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Mechanical Properties Of Unsaturated Polyester Resin

Jul 14, 2020

The relationship between the mechanical properties of the resin after curing and the polyester component and structure mainly has the following five aspects.

(1) When the molecular weight of polyester increases, the strength, hardness, and especially bending strength of the resin after curing increase.

(2) When the unsaturated bond in the polyester molecular chain increases, the cross-linking point in the resin increases, the rigidity after curing increases, and the wear resistance improves.

(3) The degree of linear growth of the polyester molecular chain during the polycondensation reaction determines the tensile strength of the resin. For example, when neither diols nor dibasic acids contain non-aromatic unsaturated bonds, strict linearity can be obtained Long-chain molecules that grow; if the reaction product contains a large number of unsaturated double bonds, cross-linking between the double bonds may occur, and the molecular chain cannot get linear growth, and the strength is affected. Therefore, to increase the tensile strength, The polycondensation reaction should be controlled to prevent crosslinking during the reaction and to maximize the esterification reaction.

(4) When the polarity of the polyester molecule increases, the bending strength of the resin after curing increases.The hydroxyl group, carboxyl group, ester bond, and ether bond in the molecular chain are all groups that increase the polarity of the resin molecule.

(5) The order of the structural arrangement in the polyester molecular chain improves the tensile strength. In order to strive for the orderly arrangement of the structure, including the ordered arrangement of polar groups, the choice of dibasic acid and diol can be made Minimize as much as possible; if necessary, use a two-step method for polycondensation.