Adhesive-free engineered plant materials, and methods for fabrication thereof

A method comprising:

• providing a plurality of pieces of plant material, at least some of the pieces being lignin-compromised plant material;
• after the providing, disposing a filler on one, some, or all of the plurality of pieces of plant material;
• arranging the plurality of pieces of plant material in at least two layers;
• and
• compressing the at least two layers so as to form a unitary layered structure,
• wherein the filler comprises a polysaccharide, and
• after the compressing, the filler fills gaps between and within adjacent one of the pieces of plant material, and/or the filler provides additional bonding points for hydrogen bond formation with cellulose fibers.

A method comprising:

• providing a plurality of pieces of plant material, at least some of the pieces being lignin-compromised plant material;
• arranging the plurality of pieces of plant material in at least two layers;
• and
• compressing the at least two layers so as to form a unitary layered structure,
• wherein:
• the lignin-compromised plant material has modified lignin with more exposed functional groups on its surface as compared to native lignin of corresponding natural plant material,
• the compressing is such that the at least some of the modified lignin from the lignin-compromised plant material acts as a bonding agent to couple together adjacent pieces of the plant material in the unitary layered structure, and
• after the compressing, the at least some of the modified lignin is physically entangled with and bonded to cellulose nanofibrils of the adjacent pieces of the plant material.