Synthesis Of Polyurethane-acrylate Sealants And Properties Of PUA Sealants And Their Cured Films

In this paper, one component thermal cured polyurethane-acrylate (PUA) sealants with storage stability were synthesized using dicumyl peroxide (DCP) as an initiator. The effect of structure and content of (meth)acrylates, different ratio of [NCO]/[OH], content of HEMA and structure of polyols on the structure and properties of PUA sealants had been studied.With the ether group concentration in (meth)acrylates increasing, the degree of phase mixing of PUA films improved. The adhesive strength of PUA sealants decreased with increasing the ether group concentration, whereas a decrease in the volume shrinkage was observed. And it was found to be less sensitive to oxygen during the cure process of PUA sealants with the increase of the ether group concentration, as well as the content of (meth)acrylates.If the NCO groups in the PU prepolymers were partily terminated by HEMA, two curing processes of PUA sealants were observed. Therefore, the tensile strength and adhesive strength of PUA selants both increased. And it was beneficial to increase the degree of phase mixing if the NCO groups in the PU prepolymers were fully reacted with HEMA. The tensile strength of PUA sealants decreased if the NCO groups in the PU prepolymers were partily reacted with KH550, due to the increase of the degree of phase separation in the PUA. However, the PUA sealants could dramatically overcome oxygen inhibition.Comparing with polyester polyols, PUA sealants synthesized by polyether polyols were less sensitive to oxygen, mainly affected by ether groups in the polyether polyols. Viscosity of PUA sealants was also a main factor affecting oxygen inhibition, and PUA sealants with a lower viscosity were less sensitive to oxygen if PUA sealants were synthesized by the same kind of polyols.