Characteristics and Kinetics of Rosin Pentaerythritol Ester via Oxidation Process under Ultraviolet Irradiation

Impact of production methods on properties of natural rosin added polylactic acid/sodium pentaborate and polylactic acid/calcium carbonate films

Nowadays biopolymers play an important role in packaging materials due to their protection properties against physical and chemical degradation or mechanical resistance. In this study, sodium pentaborate anhydride (B5NaO8), eggshell (CaCO3) nanoparticles, and natural rosin additives were introduced to pure PLA to produce a biofilm protecting from UV rays. The impact of the preparation method of hybrid biocomposite films was carried out based on the polymer casting method and using in the first case only magnetic mixing whereas magnetic mixing coupled with ultrasonic homogenizer was used in the second case. All biocomposite films were obtained for a nanoparticle content fixed at 7.5 wt% and various rosin rates (1, 5, 10, and 40 wt%). This study aims to expand the UV protection zone in PLA films. The thermal and mechanical properties, transmittance of UV-visible rays, microstructure analysis, and contact angle values were evaluated to detect the effect of the preparation method on the final properties. The results showed that the homogeneous distribution of the particles was more effective using an ultrasonic homogenizer. The increase of the rosin amount exhibited a reduction of the UV-visible light transmittance and the wettability was observed, demonstrating a potential use of these films in packaging.

Crude Wood Rosin and Its Derivatives as Hydrophobic Surface Treatment Additives for Paper and Packaging

The aim of this work is to obtain better water resistance properties with additives to starch at the size press. A further goal is to replace petroleum-based additives with environmentally friendly hydrophobic agents obtained by derivatization of wood rosin. A crude wood rosin (CWR) sample was methylated and analyzed with gas chromatography-mass spectrometry (GC-MS). Methyl abietate, dehydroabietic acid, and abietic acid were the main constituents of the sample. The crude wood rosin samples were fortified with fumaric acid and then esterified with pentaerythritol. Fortified and esterified wood rosin samples were dissolved in ethanol and emulsified with cationic starch to make them suitable as hydrophobic additives for surface treatment formulations in mixtures with starch. These hydrophobic agents (2% on a dry weight basis in a cationic starch solution) were applied to paperboard, bleached kraft paper, and test liner paper using a rod coater with a target pickup of 3-5 gsm. The solution pickup was controlled by varying the rod number. The amounts of hydrophobic material applied in the preparation of the paper samples were 32.2, 48.6, and 35.1 lb/ton pickup compared to three types of base papers. Basic surface features of fortified and fortified and esterified rosin-treated paper were compared with base paper and paper treated with starch alone. Lower Cobb₆₀ values were obtained for fortified and esterified samples than for linerboard samples that had been surface-sized just by starch. Thus, as novel hydrophobic additive agents, derivatives of CWR can be a green way to increase hydrophobicity while reducing starch consumption in papermaking.

Thermal Stability Evaluation of Resin Acids and Rosin Modified Resins

Rosin is a sustainable resource, which is mainly composed of resin acid. Rosin-modified resin is widely used in adhesives, inks, coatings, and other fields, and its stability is very important for the production, storage, and use of products. Thermal stability and reactivity of three resin acids (levopimaric acid, neoabietic acid, and dehydroabietic acid) and four rosin-modified resins were studied using an accelerating rate calorimeter (ARC). They are stable, and exothermic reactions do not occur even when they were heated to 200 °C under a nitrogen atmosphere, but they are unstable under an oxygen atmosphere. The mechanism of the oxidation reaction process was found: first, resin acids absorb oxygen, and then an exothermic oxidation occurs. The initial exothermic temperature (T ₀) of levopimaric acid, neoabietic acid, and dehydroabietic acid are 354.01, 353.83, and 398.20 K, the initial oxidation kinetics shows a second-order reaction, and the activation energies (E _a) are 42.90, 58.05, and 46.60 kJ/mol, respectively. Peroxide concentration of three resin acids were determined by iodometry. The T ₀ values of hydrogenated rosin, disproportionated rosin, hydrogenated rosin glyceride, and hydrogenated rosin pentaerythritol ester, the four rosin-modified resin, are 353.71, 348.32, 412.85, and 412.44 K. Levopimaric acid and neoabietic acid have higher oxidative reactivity and easily undergoes an oxidation reaction at lower temperature. Rosin-modified resins are stable and find it difficult to undergo oxidation reactions.

Characteristics and kinetics of the glycerol ester of rosinviaan oxidation process under ultraviolet irradiation

A self-designed mini gas–solid reaction device was applied as promising equipment to investigate the oxidation characteristics and kinetics of the glycerol ester of rosin (GER) under 254 nm UV irradiation in air.