Copolymers determination

Suspension Polymerization. At very low levels of stabilizer, eg, 0.1 wt %, the polymer does not form a creamy dispersion that stays indefinitely suspended in the aqueous phase but forms small beads that setde and may be easily separated by filtration (qv) (69). This suspension or pearl polymerization process has been used to prepare polymers for adhesive and coating appHcations and for conversion to poly(vinyl alcohol). Products in bead form are available from several commercial suppHers of PVAc resins. Suspension polymerizations are carried out with monomer-soluble initiators predominantly, with low levels of stabilizers. Suspension copolymerization processes for the production of vinyl acetate—ethylene bead products have been described and the properties of the copolymers determined (70). Continuous tubular polymerization of vinyl acetate in suspension (71,72) yields stable dispersions of beads with narrow particle size distributions at high yields. 

The composition of the copolymer determines its electroluminescence efficiency. Optimal efficiency (0.3%) was achieved in system 34 when the feed ratio of monomer 4 to monomer 34 was 9 1. This represents a 30-fold improvement in luminescence efficiency relative to PPV in the same device configuration (AlALOj/polymer/Al) 58, 62. Copolymer 33 has found uses as waveguides and... 

ISO 4577, Plastics - Polypropylene and propylene-copolymers - Determination of thermal oxidative stability in air - Oven method, 1983. 

ISO 4577 1983 Plastics - Polypropylene and propylene-copolymers - Determination of thermal oxidative stability in air - Oven method ISO 7279 1984 Polypropylene (PP) fittings for pipes under pressure - Sockets for fusion using heated tools - Metric series - Dimensions of sockets ISO 7671 2003 Plastics piping systems for soil and waste discharge (low and high temperature) inside buildings - Polypropylene (PP)... 

Chen, G. Cooks, R.G. Jha, S.K. Green, M.M. Microstructure of Alkoxy and Alkyl Substituted Isocyanate Copolymers Determined by DCI-MS. Anal. Chim. Acta 1997, 556, 149-154. 

Montaudo, M.S. Sequence Constraints in a Glycine-Lactic Acid Copolymer Determined by MALDI-MS. Rapid Commun. Mass Spectrom. 1999, 13, 639-644. 

It is to be stressed again (Section 16.4) that the molar masses of homopolymers different from PS, as well as the molar masses of copolymers determined by SEC directly from the polystyrene calibration dependences should be designated polystyrene equivalent values. The latter more or less differ from the actual values and should be used only for the assessments of tendencies. 

As reported previously, the morphology of fibrous cellulose-polyvinyl copolymers, determined by electron microscopy, depends on the method of free-radical initiation of the copolymerization reaction, the experimental conditions during the reaction, and the type of vinyl monomer used. Variations in the shape of the fibrous copolymer cross section, in layering effects in the copolymer structure, and in location and distribution of the polyvinyl polymer within the fibrous structure were shown (1,2,7,29,52). 

Table A. Composition of Styrene—Hydroxyethyl Methacrylate Copolymers Determined by Chemical Analysis...

The synthesis of polystyrene-g-polytetrahydrofurane [188] was achieved by ATR copolymerization of methacrylic PTHF macromonomer, MA-PTHF, with styrene (Scheme 105). The PTHF macromonomer was synthesized by cationic ring opening polymerization of THF with acrylate ions, formed by the reaction of methacryloyl chloride and AgC104. The polydispersity indices of the graft copolymers determined by SEC ranged between 1.3-1.4. Kinetic studies revealed that the relative reactivity ratio of the macromonomer to St was independent of the molecular weight of PTHF. 

Of particular Interest is the fact that in the alternating oopolymerization of epoxide and phthallc anhydride with the TPPAlCl-EtPhSPBr system every aluminum atom of the catalyst carries two growing polymer molecules. As seen in Table I, the observed molecular weight of the copolymer, determined by vapor pressure osmometry (VPO), is about one-half the molecular weight calculated on the assumption that every aluminum atom carries one polymer molecule. 

Other LC-based copolymers incorporating styrene-based monomers were prepared by Ober et al. [149] who chain extended pAcOSt-TEMPO (Mn=7000, Mw/Mn=1.18) with [(4 -methoxyphenyl)4-oxybenzoate]-6-hexyl (4-vinylbenzoate) (MPVB, Fig. 10). The reactions were controlled, with molecular weights ranging from Mn=12,600-23,000 and Mw/Mn=1.19-1.44. The content of pMPVB in the copolymer determined by XH NMR increased as the molar ratio of the MPVB to pAcOSt-TEMPO increased [149]. For two out of the three copolymers prepared a smectic-isotropic transition was observed however, it was at a value lower than expected based on the composition of the copolymer, even after annealing. X-Ray diffraction patterning indicated that the copolymer was oriented in a lamellar morphology and that the smectic layers were perpendicular to the block copolymer lamellae [149]. 

