Resin results

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

Heat resistance is an important characteristic of the bond. The strength of typical abrasive stmctures is tested at RT and at 300°C. Flexural strengths are between 24.1 and 34.4 MPa (3500—5000 psi). An unmodified phenoHc resin bond loses about one-third of its room temperature strength at 298°C. Novolak phenoHc resins are used almost exclusively because these offer heat resistance and because the moisture given off during the cure of resole resins results in undesirable porosity. Some novolaks modified with epoxy or poly(vinyl butyral) resin are used for softer grinding action. 

Resins can be divided into natural and synthetic types. Natural resins have a vegetable or animal origin. Typical examples are rosins. Synthetic resins result from controlled chemical reactions, and can be divided into two subgroups. 

An alternative copolymerization is illustrated by the method of Blasius. In this preparation, a phenol-formaldehyde (novolac) type system is formed. Monobenzo-18-crown-6, for example, is treated with a phenol (or alkylated aromatic like xylene) and formaldehyde in the presence of acid. As expected for this type of reaction, a highly crosslinked resin results. The method is illustrated in Eq. (6.23). It should also be noted that the additional aromatic can be left out and a crown-formaldehyde copolymer can be prepared in analogy to (6.22). ... 

The current practice is to classify as oil varnishes all varnishes and paint media prepared from drying oils and natural or preformed oil-free synthetic resins. Examples of such resins are rosin, rosin-modified phenolics and oil-soluble 100% phenolics. The introduction of the resin results in improved drying and film properties. 

A statin combined with a resin results in similar reductions in LDL cholesterol as those seen with ezetimibe. However, the magnitude of triglyceride reduction is less with a resin compared to ezetimibe, and this should be considered in patients with higher baseline triglyceride levels. In addition, gastrointestinal adverse events and potential drug interactions limit the utility of this combination. 

Resins resulting from the polymerisation of one of the fractions of coal tar. Used as processing aids, tackifiers and as non-black organic reinforcing agents in mbber compounding. 

The silicon content of 1 was determined by inductive-coupled plasma-optical emission spectroscopy (ICP-OES) of sodium tetraborate melt samples. It approximated lmmol/g resin. Results shown in Tables 13.1 and 13.2 were obtained using a resin containing 1.3 mmol Si per gram of 1, and results shown in Table 13.3 were obtained using a resin containg 0.9 mmol Si per gram of 1. 

Figure 12.3 is a plot of the sodium sulphate content in the ion-exchange resin resulting from one cycle through the RNDS process. 

Acid treatment of the uncoated resins resulted in Gd(III)-loss and, therefore, decrease in the relaxation rates, whereas the coated resins showed increase in the relaxation rate after acid treatment. Apparently, on one hand, the coating prevented the acidic solution to leach large quantities of Gd(III) ions, but on the other hand the acid treatment increased the porosity of the coating and improved the accessibility of water. 

Powder coatings were prepared by extruding stoichiometric quantities of methylene dianiline with epoxy resins varying only in branch concentration. More highly branched resins result in a more tightly cross-linRed thermoset network. 

Pure citronellal is a colorless liquid with a refreshing odor, reminiscent of balm mint. Upon catalytic hydrogenation, citronellal yields dihydrocitronellal, citro-nellol, or dihydrocitronellol, depending on the reaction conditions. Protection of the aldehyde group, followed by addition of water to the double bond in the presence of mineral acids or ion-exchange resins results in formation of 3,7-dimethyl-7-hydroxyoctan-l-al (hydroxydihydrocitronellal). Acid-catalyzed cycli-zation to isopulegol is an important step in the synthesis of (-)-menthol. 

The elimination of two or three molecules of hydrogen fluoride requires prolonged reaction time and higher base concentrations or sometimes molten potassium hydroxide. The yields are generally low. The alternative utilization of basic ion-exchange resins results in milder reaction conditions (50-60 C) and higher yields.94... 

The lignan constituents of the two roots are the same, but the proportions are markedly different. The Indian root contains chiefly podophyllotoxin (Figure 4.21) (about 4%) and 4 -demethylpodophyllotoxin (about 0.45%). The main components in the American root are podophyllotoxin (about 0.25%), p-peltatin (about 0.33%) and a-peltatin (about 0.25%). Desoxypodophyllotoxin and podophyllotoxone are also present in both plants, as are the glucosides of podophyllotoxin, 4-demethylpodophyllotoxin, and the peltatins, though preparation of the resin results in considerable losses of the water-soluble glucosides. 

Numerous authors took advantage of the reactivity of double bonds towards ozone to prepare a-(0 functional oligomers usable in the synthesis of multiblock copolymers by copolycondensation, or in the synthesis of precursors of surfactants or ionomer resins. Results in this field of investigation are numerous, mainly in terms of industrial applications. 

Intramolecular cyclization of a double bond with dienones.2 Treatment of the trienone 1 with a typical Lewis acid, C2H5A1C12, results in a non-photochemical [2 + 2] cycloaddition to form a cyclobutane ring (2). In contrast, use of the strong acidic Amberlyst 15 resin results in the bicyclic product 3. 

Introducing fluorine into polyurethane resins results in changes in properties similar to those seen with other polymers. Chemical, thermal, hydrolytic, and oxidative stability is improved. On the other hand, the polymer becomes more permeable to oxygen. Surfaces become more biocompatible and the capability to bond to other substances in contact with them is diminished.33... 

The reaction of bisnucleophiles with a-sulfonyloxy ketones bound to a resin results in the release of heterocycles 1,2-benzenedithiol gives 1,4-benzodithiins, 2-mercaptoethanol yields 1,4-oxathiins and 1,2-diols afford 1,4-dioxins <02JA5718>. 

Some catalysts, such as certain Lewis acids, are so reactive that they can provide extremely short gel times with epoxy resins at room temperature.15 For example, BC13, can polymerize epoxy resins, resulting in gel times of less than 60 s. However, these reactive systems result in a very rigid adhesive with low peel strength properties and poor impact strength. As a result, less reactive catalysts are commonly employed in adhesive formulations. 

The addition of the nitrogen-containing crosslinking agents, melamine, urea, and urea-formaldehyde (UF) resin, resulted in a substantial increase in strength (Table III, entries 7-12). The best results were obtained by the melamine-crosslinked adhesives. The addition of 33% melamine resulted in an adhesive with strength values well within exterior-grade adhesive specifications. 

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