Macro Stickies Content Evaluation of Different Cellulose-Based Materials Through Image Analysis

In this work an evaluation of Macro Stickies was performed on thirteen different cellulose-based materials through image analysis. In particular, the materials that were evaluated consisted of different types/categories of papers/products produced by the industry, namely, molded cellulose products, unbleached kraft papers, barrier papers, one recycled paper, and a laminated paper package. The Macro Stickies Evaluation was carried out using an image analysis tool developed by our research group to perform this kind of work from now on. The results indicated that eight of the processed samples revealed low/residual contents of Macro Stickies, whereas the remaining five revealed higher amounts of Macro Stickies in their surfaces. Of the eight samples showing a low/residual Macro Stickies content, five of them belonged to the unbleached kraft papers category, with an area per mass of Macro Stickies ranging from 8.60 to 29.04 mm2/kg. However, the lowest case did not belong to this category, but to the molded cellulose products category with a value of 6.10 mm2/kg. Of the five samples showing higher amounts of Macro Stickies, the worst three cases were associated to one of the barrier papers, the recycled paper and the laminated paper, with an area per mass of Macro Stickies of 28,973.42, 6998.56, and 14,058.76 mm2/kg, respectively. Macro Stickies can assume different sizes, numbers and distributions depending on the characteristics and nature of each sample, and can be a great concern in the recycling of cellulose-based materials. In this sense, the proper assessment of Macro Stickies provides valuable information for the recycling sector to classify them in the products, and to anticipate which materials might give rise to potential stickies related problems in the recycling process.