Composite cellulosic products and processes for making and using same

A composite cellulosic product, comprising:

• an at least partially cured binder and 0.5 wt % to 10 wt % of a plurality of cellulosic substrates, based on a total weight of the composite cellulosic product, wherein, prior to curing, the binder comprises a mixture formed by combining:
• magnesium oxide,
• water,
• magnesium chloride,
• (i) at least one of:
• sodium polyacrylate, magnesium (poly)acrylate, and polydiallyldimethylammonium chloride, and
• (ii) at least one of chitosan, polyacrylic acid, and polyacrylamide, wherein a weight ratio of the magnesium oxide to the magnesium chloride in the binder is at least 2.2:1 to about 8.5:1, and wherein a weight ratio of the water to the magnesium chloride in the binder is about 1.5:1 to about 4.5:1.

A process for making a composite cellulosic product, comprising:

• contacting a plurality of cellulosic substrates with a binder to produce a mixture comprising 0.5 wt % to 5 wt % of the plurality of cellulosic substrates, based on a total weight of the mixture, wherein the plurality of cellulosic substrates comprises cellulosic substrates derived from a lignin-containing material subjected to a lignin extraction process, and wherein the binder comprises:
• magnesium oxide,
• water, and
• magnesium chloride, wherein a weight ratio of the magnesium oxide to the magnesium chloride in the binder is at least 2.2:1 to 8.5:1, and wherein a weight ratio of the water to the magnesium chloride in the binder is about 1.5:1 to about 4.5:1;
• and
• allowing the mixture to set for a time period sufficient to allow the binder to at least partially cure to produce the composite cellulosic product.