Water-bath quenching

Moreover, for PP tape manufacturing with water bath quenching, the water-carryover effect can also be affected by choice of stabilizer (where the additive... 

The principal drawback of water-bath quenching is that very thin films cannot be made from crystalline polymers such as polyethylene or polypropylene. Above a certain draw-down ratio there are thickness variations in the longitudinal direction. This phenomena is called draw resonance and will be discussed in the next section. 

Coarse products suitable for the manufacture of baler twines, ropes and hawsers are made by flat film extrusion, water-bath quenching, air-oven stretching and optionally annealing thick film strips. The oriented strips are twisted and coarse fibrillation then occurs spontaneously. These polypropylene twines and ropes are stronger than ropes of sisal or manilla... 

Cool the flask using an ice-water bath. Quench the excess borane by careful addition of water (1-2 mL). 

Extrusion Resins. Extmsion of VDC—VC copolymers is the main fabrication technique for filaments, films, rods, and tubing or pipe, and involves the same concerns for thermal degradation, streamlined flow, and noncatalytic materials of constmction as described for injection-molding resins (84,122). The plastic leaves the extmsion die in a completely amorphous condition and is maintained in this state by quenching in a water bath to about 10°C, thereby inhibiting recrystallization. In this state, the plastic is soft, weak, and pHable. If it is allowed to remain at room temperature, it hardens gradually and recrystallizes partially at a slow rate with a random crystal arrangement. Heat treatment can be used to recrystallize at controlled rates. 

Prior to blending, the LCP was dried at 155°C for 5 h. The melt blending of the materials was carried out with a Berstorff ZE 25 x 33D corotating twin-screw extruder at a melt temperature of 290°C, with a screw speed of 200 rpm, and an output of 6.4 kg/h. The extrudate was immediately quenched in a water bath and repelletized. 

Cyclobutylcyclopropanol [133] To a well-stirred solution of ethyl cyclobutanecarboxylate [134] (56.47 g, 0.441 mol) and titanium tetraisopropoxide (26.3 mL, 88.2 mmol, 20 mol%) in anhydrous diethyl ether (200 mL), ethylmagnesium bromide (0.980 mol, 276 mL of a 3.55 m solution in Et20) was added over a period of 3 h. The temperature was maintained at between 20 and 25 °C with a water bath. After the addition was complete, the mixture was stirred for an additional 0.5 h at the same temperature, then cooled to —5 °C, whereupon the reaction was quenched by the careful addition of ice-cold 10 % aqueous sulfuric acid (500 mL) while the temperature was maintained between —5 and 0°C with an acetone/dry ice bath. The mixture was stirred at 0°C for an additional 1 h and then the aqueous phase was extracted with Et20 (100 mL). The combined ethereal phases were washed with saturated aq. NaHC03 solution (2 X 200 mL) and brine (200 mL), dried, and concentrated at water-pump pressure at 20 °C to give 48.92 g (99%) of 1-cyclo-butylcyclopropanol. The spectroscopic data of the product were identical to those reported in the literature [135]. 

B. (3-Bromo-3,3-difluoropropyl)trimethylsilane. A 1-L, four-necked flask is equipped with a mechanical stirrer, thermometer, Claisen adapter, septum inlet, reflux condenser (the top of which is connected to a calcium chloride drying tube), and a solid addition funnel. The flask is charged with (1,3-dibromo-3,3-difluoropropyl)trimethylsilane (78.3 g, 0.25 mol), and anhydrous dimethyl sulfoxide (200 mL), and the solid addition funnel is charged with sodium borohydride (11.5 g, 0.30 mol) (Notes 7 and 8). The stirred solution is warmed to 80°C, and sodium borohydride is added at a rate sufficient to maintain a reaction temperature of 80-90°C (Note 9). Toward the end of the addition, an additional portion of dimethyl sulfoxide (200 mL) is added via syringe to lower the viscosity of the reaction mixture. After the addition is complete, the mixture is cooled in an ice-water bath, diluted with 100 mL of pentane, and cautiously quenched with 12 M hydrochloric acid until no further gas evolution occurs. The mixture is transferred to a separatory funnel and washed with three, 100-mL portions of 5% brine. The pentane extract is dried over calcium chloride and the solvent removed through a 15-cm Vigreux column. Further fractionation yields 41.5 g (72%) of 3-bromo-3,3-difluoropropyltrimethylsilane, bp 139-141 °C (Note 10). 

A. Tri-O-acetyl-D-xylono-l,4-lactone 2. a) Bromine oxidation. A 250-mL, threenecked, round-bottomed reaction flask equipped with a magnetic stirrer, thermometer, and an addition funnel is charged with 30.0 g (0.20 mol) of D-xylose and 80 mL of water. After the clear aqueous solution is cooled with an ice-water bath, 34.0 g 0.23 mol) of potassium carbonate is added in portions, keeping the temperature below 20°C. After the mixture is cooled to below 5°C, 12 mL (0.22 mol) of bromine is added dropwise over 90 min, keeping the temperature of the reaction mixture below 10°C (Note 1). The orange solution is stirred at that temperature for 30 min, then at room temperature overnight. The reaction is quenched by careful addition of 88% formic acid (2.5 mL) to afford a colorless solution (Note 2). The solution is concentrated at 50°C on a rotary evaporator and 20 mL of acetic acid is added. The mixture is Concentrated again at 50°C to remove any residual water (Note 3). 

Tris-HCl (120 gL), CaCl2 (60 gL), BSA (60 gL), DTT (3 gL), water (87 /iL) and freshly thawed microsomal fraction (30 gL) were mixed well and divided into three reaction tubes one reaction and two control tubes (1 and 2). 40 uL of freshly prepared UDPGA was added to the reaction tube and control 1 and 40 yfL of water to the control 2. The tubes were pre-incubated for 2 min in a water bath shaker at 35 °C. Then, 20 yiL of freshly prepared solutions of substrate in 20 % DMSO was added to the reaction and control 2 tubes, as well as 20 /rL of water to the control 1 mbe. Aliquots of 50 /rL were withdrawn from aU tubes and were quenched in acidified ice-cold methanol (160 gL per each 50 gL aliquot). The quenched aliquots collected during the incubation were left on ice for at least 20 min. After centrifugation for 10 min at 12000 rpm, the supernatants were collected into glass mbes and the remaining proteinaceous pellets were washed twice with 50 /iL of water and reprecipitated with 150 /iL of ice-cold methanol. The combined supernatants were dried under N2 gas and reconstimted into 50 /iL of appropriate mobile phase. 

A. 1 -Phenyl-3-butyh-1 -ol (1) (Note 1). A 1000-mL, oven-dried, three-necked, round-bottomed flask is equipped with a magnetic stir bar and pressure-equalizing addition funnel, fitted with a rubber septum, and placed under an argon atmosphere. The flask is charged with lithium acetylide-ethylenediamine complex (50 g, 543 mmol) (Note 2), which is dissolved in anhydrous dimethyl sulfoxide (360 mL) (Note 3) with stirring. The flask is placed in a room temperature water bath (Note 4), the addition funnel is charged with styrene oxide (42.0 mL, 368 mmol) (Note 5), and styrene oxide is added dropwise over a period of approximately 5 min. The reaction mixture is stirred for 2 hr and quenched by... 

After the desired treatment was attained, the reactor was quenched in a cold water bath. The stirrer and computer recording were stopped... 

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