טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMichal Shach-Caplan
SubjectDevelopment and Characterization of Porous Multi-Component
Polymeric Particles Having a Selective Absorption
Characteristic
DepartmentDepartment of Chemical Engineering
Supervisor Professor Emeritus Narkis Moshe


Abstract

New porous semi-IPN PVC (polyvinyl chloride) particles were prepared by using a polymerization/crosslinking method, developed in our laboratory, of a monomer absorbed within a porous suspension-type PVC particle. The character of the semi-IPN PVC particles obtained can be adjusted by selection of suitable monomer/crosslinker pairs. The monomer/crosslinker pairs selected are styrene/DVB (divinyl benzene), methyl methacrylate/EGDMA (ethylene glycol dimethacrylate), butyl acrylate/EGDMA and ethylhexyl acrylate/EGDMA. The concept of this method has some similarity to a two-stage latex polymerization, though in the former larger particles are obtained.

The influence of composition, process parameters and nature of the polymerizing/crosslinking constituents on the modified PVC particle structure, was studied by microscopy methods, porosity measurements, dynamic mechanical behavior (DMTA) and small - angle x-ray scattering (SAXS). The level of grafting between the PVC and the crosslinked polymer was determined by "gel content" and solid-state NMR (Nuclear Magnetic Resonance).

This work shows that the different monomers used represent distinct courses of monomer transport within the PVC particles. The modified PVC particles' porosity indicated that the polymerization/crosslinking process occurs in both the PVC walls constituting the particles and within the PVC pores. No indication of chemical interaction, or phase miscibility, within the modified PVC particles was found.

The new particles developed are used for the purpose of removal, via adsorption/absorption, of halogenated organic compounds from water. The presence of different crosslinked polymers within the PVC particles was found to have a distinct effect on the absorption performance. Conversion of the porous PVC particles into semi-IPNs, by the polymerization/crosslinking of a second monomer, is ought to reduce swelling of particles acting as an absorbent in a packed absorption column.