low stress acrylated hyperbranched polymers

摘要: The objective of this study was to investigate the behavior highly functional acrylates, during isothermal ultraviolet (UV) curing. materials included a pentafunctional acrylate and two acrylated hyperbranched polymers, one with stiff polyester core more flexible polyether core. In particular, influence UV intensity reactive blend composition on structural transitions, such as gelation vitrification, dynamics internal stress considered. Curing kinetics were studied photo differential scanning calorimetry. chemical conversion analyzed using an autocatalytic model criterion for identifying vitrification directly from photocalorimetric experiments proposed. It observed that blends containing HBPs had higher at compared pure penta-functional acrylate. Strong dependence maximum rate weak ultimate observed. latter found be controlled by vitrification. transitions modulus build-up polymerization determined photorheology. A refined data processing algorithm developed, allows monitoring shear over 5 orders magnitude within short experimental time scale, millisecond resolution. Gelation – liquid-solid transition below % all acrylates investigated. contrast, strongly dependent actual monomer increased increasing intensity. results DSC photorheology synthesized in form timeintensity- transformation diagrams. cure shrinkage beambending interferometry-based method, respectively. largely reduced standard monomer. Moreover, case HBP acrylate, reduction obtained combined increase Young's modulus, which attributed retarded final conversion. curing lower led earlier hence build-up, but limited thus stress. later stresses. Polymer microstructures fabricated different photolithographic process SU-8, epoxy frequently used kind application. shown shape accuracy is linked processinduced stresses: best result thick high aspect ratio example microfluidic devices