Stabilizing alkenyl succinic anhydride (ASA) emulsions with starch nanocrystals and fluorescent carbon dots

N, S/P co-doped hemicellulose-based carbon dots with tunable fluorescence for anti-counterfeiting

Based on the status quo of high energy consumption and low utilization of nonfibrous components in traditional pulp and paper industry, a sustainable and facile approach was proceeded to realize the high-value utilization of hemicelluloses from papermaking waste liquor. The hemicellulose waste produced by ethanol precipitation in pre-hydrolysis liquor (PHL), was directly used to fabricate carbon dots (CDs) via a hydrothermal method. The hydrothermal carbonization and heteroatoms doping contributed to the sp2 conjugated domains and surface defect states of CDs, thus creating the bright blue (N-CDs), deep cyan (N/S-CDs), and light cyan (N/P-CDs) fluorescence under UV radiation. The XPS analysis and density functional theory (DFT) calculations demonstrated that the large sp2 conjugated system and the synergistic effect of CO, N-(C)3, CS, and PO groups promoted the narrow of band gap and the red-shift of fluorescence emission. Importantly, the prepared CDs grew in situ on cotton fibers, showed excellent fluorescent performance. The obtained CDs could be also utilized to prepare anti-counterfeiting film and ink due to their excellent optical features, verifying the great potential application as security material. The feasible strategy of the high-value conversion of biomass waste opens a window of opportunity for the practical anti-counterfeiting utilizations.

An Efficient Approach to Prepare Water-Redispersible Starch Nanocrystals from Waxy Potato Starch

Starch nanocrystals (SNCs) are a biodegradable polymer which has been widely studied and used in many fields. In this study, we have developed an efficient procedure for the preparation of SNCs. First, sodium hexametaphosphate (SHMP) and vinyl acetate (VAC) were used to modify waxy potato starch (WPS). Then, the modified starches were hydrolyzed with sulfuric acid to prepare SNCs. Results showed that SNCs prepared with modified starch had higher zeta potentials and better dispersion properties than the original starch. After modification, WPS still maintained its semi-crystalline structure, but the surface became rougher. SHMP-modified WPS showed a decrease in viscosity peak and an increase in gelatinization temperature. VAC-modified WPS showed increased swelling power. Additionally, SNCs prepared with VAC-modified WPS had better water redispersibility and dispersion stability than those from SHMP-modified starch—which will have broader application prospects in the field of safe and biodegradable food packaging.

Polyacrylamide stabilized alkenyl succinic anhydride emulsion as sizing agent for various cellulosic pulps and fillers

Cellulosic fiber is hydrophilic in nature and making it hydrophobic represents a process called sizing in papermaking. Alkenyl succinic anhydride (ASA) sizing is dominating over other sizing processes due to its high reactivity and economy. The shelf life of conventionally used cationic starch (CS) stabilized ASA emulsion is 20-25 min. In our previous study, the ASA emulsion was found to be stable up to 4 h using anionic polyacrylamide (APAM) as stabilizer. Present communication was aimed to utilize, the APAM stabilized ASA emulsion with most commonly utilized cellulosic pulps (mixed hardwood, bagasse and recycled) and fillers to assist its commercial utilization in papermaking. APAM stabilized ASA emulsion facilitated back water utilization with improved sizing degree unlike CS based ASA emulsion. Lower amount of ASA sizing was required in bagasse pulp compared to other pulps which might be attributed to low crystallinity ratios and hydrogen bond energy.