Journal of Plastic Film & Sheeting

For commercial success, bioplastics have to possess adequate physical properties. But the same properties of biopolymers — such as starch — that make them environmentally attractive feedstocks can affect their performance as materials. Despite the attractive properties of plant-based plastics, there have been few commercial applications due to their property drawbacks (e.g., high cost, brittleness, and lower impact resistance). Many biopolymers, such as starch, are often hydrophilic and some are even soluble in hot water. These properties have to be managed and controlled through the development of adequate formulations and processing. The primary challenge is to develop fast reactions that can be transformed into viable processes and integrated into existing process lines with economically viable formulations that are friendly to the environment. Cross-linking of starches is the most common method used in polysaccharide chemistry. This article briefly reviews some of the most promising chemistries available for the cross-linking of biodegradable starch materials and their applications.

Polysaccharides and protein biopolymers are of increasing interest for their use as sustainable film and coating materials. However, their main drawback in these applications is their inherent high water permeability and low water resistance at high relative humidity conditions. In this study, two specifically designed commercial fillers of different nature and aspect ratios were successfully incorporated into two polysaccharides: methyl cellulose and chitosan. The morphology study indicated that a good dispersion with intercalation of the fillers was observed in both matrices. The water barrier properties of the nanobiocomposites were found to be enhanced to a significant extent, particularly for the higher aspect ratio filler, as compared to the pure matrix materials, while the biodegradability of the composite materials was maintained.

The specific peel system low-density polyethylene/isotactic polybutene-1 (PE-LD/iPB-1), which is often used for protective packages, was investigated in this study. The required peel force to open the package depends on the content of iPB-1 and on the processing conditions of the blowing process. Commercial products have a constant amount of iPB-1. Thus, a defined peel force can be adjusted by varying the processing conditions. The standard peel system PE-LD with 6 wt% iPB-1 was investigated in dependence on the processing conditions. The most important processing parameters of the processing line (extruder, die head, tube forming area) were varied and their influence on the peel properties was examined. For example the temperatures of the melt within the extruder, the size of the die gap within the die head, and the cooling behavior of the film bubble were investigated. Higher melt temperatures within the extruder decreased the peel force. The investigations also revealed a strong dependence of the peel force on the size of the die gap and on the degree of cooling. The new developed parameter time of solidification was used to characterize the cooling behavior.