The Effect of Inorganic Pigments on the Rheological Properties of the Color Masterbatches from Polylactic Acid

Due to the large amount of plastic waste that is currently produced, the demand for ecological solutions to this situation has been growing. Many research studies in recent years have focused on polylactic acid (PLA) as a biodegradable material made from renewable resources. The individual components of biodegradable materials should comply with the EN 13432 standard, which defines the properties of a “compostable” material. Careful selection of dyes and pigments is therefore important in terms of maintaining the biodegradability of the finished products. In this article, we focus on evaluating the flow properties of color masterbatches modified with inorganic biodegradable pigments. Two types of PLA were used as polymer pigment carriers, and titanium dioxide, carbon black, and two iron oxides were used as inorganic pigments. We monitored the effect of the type and concentration of pigments on the processability and rheological properties of the prepared color PLA masterbatches. The capillary viscometer and rotary rheoviscometer were used to determine rheological properties. The flow properties of color masterbatches containing 1 and 3 wt.% inorganic pigments with two types of pure polymers, PLA6100 and PLA175, were compared. We found that the color PLA masterbatches had good processability and satisfactory rheological properties, and therefore they are usable for further processing.