2016 Volume 28 Issue 3 Pages 51-61
To evaluate functional component durability of valves and nozzles in cup-dispensing vending machines and drink dispensers, three thermoplastic resin types (linear low density polyethylene (LLDPE), polyoxymethylene (POM) and polyamide 612 (PA612)) used as such components were soaked in various syrups differing in ingredient composition (citric acid, ascorbic acid, ethanol, sucrose, and limonene) and the influence on resin physical properties and syrup taste were investigated. We found that syrups have the ability to alter the physical properties of the resin, such as tensile strength, elongation, and elasticity, while simultaneously, resins have a negative effect on syrup taste. In relation to LLDPE, swelling of the resin and a remarkable drop in tensile strength were observed in case of soaking in the syrup containing limonene. In the case of PA612, the physical properties of the resin underwent significant changes with respect to swelling, tensile strength, elongation and elastic modulus. POM soaked in ethanol showed swelling and lower elastic modulus. Furthermore, syrup taste changed considerably when in contact with POM for syrups containing both ethanol and citric acid. This study revealed the importance of choosing suitable resins for syrup ingredients to improve the durability of parts and quality of drinks.
