Showing papers in "Polymer Journal in 1988"

Structural Distribution of Linear Low-Density Polyethylenes

Abstract: Molecular and crystalline structures of linear low-density polyethylenes (LLDPE) were investigated by a series of characterization techniques. Molecular structural characteristics were elucidated by temperature-rising elution fractionation (TREF) and solvent-gradient elution fractionation (SGEF). A bird’s eye view and a contour map of LLDPE obtained by a combination of TREF and size exclusion chromatography exhibited a broad and multimodal chemical composition distribution (CCD), in contrast to a sharp and single CCD of conventional high-pressure low-density polyethylene (HP-LDPE). Short chain branching (SCB) was found to decrease with increase of molecular weight by SGEF technique. Thermal analysis of cross-fractions proved that a characteristic broad endothermic curve of LLDPE is attributable to its broad and multimodal CCD. Then, using DSC results, an indicative index (DI) which expresses the degree of the distribution of lamellar crystal thickness is proposed. DI was found to be sensitive both to CCD and to a kind of SCB. The crystallinity and melting temperature of cross-fractions having comparable molecular weights decrease with increasing comonomer content in the order of octene-1≍4-methyl-pentene-1>hexene-1>butene-1. From a statistical approach to the relationship between crystallinity and degree of SCB, the probability of exclusion of a bulky branching such as isobutyl from a crystalline lattice is considered to be twice as large as than that of ethyl branching.

Radical grafting from carbon black graft polymerization of vinyl monomers initiated by peroxyester groups introduced onto carbon black surface

Abstract: The radical graft polymerization of vinyl monomers from carbon black initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto the carbon black surface was achieved by three methods: (1) the reaction of 2,2′-azobis(2-cyano-n-propanol) with acyl chloride groups on the surface, which were introduced by the reaction of carboxyl groups on the surface with thionyl chloride, (2) the reaction of 4,4′-azobis(4-cyanovaleric acid) with isocyanate groups on the surface, which were introduced by the treatment of carbon black with tolylene 2,4-diisocyanate, and (3) the reaction of hydroxyl groups on the surface with 4,4′-azobis(4-cyanovaleryl chloride). It was found that the polymerization of vinyl monomers such as methyl methacrylate and styrene was initiated by azo groups introduced onto the carbon black surface. During the polymerization, the corresponding polymer was effectively grafted onto the carbon black surface based on the propagation of the polymer from the radical produced on the surface by the decomposition of the azo groups. The percentage of grafting of poly(methyl methacrylate) and polystyrene using azo groups introduced by the method 2 increased to 40.0% and 28.5%, respectively. Furthermore, the effects of temperature and e-value of vinyl monomers on the graft polymerization were discussed.

Morphology and mechanical properties of poly(ethylene terephthalate)-poly(hydroxybenzoic acid) and polycarbonate blends.

Abstract: Blends of an engineering plastic; polycarbonate (PC) and a liquid crystalline polymer; random copolymers of the poly(ethylene terephthalate) and the poly(hydroxybenzoic acid) were prepared in an internal mixer. Fibers were extruded from the capillary rheometer and spin-drawn at varying draw ratios. The morphology and the mechanical properties were investigated by DSC, SEM, polarizing optical microscopy, X-ray diffraction, and tensile tests. SEM studies revealed that the liquid crystalline polymer (LCP) formed finely dispersed spherical domains with a diameter of 0.2—2.0 micron in the PC matrix and the inclusions were deformed from the spherical droplets to fibrils as the draw ratio increased. The interphase adhesion between the two polymers was good and therefore it was confirmed that the LCP could act as a reinforcement of PC.