Essential properties are described mainly for the sodium type membrane made of copolymers of tetrafluoroethylene and carboxylated vinyl ether (Ml), soaked in caustic solutions. The content of carboxylated vinyl ether in the copolymer determines ion exchange capacity of the resulting membrane, which is expressed as milliequiv-alent of carboxylic acid group per gram weight of dry sodium type membrane. 

EO content represents the amount of EO units (-CH2CH20-) in copolyether polyols (PO-EO), and random and block copolymers. Determination of EO content is based on two NMR spectroscopic methods (Standard Test Method ASTM D4875 [113]) Method A (1H NMR) and Method B (13C NMR) which are used for an EO content greater or equal to 6%. 

Poly(styrene-co-methacrylonitrile)/ acrylic copolymers Determination of CPC. Complex phase diagrams dependent on the composition of the two types of copolymers Nishimoto et al., 1995... 

The SEC was equipped with a refractive index and photodiode array detector which were calibrated with poly(styrene) standards. Tetrahydrofuran was used as eluent and the data recorded by the photodiode array detector was evaluated at a wavelength of X = 257 nm, where poly(styrene) has an absorption maximum. The poly(styrene)-equivalent molecular weight of the copolymers determined by the SEC were found to be higher than the theoretical values. More accurate values were calculated using the SEC determined molecular weight of the styrenic macroinitiator together with the weight ratio of the two copolymer chains extracted from NMR data. 

Montaudo, M.S., Sequence Constraints in Glycine-Lactic acid Copolymer Determined by MALDl-MS analysis, Rapid Comm Mass Spectrom, 13, 639 (1999). 

ZoUer, D. L. and Johnston, M. V., Microstructure of Butadiene Copolymers Determined by Ozonolysis/MALDI Mass Spectrometry, Macromolecules, 33, 1664, 2000. 

The number-average molecular weight (M ) and the PEG/PCL block ratios of PECE triblock copolymer synthesized in this work were calculated from H-NMR spectra. The M of PECE triblock copolymer was 3408 and the PEG/PCL block ratios was 960/2448, which was consistent with theoretical value calculated from feed ratio (M =3300, PEG/PCL= 1100/2200). Mn and polydispersity (PDI, Mw/Mn) of PECE copolymer determined by GPC were 4391 and 1.30 respectively. 

DS/EN ISO 1158 1998 Plastics - Vinyl chloride homopolymers and copolymers - Determination of chlorine content... 

If one wishes to attain high conversion at constant composition, the more reactive monomer must be added in a programmed manner. The procedure is as follows from the copolymerization diagram (or from the reactivity ratios) one obtains the monomer composition that will lead, at low conversion, to the desired copolymer composition. A conversion/time curve is drawn up for this system and the composition of the copolymer determined from time to time. From this, one can find how much of the more reactive monomer is to be added at given times during the polymerization in order to maintain an approximately constant composition (see Example 3.39). Special computer software has already been developed for this. 

Aery 1 ate/acry 1 amide copolymer Determined diffusion coefficients by photon correlation light scattering ... 

Analysis of plastics is a complex task and involves preliminary tests, determination of nonmetallic and metallic elements, analysis of functional groups and double bonds, molecular weight determinations, chemical compositional analysis, sequence length distribution in copolymers, determination of tacti-city and branching in polymers, and analysis of additives. Because of the great variety in structures in commercially produced plastics, the number of methods that can be applied for their analysis is considerable. 

PPE (400)/SAN (600) quinone dioxime (2) Brabender ot TSE/mechanical properties vs. blends without dioxime or with Rl/copolymer determined by selective solvent extraction/PS used in place of SAN/also used p-dinitrosobenzeue Ueuo and Maruyama, 1982b... 

FIGURE 5.1.8 (a) Chemical structure of PEO-f)-P(NIPAAM-r-Ru(bpy)3). (b) Hydrodynamic radius (Rh) of the diblock copolymer in the reduced and the oxidized states of Ru(bpy) side chain as a fuixtion of temperature, (c) Oscillating profile of the of / h the diblock copolymer determined by time-resolved DLS measurements. 

Properties Most of the testing done on the copolymers determined rheological properties of solutions of the copolymers in water. Since similar data exists for copolymers without N-substitution, general comparisons of the effect of N-substitution on solution flow can be made. These comparisons cannot be taken very far, however, because the molecular weights and repeat-unit-composition of the copolymers were not determined. 

The most widely used rubbers in epoxy technology are butadiene-acrylonitrile copolymers end-capped with carboxyl, vinyl or amine groups. The end-groups control the rubber s particle size and they can also be chosen to ensure that precipitation occurs regardless of the nature and polarity of the curing agent. The polarity of the copolymer determines the compatibility of the modifier with the polymer. 

Table 8. Compositions of block copolymers determined by pyrol gas chromatography ...

Table 6A. Comparison of Molar Masses of Block Copolymers determined by various Methods...

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