Hands-on Laboratory Experiments for Demonstrating Mixed Plastic Recycling

Abstract

Plastic waste is a growing concern in recent years due to the massive increase in single-use plastic applications. Despite the ever-increasing amount of waste, recycling plastics is not a simple process due to difficulties in sorting, which results in significantly downgraded material properties. This handson lab experiment showcases the important knowledge steps in a typical recycling process, including waste collection, plastic separation and sorting methods, processing techniques, and characterization methods including scanning electron microscopy (SEM) and tensile testing. Additionally, this lab demonstrates the importance of miscibility between materials and provides evidence that small amounts of block copolymers (BCPs) can compatibilize immiscible mixed plastic waste, leading to enhanced material properties of recycled products. Through these engaging hands-on lessons, students can not only obtain a better understanding about the challenge and industrial solution of mixed plastic waste recycling, but also realize the importance for protecting environments through waste management.

Hands-On Activity Illustrating the Sorting Process of Recycled Waste and Its Role in Promoting Sustainable Solutions

“…Size exclusion could be applied to separate recycled waste of assorted sizes using sieves. Plastic could be separated based on density through the floating test, where some material would sink or float. , The density of water was assumed to be ∼1g/mL, while the approximate densities of PLA, PE, and PS were 1.24, 0.92, and 0.91 g/mL, respectively. − For that reason, PLA would sink, while PE and PS would float. For materials with similar densities, like PE and PS, a transparency test can be performed.…”

“…Plastic could be separated based on density through the floating test, where some material would sink or float. 16 , 29 The density of water was assumed to be ∼1g/mL, while the approximate densities of PLA, PE, and PS were 1.24, 0.92, and 0.91 g/mL, respectively. 30 − 32 For that reason, PLA would sink, while PE and PS would float.…”

Atomic Force Microscopy for Teaching Polymer Crystals and Polymer Blends

“…Importantly, immiscible blends produce separate phases resulting in a heterogeneous mixture at a micrometer or nanometer scale . Sadri et al showcased the significance of polymer blending for its properties by examining its morphology with scanning electron microscopy and evaluating the tensile strength of various plastic wastes after recycling . Unlike previous experiments focused on evaluating the bulk physical characteristics of polymer blends, this laboratory experiment employs AFM to analyze the nanostructure of immiscible blends and assesses the mechanical properties of individual phases within the heterogeneous material on the nanoscale.…”