The relation between the surface topography of injection‐molded plastic objects with deliberately imposed textures and their gloss, measured by means of a conventional glossmeter at incident angles of 20°, 60°, and 85°, was investigated. A modification of the general scalar Kirchhoff approximation, which accounts for geometrical features of the glossmeter, is used to describe the experimental gloss values of the textured surfaces. The agreement between the measured and the calculated values for incidence angles of 20° and 60° confirms the usefulness of the approach, though several of the textured surfaces used here are too rough for the Kirchhoff theory to be strictly valid. A poorer agreement, however, was noted at higher incidence angles (85° in this case). For very smooth surfaces (without any texture), the classical Bennett‐Porteus theory could in many cases describe the gloss level with sufficient accuracy. The influence on the measured gloss of the polymer material (in terms of its refractive index) and the color of the injection‐molded object is also discussed. Light beige specimens in three different polymeric materials (acrylonitrile‐butadiene‐styrene, acrylonitrile‐butadiene‐styrene/polycarbonate blend, and polypropylene) as well as three acrylonitrile‐butadiene‐styrene products with different colors were used. The refractive index of the polymer had no major influence on the measured gloss. The gloss level increased slightly with increasing lightness of the specimens, which can be associated with an increased contribution from the bulk scattering. However, the surface texture governed most of the gloss variations. POLYM. ENG. SCI., 45:1343–1356, 2005. © 2005 Society of Plastics Engineers

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

The concept of contrast gloss and its relation to visually perceived gloss was examined for textured polymeric specimens. The specimens were injection‐molded plaques manufactured in three different polymers (acrylonitrile‐butadiene‐styrene copolymer, polypropylene, and a blend of polycarbonate and acrylonitrile‐butadiene‐styrene copolymer). A contrast gloss factor was determined from the reflectance data obtained with a conventional multiangle spectrophotometer. To evaluate the visual impression of gloss of the specimens a psychometric study was performed. The contrast gloss factor corresponded well with the visual assessment of the gloss and it was able to discern the visual differences between several specimens not significantly discriminated by their gloss values. These latter gloss values were obtained with a conventional glossmeter measuring specular gloss. In correspondence with the visual assessments and practical experience, the relation between the contrast gloss factor and the specular glossmeter measurements was found to depend on the type of polymer used. When evaluating gloss of specimens varying in color, the contrast gloss factor corresponded well with the visual assessments. This was in contrast to the specular glossmeter measurements which ranked the specimens essentially in the opposite order. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

The effect of the concentration of a colorant (masterbatch) and the surface texture on the color of an opaque injection‐molded plaque is experimentally described by means of the spectral reflectance and the CIELAB coordinates. It was noted that the surface texture had a marked influence on the experimental results and on the perceived color. The relation between the color of these pigmented plastic plaques and intrinsic physical material properties, such as light absorption and scattering coefficients, is described by means of the Kubelka‐Munk equation for pigment/paste mixtures. The concentration dependence of this Kubelka‐Munk equation for different masterbatch‐polymer mixtures can be modeled in terms of the color of the individual constituents using a fitting parameter. Further experiments were carried out which indicated that the fitting parameter had a physical meaning. The effect of the surface texture on the optical appearance of the plaques can also be accounted for by this parameter.

A model that describes the influence of gloss on the measured (reflected) color, initially developed for xerographic prints and which takes into account the geometry of the color measuring device, was applied to colored injection-molded plastics used in the interior of a car. The model is shown to give reasonable results for the material used (acrylonitrile-butadiene-styrene polymer) in four different colors. The gloss dependence of the measured color can also be expressed in terms of suitable surface topography descriptors, in this case the root-mean-square roughness and the lateral correlation length. The relation between the color of these pigmented plastics and material properties such as the light absorption and scattering coefficients is described using the Kubelka-Munk equation for pigment-paste mixtures. The scattering coefficient was found to be significantly affected by the surface texture, with a coarser texture giving a higher scattering. POLYM. ENG. SCI., 45: 733-744, 2005.