THE COMPATIBILITY OF BLENDS OF POLY(VINYL CHLORIDE) OR CHLORINATED POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE)

IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.     

Raman spectra of extended-chain syndiotactic poly(vinyl chloride)

Raman spectra have been obtained for a typical poly(vinyl chloride) (PVC) of low crystallinity and for a highly crystalline sample of syndiotactic PVC obtained by irradiation of a urea-canal complex. Raman measurements have been made on the three different ordered chain structures possible for ordinary PVC. Extended and folded conformations for the syndiotactic structure and a helical structure for the isotactic molecule obey different selection rules and have different dichroic properties in the infrared and Raman spectra. The observed Raman spectrum is consistent with the model of the extended syndiotactic conformation for crystalline PVC. With the new Raman data some additional assignments can be made in the vibrational spectra of PVC.     

Investigation of some vinyl polymers by pyrolysis—gas chromatography—mass spectrometry

Although much has been published on the thermal degradation behaviour and products of vinyl polymers, the possibilities of using gaschromatography—mass spectrometry in the investigation of pyrolysate composition have much to offer.Results for poly(vinyl chloride), poly(vinyl acetate), polystyrene and poly(α-methyl-styrene) homopolymers and styrene—acrylonitrile copolymer obtained by pyrolysis—gas chromatography—mass spectrometry are presented. Numerous additional fragments not previously specified have been determined. The possible mechanisms of their origin as regards the polymer chain structure are discussed.     

Thermal and radiation-induced dehydrochlorination of poly(vinyl chloride). II. Head-to-head structures

The mechanism of dehydrochlorination of 2,3-dichlorobutane and chlorinated polybutadiene which are model compounds of head-to-head poly(vinyl chloride) has been investigated by pyrolysis, thermal, and ultraviolet-induced decomposition. The activation energy of dehydrochlorination for head-to-head poly(vinyl chloride) in nitrogen was 23 kcal/mole at temperatures of 150–190°C, which is slightly smaller than that (29 kcal/mole) for head-to-tail poly(vinyl chloride). The conjugated double bonds were formed by thermal and radiation decomposition of head-to-head poly(vinyl chloride), similar to head-to-tail poly(vinyl chloride). The probability of polyene formation by radiation-induced dehydrochlorination is larger than that by thermal decomposition and is affected by the conformation and the molecular motion of the main chain. This may be due to the alternative mechanism of dehydrochlorination in the thermal and radiation decomposition. The amount of head-to-head linkage of poly(vinyl chloride) samples prepared with various catalysts is dependent on polymerization temperature rather than the kinds of catalyst. Commercial poly(vinyl chloride) has 6–7 head-to-head linkages per 1000 monomeric units.     

Theory of the local mode relaxation in the glassy state of polymers

The local modes refer to vibrational motions of the main chain in the glassy state which are thermally excited with a relatively large amplitude and are consequently strongly damped into relaxational motions by the intermolecular viscous force. This paper describes a theory of strengths of the dynamic mechanical and dielectric local mode relaxations, in the latter of which the correlation of dipole arrangement along the main chain is considered. The results are compared with the observed strength and its dependence on temperature and pressure, in particular for the dielectric β relaxation of poly(vinyl chloride). Satisfactory agreement is obtained between theory and experiment.     

Complexation du chlorure de vinyle par le tetrahydrofuranne et le n-butyraldéhyde: Étude par résonance magnétique nucléaire haute résolution

Examination of the HR-NMR spectra of vinyl chloride in the presence of tetrahydrofuran and n-butyraldehyde suggests the formation of donor-acceptor type complexes. The equilibrium quotients and NMR constants were estimated by using the Benesi-Hildebrand method. The existence of these complexes would explain the anomalies observed: first, in the anionic polymerization of vinyl chloride initiated by tert-butylmagnesium chloride is tetrahydrofuran. The initiation step seems to be governed by this complexation phenomenon; second, in the radical polymerization of the same monomer in n-butylaldehyde the obtained poly(vinyl chloride) is more syndiotactic than the radical polymer prepared in bulk by the usual methods.     

Properties of poly(vinyl chloride) blends with polycarbonates and chlorinated polyethylene

The miscibility of polycarbonates derived from Bisphenol A or 2,5,2′,5′-tetramethyl-Bisphenol A with poly(vinyl chloride), chlorinated poly(vinyl chloride), and vinyl chloride-vinylidene chloride copolymers has been investigated. In miscible blends a shift of the position of the carbonyl absorption in the IR spectra indicates dipolar interactions between the polymers. The miscibility of chlorinated polyethylenes and reduced poly(vinyl chloride)s among each others demonstrates besides the importance of polar groups the influence of their distribution within the polymer chains for the compatibility of the polymers. The investigations on the miscibility have been carried out by differential scanning calorimetry, and by casting films with microscopical observation of the resulting structures.     

