Visual perception and measurements of texture and gloss of injection‐molded plastics

Abstract

The effect of an imposed texture on the gloss of injection‐molded polymeric surfaces was evaluated as well as the way in which these properties are visually perceived. Specimens having small differences in surface topography were produced using two mold cavities with slight differences in texture and three different polymers. The texture and gloss were characterized using laser profilometry, gloss measurements, and by means of psychometric evaluations. The measured surface topography parameters and gloss were determined mainly by the texture of the mold surface and the gloss also by the processing conditions. Variations in surface topography due to differences in the rheological properties of the polymer melts were, in most cases, too small to be reflected in the measurements. The visual assessments of the texture and the gloss of specimens from the same cavity were in fair agreement with the measurements, although the observers could discern differences between some specimens not revealed by the measurements. When the specimens molded in the two cavities differing significantly both in gloss and texture were compared, the agreement between the measured topography parameters and the perceived roughness was poorer. It is suggested that higher gloss of a textured surface enhances the perception of a higher roughness. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

Three‐dimensional scanning electron microscopy characterization of the topography of textured polymeric surfaces

“…The same type of injection‐molded specimens manufactured from three different polymers used in the previous work [10] were employed also in the present case. The acrylonitrile–butadiene–styrene copolymer (ABS) was a commercial grade from BASF AG (Ludwigshafen, Germany), denoted Terluran GP 22, with a density of 1.04 g/cm 3 (ISO 1183) and a melt volume‐flow rate at 220°C and 10 kg of 20.0 cm 3 /10 min (ISO 1133).…”

“…The mold cavities were photoetched with identical surface textures but Cavity II was subjected to an additional light etching giving a slightly more detailed pattern, cf. Ref 10…”

“…The numerical gloss values (GU) range normally from 0 (low gloss) to 100 GU (high gloss). Ignell et al [10] measured the gloss of the plaques at an angle of 60° at 23°C, in accordance with ISO 2813‐1994, using a glossmeter. Their results are shown in Table 2 below.…”

“…In an earlier work [10], the gloss differences between injection‐molded specimens with only slight differences in surface texture were analyzed. These slightly different specimens were obtained by making small adjustments of the surface patterns of the mold cavity, varying the rheological properties of the melts by altering the polymeric materials, and changing the processing conditions.…”

Rheological properties of elastomer‐modified polypropylene and their influence on the formation of flow marks

“…Ref. 1. A premium appearance is of vital importance for many plastic products, not least within the automotive sector and applies to interior as well as exterior parts (like bumpers).…”