Modification of unsaturated polyesters using polyethylene glycol

Abstract

The fracture toughness and impact resistance of rigid unsaturated polyesters can be modified by various physical and chemical methods. In this study, flexible unsaturated polyesters were prepared by condensation polymerisation of maleic anhydride, phthalic anhydride and propylene glycol in the presence of polyethylene glycol. By this method, copolymers of unsaturated polyesters with polyethylene glycols of different molecular weights were prepared. A two stage process was used for the synthesis, which resulted in segmental structures containing alternating rigid cross-linked segments and linear soft segments displaced regularly in the polymer chain. Properties such as tensile strength, tensile modulus, elongation at break, toughness, impact strength, surface hardness, abrasion resistance and water absorption were tested after the resin was cured in appropriate moulds and compared with those of the control resin. Polyethylene glycols of lower molecular weight (,200) impart flexibility to the polyester chains and increase fracture toughness and impact resistance of rigid unsaturated polyester without seriously affecting other properties. Glass reinforced specimens prepared using the modified resin also show improved toughness and elongation at break.

Fused filament fabrication of copolyesters by understanding the balance of inter- and intra-layer welding

“…Hence, the exposed degradation for CP-CH has no genuine effect on the macroscopic properties in Figure 5, at least at the selected layer thickness. The chains are still long enough and interacting sufficiently to enable strength and impact [26], the latter specifically at higher temperature.…”

Polymer blends of epoxy resin and epoxidized natural rubber

“…Blends of unsaturated polyesters and functional rubbers such as hydroxy terminated polybutadiene, epoxidized natural rubber (ENR), hydroxy terminated natural rubber (NR), and maleated nitrile rubber were studied. It was reported that the elastomers bearing reactive functional groups show better compatibility with the resin and improve the toughness and impact resistance of the cured resin substantially, compared with unmodified elastomers 12, 13…”

The potential of unsaturated polyesters in biomedicine and tissue engineering: Synthesis, structure-properties relationships and additive manufacturing

“…The mechanical properties of the UPRs were evaluated and the results showed that CTBN is the most promising in improving the mechanical properties of the UPRs because the toughness and the impact strength were significantly enhanced, without jeopardizing extensively the remaining properties. Another approach was studied by the same researchers [38], in which poly(ethylene glycol) (PEG) segments were incorporated in the UP structure. The mechanical properties of the ensuing UPRs (35 %wt styrene) were evaluated and the influence of the incorporation of PEG in the UP structure was accessed.…”