Effects of film forming and hydrophobic properties of starches on surface sized packaging paper

Abstract

The effect on mechanical and barrier properties upon addition of glycerol to temperature-responsive hydrophobically modified (HM) potato starch was studied on free films. The addition of glycerol lowered the glass transition temperature, the storage modulus, and the water vapor permeability (WVP) for the HM starch films. The HM starch phase separates upon cooling below an upper critical temperature into a solid and a liquid phase. Adding glycerol to the warm starch solution had an inhibiting effect on the particulate precipitation. Substrates surface sized with HM starch with various amounts of glycerol were investigated with respect to barrier properties; WVP, contact angle and Cobb values. Hydroxypropylated starch was used as a reference. Cobb values and WVP results on surface-sized substrates indicated that the film formation properties of the starches were of great importance for the final surface properties. Good film formation properties were essential for the gas barrier and water resistance while they were less important for high contact angles. The WVP decreased as the glycerol content of the sizes increased, but no sufficient water vapor barrier could be obtained. The HM starches investigated in this work provided good oxygen barrier and the contact angles indicated a hydrophobic character of the surface. The role of the precipitate was investigated, and surface sizing with the precipitate gave low WVP and high contact angles despite its poor film-forming properties under the experimental conditions. Cobb 60 values were slightly improved for HM starch with increasing glycerol content over glycerol-free sizing.

Controlled Release of Peppermint Oil from Paraffin‐Coated Activated Carbon Contained in Sachets to Inhibit Mold Growth During Long Term Storage of Brown Rice

“…Therefore, tapioca and corn starch had the lowest inhibition activity. Moreover, this might be a result of the low permeability of large peppermint oil molecules into the environment because starch film has been reported to be an efficient gas barrier because it can block the transportation of the smallest of gas molecules such as oxygen and carbon dioxide owing to its crystalline structure (Jonhed and others ). Usually, in the presence of oxygen, AC has a hydrophilic surface imparted by the oxygen containing a functional group, and its pore structure has an affinity to water that subsequently adsorbs moist vapour into the system.…”

Enhancement of flexographic print quality on bleached kraft liner using nano-silica from rice husk

“…However, it is clearly seen that the water absorption was drastically decreased when only the polymeric coating agent without any nano-RHS composition was used. This is because the paper surface was covered by a film layer formed by the polymeric phase of such a coating agent, preventing water absorption [36]. On the contrary, when nano-RHS in different proportions was used, the subsequent coating agents increased the water absorption as the amount of nano-RHS in the coating agent increased.…”

Machine-coated starch-based dispersion coatings prevent mineral oil migration from paperboard

“…When comparing the different formulations, it was observed that WVTR decreased as the proportion of starch decreased and latex content increased. In general, the WVTR values are consistently in the same scale as reported for similar starch-based coatings [22]. The analysis setup was specifically designed to position the coated side of the paperboard towards the penetrant (water vapor) to minimize error caused by the paperboard's large thickness and porosity.…”

“…The challenge with biopolymer materials is their runnability on the coating unit, film formation properties, and film products' high affinity for water and water vapor. Therefore, studies of the physico-chemical and barrier properties of biopolymers, starch, and starch blends as coating materials are widely performed [3,[20][21][22][23][24][25]. Thorough studies have been performed to identify the best formulations for coating processability [5] and an improved grease barrier [5,26,27].…”