Encapsulation of calcium carbonate by styrene polymerization

✍ Scribed by Yong Yang; Xiang Zheng Kong; Cheng You Kan; Chang Gao Sun

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 487 KB
• Volume: 10
• Category: Article
• ISSN: 1042-7147
• DOI: 10.1002/(sici)1099-1581(199901/02)10:1/2<54::aid-pat766>3.0.co;2-j

✦ Synopsis

In order to obtain composites of calcium carbonate (CaCO 3 ) encapsulated by polystyrene (PS), soapless polymerization of styrene (S) in aqueous phase in the presence of CaCO 3 was carried out. Influences on the encapsulation and on monomer conversion were studied. Results showed that monomer conversion higher than 52% can be achieved by increasing the stirring speed of polymerization to 1000 rpm. In order to remove the polymer adsorbed on the surface of the inorganic powder, the crude PS/CaCO 3 composite obtained was treated by Soxhlet extractor, and the PS/CaCO 3 ratio after the extraction was measured and defined as the real encapsulation ratio. A maximum real encapsulation ratio of 6.4% was obtained regardless of variations in experimental conditions such as monomer/CaCO 3 ratios, monomer and initiator concentrations.

The presence of PS on the surface of CaCO 3 was tested by scanning electron microscopy and zeta potential (x) measurement of CaCO 3 particles encapsulated by PS. With an increase in monomer conversion, x approached the value obtained from particles of pure PS prepared by soapless emulsion polymerization in the absence of CaCO 3 powder.