Photorheology of Fast UV‐Curing Multifunctional Acrylates

Abstract

AbstractSummary: The fast photopolymerization of different multifunctional acrylates was analyzed by means of photorheology. The materials studied included a penta/hexaacrylate monomer and two different acrylated hyperbranched polymers. The sensitivity of the commercial rheometer was improved several‐fold, by a combination of an adaptive filter algorithm and improved data treatment, using powerful oversampling acquisition hardware. The novel set‐up was capable of monitoring up to a five orders of magnitude increase in shear modulus within short experiment timescales (about 10 s). The improvement in sensitivity and acquisition rate enabled the induction time, gelation, and vitrification of the multifunctional acrylates to be determined. In addition, the influence of UV intensity on stiffness build‐up within these materials was studied. In the case of the penta/hexaacrylate system, gelation and vitrification were detected as distinct events, in contrast to the second‐generation hyperbranched polyester, for which vitrification could not be identified. These findings are related to the difference in the glass transition temperature of the cured networks.Absolute value of the complex shear modulus as a function of time for different acrylate monomers during UV curing.imageAbsolute value of the complex shear modulus as a function of time for different acrylate monomers during UV curing.