Resistances and Permanencies

A little later, in 1700, the Jesuit Joachim Bouvet, a mathematician and musician, was corresponding with Leibniz about the I Ching. This Chinese document, wrote Bouvet, is in accordance with The most admirable remains we have of the wisdom of the Ancients. And this is how Bouvet links up with the idea of tradition  

The fable of the shipwreck and the goat, somewhat alfied to that of Hai Ibn Yoqdan, the Self-Taught Philosopher whose history was popular at this period, seems to have been intended to introduce the moral of the story Cyrus understood, says Ramsay, that the mythologies of the Egyptians and the Persians were founded on the same principles, for they were merely different names for expressing the same ideas. One also notes the bucolic 

Hermes Trismegistus obviously possesses several of the essential attributes of this god Hermes mobility, mutability (eclecticism), discourse and interpretation (hermeneutics), the function of crossroads (tolerance, irenicism). Most important, it seems, is this role of the middle term, held by both figures Mercury holds the equilibrium between Apollo and Dionysus, while Trismegistus is 

The gods would remain invisible without our aptitude to receive them. Their luminous source passes through various channels, or inmrors, thanks to which they become intelligible to us. The Hermetic works are one of the mirrors of Hermes-Mercury, who signs them as Hermes-Trismegistus, the figure who holds the armillary sphere. 

Vigiliae Christianae 45 (1991), which contains a full bibliography. Mah6 has written a most informative article on the Hermetica La Creation dans les Hermetica, pp.3-53, in Recherches Augustiniennes (21), 1986. See also, besides vol. II of Hermes en Haute-Egypte (cited above), vol. I Les textes hermetiques de Nag Hammadi et leurs paralleles grecs et latins, Quebec Presses Universitaires de Laval, 1978. 

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PERMANENT-PRESS RESIN. A thermosetting resin used as a textile impregnate or fiber coating to impart crease resistance and permanent hot-creasing to suitings, dress fabrics, etc. Chemicals such as formaldehyde and maleic anhydride are the basis of these products. The resin is cured after the fabric has been tailored into a garment. A permanent-press fabric that requires no resin has been developed (a blend of polyester with cotton or rayon). 

Epoxy resins are used in cold setting or thermo setting adhesives, in production of industrial composites and films of high resistance and permanence. Over half of production is used in protective coatings. Electrical laminates and filament windings are also important uses, representing about 20% of consumption. 

Textiles—upholstery, wrinkle resisters, and permanent press clothing... 

Textiles. Sorbitol sequesters iron and copper ions in strongly alkaline textile bleaching or scouring solutions (see Textiles). In compositions for conferring permanent wash-and-wear properties on cotton fabrics, sorbitol is a scavenger for unreacted formaldehyde (252) and a plasticizer in sod-resistant and sod-release finishes (253). 

Plasticizers. Plasticizers are materials that soften and flexibilize inherently rigid, and even britde polymers. Organic esters are widely used as plasticizers in polymers (97,98). These esters include the benzoats, phthalates, terephthalates, and trimeUitates, and aUphatic dibasic acid esters. Eor example, triethylene glycol bis(2-ethylbutyrate) [95-08-9] is a plasticizer for poly(vinyl butyral) [63148-65-2] which is used in laminated safety glass (see Vinyl POLYMERS, poly(vinyl acetals)). Di(2-ethyUiexyl)phthalate [117-81-7] (DOP) is a preeminent plasticizer. Variation of acid and/or alcohol component(s) modifies the efficacy of the resultant ester as a plasticizer. In phthalate plasticizers, molecular sizes of the alcohol moiety can be varied from methyl to tridecyl to control permanence, compatibiUty, and efficiency branched (eg, 2-ethylhexyl, isodecyl) for rapid absorption and fusion linear (C6—Cll) for low temperature flexibiUty and low volatility and aromatic (benzyl) for solvating. Terephthalates are recognized for their migration resistance, and trimeUitates for their low volatility in plasticizer appHcations. 

In Chapter 17 we showed that, when a material is loaded at a high temperature, it creeps, that is, it deforms, continuously and permanently, at a stress that is less than the stress that would cause any permanent deformation at room temperature. In order to understand how we can make engineering materials more resistant to creep deformation and creep fracture, we must first look at how creep and creep-fracture take place on an atomic level, i.e. we must identify and understand the mechanisms by which they take place. 

Triphenyl phosphate is a crystalline solid which has less compatibility with the polymer. This may be expected from solubility parameter data. It is often used in conjunction with dimethyl phthalate and has the added virtues of imparting flame resistance and improved water resistance. It is more permanent than DMP. Triacetin is less important now than at one time since, although it is compatible, it is also highly volatile and lowers the water resistance of the compound. Today it is essential to prepare low-cost compounds to allow cellulose acetate to compete with the synthetic polymers, and plasticisers such as ethyl phthalyl ethyl glycollate, which are superior in some respects, are now rarely used. 

Polychloroprene polymers also vary in the degree of branching in the polymer. Polychloroprenes with little or no branching are called sol polymers, whereas those with considerable branching are referred to as gel polymers. Sol polymers are soluble in aromatic solvents. All of the solvent-grade polychloroprene polymers (except Neoprene AG) are sol polymers. The gel content in the polychloroprene affects the cohesive strength, resilience, elongation, open tack time, resistance to permanent set, and oil swell. 

PBT is easily made into fiber and monofilament and has been used in some fiber applications. For example, PBT fibers are used commercially as toothbrush bristles. Compared to PET, PBT fiber is more resistant to permanent deformation. Compared to nylon, PBT shows almost no change when exposed to moisture. PBT shows much more resistance to staining than nylon and can be colored by the use of pigments. However, PBT is more difficult to color by solution dying than nylon. PBT is not typically used in textile applications due to its perceived high price. 

TPS are handicapped by risks of creep, relaxation and permanent set, the more so as the temperature rises (high compression set at 70°C for certain grades) swelling in mineral oils and oily products limited ageing resistance for SBS limited thermal behaviour (50°C maximum for certain SBS). 

MPRs are handicapped by a lower elasticity than conventional rubbers, the more so the higher the hardness certain risks of creep, relaxation and permanent set, the more so the higher the temperature sometimes limited flex fatigue resistance ecological problems involved with halogens tool corrosion risks lack of sources cost. 

Uses. About 35-40% of the methanol made is converted to formaldehyde. That s not because the embalming business is so good. Formaldehyde is a feedstock for amino and phenolic resins, which are used as adhesives in plywood, and in the automotive and appliance industry to make parts (all the agitators in washing machines used to be made out of phenolic resins). It is used as feedstock for hexamethylene tetramine, used in electronic plastics for pentaerythritol, used for making enamel coatings and for floor polish and inks for butanediol, a chemical intermediate and for acetic acid, which is widely used itself as a feedstock and solvent and warrants its own treatrnent later on. In the textile business, formaldehyde is used to make fire retardants, mildew resistant linens, and permanent press clothing. 

There are two broad classes of separators employed in nickel—zinc batteries a main separator, which exhibits resistance to dendrite penetration, and an interseparator, which principally acts as an electrolyte reservoir and wicking layer. Both main and interseparator should be resistant to chemical attack by the alkaline electrolyte and resistant to oxidative attack by nascent oxygen, permanently wettable by the electrolyte, flexible, heat sealable, tear resistant, and inexpensive. 

Polyester Dihydric acid- Strong, resistant to stretching and Permanent press Vycron,... 

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