Wormlike Chain Parameters of Poly(hexyl isocyanate) in Dilute Solution

Abstract: Intrinsic viscosity-molecular weight relationships were determined for poly(hexyl isocyanate) in toluene and dichloromethane using a number of narrow-distribution samples covering a wide molecular weight range. The data were analyzed according to the Yamakawa–Fujii–Yoshizaki theory of viscosity of wormlike cylinders, yielding the following values for the persistence length q and molar mass ML per unit contour length: q=41—34 nm and ML=730—760 nm−1 in toluene between 10 and 40°C and q=21 nm and ML=750 nm−1 in dichloromethane at 20°C. These parameter values are favorably compared with those reported for other solvent conditions for the same polymer.

Some Characteristic Features of Dilute Aqueous Alkali Solutions of Specific Alkali Concentration (2.5 mol l −1 ) Which Possess Maximum Solubility Power against Cellulose

Abstract: Some Characteristic Features of Dilute Aqueous Alkali Solutions of Specific Alkali Concentration (2.5 mol l −1 ) Which Possess Maximum Solubility Power against Cellulose

Effects of molecular weight distribution on the thermal properties of side-chain liquid crystalline poly(vinyl ether)s.

Abstract: Effects of Molecular Weight Distribution on the Thermal Properties of Side-Chain Liquid Crystalline Poly(vinyl ether)s

Main-chain flexibility and side-chain crystallization of widely spaced comb-like polymers

Abstract: Widely spaced comb-like polymers in which teeth (alkyl side-chains) appear on every four main-chain carbon atoms were synthesized as copolymers of styrene, or α-methylstyrene with alkyl acrylates, alkyl methacrylates, or dialkyl itaconates. Alkyl groups were dodecyl, tetradecyl, hexadecyl, and octadecyl. The long alkyl side-chains of these comb-like polymers crystallized as in conventional comb-like polymers but the extent of crystallization varied with cumulative substitution of phenyl and methyl groups on the copolymer main-chains. This is due to the influence of these substituents on the flexibility of the main-chain.

ESCA analysis of polymer-acceptor interactions in chemically synthesized polypyrrole-halogen complexes.

Abstract: ESCA Analysis of Polymer–Acceptor Interactions in Chemically Synthesized Polypyrrole–Halogen Complexes

Polynorbornenes with Oligodimethylsiloxanyl Substituents for Selectively Oxygen Permeable Membrane Material

Abstract: 2-Oligodimethylsiloxanyl substituted 5-norbornene-2-carbonitriles and carboxylates were synthesized from 5-norbornene-2-carbonitrile and methyl 5-norbornene-2-carboxylate by metalation at the 2-position followed by reaction with monochloro functionalized oligodimethylsiloxane. Polymers were obtained by the ring-opening polymerization of the monomers by a metathesis catalyst. Permeation of oxygen through the polymer films was highly selective over nitrogen. The diffusion coefficient was shown to play the principal role in the permeation.

XPS studies of some chemically synthesized polypyrrole-organic acceptor complexes.

Abstract: X-Ray photoelectron spectroscopy (XPS) studies have been performed on polypyrrole–2,3-dichloro-5,6-dicyano-p-benzoquinone (PPY–DDQ) and polypyrrole–tetrachloro-o-benzoquinone (PPY–chloranil) complexes prepared via the simultaneous chemical polymerization and oxidation of pyrrole by the respective acceptor. XPS data suggested that the charge transfer interactions in both complexes probably proceeded further than the pure formation of a molecular complex. The negative charges of both organic anions were mainly localized on the oxygen and the chlorine atoms and to some extent on the nitrogen of DDQ. More extensive charge transfer interaction and higher fraction of pyrrole nitrogen with positive charge were observed in the PPY–DDQ complex, which exhibited a substantially higher electrical conductivity than the corresponding PPY–chloranil complex.

Ionic transport in poly(ethylene oxide) PEO-LiX polymeric solid electrolyte.

Abstract: The ionic conductivity behavior of poly(ethylene oxide) complexed with lithium salts was investigated using an a.c. impedance technique. The composition range of the salt was from 0.01 to 0.5 mole fraction. The result showed that anions strongly influence the conductivity behavior of the polymer electrolyte. A simple model is proposed whereby the conductivity decrease at higher salt concentration is due to ion-pair formation. This results in an increase in the activation energy with increasing salt concentration and a reduction in the ionic mobility of Li+ ions.

