A Protein-Based Material from a New Approach Using Whole Defatted Larvae, and Its Interaction with Moisture.

A protein-based material created from a new approach using whole defatted larvae of the Black Soldier fly is presented. The larvae turn organic waste into their own biomass with high content of protein and lipids, which can be used as animal feed or for material production. After removing the larva lipid and adding a plasticizer, the ground material was compression molded into plates/films. The lipid, rich in saturated fatty acids, can be used in applications such as lubricants. The amino acids present in the greatest amounts were the essential amino acids aspartic acid/asparagine and glutamic acid/glutamine. Infrared spectroscopy revealed that the protein material had a high amount of strongly hydrogen-bonded ß-sheets, indicative of a highly aggregated protein. To assess the moisture⁻protein material interactions, the moisture uptake was investigated. The moisture uptake followed a BET type III moisture sorption isotherm, which could be fitted to the Guggenheim, Anderson and de Boer (GAB) equation. GAB, in combination with cluster size analysis, revealed that the water clustered in the material already at a low moisture content and the cluster increased in size with increasing relative humidity. The clustering also led to a peak in moisture diffusivity at an intermediate moisture uptake.

VOC-Induced Flexing of Single and Multilayer Polyethylene Films As Gas Sensors.

The differential swelling and bending of multilayer polymeric films due to the dissimilar uptake of volatile organic compounds (VOCs; n-hexane, limonene) in the different layers was studied. Motions of thin polyethylene films triggered by the penetrant were investigated to learn more about how their deformation is related to VOC absorption. Single layers of metallocene or low-density polyethylene, and multilayers (2-288 layers) of these in alternating positions were considered. Single-, 24-, and 288-layer films displayed no motion when uniformly subjected to VOCs, but they could display simple curving modes when only one side of the film was wetted with a liquid VOC. Two-layer films displayed simple bending when uniformly subjected to VOCs due to the different swelling in the two layers, but when the VOC was applied to only one side of the film, more complex modes of motion as well as dynamic oscillations were observed (e.g., constant amplitude wagging at 2 Hz for ca. 50 s until all the VOC had evaporated). Diffusion modeling was used to study the transport behavior of VOCs inside the films and the different bending modes. Finally a prototype VOC sensor was developed, where the reproducible curving of the two-layer film was calibrated with n-hexane. The sensor is simple, cost-efficient, and nondestructive and requires no electricity.