Preparation and characterization of colloidal dispersions of vinyl alcohol–vinyl acetate copolymers: application as stabilizers for vinyl chloride suspension polymerization

Abstract

Well‐defined colloidal dispersions of vinyl alcohol–vinyl acetate copolymers (PVAs) with different degrees of hydrolysis (DH) were prepared by a coacervation technique. Colloidal particles in the size range 150–250 nm, with an acetate‐rich core and a hydrophilic PVA corona, were obtained using a combination of a hydrophobic PVA (PVA II) having an average DH ($\overline{DH}$) value of 43 mol% with a ‘blocky’ hydrophilic PVA (PVA I) with a $\overline{DH}$ value of 72 mol%. The core–shell structure of these particles was demonstrated using 1H NMR and using fluorescence‐labelled PVA I. The stabilization efficiency of PVA I and PVA II and their combination was examined for 1‐chlorobutane–water emulsions, as a ‘model solvent’ for vinyl chloride–water emulsions. Preliminary tests of vinyl chloride suspension polymerization confirmed the beneficial effect of PVA I and PVA II combinations as stabilizers on the granulometry and the porosity specifications of the poly(vinyl chloride) grains. Copyright © 2006 Society of Chemical Industry

Effect of poly(vinyl alcohol-co-vinyl acetate) copolymer blockiness on the dynamic interfacial tension and dilational viscoelasticity of polymer–anionic surfactant complex at the water–1-chlorobutane interface

“…[1][2][3] PVAs, with a DH in the range of 70-90 mol%, have been the most extensively studied in the literature due to their surfactive properties and have found important application possibilities as sizing agents and adhesives, as emulsiers, dispersing agents in various industrial areas such as in emulsion and suspension polymerization processes where PVAs in the DH of 70 to 75 mol% are of major interest due to their pronounced amphiphilic characteristics. [4][5][6] A particular feature of these polymers is their strong tendency to form colloidal aggregates in water by inter-and intra-molecular hydrophobic interactions of the vinyl acetate sequences. [7][8][9][10] The proportion of these colloidal aggregates is inuenced not only by the DH but also by the average acetate sequence length n VAc 0 , which is representative for the blockiness, and they may have an incidence on the PVAs emulsifying efficiency.…”

Thermal Cloud Point Fractionation of Poly(vinyl alcohol-co-vinyl acetate): Partition of Nanogels in the Fractions

“…The molecular characteristics of PVA's, mainly their polymerization degrees DPn , DPw and the average degree of hydrolysis DH , in general in the range of 70 to 90 mol%, have a major influence on the monomer droplet size, the dispersion stability and on the properties of the final PVC resins [3,4].…”

“…The evolution of the size average (Dv) of different fractions of samples PVA-73-650 and PVA-73-685 at a SDS concentration of 1 and 5 wt% respectively with respect to PVA. PVA-73-685 1% SDS 5% SDS 1% SDS 5% SDS F 1 19.3 ± 0.9 7.6 ± 0.7 16.6 ± 0.3 7.1 ± 0.5 F 2 16.2 ± 0.7 7.4 ± 0.5 13.8 ± 0.7 6.9 ± 0.6 F 3 14.7 ± 0.4 6.9 ± 0.3 14.1 ± 0.7 7.7 ± 0.3 F 4 8.3 ± 0.3 7.8 ± 0.3 9.3 ± 0.2 7.6 ± 0.3…”

On‐line acoustic attenuation spectroscopy of emulsions stabilized by vinyl alcohol–vinyl acetate copolymers: a model system for the suspension polymerization of vinyl chloride

“…Chlorobutane (>99%), supplied by Acros, was selected as organic phase model for VCM. This model has been used quite extensively by different authors,5, 19, 20 as its characteristics such as density, refractive index and solubility are close to those of VCM, with the advantages of easier handling and less toxicity.…”