Hydrogel Microspheres I. Preparation of Monodisperse Hydrogel Microspheres of Submicron or Micron Size

Abstract: Precipitation polymerization of acrylamide derivatives in water resulted in the formation of monodisperse submicron particles. Repetitive seeded polymerizations using the product of precipitation polymerization or precipitation polymerization in ethanol–water media gave larger monodisperse particles. Especially, the latter was very effective for the preparation of micro-size particles.

Chain-extended polyethylene in composites. Melting and relaxation behaviour.

Abstract: The melting and relaxation behaviour of chain-extended polyethylene/epoxy composites was studied. Using X-ray, DSC and birefringence techniques, it was shown that chain-extended ultra-high molecular weight polyethylene can be constrained fairly effectively by embedding in an epoxy resin, to prevent complete melting of the polyethylene far above the equilibrium melting point. Although the X-ray results look quite promising with respect to preservation of chain orientation in the fibres, both DSC and birefringence measurements indicate the presence of some relaxation/melting if the sample is heated above the orthorhombic to hexagonal transition point at 155°C. This solid-solid phase transition within the PE fibres is detrimental for the mechanical properties and consequently for the composite structure as a whole and sets an upper limit to the maximum use temperature.

Studies on Chitin XVI. Influence of Controlled Side Chain Introduction to Chitosan on the Adsorption of Copper(II) Ion

Abstract: N-Nonanoylation of chitosan was studied in comparison with N-acetylation, and the influence of modifications on the adsorption of copper(II) ion was elucidated to develop high performance adsorbents based on this under-utilized abundant resource. Controlled acylations with the corresponding acyl chlorides were established in a highly swelled state. The adsorption capacities proved to be highly enhanced at low extents of substitution; more remarkable improvement was achieved with nonanoyl groups than acetyl groups.

Anionic Polymerization of Tertiary Aminostyrenes and Characterization of the Polymers

Abstract: The polymers of three tertiary aminostyrenes: poly(N,N-dimethyl-4-vinylphenylamine), abbreviated as PPA; poly(N,N-dimethyl-4-vinylbenzylamine), PBA; and poly-(N,N-dimethyl-4-vinylphenethylamine), PPTA, were prepared via anionic polymerization in THF at −78°C. GPC measurement was carried out to estimate the molecular weights and molecular weight distributions (MWD) of the polymers. A mixture of THF and N-methylpyrrolidine (2 v/v%) was used as carrier solvent to avoid the adsorption of the polymers on the surface of the GPC gels. When n-butyllithium was used as an initiator, 100% polymer conversion was attained. The values of Mw/Mn were more than 1.20. The Mn was equal to Mk, calculated from the amounts of monomers and initiators. No polymer having narrow MWD was obtained, even when N-methylpyrrolidine was used as an additive. On the other hand, when cumyl potassium and cumyl cesium were used as initiators, polymers having narrow MWD were produced. The values of Mw/Mn were less than 1.08. The apparent rate constant of polymerization of cumyl cesium for PPA was small, compared with those for PBA and PPTA.

Determination of the distribution of the substituent group in cellulose acetate by full assignment of all carbonyl carbon peaks of 13C{1H} NMR spectra.

