Biodegradable lightweight construction boards based on tannin/hexamine bonded hemp shaves

Abstract

Interior grade hemp shave lightweight construction boards of about 0.260 g/cm 3 , with a dry I.B. strength of up to 0.34 MPa, a formaldehyde release well within the emission class E1 and certificate as normal flammable and not burning dripped off (DIN 4102-B2) were fabricated by mixing hemp shaves with a borate-modified mimosa tannin-hexamine binder and press the masses as fast as 6 s/mm thickness at 70°C to one-layer boards. Different drying processes indicate that fast drying at 100°C is needed both for satisfactory strengths and for a sufficient dimension stability performance of soaked samples, but, as well for a lower boron leaching during soaking. For dry environments the resistance to fungal attack is sufficient enough to have boards for interior application. Biologisch abbaubare Leichtbauplatten basierend auf Tannin/Hexamin gebundenen HanfschäbenHanfschäben wurden mit Borat modifizierten Mimosa Tannin-Hexamin Bindern gemischt und bei 70°C und Presszeiten von 6 s/mm Dicke zu einlagigen Leichtbauplatten mit Dichten von etwa 0.260 g/cm 3 verpresst. Querzugfestigkeiten bis zu 0.34 MPa, Formaldehyd-Emissionen die innerhalb der Emissionsklasse E1 liegen und Brandschutzeinstufungen als normal entflammbar und nicht brennend abtropfend (DIN 4102-B2) wurden bestimmt. Verschiedene Trocknungsprozesse zeigen, dass schnelles Trocknen bei 100°C zu höheren Festigkeiten und, nach wässern der Proben, zu ausreichender Dimensionstabilität bei geringerer Borauswaschung führt. Für trockene Umgebungen ist die Resistenz gegen Pilzbefall ausreichend genug um die Bretter für Innenanwendungen einzusetzen.

Dynamically Cross-Linked Tannin as a Reinforcement of Polypropylene and UV Protection Properties

“…In our case, although tannins undergo a dynamic extrusion process of a high temperature in an extruder, its crosslink with hexamine did not consume whole hydroxyl groups. Moreover, the limited residence time in the extruder (approximately 2 min 30 s), compared with more than 5 min for wood bonding [53], and the steric hindrance of tannin might also contribute to an incomplete cross-linked.…”

Thermo-Insulation Properties Of Hemp-Based Products

“…Hemp chaffs may be utilized in biodegradable boards for different lightweight constructions, such as mobile homes, packing material, etc. [6]. It should be noted that the quantitative relationship between fibres and chaffs is here more or less stable.…”

Synthetic-resin-free wood panel adhesives from mixed low molecular mass lignin and tannin

“…The tannin solution in water was prepared at 45% concentration, and its pH was adjusted to 10.4 with NaOH 33% water solution. The high pH was chosen as the hardener used performs best at such a pH (Pichelin et al 2006, Hillis and Urbach 1959, Pizzi 1978Theis and Grohe 2002). Hexamine was dissolved in water to form a 30% solution.…”