Lightweight, highly compressible, noncrystalline cellulose capsules

Area of Science:

• Materials Science
• Polymer Science
• Mechanics of Materials

Background:

• Cellulose is a widely available biopolymer with potential for advanced material applications.
• Developing novel cellulose-based materials with unique mechanical properties is an active area of research.

Purpose of the Study:

• To prepare and characterize extraordinarily deformable, gas-filled capsules from nonmodified cellulose.
• To develop a constitutive model for the large deformation compression of these capsules.
• To investigate the gas barrier properties and potential applications of these novel capsules.

Main Methods:

• Preparation of gas-filled, spherical capsules from nonmodified cellulose.
• Mechanical testing, including elastic deformation and compression to failure.
• Development and validation of a quantitative constitutive model for large deformation.
• Measurement of force relaxation to determine gas permeability.

Main Results:

• Successfully prepared highly deformable cellulose capsules with low density (7.6–14.2 kg/m³).
• Capsules exhibited elastic deformation up to 70% and did not rupture even when compressed into a disk.
• A constitutive model accurately predicted the mechanical response, including high-frequency and low-frequency behaviors.
• Estimated air permeability through the capsule wall at 0.4 mL μm/m² days kPa.

Conclusions:

• Nonmodified cellulose can be used to create exceptionally deformable and robust capsules.
• The developed constitutive model provides a quantitative understanding of their mechanical behavior.
• These capsules offer significant potential for applications in lightweight materials, adsorption, and adhesion studies.