SYNTHESIS AND INVESTIGATION OF THERMOSTABILITIVE ACTION ON POLYSTYRENE OF NEW METHACRYLIC MONOMERS BASED ON AURONE

DOI: https://doi.org/10.17721/1728-2209.2018.1(55).16

Abstract

In this work, 6-hydroxy- and 4'-hydroxyaurones were synthesized by condensation reaction of 6-hydroxybenzofuran-3-one with benzaldehyde and benzofuran-3-one with 4-hydroxybenzaldehyde. Methacrylic monomers – (2Z)-6-methacryloxy-2-(4-R-benzylidene)-1-benzofuran-3-(2H)-one and a new 4-[(Z)-(3-oxo-1-benzofuran-2-(3H)ilidene)methyl]phenyl-2-methyl acrylate were obtained by acylation with the methacryloyl chloride in the presence of
triethylamine as HCl acceptor at the temperature 0–5°C. These monomers were synthesized to create special purpose polymers. New methacrylic derivatives are not deeply painted and stable in air crystalline monomers. The structure of the synthesized compounds was confirmed by spectral methods. 1H NMR (400 MHz) spectra were recorded on a Mercury (Varian) 400 spectrometer with tetramethylsilane as internal standard in DMSO-d6. The intrachain thermostabilizing effect of these monomers on the polystyrene destruction processes was studied. Polystyrene and its modified samples were obtained by radical thermoinitiated polymerization (initiator – azo-bis-isobutyronitrile – 1 mass percent) in ethyl acetate at the temperature 78°C during 16 hours. In a case modified samples, 3 mol percent of aurone containing monomers were added. Destruction of modified polystyrene was studied by using dynamic thermogravimetric analysis. Destruction of modified polystyrene was carried out in a Simultaneous Differential Thermogravimetric Analyzer which combines a heat-flux type DTA with a TGA (Shimadzu, DTG-60, Japan). Simultaneous TG, DTG and DTA curves were obtained and sample weight loss as functions of time and temperature were recorded continuously under dynamic conditions. Sintered a-alumina was used as the reference material. Sample with mass of 4 mg was inserted directly into platin crucible and temperature was ramped from 20 to 600°C. The heating rates were controlled at 10 ºC/min. Experiments were performed under an air atmosphere. It was established, that the investigated additives covalently attached to the polystyrene are inhibited the polystyrene destruction processes. Moreover, the additive with the methacrylic group in 6-position of the aurone is significantly more efficient than with the methacrylic group in 4'- position. It has been shown that samples of modified polystyrene by the applications of 4'-methacryloxy aurone and 6-methacryloxy aurone are more thermostable than the industrial sample of polystyrene of brand STYRON (Switzerland). It was shown that the temperature of 10% of the mass loss of modified samples is higher on 14–34 degrees than for the sample of polystyrene of brand STYRON. Thus, the new additives could be proposed for thermostabilizing of polystyrene production.