Acidity, enhanced strength

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

This is a typical reaction of an active metal with an acid. The strength of sulfuric acid as an oxidizing agent is greatly enhanced when it is both hot and concentrated. In such a solution, the oxidizing agent is actually the sulfate ion rather than the hydrated proton, H+(ag). Thus, copper reacts with concentrated sulfuric acid as follows ... 

Several routes are available for synthesis of PET, starting from different monomers terephthalic acid (TPA), dimethylterephthalate (DMT) and bis-hydroxyethylterephthalate (BHET). The most common method of PET synthesis is based on the copolymerization of TPA and ethylene glycol. PET is a thermoplastic which can exist in amorphous, partially crystalline and highly crystalline states. For most PET applications, crystallinity is desired because it leads to enhanced strength and increases the maximum working temperature. 

Matching of Lewis acid strength with substrate reactivity possibility of Lewis acid enhancement of reactivity... 

Resonance stabilization of conjugate acids enhances ba.se strengths. 

Silicon-29 MAS NMR spectra of the expanded clays contain two separate resonances representing silicon atoms in a and environment. Furthermore, IR results have indicated that these expanded clays contain both Bronsted and Lewis acid sites, and that SCD enhances Bronsted-type acidity. Steaming greatly decreases acid site strength in these catalysts. 

In the AD expanded saponite, acidity increases, Hgure 5-9C. As expected, the amount of pyridine retained on the clay acid centers monotonically decreases with temperature. If AD is replaced by SCD, Bronsted acidity is enhanced. Figure 5-9D. The steam-aged clays retain their sorption capacity for pyridine. However, their acid site strength is greatly reduced, and after degassing in vacuo for 2h at 200 C, pyridine is essentially removed from the steam-aged expanded clay samples. 

A second series of LARC-13 adhesives was synthesized containing aromatic amine-terminated silicone elastomers of varying chain lengths. Changing the elastomer repeat unit from n = 10 to n = 105 had very little effect on polymer properties. However when a 50 50 combination of long and short-chained elastomers were reacted into the LARC-13 amic acid, adhesive strengths were enhanced. A concentration of 15% by weight of elastomers was found to maximize adhesive properties for this system. 

Table 8 agrees with experimental findings in the gas phase, and reproduces the main trends shown by Table 7 for dissociation in solution. As might be expected, the comparison with solution reactions reveals some anomalies. For example, PH3 emerges as a stronger acid than HF presumably the enhanced strength of HF in solution is due to the greater... 

Lowery LM, Appicelli PA, and Lemon PWR. 1998. Conjugated linoleic acid enhances muscle size and strength gains in novice bodybuilders. Med. Sci. Sports Exerc., 30, S182. 

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