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What are the physical and chemical properties of unsaturated polyesters?

Jan 23, 2019

Physical properties

    The relative density of the unsaturated polyester resin is about 1.11 to 1.20, and the volume shrinkage is large at the time of curing. Some physical properties of the cured resin are as follows:
(1) Heat resistance. Most of the unsaturated polyester resins have a heat distortion temperature of 50 to 60 ° C, and some resins with good heat resistance can reach 120 ° C. The red thermal expansion coefficient α1 is (130 to 150) × 10 -6 ° C.
(2) Mechanical properties. The unsaturated polyester resin has high strength such as stretching, bending, and compression.
(3) Chemical resistance. Unsaturated polyester resin has good performance against water, dilute acid and dilute alkali, and has poor resistance to organic solvents. At the same time, the chemical resistance of the resin can vary greatly depending on its chemical structure and geometrical switch.
(4) Dielectric properties. The dielectric properties of the unsaturated polyacid resin are good.

Chemical properties

    The unsaturated polyester is a linear polymer compound having a multifunctional group having a polyester chain bond and an unsaturated double bond in its skeleton main chain, and a carboxyl group and a hydroxyl group at each end of the macromolecular chain.
The double bond on the main chain can be copolymerized and crosslinked with the vinyl monomer to convert the unsaturated polyester resin from a soluble, fusible state to an insoluble, infusible state.
The ester bond on the main chain can undergo a hydrolysis reaction, and an acid or a base can accelerate the reaction. When copolymerized with styrene, the hydrolysis reaction can be greatly reduced.
In acidic media, hydrolysis is reversible and incomplete, so polyester can withstand the attack of acidic medium; in alkaline medium, due to the formation of a resonance-stable carboxylate anion, hydrolysis becomes irreversible, so polyester is resistant to alkali. Poor sex.
The carboxyl group at the end of the polyester chain can react with an alkaline earth metal oxide or hydroxide [e.g., MgO, CaO, Ca(OH)2, etc.) to expand the molecular chain of the unsaturated polyester, eventually forming a complex. The molecular chain extension can be such that the initial viscosity is 0.1 to 1.0 Pa·s of a viscous liquid resin, and the viscosity is sharply increased to 103 Pa·s or more in a short period of time until it becomes a non-flowable, non-sticky gel-like substance. When the resin is in this state, it is not crosslinked, it is still soluble in a suitable solvent, and has good fluidity upon heating.

QuanZhou Neweco High Polymer Material Co.,Ltd.

Neweco is one of the leading unsaturated polyester resin manufacturers and  suppliers,widely used in automobiles, ships, rail transit, wind power  generation, pipe cans, heat and corrosion protection, building  materials, stone repair, sanitary ware, artificial stone and other  industries. Suitable for hand lay-up, spray, pultrusion, winding,  molding, vacuum introduction / RTM, casting and other molding processes. Neweco Resin is committed to excellence and focuses on the application  of composite materials to provide customers with comprehensive  solutions.

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