A gas phase surface treatment for treating carbon fiber including (a) exposing a carbon fiber to a gaseous oxidizing atmosphere to form a modified carbon fiber with an oxidized fiber surface; followed by (b) exposing the oxidized fiber surface to a gaseous nitrogen-containing atmosphere to form a modified carbon fiber with a nitrogen-enriched surface, wherein the nitrogen-enriched surface exhibits an increase in surface nitrogen to surface carbon (N/C) ratio as compared to the surface of the carbon fiber prior to exposure at (a). Steps (a) and (b) are carried out continuously without any additional intervening surface treatment.

A gas phase surface treatment for treating carbon fiber including (a) exposing a carbon fiber to a gaseous oxidizing atmosphere to form a modified carbon fiber with an oxidized fiber surface; followed by (b) exposing the oxidized fiber surface to a gaseous nitrogen-containing atmosphere to form a modified carbon fiber with a nitrogen-enriched surface, wherein the nitrogen-enriched surface exhibits an increase in surface nitrogen to surface carbon (N/C) ratio as compared to the surface of the carbon fiber prior to exposure at (a). Steps (a) and (b) are carried out continuously without any additional intervening surface treatment.

One aspect of the present application relates to a method of synthesizing a thermoplastic polymer. This method includes providing a depolymerized lignin product comprising monomers and oligomers and producing lignin (meth)acrylate monomers and oligomers from the depolymerized lignin product. A thermoplastic lignin (meth)acrylate polymer is then formed by free radical polymerization of the lignin (meth)acrylate monomers and oligomers. The present application also relates to a branched chain thermoplastic lignin (meth)acrylate polymer which includes a chain transfer agent. The thermoplastic lignin based polymers of the present application can be used to prepare carbon fibers, and engineering thermoplastics. Mixtures of lignin (meth)acrylate monomers and oligomers are also disclosed.

One aspect of the present application relates to a method of synthesizing a thermoplastic polymer. This method includes providing a depolymerized lignin product comprising monomers and oligomers and producing lignin (meth)acrylate monomers and oligomers from the depolymerized lignin product. A thermoplastic lignin (meth)acrylate polymer is then formed by free radical polymerization of the lignin (meth)acrylate monomers and oligomers. The present application also relates to a branched chain thermoplastic lignin (meth)acrylate polymer which includes a chain transfer agent. The thermoplastic lignin based polymers of the present application can be used to prepare carbon fibers, and engineering thermoplastics. Mixtures of lignin (meth)acrylate monomers and oligomers are also disclosed.

A gas phase surface treatment for treating carbon fiber including (a) exposing a carbon fiber to a gaseous oxidizing atmosphere to form a modified carbon fiber with an oxidized fiber surface; followed by (b) exposing the oxidized fiber surface to a gaseous nitrogen-containing atmosphere to form a modified carbon fiber with a nitrogen-enriched surface, wherein the nitrogen-enriched surface exhibits an increase in surface nitrogen to surface carbon (N/C) ratio as compared to the surface of the carbon fiber prior to exposure at (a). Steps (a) and (b) are carried out continuously without any additional intervening surface treatment.