Abstract: An attempt was made to assign a number of peaks, observed in carbonyl region (168—171 ppm) of 13C{1H} NMR spectra of cellulose acetate (CA), to twelve magnetically different acetyl groups existing in 8 kinds of glucopyranose units constituting CA. CA samples with total degree of substitution «F» ranging 0.43 to 2.46 were prepared by acid-hydrolysis of CA with «F»=2.92 dissolved in acetic acid. 13C{1H} NMR measurements were made on these ten CA samples in deuterated dimethylsulfoxide and 14 peaks in total were observed definetely over the whole range of «F» from 2.92—0.43. From the spectra of CA samples with highest «F» (2.92) and lowest (0.43) carbonyl carbon peaks at C6, C3, and C2 positions in trisubstituted and monosubstituted glucopyranose units were successfully assigned. Deducing the effect of an acetyl group on the chemical shift of other acetyl groups, and vise versa, based on an empirical rule, 6 carbonyl carbon peaks in 3 kinds of disubstituted glucopyranose units were assigned. Eight average molar fractions «flmn» (l=1 or 0 means that a hydroxyl group attached directly at C2 position is or is not substituted and m=1 or 0 means that C3 position is or is not substituted, and n corresponds to C6 position) [i.e., «f000», «f100», ···, «f111»] were evaluated from integrated intensity ratios. The probability of substitution at Ck position «fk» (k=2, 3, and 6) and «F», both evaluated from the above «flmn» values, fairly agree with those estimated by the conventional NMR method, indicating the validity of the assignment in this paper.

Living cationic homo- and copolymerizations of vinyl ethers bearing a perfluoroalkyl pendant.

Abstract: Two vinyl ethers with a perfluoroalkyl group, CH2= CH–OCH2CH2N(n-C3H7)-SO2C8F17 (1) or CH2= CH–OCH2CF2CF2H (2), were polymerized with boron trifluoride etherate (BF3OEt2) and hydrogen iodide/iodine (HI/I2) as initiators at –15°C in methylene chloride or 1,1,2-trichloro-1,2,2-trifluoroethane. With both initiators, vinyl ether 1 was quantitatively polymerized. The polymers obtained with HI/I2 at conversions below 50% were soluble, and in this range their number-average molecular weight increased with monomer conversion, indicating the involvement of a long-lived growing species. In contrast, monomer 2 gave insoluble products with BF3OEt2, and it could not be polymerized with HI/I2 above 30% conversion. The HI/I2-initiated copolymerizations of 1 and 2 with 2-chloroethyl vinyl ether (CEVE) showed that the reactivity of these monomers are in the order CEVE > 1 > 2. The 13C NMR absorptions of their vinyl β-carbons shifted downfield in the same order; i.e., the closer the perfluoroalkyl and vinyl groups are located, the lower is the electron density on the vinyl carbon or the lower the reactivity of the monomers. In spite of its relatively low reactivity, vinyl ether 1 yielded not only long-lived homopolymers but also long-lived copolymers with CEVE, when polymerized by HI/I2.

Group transfer and cationic polymerization of 1-butadienyloxytrimethylsilane

Abstract: As requirement for the synthesis of new C4-type periodic polymers, group transfer polymerization of 1-butadienyloxytrimethylsilane (BdTMS) was examined. Equimolar Benzaldehyde (BAld)–ZnCl2 catalysts in benzene at 20°C were effective to give a soluble polymer in organic solvents. The structure of the polymer was revealed by NMR and IR analyses as 1,4-trans addition mode of diene. Dispersities (Mw/Mn) of molecular weight distribution evaluated by GPC reduced to about 1.5, clearly differing from about 3 in the case of ZnCl2 alone. SnCl4 or (C2H5)3Al2Cl3 without BAld polymerized BdTMS rapidly, accompanying gelation even at −78°C. Living propagation in BdTMS/BAld/ZnCl2 system was confirmed by the incremental monomer addition method. In NMR-monitoring the equimolar reaction of BdTMS/BAld catalyzed by ZnCl2 in C6D6, it was found that an aldol adduct appeared at the first stage and then a formyl group regenerated in the adduct began to react with the monomer.

