Copolymers inherent viscosity

Measurement Methods. Copolymer inherent viscosities () are reported in L/g. They were determined at 30° C at a concentration of 1 g/L in m-cresol or of 5 g/L in a 60/40 (wt %) mixture of phenol and 1,1,2-trichloroethane (TCE). The latter were corrected to their expected values in m-cresol by the empirically determined relationship ... 

The polymerization is carried out at temperatures of 0—80°C in 1—5 h at a soHds concentration of 6—12%. The polymerization is terminated by neutralizing agents such as calcium hydroxide, calcium oxide, calcium carbonate, or lithium hydroxide. Inherent viscosities of 2-4 dL/g are obtained at 3,4 -dianiinodiphenyl ether contents of 35—50 mol %. Because of the introduction of nonlinearity into the PPT chain by the inclusion of 3,4 -dianiinodiphenyl ether kinks, the copolymer shows improved tractabiUty and may be wet or dry jet-wet spun from the polymerization solvent. The fibers are best coagulated in an aqueous equiUbrium bath containing less than 50 vol % of polymerization solvent and from 35 to 50% of calcium chloride or magnesium chloride. 

Experiments in rats (38) have shown that y irradiation decreases the inherent viscosity of lactide/glycolide copolymers and increases the biodegradation rate. The in vivo lifetime of a 92 8 DL-lactide/ glycolide copolymer was decreased from about 40 weeks to about 30 weeks after treatment with 2 Mrad of y irradiation. 

Recent studies on 85 15 and 50 50 copolymers show decreases of about 15—20% in inherent viscosity after treatment with 2.0-2.5 Mrad of y rays. For example, an 85 15 DL-lactide/glycolide copolymer showed a drop in inherent viscosity from 0.71 to 0.56 dl/g (30°C in chloroform) upon treatment with 2.41 Mrad of y radiation. In most... 

A similar variety of samples was tested for thermal stability by capillary rheometry and TGA. Figure 6.3 shows the viscosity-shear rate dependence for PCTFE homopolymers and one copolymer (Alcon 3000). All materials, save one, showed virtually identical viscosity relationships despite large changes in inherent viscosity. Only the polymers from runs initiated by fluorochemical peroxides (FCP) showed a dependence of molecular weight (as measured by inherent viscosity) upon melt viscosity. 

Adhesion of Coatings. Except for K-l polycarbonate [4,4 -(2-nor-bornylidene)diphenol polycarbonate] (4), an experimental polymer (inherent viscosity 0.85), all the coatings were prepared with commercial products EAB-381-0.5 and EAB-381-20 cellulose acetate butyrates from Eastman Chemical Products, Inc. VYHH vinyl chloride (87%)/vinyl acetate (13%) copolymer from Union Carbide Corp. Butvar B76 poly-(vinyl butyral) from Shawinigan Resins Corp. Plexiglas V poly (methyl methacrylate) from Rohm and Haas Co. Dylene P3I polystyrene from... 

This finds some support in a comparison of solution viscosities with polymerization time of a few isolated cases of Diels-Alder polymerization reactions. In the polymerization of 2,5-dimethylene-3,4-diphenylcyclo-pentadieneone with N.N -hexamethylene-fo s-maleimide, the reduced viscosity of the polymer increases from 0.97 after 1 hr to 1.20 after six hours (7). It is necessary to assume that the rate controlling step in this reaction is neither the formation of the initial adduct nor the loss of carbon monoxide. The inherent viscosity of the l,6-6is-(cyclopenta-dienyl)hexane-quinone copolymer increases from 0.10 after sixteen hours to 0.12 after twenty four hours reaction time in refluxing benzene (14). 

Synthesis of the 2G-based copolymer can be somewhat more difficult than synthesis of the analogous 4G-based copolymer. If the ethylene glycol and dimethyl terephthalate monomers are prereacted to form bis (2-hydroxy ethyl) terephthalate, and this product is then copolymerized with poly(tetramethylene ether) glycol to form the block copolymer using tetrabutyl titanate as the transesterification catalyst, the reaction proceeds readily and copolymer of high inherent viscosity is easily obtained. If the ethylene glycol monomer is not prereacted and tetrabutyl titanate is again used as the transesterification catalyst, the copolymerization proceeds more slowly and a block copolymer of lower inherent viscosity is usually obtained. 

Cyclohexanedimethylene Terephthalate (wt %) Copolymer properties Inherent viscosity (L/g)... 

Copolymer properties Inherent viscosity (L/g) Yield strength (MPa) Stress at 100% (MPa) Tensile strength (MPa) Elongation (%) Permanent set (%)... 

Among the terephthalate-based polyether-ester copolymers, those prepared using 1,4-butanediol as the diol monomer exhibit the best overall physical properties. The use of ethylene glycol as the diol monomer retards the rate of polymer formation and results in copolymers which crystallize slowly. Other aliphatic ,w-diols yield terephthalate-based polyether-ester copolymers which are low in tensile strength and tear strength relative to the 1,4-butanediol-based copolymer. Terephthalate-based copolymers prepared with 1,4-benzenedimethanol as the diol monomer are relatively low in inherent viscosity, tensile strength, and tear strength. 

Fig. 16 ESC (50% failure) of various ethylene-butene copolymers for different amounts of C2H5 branches and different molecular weights (inherent viscosities)...

