Indirect methods for determination of the protective effects of coating films on the surface of crystals

J. Bajdik, K. Pintye-Hódi, Cs Novák, A. Kelemen, G. Regdon, I. Eros

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The extents of the protective effects of coating films on the surface of crystals were determined. Three different samples were made with different quantities of coating fluid (Sepifilm LP 010 in 10% aqueous solution). Since the atomizing rate was constant, the coating time increased in parallel with the volume of coating fluid applied. The direct measurement of film thickness and smoothness is very difficult, and therefore indirect methods were used. Dimenhydrinate was chosen as model drag; this is a heat-sensitive antihistamine with a low melting point. This temperature can be reached during the tableting process. The behaviour of samples on exposure to heat was examined by differential scanning calorimetry. The water uptakes of the samples were determined with an Enslin apparatus. Plasticity was studied with an instrumented tablet machine. These indirect methods (thermal conductivity, water uptake and plasticity measurements) revealed connections between the results of the various experiments. An overlong coating time decreased the protective effect of the coating film.

Original languageEnglish
Pages (from-to)613-627
Number of pages15
JournalJournal of Thermal Analysis and Calorimetry
Volume68
Issue number2
DOIs
Publication statusPublished - Jun 20 2002

Keywords

  • DSC
  • Dimenhydrinate
  • Film coating
  • HPMC
  • Plasticity
  • Thermal conductivity
  • Water uptake

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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