Small angle X-ray study of cellulose in cotton using correlation functions

Abstract: This work shows that the small angle X-ray scattering (SAXS) intensity of dewaxed cotton of local origin at 25°C deviates from Porod’s law establishing that cotton at 25°C falls under non-ideal two-phase structure characterised by continuous variation of electron density at the phase boundary. Therefore the mean square of the electron density gradient ‹|grad η|2› in isotropic structure is proportional to the fourth moment ∫s4I(s)ds, of the SAXS intensity distribution in the reciprocal space and to the second derivative of the correlation function in the origin. The above relation given by Vonk has been used to find the thickness E of the transition region along with the following important physical parameters. They are D, the average periodicity transverse to the layer, S/V, the specific inner surface, φ1 and φ2, the volume fraction of two phases, i.e., matter and void, lc, the length of coherence, l1 and l2, the transversal lengths, lr, the range of inhomogeneity and 2E/D, the volume fraction of the transition layer. Two values of E have been obtained by the method of Vonk and Ruland. The SAXS intensity data of cotton sample was obtained by a technique using a compact Kratky camera.

Measurement of Li+ ion transport numbers in poly(ethylene oxide)-LiX complexes.

Abstract: The transport number for Li+ ions in Poly(ethylene oxide)–LiX complexes was measured using a potentiostatic polarization technique. The results indicate that the Li+ ion transport is strongly influenced by the salt concentration and the type of counter ions.

Thermal and rheological properties of agarose-dimethyl sulfoxide-water gels.

Abstract: DSC and dynamic viscoelastic measurements were carried out for agarose–DMSO–water gels in order to clarify the relation between the structure and gelling properties of agarose. Gelling ability showed a maximum at DMSO concentration of 0.277 mol fraction (mf). It is suggested that DMSO molecules interact strongly with water molecules and as a result the effective concentration of agarose increases with increasing concentration of DMSO up to 0.277 mf. Then, the gelling ability increases with increasing concentration of DMSO. Beyond this concentration of DMSO, the free DMSO, which has high dissolving power, increases, and then the formation of junction zones is inhibited. Thus, the gelling ability decreases with increasing concentration of DMSO. At a concentration of DMSO of 0.277 mf, the number and structures of junction zones and the conformation of flexible chain molecules connecting junction zones are optimized to give maxima of the elastic modulus, the melting temperature and endothermic enthalpy of melting. The gel containing 0.277 mf DMSO showed no melting endothermic DSC peak when heated from −100°C.

Two-Dimensional Nuclear Magnetic Resonance Spectra of Cellulose and Cellulose Triacetate

Abstract: An attempt was made to give a full assignment, using only NMR information, to all peaks in 1H and 13C NMR spectra for systems of cellulose in 2.5 N NaOD/D2O and of cellulose triacetate (CTA, total degree of substitution 2.92) in deuterated trichloromethane (TCM-d), and in deuterated dimethylsulfoxide (DMSO-d6). For this purpose two-dimensional (2D) homonuclear 1H shift correlation spectroscopy (COSY), heteronuclear 1H–13C shift correlation spectroscopy (C–H COSY), and long-range heteronuclear 1H–13C shift correlation spectroscopy (long-range C–H COSY) were applied to the above systems. By COSY 1H peaks of cellulose/aq. alkali solution were assigned, from lower magnetic field, to H1, H6, H6′, (H3+ H4+ H5), and H2 protons, respectively. Here, two unequivalent H6 peaks heavily overlapped in the one-dimensional spectrum were observed very separately in 2D spectrum. By C–H COSY 13C peaks of cellulose were assigned, from lower magnetic field, to C1, (C3, C4, C5), C2, and C6 carbons, respectively. C3, C4, and C5 carbon peaks were unable to be assigned separately, due to mutual and heavy overlapping of H3, H4, and H5 peaks. For cellulose triacetate, through use of COSY and C–H COSY all peaks in the region of glucopyranose backbone in 1H and 13C NMR wre able to be successfully and completely assigned. Long-range C–H COSY confirmed definitely the existence of the close correlationships between acetyl methyl proton and carbonyl carbon at the different carbon positions of CTA, which showed again the validity of the previous assignment with respect to carbonyl carbons (i.e., C6, C3, and C2 carbons from lower magnetic field).

