) is simply methyl methacrylate liquid, into which a polymerization catalyst is added and mixed, causing it to "set" (polymerize). The polymerization creates a block of PMMA plastic ("acrylic glass") which holds the display object inside a transparent block.
Another synthetic polymer, sometimes called by the same general category, is acetal resin. By contrast with the other synthetics, however, it has a simple chain structure with the repeat unit of form &#;[CH2O]&#;.
Ion-exchange resins are used in water purification and catalysis of organic reactions. (See also AT-10 resin, melamine resin.) Certain ion-exchange resins are also used pharmaceutically as bile acid sequestrants, mainly as hypolipidemic agents, although they may be used for purposes other than lowering cholesterol.
Solvent impregnated resins (SIRs) are porous resin particles which contain an additional liquid extractant inside the porous matrix. The contained extractant is supposed to enhance the capacity of the resin particles.
A large category of resins, which constitutes 75% of resins used,[citation needed] is that of the unsaturated polyester resins.
The production of PVC entails the production of "vinyl chloride resins", which differ in the degree of polymerization.[5]
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Silicone resins are silicone-based polymers that exhibit various useful properties like weatherability (durability), dielectricity, water repellency, thermal stability, and chemical inertness.[6]
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Health hazards potentially associated with synthetic resins are typically less of a concern than the hazards associated with the cured products, which are more commonly in contact with consumers. Issues of interest include the effects of unconsumed monomers, oligomers, and solvent carriers.
Dental restorative materials based on bis-GMA-containing resins[7] can break down into or be contaminated with the related compound bisphenol A, a potential endocrine disruptor. However, no negative health effects of bis-GMA use in dental resins have been found.[8][9]
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Casting is a common manufacturing process that involves pouring liquid material &#; usually material that&#;s been preheated &#; into a mold cavity. As the liquid material cools, it hardens to create a new object in the shape of the mold. The newly created object, known as a casting, is then removed from the mold and either used for other manufacturing processes or packaged and sold as a final product. Resin casting, however, is a unique casting process that&#;s characterized by the use of synthetic resin. To learn more about resin casting and how it works, keep reading.
As the name suggests, resin casting is a casting process that involves the use of synthetic resin. To better understand how it works, you must first look at the synthetic resin used in this casting process. Synthetic resin is any type of resin that&#;s converted into strong and rigid polymers via curing. In other words, it begins in a liquid state but converts to a solid state after being cured.
In resin casting, liquid synthetic resin is mixed with a curing agent &#; typically at room temperature or near-room temperature. Next, the two substances are poured into a mold cavity. The curing agent then converts the resin into rigid polymers, essentially hardening it. After this chemical reaction has finished, the hardened casting is ejected and removed from the mold cavity.
Resin casting is a simple process that can be performed using just a few basic tools and materials. In fact, many hobbyists use resin casting to create small objects. It&#;s a simple and low-cost way to produce small objects, making it a popular choice among individuals and hobbyists for leisure purposes.
Resin casting is also capable of producing objects in complex shapes. The shape of the casting is dependent upon the shape of the mold cavity. By using the right type of mold cavity, a manufacturing company &#; or a hobbyist &#; can create a casting in their desired shape.
On the other hand, resin casting is a poor choice for manufacturing companies looking to mass-produce a large quantity of objects or products. For starters, the synthetic resin used in this casting process is highly aggressive when exposed to a curing agent. As a result, molds typically only last for 50 to 100 uses, after which the mold must be discarded and replaced with a new mold.
Additionally, there are health concerns regarding the use of synthetic resin. During the curing stage, synthetic resins may release toxic and harmful fumes.
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