Chitosan-based biodegradable adhesive from crab shell waste for multilayer food packaging

Overview

This technology develops a chitosan-based biodegradable adhesive formulated from crab shell waste for use in multilayer food packaging films made from polyhydroxyalkanoate (PHA) biopolymers. The adhesive addresses the growing demand for fully biodegradable packaging solutions by enabling strong adhesion between PHA films and metal layers (such as aluminum) without compromising compostability. Chitosan offers additional value through its inherent antimicrobial and gas barrier properties, making it well-suited for food-contact applications. The solution is derived from a readily available seafood industry byproduct, supporting circular economy principles.

Technical specifications

Key features:

• Biodegradable chitosan base sourced from crab shell waste, fully degradable in seawater and soil conditions
• Mild-acid water solubility (2% v/v acetic acid) compatible with PHA films, which are immiscible in such solutions
• Target adhesion strength exceeding 50 gf/in on metal and ink substrates, with prior data showing chitosan-on-aluminum shear strength of approximately 40 MPa
• Low working concentrations below 10 wt%, reducing material costs
• Antimicrobial and gas barrier properties inherent to chitosan, beneficial for food packaging performance
• Plasticizer compatibility tested with glycerol, sorbitol, xylitol, propylene glycol, polyethylene glycol, Tween 80, poly(vinyl alcohol), and sucrose at 0.5–1.5% to overcome chitosan brittleness
• Molecular weight tuning to optimize adhesive performance

Validation approach:

• 180-degree peel testing on aluminum (pre-treated with NaOH) bonded to solution-cast and annealed PHBHx PHA films
• Failure surface analysis via SEM to classify adhesion failure modes
• Concentration screening at 4, 6, and 8 wt% chitosan in acetic acid solution

Technology readiness level

This technology is at an early research stage (TRL 2–3). The research team at Drexel University brings deep expertise in film preparation, chitosan chemistry, PHA processing, and film characterization, though the specific adhesive formulation has not yet been directly tested. The team is also developing in-house biodegradation testing capabilities to support future validation. Initial experimental work will focus on establishing adhesive strength, optimizing formulation parameters, and characterizing failure modes to demonstrate feasibility for food packaging applications.