Ultrasonic and conversion-based inline fouling measurements for continuous emulsion copolymerisation of vinyl acetate in a tubular reactor.

One of the serious challenges for the implementation of continuous emulsion polymerisation is their significant fouling. The elucidation of time-dependent fouling processes and the development of inline analysis methods for fouling mass quantification are crucial to making progress in this area. Inline-sensor concepts based on ultrasonic measurements as well as residence time and conversion analysis were investigated regarding their suitability for the detection of time-dependent fouling formation and compared with gravimetrical results in order to validate their precision.

Tough, Stretchable, and Thermoresponsive Smart Hydrogels.

Self-healing, thermoresponsive hydrogels with a triple network (TN) were obtained by copolymerizing N-isopropyl acryl amide (NiPAAm) with polyvinyl alkohol (PVA) functionalized with methacrylic acid and N,N'-methylene bis(acryl amide) crosslinker in the presence of low amounts (<1 wt.%) of tannic acid (TA). The final gels were obtained by crystalizing the PVA in a freeze-thaw procedure.

Fabrication of Thermo-Responsive Controllable Shape-Changing Hydrogel.

Temperature response double network (DN) hydrogels comprising a network formed by polymerization of methacrylic acid (MA) modified PVA, N,N'-methylene bis(acrylamide), N-isopropylacryl amide (NIPAM), and one formed from crystalline polyvinyl alcohol (PVA) are prepared in a 3D printed tailor-made mold. The (PVA-MA)-g-PNIPAAm thermoset intermediate is formed in water by a radical, photo-initiated process, and in the presence of dissolved PVA polymers. A subsequent freezing-thawing sequence induces the crystallization of the PVA network, which forms a second network inside the thermoset NIPAM polymer.

Influence of redox initiator component ratios on the emulsion copolymerisation of vinyl acetate and neodecanoic acid vinyl ester.

Redox initiated emulsion polymerisation of vinyl acetate and neodecanoic acid vinyl ester was investigated at temperatures ranging from -1 °C to 87 °C (initiation temperature between -1 °C and 60 °C), using varying molar ratios of the following redox components: l-ascorbic acid, -butyl hydroperoxide and ammonium iron(iii) sulfate dodecahydrate as a catalyst. The high flexibility of redox initiators enables product properties, as well as space-time-yield, to be adjusted as required. Polymers being products by process, it was presumed that modifying the conversion rate would lead to a different product.

Scale-up of Emulsion Polymerisation up to 100 L and with a Polymer Content of up to 67 wt%, Monitored by Photon Density Wave Spectroscopy.

The scale-up process of the high solid content (up to 67 wt%) emulsion polymerisation of vinyl acetate and Versa10 from 1 L over 10 L to 100 L was investigated. An emulsion copolymerisation of vinyl acetate and neodecanoic acid vinyl ester in a molar ratio of 9:1 was carried out in a starved-fed semi-batch operation. As a radical source, a redox initiator system consisting of L-ascorbic acid, tert-butyl hydroperoxide and ammonium iron (III) sulphate was used.