NMR studies of chlorinated poly(vinyl chloride) and polybutadiene

Molecular structures of chlorinated poly(vinyl chloride) and polybutadiene have been studied by high resolution NMR. The spectra of the chlorinated polymers give broad signals. New peaks appear in the lower fields of the ? CH₂? and ? CHCl? groups with increasing chlorine content. The chlorination of poly(vinyl chloride) takes place predominantly on ? CH₂? rather than on ? CHCl? , e.g., a 70% chlorinated polymer has about 10 mole-% of ? CCl₂? groups. Polybutadiene reacts first with chlorine by addition to give a head-to-head poly(vinyl chloride), and then the substitution of the hydrogen atom takes place. Chlorinated polybutadiene with 70% Cl has about 18 mole-% of ? CCl₂? . The multiplets characteristic of spin-spin couplings in the spectrum of the original poly(vinyl chloride) are still observed in that of the highly chlorinated product. This fact shows that a considerable number of poly(vinyl chloride) sequences of certain lengths persist in the highly chlorinated polymer.     

Polymerization mechanism of vinyl chloride with titanium tetrabutoxide–ethylaluminum sesquichloride catalyst and some physical properties of poly(vinyl chloride) prepared at low temperature

The mechanism of vinyl chloride polymerization by titanium tetrabutoxide–ethylaluminum sesquichloride catalyst system was investigated from the view of the stereoregularity of poly(vinyl chloride). The samples were prepared at a selected temperature in the range from 23 to ?78°C. The tactic triads, obtained from 220-MHz NMR spectra, show clearly the adequacy of Bernoullian statistics in describing the mechanism for stereochemical propagation. The chain propagation proceeds according to Bernoullian statistics with syndiotactic placements favored by 550 cal/mole. These results suggest that vinyl chloride polymerizes by a free-radical mechanism under the action of the present catalyst system.     

Laser Raman spectroscopy of polyacrylamide

The Raman spectra of polyacrylamide and its covalently crosslinked gel (with N,N′-methylenebis-acrylamide as the crosslinking agent) in the region of 200–3600 cm^?1 are discussed. The vibrational band assignments for polyacrylamide are made on the basis of a comparison with the spectra of acrylamide, acrylic acid, polyacrylic acid, poly(vinyl alcohol), and other vinyl polymers. The Raman spectra of polyacrylamide in the solid phase and in aqueous solution have similar spectral features. The Raman spectra of gels with low crosslink content and of polyacrylamide in aqueous solution are comparable except that one new band, predominantly due to the residual monomer, appears in the gel phase. An analysis based on polarized Raman, infrared and NMR spectra, model building, and group theoretical calculations suggests a structure dominated by isotactic species.     

Vinyl chloride polymers and their use in polymer blends

A short introduction to polymer-polymer miscibility and to the prediction of the miscibility of polymers is given. The four main types of polymer-modified poly(vinyl chloride) (plastification, impact modification, processing aids and heat deflection temperature modification) are explained by examples. The thermal stability of poly(vinyl chloride) in such blends is discussed; the effectivity of tin-stabilizers may be higher in such blends than in pure poly(vinyl chloride).     

Infrared,raman and nmr study of (Ch2CH)3Snx compounds (X = Cl,Br, I)

The infrared, Raman and (¹H, ¹³C) NMR spectra of trivinyltin chloride, bromide and iodide have been analyzed and discussed. The vibrational assignment has been confirmed by an approximate normal coordinate analysis. Evidence has been found for a marked influence of the X substituent on the tin-carbon bond due to isovalent rehybridization. Variations in the π electron system of the vinyl group are hardly significant.     

Spectral quality enhancement as an aid to polymer characterisation

The limit to the information on the microstructure of polymers that may be obtained from their vibrational spectra is often set by overlapping bands, markedly broader than the spectrometer resolution. Following the initial pioneering work of Pohl and Hummel, using a simple curve fitting technique, mathematical methods of spectral quality enhancement have progressed very considerably. These methods are reviewed critically and new results are presented. The desirability of imposing some parameter constraints in curve fitting is demonstrated, and this has led to the development of methods for peak narrowing, as an aid to peak finding. The two important approaches, derivative spectroscopy and Fourier selfdeconvolution (FSD), are discussed in terms of their application to the complex of overlapping bands in the v(C-Cl) region of the infrared spectrum of poly(vinyl chloride). A development of the FSD method termed Fourier band isolation, is described and preliminary results indicate that it has considerable promise. The maximum entropy method is discussed briefly.     

Fourier-transform infrared study of conformational changes in plasticized poly(vinyl chloride)

Fourier-transform infrared spectroscopy has been used for the detection of conformational changes induced by plasticization in atactic poly(vinyl chloride) (PVC). The amount of short trans syndiotactic sequences decrease upon plasticization. This change depends on the amount and kind of plasticizer. Difference spectra emphasize changes in the distribution of gauche defects in the chains as a function of temperature in plasticized PVC films.     

Pyrolysis/chemical ionization mass spectrometry of polymers

Pyrolysis/mass spectrometric studies have been made on polystyrene, poly(vinyl chloride), and poly(methyl methacrylate) with electron ionization (EI) and chemical ionization (CI) mass spectrometry and a variable temperature probe for direct insertion into the source of the mass spectrometer. Similar results obtained with EI and CI mass spectrometry are in agreement with previous experiments. Advantages of the simplification of spectra in the CI made, as well as the advantages of using both techniques for identification of pyrolysis products, are discussed.     

