Effects of reactive low-profile additives on the volume shrinkage and internal pigmentability for low-temperature cure of unsaturated polyester

N-Activated 1,3-Benzoxazine Monomer as a Key Agent in Polybenzoxazine Synthesis

A novel and successful application of ring-closing reactions of aminophenols has been proposed for the formation of a new type of 1,3-benzoxazine ionic derivatives. The optimization of the reaction and detailed computational studies have been reported for the estimation of heterocyclic ring stability and its further transformation, which is crucial in the polymerization process. The molecular structure of the obtained compounds has been fully characterized by applying X-ray analysis and spectroscopic methods. The novel benzoxazines undergo an intriguing thermal reaction leading to classical benzoxazines and chloroalkanes, which is the first step of transformation before polymerization. To gain more insights into the transformation behavior of ionic benzoxazine derivatives, the Fourier transform infrared (FT-IR) spectra of gaseous products were recorded in experiments with near simultaneous FT-IR/TGA measurements. The combination of thermogravimetry with FT-IR spectroscopy enables the quantitative and qualitative characterization of thermal transformation products and clarification of the reaction mechanism. The experimental data have been verified by applying DFT(B3LYP) and DFT(M062x) theoretical studies.

(Meth)Acrylate Vinyl Ester Hybrid Polymerizations

In this study vinyl ester monomers were synthesized by an amine catalyzed Michael addition reaction between a multifunctional thiol and the acrylate double bond of vinyl acrylate. The copolymerization behavior of both methacrylate/vinyl ester and acrylate/vinyl ester systems was studied with near-infrared spectroscopy. In acrylate/vinyl ester systems, the acrylate groups polymerize faster than the vinyl ester groups resulting in an overall conversion of 80% for acrylate double bonds in the acrylate/vinyl ester system relative to only 50% in the bulk acrylate system. In the methacrylate/vinyl ester systems, the difference in reactivity is even more pronounced resulting in two distinguishable polymerization regimes, one dominated by methacrylate polymerization and a second dominated by vinyl ester polymerization. A faster polymerization rate and higher overall conversion of the methacrylate double bonds is thus achieved relative to polymerization of the pure methacrylate system. The methacrylate conversion in the methacrylate/vinyl ester system is near 100% compared to only ~60% in the pure methacrylate system. Utilizing hydrophilic vinyl ester and hydrophobic methacrylate monomers, polymerization-induced phase separation is observed. The phase separated domain size is on the order of ~1 μm under the polymerization conditions. The phase separated domains become larger and more distinct with slower polymerization and correspondingly increased time for diffusion.