Rosins, oxidative stability

Rosin is a complex mixture, mainly consisting of various isomers of rosin acid. When exposed to air for a long period, rosins are easily discolored by oxidation. High-pressure DSC (HPDSC) can be used to determine oxidative stability of various rosins and rosin products. The measurement method is as follows ... 

Carbon tetrachloride [56-23-5] (tetrachloromethane), CCl, at ordinary temperature and pressure is a heavy, colorless Hquid with a characteristic nonirritant odor it is nonflammable. Carbon tetrachloride contains 92 wt % chlorine. When in contact with a flame or very hot surface, the vapor decomposes to give toxic products, such as phosgene. It is the most toxic of the chloromethanes and the most unstable upon thermal oxidation. The commercial product frequendy contains added stabilizers. Carbon tetrachloride is miscible with many common organic Hquids and is a powerhil solvent for asphalt, benzyl resin (polymerized benzyl chloride), bitumens, chlorinated mbber, ethylceUulose, fats, gums, rosin, and waxes. 

For rosins and rosin esters, the produets having high aeid numbers are the most susceptible to oxidation and have inferior viscosity stability and colour stability in adhesive formulations. Thus, when stability properties are essential in adhesives, rosin esters rather than high aeid number rosins are used. However, the high acid number resins are polar and display better adhesion to polar elastomers and polymeric surfaces. 

One of the most industrially important characteristics of papers is their chemical stability, which enables them to withstand degradation with its consequential loss of tensile and tear strength and fold endurance under normal conditions of use. However, this stability is not absolute. Cellulose is susceptible to oxidation and the glycosidic linkage is susceptible to hydrolysis. In order to protect book papers from acid degradation, they must not be exposed to acid. Acids are generated from the alum-rosin size as well as from such... 

Metallic sulfonates, such as sodium sulfonate, are often used as emulsifiers in both water-in-oil and oil-in-water emulsions. Other emulsifiers used include ethylene oxide condensation products and derivatives of polyhydroxy alcohols such as sorbitol and sulfosuccinates for water-in-oil emulsions. For oil-in-water emulsions, soaps of fatty acids, rosins, or naphthenic acids are often used as emulsifiers. In either application, the role of emulsifiers is to change the interfacial tension at the water and oil interface. In cases where emulsification with water is undesirable, demulsifiers are used. Frequently, the demulsifiers are heavy metal soaps, such as alkaline earth sulfonates. These surfactants function by lowering emulsion stability. 

CTO consists of approximately 35-50% fatty acids, 15-55% rosin acids, and 5—35% unsaponifiable and neutral material. CTO can be used right away as a surfactant for oil and gas drilling applications or can previously be oxidized by blowing with air at a temperature of 120-130°C for 24h. It forms water-in-oil emulsions and stabilizes the oil-based drilling mud when pumped at high bottom-hole temperature under pressure through the kelly, drill pipe, drill collars, and drill bit (Figure 3B.11). It is then returned... 

Although unmodified rosin has some application in low quality mastics and construction adhesives, rosin is typically modified to enhance its oxidative and thermal stability and to obtain a range of physical properties such as softening point and melt viscosity. Rosin is a complex mixture of tricyclic unsaturated resin acids with some nonacidic components. At least... 

The choice of resin tackifier influences not only the initial adhesive performance, but also the retention of adhesive properties upon aging. Color retention and resistance to oxidation and UV degradation are key considerations in choosing a tackifying resin. Glycerine or pen-taerythritol esters of unmodified wood rosin exhibit fair tack properties initially, but have poor aging characteristics primarily because of resin oxidation. Esters of rosins which have been stabilized by hydrogenation or polymerization, e.g., Foral 85 or Foral 105, possess the best combination of properties for adhesive use. 

Rosins - These are abietie aeid resins obtained from wood sourees. There are several different types wood rosins obtained from the naptha extraetion of pine stumps, gum rosins obtained from the destruetive distillation of turpentine, and tall oil rosins obtained by the destruetive steam distillation of tall oil from the manufacture of paper. Rosins are widely used in the adhesive and sealant industry. In hot melts they oxidize and diseolor easily at high temperatures due to the imsaturation in the resin. Hydrogenated grades are available which have much better thermal stability. 

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