Optically active polymers containing side chain azobenzene chromophores: Chiroptical properties and photochromic behaviour of 4-methacryloxyazobenzene/(-)-menthyl methacrylate copolymers.

Abstract: Copolymers of trans-4-methacryloxyazobenzene (MAB) with (−)-menthyl methacrylate (MtMA) have been prepared by using AIBN as free radical initiator. The resulting polymer samples are characterized by a substantially random distribution of monomeric co-units, as evaluated from reactivity ratios. Kinetics of photoinduced trans to cis and thermally induced cis to trans back-isomerization of azobenzene side chains have been examined and the relevant kinetic parameters evaluated. Dependence of chiroptical properties on both copolymer composition and extent of cis/trans isomerization has been investigated. The circular dichroism induced on azobenzene chromophores has been shown to arise mainly from isolated MAB units, as the chiral perturbation is not appreciably transmitted along MAB sequences. The results have been discussed in terms of tertiary structure reversible variations connected to photoinduced change of local conformation.

Sequence Determination in Methyl Methacrylate–n-Butyl Methacrylate Copolymers by 13C NMR Spectroscopy

Abstract: Methyl methacrylate (MMA) and n-butyl methacrylate (n-BuMA) were bulk copolymerized at 70°C using benzoyl peroxide as an initiator. The composition of the copolymer samples was estimated by 1H NMR spectroscopic technique. Reactivity ratios were calculated by Tudos method. 13C [1H] NMR spectra were used to study the monomer sequence distribution in copolymers. Various triads fractions were calculated by using the carbonyl resonance. The experimental triad concentrations showed good agreement with calculated values from Bernoullian and Harwood statistical programs.

Studies on Curing Process of Epoxy Resins by High-Resolution Pyrolysis-Gas Chromatography

Abstract: The curing processes of epoxy resins cured with a dicarboxylic acid anhydride or in the presence of an imidazole catalyst were studied by high-resolution pyrolysis-gas chromatography. The yields of the pyrolyzates with epoxide groups decreased with increase in the degree of curing, while those of various phenols characteristic of prepolymer skeleton increased. Additionally, the yields of low boiling pyrolyzates such as ethylene oxide, propylene, acrolein and acetone also specifically changed with the degree of curing. The obtained results are discussed in comparison with the results from other techniques such as glass transition temperature measurements and FT-IR.

