PAE adsorption on polyelectrolyte-grafted pulp fibers.

Area of Science:

• Materials Science
• Polymer Chemistry
• Pulp and Paper Science

Background:

• Paper wet-strength resins are crucial for product durability.
• Optimizing resin adsorption onto pulp fibers is key to improving paper properties.
• Understanding surface modification effects on adsorption is vital for material development.

Purpose of the Study:

• To investigate the impact of grafting hydrolyzed poly(ethylene-alt-maleic anhydride) (PEMAc) onto bleached kraft pulp fibers.
• To enhance the adsorption of cationic polyamide-amine epichlorohydrin (PAE) wet-strength resin.
• To analyze adsorption isotherms and introduce a new measure of isotherm ideality (IX).

Main Methods:

• Grafting PEMAc onto bleached kraft pulp fibers.
• Adsorption studies using PAE and poly(diallyldimethylammonium chloride) (PDADMAC).
• Analysis of adsorption isotherms to determine exterior adsorbed PAE (Γex) and isotherm ideality (IX).
• Comparison of unmodified, PEMAc-grafted, and TEMPO-oxidized pulps.

Main Results:

• Grafting PEMAc onto pulp fibers significantly increased PAE adsorption.
• A PEMAc content of 4.1 mg/g fiber tripled the amount of PAE adsorbed on exterior surfaces.
• Approximately two PEMAc anionic carboxylic acid groups were required per PAE cationic charge.
• Modification of PEMAc with pendent chains had minimal effect on PAE adsorption.
• TEMPO oxidation did not enhance PAE adsorption at similar charge content.

Conclusions:

• Surface grafting with PEMAc is an effective strategy to enhance PAE wet-strength resin adsorption onto pulp fibers.
• The study introduces and utilizes the isotherm ideality index (IX) to characterize adsorption behavior.
• PEMAc grafting offers a promising route for improving paper wet strength through optimized resin-fiber interactions.