The Influence of Surface Quality on Flow Length and Micro-Mechanical Properties of Polycarbonate

Abstract

This study describes the influence of polymer flow length on mechanical properties of tested polymer, specifically polycarbonate. The flow length was examined in a spiral shaped mould. The mould cavity’s surface was machined by several methods, which led to differing roughness of the surface. The cavity was finished by milling, grinding and polishing. In order to thoroughly understand the influence of the mould surface quality on the flow length, varying processing parameters, specifically the pressure, were used. The polymer part was divided into several segments, in which the micro-mechanical properties, such as hardness and indentation modulus were measured. The results of this study provide interesting data concerning the flow length, which was up to 3% longer for rougher surfaces, but shorter in cavities with polished surface. These results are in disagreement with the commonly practiced theory, which states that better surface quality leads to greater flow length. Furthermore, evaluation of the micro-mechanical properties measured along the flow path demonstrated significant variance in researched properties, which increased by 35% (indentation hardness) and 86% by indentation modulus) in latter segments of the spiral in comparison with the gate.

The influence of tool’s surface topography on mechanical properties of injection moulded product

“…These results were confirmed by multiple other tested materials, as can be seen in previously published studies [29][30][31][32]. The measurements indicate that rougher surfaces left after electrical discharge machining (Ra 4.4), milling (Ra 1.6) and grinding (Ra 0.8) consist of irregular structures, which are not fully filled by the hot melt during injection moulding.…”

“…These depressions remain filled by air (isolant), which creates a heat barrier between the injection mould (mould temperature 30 °C) and polymer (melt temperature of injected polycarbonate 220 °C). This behaviour was also observed and studied in our previous study [29].…”

Comparative study on the mechanical and thermal properties of polycarbonate composites reinforced by KH570/SA/SDBS modified wollastonite fibers

“…Polycarbonate (PC) is an important thermoplastic engineering polymer having fine processing, thermal, mechanical, optical, and electromagnetic properties, which has been widely used in high stability capacitor, construction material, dielectric material, data storage, automotive, aircraft, security component, bullet‐proof glass, poster protection, displays, bullet‐resistant windows. [ 9–11 ] Recently, because of their advantages such as environment friendly, easy recovery, and regeneration, polycarbonate is even applied as construction formwork in the architecture field. [ 12 ] However, there are still some difficulties in the bulk utilization of polycarbonate construction formwork in architectural engineering due to the poor toughness and lower tensile strength as well as the high cost of pure polycarbonate material.…”