A study of free-radical copolymerisation of styrene with butyl acrylate using photo-initiation in an intensified spinning disc reactor
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Alternative Energy Forms & Transfer Mechanisms (AE)
Keywords: Free- radical photo-copolymerisation, styrene, butyl acrylate, static thin films, spinning disc reactor
Abstract
Co-polymerisation plays a very important role across a wide range of industries including chemical, digital/photographic printing, coatings, aviation, electronics etc. since it allows enormous flexibility to extend the range of polymers having narrowly defined properties. This paper reports on an experimental study concerning UV-initiated free-radical co-polymerisation reactions under conditions of high efficiency micromixing promoted by centrifugal fields achieved on rotating surfaces. The thin films, excellent heat transfer rates and enhanced mixing characteristics of the spinning disc reactor (SDR) provide a very promising basis for exploitation of photo-polymerisation for polymer synthesis using bulk procedure.
We have assessed the performance of an intensified spinning disc polymer reactor in comparison with a thin static film system for the free-radical photo-copolymerisation of styrene with butyl acrylate at room temperature. The initiator used was 2,2-dimethoxyacetophenone (DMPA) and free-radicals were generated through 366 nm wavelength UV irradiation.
We have studied the effects of UV intensity (range 25-140 mW/cm2 ), disc speed (range 300-1200 rpm) and monomer flow rate (range 1-15 ml/s) on percentage conversion, copolymer composition, sequence distribution and molecular weights of the co-polymer produced in one and multi disc passes. All co-polymerisations were carried out at room temperature, with film temperature control in the SDR being maintained by the internal heating/cooling facilities provided by the reactor.
We have benchmarked our SDR results against static film co-polymerisation of the styrene and butyl acrylate system performed in specially designed temperature controlled static test cells made of stainless steel blocks with machined grooves of depth between 200-800 microns. Online FTIR analysis of the co-polymerisation reaction allowed the effects of film thickness, exposure time and UV intensity on monomer conversion to be determined. Other properties of interest (copolymer composition, sequence distribution and molecular weights) were also measured using NMR spectroscopy and gel permeation photography (GPC) respectively.
We demonstrate that the SDR technology offers the possibility for the continuous, intensified production of co-polymers. The use of ultra-violet radiation in conjunction with a thin film spinning disc reactor allows a new route for synthesising co-polymers with well controlled properties. This technology has a distinct potential for developing sustainable, mobile polymer plants capable of producing co-polymers having improved compositional homogeneity. Furthermore, the SDR process has the advantages of a truly intensified process plant with the benefits of process flexibility, reduced inventory, improved intrinsic safety and improved product quality.
Presented Wednesday 19, 11:40 to 12:00, in session EPIC-1: Alternative Energy Forms & Transfer Mechanisms (AE).