Radiolysis of poly(vinyl chloride)

Allyl free-radical intermediates are detected by ultraviolet absorption at 255 mu in poly(vinyl chloride) irradiated at ?196°C and stored at 25°C. In vacuum at 25°C, allyl radicals are converted into polyenyl free radicals and polyenes. From the nature of allyl radical decay in vacuum, radical chain transfer between polyenyl radicals and poly(vinyl chloride) is inferred. Allyl and polyenyl free radicals are scavenged by oxygen on post-irradiation storage in air.     

Vibrational assignments for the CCL stretching region of the Raman spectrum of poly(vinyl chloride)

It is shown that, by assuming that each of the peaks resolved in the CCl stretching region of the Raman spectra of a series of poly(vinyl chloride) gels can be associated with a definite triad structure, most of the peaks can he assigned to syndiotactic, isotactic, or heterotactic triad configurations without reference to the spectra of model compounds or to vibrational calculations. The results are in general agreement with most previous assignments except for the assignment of the peak at 646 cm^–1. Previously this was assigned to syndiotactic material, but it is here assigned to a structure consisting of consecutive syndiotactic, isotactic, and syndiotactic placements in a conformation not very distorted from the planar zigzag conformation.     

Reaction of aluminium chloride with poly(divinyl benzene) particles--a reaction kinetic study using infrared spectroscopy

Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted using aluminium chloride with dichlorobenzene as a catalyst. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the vinyl group consumption. Infrared spectra of the particles in the mid IR were also measured to understand changes taking place in the polymer matrix during the reaction. The results indicated that residual vinyl groups in these polymer particles were consumed during the reaction with aluminium chloride. The reaction of aluminium chloride with the polymer matrix was explained by proposing mechanisms for the formation of different products during the reaction. The complex formed between aluminium chloride and the residual vinyl groups seemed to induce addition of HCl to the vinyl group or leads to crosslinking and/or cyclisation in the case poly(para-DVB) particles. The reaction of aluminium chloride with poly(meta-DVB) takes place to a lesser extent.     

Theoretical determination of the infrared spectra of amorphous polymers

The simple procedure of calculating the infrared spectra of polymers is presented. It is based on selecting the relevant, medium-size representative fragments of a polymer, for which the vibrational frequencies are computed within the harmonic approximation, in conjunction with the multiparameter scaling techniques. Scaling is necessary to predict the reliable fundamentals, which, along with the calculated intensities and properly chosen band widths, reproduce the observed band shapes with high accuracy. Applications to the three polymers: poly(methyl methacrylate), poly(vinyl acetate), and poly(isopropenyl acetate) are presented. The simulated spectra are in good agreement with the experiment. The assignment of bands is reported. The obtained results indicate strong delocalization of the vibrational modes within polymers, which is in accord with the most recent experimental finding [Macromolecules2008, 41, 2494-2501]. Good agreement between the observed and the calculated spectra of deuterated PMMA confirms the correctness of our approach. The preliminary results obtained for the highly irregular macromolecular compound (vinyl-functionalized silica) are also shown.     

Cyclic imino ethers — Polymerization chemistry and polymer characteristics

This paper describes recent developments in polymerization of cyclic imino ethers, 2-oxazolines and 5,6-dihydro-4H-1,3-oxazines, which have been performed mainly in our laboratory. Cationic ring-opening polymerizations of these two kinds of monomers gave poly(N-acylethylenimine)s and poly(N-acyltrimethylenimine)s, whose hydrolysis produced linear poly-ethylenimine and poly(trimethylenimine), respectively. The mechanism of the polymerization is mainly governed by the nature of monomer and of the counter anion derived from initiator. There are two types of stable propagating species; cyclic onium species and covalent alkyl halide species. In a specific case, e.g., the polymerization of 5-methyl-2-oxazoline with MeI initiator, both ionic and covalent species are involved in equilibrium and propagate concurrently. Then, a new terminology of “Electrophile Polymerization” has been proposed as a broader expression including cationic and covalent propagating species. By utilizing living nature of the cyclic imino ether polymerization, block copolymerizations between these monomers were performed. A poly(cyclic imino ether) chain becomes hydrophilic or lipophilic depending on the monomer. Product AB and ABA type block copolymers were soluble in water and showed excellent surface properties reflected by values of surface tension (γ), when A (or B) and B (or A) are hydrophilic and lipophilic. Thus, various nonionic polymer surfactants of block and graft type have been prepared from cyclic imino ethers. Finally, poly(N-acetylethylenimine) chain showed good compatibility with poly(vinyl chloride). Cellulose diacetate and poly(vinyl chloride) are not miscible, but cellulose diacetate g-poly(N-acetylethylenimine) is miscible with poly(vinyl chloride), the graft chain acting as a “compatibilizer”.