Preventing Discoloration of Poly(vinyl alcohol)-Coated Paper Hydrophobized by Gas Grafting with Palmitoyl Chloride

Abstract

Gas grafting with fatty acid chloride (FAC) is a simple and ultrafast paper treatment, which produces only hydrochloric acid as a byproduct. In this study, poly­(vinyl alcohol) (PVOH)-coated paper was treated by gas grafting with palmitoyl chloride, and the effects of temperature, time, and concentration of palmitoyl chloride on discoloration were investigated. The grafting efficiency expressed by the water absorption capacity (Cobb size) and the amount of grafted FAC increased with increasing temperature, reaction time, and concentration of palmitoyl chloride. However, discoloration of PVOH was inevitable at high temperature and long reaction time, and under excessive FAC dosage. PVOH was converted into polyene via dehydration by the acid catalyst at high temperature. Calcium carbonate applied to PVOH coating for preventing discoloration of the PVOH-coated paper could neutralize gaseous hydrochloric acid. Unfortunately, the hydrophobicity decreased slightly with an increase in the calcium carbonate blending ratio due to the additional consumption of FAC. The grafting efficiency could be improved without discoloration if the blending ratio was appropriately controlled based on the specific surface area of the calcium carbonate particles.

MOF@PVA beads for dynamic and low concentration VOC capture

“…The discoloration is inevitable after exposure to high temperatures for an extended period of time. 30 Besides, it can be observed that no significant changes in the crystallinity are seen from the PXRD patterns measured after the 5th and 10th cycle (Fig. S8c, ESI †), thus considerably high values of toluene adsorption can still be observed after the 7th cycle towards the 10th cycle.…”

Experimental evidences and calculation of the limited penetration of acyl chloride reagent in a dense layer of PVA coated on a paperboard after chromatogeny grafting

“…Its application to PVA material has been investigated and has shown an increase of the water repellency and a decrease of the water vapor transmission rate (Stinga & al., 2009;Schmid & al., 2012Schmid & al., & 2014Haas & al., 2017). The esteri cation reaction involved in the chromatogeny process leads to the production of gaseous hydrochloric acid as by-product, which in the case of PVA with high hydrolysis degree leads to a discoloration attributed to polyene formation (Lee & al., 2018(Lee & al., & 2023. It has been recently shown that hydrochloric acid was able to permeates PVA coating about 7g/m² (Lee & al., 2022).…”