Development of a novel color inhomogeneity test method for injection molded parts

Abstract Nowadays most research and development concerning injection molded products are focused on their mechanical properties although visual appeal plays an even more important role on the market. There are several standards and recommendations for the testing of mechanical properties, but appearance cannot be quantified easily. The visual aspects are almost completely neglected, and there is not a commonly accepted method for measuring color inhomogeneity. The appearance and color homogeneity of injection molded parts depends on the coloring method itself, the applied technology and several other conditions. The method used nowadays to evaluate color inhomogeneity is based on visual inspection by humans. This research focuses on developing a new and automated method that can replace visual inspection. The functionality and precision of the new method and software have been tested and compared with visual inspection to prove its applicability

Preparation and characterization of in situ polymerized cyclic butylene terephthalate/graphene nanocomposites

Graphene reinforced cyclic butylene terephthalate (CBT) matrix nanocomposites were prepared and characterized by mechanical and thermal methods. These nanocomposites containing different amounts of graphene (up to 5 wt%) were prepared by melt mixing with CBT that was polymerized in situ during a subsequent hot pressing. The nanocomposites and the neat polymerized CBT (pCBT) as reference material were subjected to differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA), thermogravimetrical analysis (TGA) and heat conductivity measurements. The dispersion of the grapheme nanoplatelets was characterized by transmission electron microscopy (TEM). It was established that the partly exfoliated graphene worked as nucleating agent for crystallization, acted as very efficient reinforcing agent (the storage modulus at room temperature was increased by 39 and 89% by incorporating 1 and 5 wt.% graphene, respectively). Graphene incorporation markedly enhanced the heat conductivity but did not influence the TGA behaviour due to the not proper exfoliation except the ash content