Discovery of a Strain of Tristeza Virus (K) Inducing No Symptoms in Mexican Lime

Abstract: In a rootstock trial, six kumquat cultivars were grafted on trifoliate orange and on Troyer citrange. All six cultivars did well on trifoliate orange, but only one thrived on citrange. This finding prompted us to search for potential viruses in our kumquat cultivars. In addition to indexing on indicator plants, we looked for inclusion bodies and found that two kumquat trees on trifoliate orange had inclusion bodies in the phloem, suggesting citrus tristeza virus (CTV) infection. ELISA (enzyme-linked immunosorbent assay) tests were positive for CTV using antibodies to the Reunion strain of CTV. Filamentous virions similar to CTV could be seen by electron microscopy in the phloem of the two kumquat trees and were purified from young shoots. The purified virions were ultrastructurally and serologically indistinguishable from typical CTV. These results prove that the two kumquat trees are infected with a strain of CTV referred to here as strain K. The two CTV-positive kumquat trees were among three trees introduced to Corsica from Morocco in 1959. These trees indexed negatively on Mexican lime seedlings in 1963 and were considered free from CTV. When it was realized in 1981 that two of the three trees were infected with CTV, they were again indexed on Mexican lime seedlings in Corsica and Bordeaux. No vein clearing or stem pitting was observed, but ELISA showed that the limes were infected with CTV. Because strain K is symptomless on Mexican lime CTV infection in the two kumquat trees was not detected earlier. Indexing by ELISA has shown that no spread of CTV has occurred from the two initial kumquat trees or their progeny. Index words. kumquat, ELISA, inclusion bodies, electron microscopy, indexing. Several lines of kumquat (Marumi K123, K124 and K154 ; Nagami K125 and K169 ; Meiwa K153) have been introduced into Corsica and have been propagated on two rootstocks: trifoliate orange and Troyer citrange. All kumquat lines did well on trifoliate orange, but some declined on Troyer citrange (K123, K124, K125, K153) or induced vein clearing on sweet orange (K153), as reported by Navarro, et al. (6). These results prompted us to determine the pathogen content of the kumquat lines (7). Citrus tristeza virus (CTV) was the first agent to be tested. Two techniques were used: staining for virus inclusion bodies by Azure A stain (2) and ELISA using IgGs against the Reunion strain of CTV (3). By these methods, one kumquat line (K123) was found to be infected with CTV. Virus particles similar to CTV could be seen by electron microscopy in the sieve tubes of ELISA-positive kumquat trees. This paper reports the first graft-transmission experiments carried out with this strain (strain K) and its purification. A companion paper (1) describes additional unusual properties of this strain of CTV. EXPERIMENTS AND RESULTS Mexican lime seedlings infected with CTV strain K are symptomless. The CTV-infected K123 kumquat line is an old line imported from Morocco in 1959. Three trees budded on rough lemon were imported: K123-T22, K123-T23 and K123-T24. In 1981, trees T22 and T24 were found positive for CTV by both inclusion body staining and ELISA, whereas tree T23 was negative. When the trees were indexed for CTV on Mexican lime seedlings in 1963, no symptoms of vein clearing or stem pitting were noticed. Repeated indexing on Mexican lime at San Giuliano and Bordeaux since 1981 has never revealed the slightest tristeza symptom. ELISA was used to verify whether the symptomless lime seedlings contained CTV. Sixty-four of 65 Mexican lime seedlings graft-inoculated with CTV-K-infected kumquat bark from trees T22 and T24 were found positive for CTV by ELISA within 4 yr after inoculation. None of the 64 plants showed CTV symptoms and/or stunting. In the same experiment, groups of five Mexican lime seedlings were Tristeza and Related Diseases graft-inoculated with Mexican lime bark infected with CTV strain T1 or CTV strain T4 (4). Five of the seedlings inoculated with CTV-T1 and four of those inoculated with CTV-T4 were positive by ELISA and all nine ELISA-positive seedling showed stunting and typical symptom of CTV. Five uninoculated Mexican lime seedlings were used as a control. In another experiment, groups of five Mexican lime seedlings were used to study the time required for CTVK, CTV-T1 and CTV-T4 to pass from bark inoculum to Mexican lime seedlings. Seedlings were graft-inoculated with bark infected with the respective CTV strains. The bark inoculum was removed 2, 4, 6, 8 and 15 days after grafting. ELISA was used to determine the presence of CTV in the seedlings 6 weeks after graft inoculation. No CTV transmission was obtained within 4 days after inoculation. After 6 days, 2 of 5, 3 of 5 and 2 of 5 seedlings, respectively, inoculated with CTV-K, CTV-T1 and CTV-T4 were ELISA positive. After 8 days all inoculated seedlings were infected. No