A porous PMMA material has been reinforced by clay particles, and properties of the resulting material were evaluated. The clay has been intercalated in a first step by melt-extrusion with a suitable block copolymer. A radical polymerisation reaction after swelling of the intercalated clay with monomer leads in a subsequent step to a nanocomposite material with improved mechanical properties. The optimum load of modified clay was determined to be about 3 to 4 wt.-%. A separation of the reinforcing mineral into single sheets and a subsequent homogeneous incorporation of these sheets into the polymer matrix material increased different mechanical properties by approximately 60%. The lifetime of porous polymer moulds used for pressure casting of sanitary ware has been analysed, modelled and increased. The mechanical behaviour of the existing porous PMMA mould material was analysed using mechanical tests to assess the lifetime under cyclic loading. The relevant stress levels were obtained through in situ strain gauge measurements on a polymer mould for the production of a washing basin. These results were confirmed by means of finite element stress analyses. The lifetime of the washing basin mould under the relevant production conditions was predicted from these data and found to be in good agreement with practical experience. A method to improve the limited lifetime under higher pressures was developed by applying nanodispersed clay as reinforcement. The improved material shows an increase in lifetime under cycling loading by about 1000% in mechanical tests. This improvement is confirmed for a pressure casting mould made of the improved material when used in the actual production process.