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Abstract: We investigate the kinetics and dynamics of the reaction between Na2CO3 and the cathode ray tube panel glass powder at 923–1173K. The reaction causes foaming of the glass melt. After the reaction, the T g decreases with increasing Na2CO3 content and reaches a minimum value of T g. However, this T g value is even lower than that of the homogeneous bulk glass with the same chemical composition. The lower T g of the foam glass could be attributed to inhomogeneous incorporation of Na in the glass, leading to Na-rich domains that cause an overall decrease of T g. Remarkably, after 5min treatment at 1073K, the T g drops by 120K, indicating that the reaction between Na2CO3 and glass is very fast. Increasing treatment duration causes a slight increase of T g likely due to both a more homogeneous Na distribution and the compositional change of the glass as a result of Na2SrSi2O6 crystal formation. [Copyright &y& Elsevier]

The recycling of glass from obsolete cathode ray tubes (CRT) has hitherto only occurred to a very limited extent, but the production of foam glass used as an insulation material component has recently been proposed as a promising recycling method. CRT panel glass has high recycling potential due to its non-hazardous composition. Here we report on the foaming of CRT panel glass using Na2CO3 as the foaming agent. We explore how heat treatment temperature and concentration of Na2CO3 affect the density and porosity of the foam glasses, and whether Na2O is incorporated in the glass network. The optimum foaming temperature for minimising density and maximising closed porosity is found to be between 1023 and 1123 K. The pore structure depends on the amount of added Na2CO3, viz, the pores generally become more open with increasing Na2CO3 content. A minimum density of 0 ⋅ 28 g/cm³ is found when 14 wt% Na2CO3 is added and the heat treatment temperature is 1023 K. Interestingly, the glass transition temperature (Tg) of the final foam glass decreases linearly with increasing [Na2CO3], indicating that the Na2O is incorporated into the glass network. [ABSTRACT FROM AUTHOR]