Yield polymer

Polymer yield may be increased by increasing the area of the interface between the two solutions by stirring. 

Hydrolysis of the polymers yields H2SO4 and H2SO5 (p. 712), with H2O2 and O2 as secondary products. 

In the polymerization of phenyl acetylene [27] by tungsten and mo]ybdenum hexcarbonyls, high-polymer yields were obtained in CCI4 solvent. The following reaction scheme was proposed, which is different from that reported by Bamford and coworkers [17-20] ... 

After the desired peptide has been made, treatment with anhydrous HF removes the final Boc group and cleaves the ester bond to the polymer, yielding the free peptide. 

Data of Figs 8-10 give a simple pattern of yield stress being independent of the viscosity of monodisperse polymers, indicating that yield stress is determined only by the structure of a filler. However, it turned out that if we go over from mono- to poly-disperse polymers of one row, yield stress estimated by a flow curve, changes by tens of times [7]. This result is quite unexpected and can be explained only presumably by some qualitative considerations. Since in case of both mono- and polydisperse polymers yield stress is independent of viscosity, probably, the decisive role is played by more fine effects. Here, possibly, the same qualitative differences of relaxation properties of mono- and polydisperse polymers, which are known as regards their viscosity properties [1]. 

Heat- Carbon fibers cost cost polymers yield much greater... 

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

When the load is high enough, a polymer yields and loses its resistance. The corresponding stress level is specific to the polymer and the actual temperature. Knowledge of the yield strength of a polymer is crucial in order to avoid the risk of failure in application. However, the polymer can fracture even at loads below... 

From the earliest days of radiation chemistry it has been known that acetylene polymerizes to a cuprene-like ( alprene ) solid (5, 6,25,28). The characteristics of the polymerization—e.g., lack of effect of temperature, doso rate, and pressure on polymer yield and negligible effect of radical scavengers—led Lind (24) to postulate an ion cluster mechanism. 

According to the data in Table 3, the t-BuCl/Me3 AI/MeCl system produces higher polymer yield and is active over a wider temperature range than any other initiator/solvent combinations. While yields obtained with f-BuCl and f-BuBr using MeCl are comparable up to about —40 °C, lower yields are obtained with f-BuBr than with t-BuCl below -40 °C. 

Using the f-BuX/Me3Al/MeX system, a preferred reagent addition sequence has been found to be /-C4Hg/MeX/Me3 Al/t-BuX. This sequence has been used in these investigations. Based on polymerization rates at —40 °C, overall polymer yields, floor temperature and initiator efficiencies at —40 °C, overall initiator reactivity is found to decrease as f-BuCl > f-BuBr > t-BuI = 0 and initiator reactivity is dependent on solvent as MeCl > MeBr > Mel = 0. Similarity of reactivity sequences in isobutylene polymerization and in cationic model initiation and termination studies13) suggest that initiator reactivities are determined by the rate of initiation, Rj. 

Figure 5 is a plot of the calculated polymer yields from the continuous model C0NGAS vs. the yields from the semibatch model... 

Solution polymerizations of 1,3-butadiene were carried out in a high-pressure glass reactor (40 mL) connected with a vacuum system. In a typical procedure, 4 pmol of precatalyst (EAS/precatalyst =100 mol/mol) was dissolved in 20 mL of toluene. The polymerization started by adding 1.08 g of 1,3-butadiene and EAS to the solution in this order. The reaction mixture was stirred at a specific temperature (30 to 70 °C) for 40 min. The resulting solution was poured into acidified methanol (100 mL of a 5% v/v solution of HCl). The polymer was then isolated by filtration and washed with methanol before drying overnight at 40 °C. Polymer yield was determined by gravimetry. 

Monomer conv. quant. Polymer yield 50% Molecular weight 6700... 

Polyester synthesis was carried out hy insertion-dehydration of glycols into polyanhydrides using lipase CA as catalyst (Scheme 6). The insertion of 1,8-octanediol into poly(azelaic anhydride) took place at 30-60°C to give the corresponding polyester with molecular weight of several thousands. Effects of the reaction parameters on the polymer yield and molecular weight were systematically investigated. The dehydration reachon also proceeded in water. The reaction behaviors depended on the monomer structure and reaction media. 

The peroxidase-catalyzed polymerization of m-alkyl substituted phenols in aqueous methanol produced soluble phenolic polymers. The mixed ratio of buffer and methanol greatly affected the yields and the molecular weight of the polymer. The enzyme source greatly affected the polymerization pattern of m-substituted monomers. Using SBP catalyst, the polymer yield increased as a function of the bulkiness of the substituent, whereas the opposite tendency was observed when HRP was the catalyst. 

The HRP-catalyzed polymerization of (-l-)-catechin was carried out in an equivolume mixture of 1,4-dioxane and buffer (pH 7) to give the polymer with molecular weight of 3.0 x 10 in 30% yield. Using methanol as co-solvent improved the polymer yield and molecular weight. In the polymerization of... 

Comparable polymer yields are obtained for the four samples however, the Phosnic 390 samples IJ 3 and IL-22 have appreciably iK)re high and intermediate MW oligomer products. Nearly half the trin r in the Phosnic 390 samples undergoes conversion compared to 35% for the purified trimer. Finally, it is noted that the Phosnic 390 samples achieve similar polymer yields in about one-fifth to one-half the time as the pure PN trimers. These observations suggest that the Phosnic 390 sanqjles may contain component (s) that behave as catalysts or accelerators and that also tend to increase the high and intermediate MW oligomer yields. 

Each section was handled separately to determine the average polymer yield (Table I) and the polymers PN-la, -lb and -Ic were characterized at different times over a period of one month. 

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