CTV symptoms were observed in CTV-K infected seedlings while characteristic symptoms developed on the seedlings carrying CTV-T1 or CTV-T4. Finally, symptomless Mexican lime seedlings infected with CTV-K seemed to contain as much virus as symptomatic Mexican lime seedlings infected with CTV-T1 or CTV-T4, as judged from the number of inclusion bodies observed and the ELISA readings, which were between 0.8 and 1.0 OD at 405 nm. These experiments demonstrated that CTV-K infects and multiplies to normal titers in Mexican lime, but that it does not induce tristeza symptoms or stunting in these seedlings. This result explains why CTV-K was not detected in 1963 when the K123 kumquat trees were indexed on Mexican lime seedlings in Corsica. Transmission of CTV strain K by bud propagation. Until it was recognized in 1981 through ELISA and inclusion body staining that two of the three initial K123 kumquat parent trees were infected with CTV, all three trees were used indistinguishable as sources of budwood for propagation on trifoliate orange. The percentage of infected trees in various kumquat orchards has been determined by ELISA. Twenty-five of 35 (71%) were found infected in the San Giuliano Station, 40 of 114 (35%) in one commercial orchard and 22 of 87 (25%) in another orchard. These percentages probably reflect the proportion of budwood taken from the two infected parent trees to that taken from the single healthy tree and indicate that CTV-K is easily graft-propagated. To prove this, buds from CTV-K-infected tree K123-T22 and from uninfected tree K123-T23 were respectively propagated on two groups of six trifoliate orange seedlings. All the six trees propagated from CTV-K infected buds were CTV positive by ELISA and inclusion body staining, whereas none of the budlings propagated from CTV-free budwood were positive. Graft-inoculation of kumquat trees on trifoliate orange by various strains of CTV. Buds from CTV-free tree K123-T23 were propagated on trifoliate orange and groups of eight trees were graft-inoculated with infected bark of kumquat tree K123T22, CTV-TI-infected Mexican lime bark, and CTV-T4-infected Mexican lime bark, respectively. Eight and six trees were grafted with bark from the CTV-free tree K123-T23 and healthy Mexican lime bark (negative controls), respectively. ELISA was done 3 months after graft-inoculation and inclusion body staining after an additional 3 months to determine presence of CTV. All trees inoculated with CTV-TI, or CTV-T4 were found positive, whereas seven of eight trees grafted with CTV-K-infected bark gave positive reactions. Control trees were all negative. ELISA reactions of CTV-strain K and CTV from Reunion. CTV-K was purified by the technique of Gon16 Tenth IOCV Conference salves et al. (5) from bark of K123kumquat trees shown CTV-positive ELISA, and compared with CTV purified from a Reunion source. Morphologically and spectrophotometrically, the two strains were very similar. With IgGs against CTV-Reunion, strain CTV-K gave almost the same optical density readings in ELISA at 405 nm as CTV-Reunion. Virus concentration ranged from 500 to 0.5 ngl well assuming an extinction coefficient E (O.l%/cm) at 260 nm of 3.0. Lack of evidence for natural transmission of CTV-K. Many trees (sweet orange, Clementine, etc. ) on sour orange growing next to K123 kumquat trees known to carry CTVK were examined by ELISA for possible CTV-K contamination. All assays were negative. In one commercial K123 kumquat orchard, all trees were indexed by ELISA for CTV infection in 1981 and again in 1986. All trees that were found CTV-negative in 1981 were still negative in 1986.

Effects of the Structure of p -Oligodimethylsiloxanyl Substituents of Polystyrene on Glass Transition Temperature and Oxygen Permeability of the Polymer

Abstract: Polystyrenes with isomeric p-oligodimethylsiloxanyl substituents were synthesized in order to elucidate the roles of these substituents on their film forming properties and oxygen permeation behavior. Branched chain oligodimethylsiloxanyl substituents gave polymers with higher glass transition temperatures than did straight chain substituents. It was indicated from the permeation experiments that trimethylsiloxyl groups in p-oligodimethylsiloxanyl substituents played essential roles in permeation by increasing the diffusion coefficient. The roles of the substituents are further discussed based on the spin-relaxation behavior of the polymers in the solid state.

Anionic polymerization of vinylsilanes. I. Novel isomerization in the anionic polymerization of trimethylvinylsilane.

Abstract: Anionic Polymerization of Vinylsilanes I. Novel Isomerization in the Anionic Polymerization of Trimethylvinylsilane

Asymmetric Selective Polymerization of β-Butyrolactone Catalyzed by Optically Active Cobalt Complex/Triethylaluminum System

Abstract: Asymmetric Selective Polymerization of β-Butyrolactone Catalyzed by Optically Active Cobalt Complex/Triethylaluminum System