Figure 3. Inherent viscosity versus concentration for test copolymer in THF. The intercept at zero concentration yields an intrinsic viscosity of 30.0 0.3 mL/g.

Pyran Copolymer. Pyran copolymer used In calorimetric studies of red cell ghosts was NSC-46015, a gift of Dr. David S. Breslow of Hercules, Inc. For studies of pyran-llpld mixtures, the polymer was prepared by radical copolymerization of maleic anhydride and dlvlnyl ether according to the technique of Breslow (1), using 9/1 acetone/tetrahydrofuran mixture as solvent, and azoblslsobutyronltrlle as Initiator. The Inherent viscosity of the sample was 0.189 dl/g (0.5 g/100 ml In 0.05H NaCl, 30 C). 

Polymerization. Monomers V and VI were polycondensed at 100°C using standard Yamazaki reaction conditions. A copolymer was prepared in a similar manner by polymerization of equimolar amounts of V and VI [8]. VI also was copolymerized [9] with different amounts of -arainobenzoic acid (PAB) to yield PBA copolymers having varying degrees of N-raethyl amide substitution. The several polymers, with their mole percent N-methyl PBA contents and Inherent viscosities, are given in Table II. 

As expected, inherent viscosities of the copolymers prepared under identical reaction conditions decreased with increasing m-phenylene content while the rate of methyl hydrazide formation was similar for polymers of 0 and 50% meta substitution. 

By proper combination of acld-ester/para-meta monomer ratios, a variety of oxadiazole/N-methyl hydrazide copolymers could be prepared and evaluated in fiber form. High molecular weight polymers were easily prepared with inherent viscosities of 3-6. The sulfuric acid dopes were spun to fiber by dry-jet or wet-jet solution spinning into dilute sulfuric acid at ambient temperature in a conventional solution spinning process including a fiber neutralization step as well as a hot-drawing operation 350-400°C. Representative fiber properties are given in Table I. 

Inherent chain flexibility also manifested itself quite strongly in a decrease of polymer inherent viscosity with increased m-phenylene content for a series of copolymers prepared... 

In the DHA-4VP studies, we found that copolymer yield and inherent viscosity varied considerably with the solvent used for polymerization (Table I). Solvents greatly affect free radical polymerization, although the mechanisms of some interactions is uncertain. For example, the effect of solvents on the rate of polymerization has been attributed to complex formation and to viscosity effects which alter rates of initiation, propagation, and termination (13, 14, 15). The data in Table I do not indicate any clear tendency, and no molecular weight-conversion correlation of the copolymers is apparent. The variation in copolymer yields is readily explained by differences in solubility of DHA. 

The inherent viscosity of the DHA-NVP copolymer solutions varied with the feed composition (see Tables II and IV) the value was minimum for 80 mole % DHA in the monomer feed. Similar behavior, i.e. decrease in molecular weight with increase in DHA content in feed, was observed for the DHA-4VP systems. This is further evidence of DHA participation in lowering molecular weight by increased monomer-induced chain transfer reactions. 

In methanol, the viscosities of the polycation materials resembled those of other polyelectrolytes (18), i.e. the inherent viscosity of a typical sample in creased from 0.41 to 0.64 upon dilution from 0.5 to 0.125 g/dl. The IR spectra of the quaternized copolymers had aminimide absorption bands at 1585 cm"1 (as in the original polymer), a strong band at 1650 cm"1 (pyridine ring), and, with —CH2C02CH3, a strong band at 1750 cm"1. 

Materials. The copolyether-urethane-ureas were prepared from polypropylene glycol, methylene bis(4-phenylisocyanate), and ethylenediamine using a modified solution polymerization technique (7). The polypropylene glycols used had molecular weights of 700, 1000, and 2000 the resulting copolymers were coded PEUU 700, PEUU 1000, and PEUU 2000. Inherent viscosities in N,iV-dimethyl-formamide at 30°C and 0.5% concentrations were 0.47, 0.65, and 0.50, respectively. 

Fraction No. Cumulative volumes (ml) of methanol added to 4,465 gm of Copolymer in 70 mlofTHF Polymer recovered (%) Inherent viscosity of fraction (at 30 C) Allyl ester content (%)... 

The results for another copolymer series Is presented In a different way In Figure 2. The partial plots show melting points based on DTA determinations and the temperature at which fibers could be pulled from the melt. The horizontal scale Is the proportion of Y-component. In this series all of the polymers were prepared In a melt system by reaction of the diamines with a blsazomethlne. There was some variation In Inherent viscosity which appears not to have affected the regularity of the data. 

Following the tenets of fhis design, if was possible to prepare a model system that is a crystalline copolymer made of Hacfide and af least one cyclic monomer that is a liquid at or melts above about 40°C. In this model system the I-lactide-derived sequences of fhe polymer chain comprise from about 60 to about 90% of all sequences, and fhe copol5mier has a T, of at least 150°C, exhibits a crystallinity of af leasf abouf 20%, and has an inherent viscosity of at least about 1.1 dl/g. In t5q ical compositions for preparing representative copolymers, the cyclic monomer, other than Hactide, was e-caprolactone, trimethyl-ene carbonate, or both. Useful molar ratios of Z-lactide to cyclic monomers were 60 40, 62 38, 65 35, 68 32, 72 28, 76 24,80 20,84 16,85 15,86 14,90 10, and 94 6. 

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