in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: Conventional and chain extended-modified solid-state polymerization (SSP) of postconsumer poly(ethylene terephthalate) (PET) from beverage bottles was investigated. SSP was carried out at several temperatures, reaction times, and 2,2 0 -bis-2-oxazoline (OXZ) or pyromellitic anhydride (ANP) concentrations. The OXZ was added by impregnation with chloroform or acetone solution. Higher molecular weights were reached when the reaction was carried out with OXZ, resulting in bimodal distribution. The molecular weights of the flakes reacted at 230 C for 4 h were 85,000, 95,000, and 100,000 for samples impregnated with 0, 0.5, and 1.25 wt % OXZ solution, respectively. In the case of reactions with ANP, branched chains were obtained. The thermal and thermal-mechanical-dynamic properties of these high-molecular-weight recycled PET were determined. For OXZ-reacted samples, the reduction of crystallinity was observed as the reaction time was increased, becoming evident the destruction of the crystalline phase. The chain extended samples did not show changes in thermal relaxations or thermal degradation behavior.

Dynamic mechanical and dielectric properties of substituted polypentenamers with phosphonate side groups and their hydrogenated derivatives have been studied. Methyl esters, acids, and salts were investigated at two concentrations, 6.5 and 11.1 mole percent. In the unhydrogenated derivatives, one principal relaxation, labeled (3, is observed mechanically in the temperature range from-160 to 100°C. This (3 relaxation arises from micro-Brownian segmental motion accompanying the glass transition. Its temperature is substantially affected by the substituent concentration while its breadth is affected by the chemical nature of the substituent. An extended "rubbery plateau" region exists in the acid and salt derivatives. The dielectric results generally reinforce the mechanical assignments. In the hydrogenated derivatives, three relaxations labeled a, (3, and 'Y in order of decreasing temperature occur mechanically in this temperature range. The temperatures at which the a and (3 relaxations occur depend greatly on the chemical nature of the substituents, the substituent concentration, and the thermal history of the sample; while the 'Y relaxation appears to be independent of these variables. Suggested assignments for the relaxations observed in these polymers, based on the duiil glass transition theory of Boyer for semicrystalline polymers, have been proposed. The dielectric results are consistent with the proposed assignments.

cis‐1,4‐Polybutadiene and polypentenamer having pendant functional groups such as formyl, aldoxime, hydroxymethyl, or cinnamoyloxymethyl groups have been prepared, and some of their properties were investigated in terms of structural effect on physical properties of these polymers. cis‐1, 4‐Polybutadiene and polypentenamer having a different content of formyl group were prepared by the hydroformylation reaction with rhodium catalyst under mild conditions. The pendant formyl group was reduced to a hydroxymethyl group by using various reducing agents such as sodium borohydride or sodium trimethoxyborohydride which were effective to avoid a crosslinking reaction among the formyl groups. Glass transition temperature of polypentenamer having hydroxymethyl groups increased with increasing the content of the hydroxymethyl groups in the polymer. Cinnamoyl group was introduced into the polypentenamer having hydroxymethyl groups by reacting with cinnamoyl chloride so as to prepare a photosensitive rubber. The relationships between the photosensitivity of the cinnamoylated polypentenamer and the mobility of polymer main chains have been elucidated. A linear relationship between the photodimerization rate constant and the difference between ultraviolet (UV) irradiation temperature and the glass transition temperature of the polymer was found. It has become apparent that the photosensitivity of cinnamoylated polypentenamer can be estimated by the glass transition temperature of the original polymer, UV irradiation temperature, activation energy of the dimerization, and γ, which is a coefficient of the relationship between the photosensitive group concentration and the glass transition temperature of the polymer.

In order to investigate the topological effects of chain molecules, united-atom molecular dynamics simulations of a 500-mer polyethylene linked by 50 hexyl groups (a grafted polymer having 52 ends) are carried out and analyzed in terms of Voronoi space division. We find that the volume of a Voronoi polyhedron for a chain end is larger than that for an internal or junction atom, and that it is the most sensitive to temperature, both of which suggest higher mobility of chain ends. Moreover, chain ends dominantly localize at the surface of the globule: The striking evidence is that while the ratio of surface atoms is only 24% of all atoms, the ratio of ends at the surface is 91% out of all ends. The shape of Voronoi polyhedra for internal atoms is prolate even in the bulk, and near the surface it becomes more prolate. We propose the concept of bonding faces, which play a significant role in the Voronoi space division of covalently bonding polymers. Two bonding faces occupy 38% of the total surface area of a Voronoi polyhedron and determine the prolate shape.

Wholly aromatic poly(azomethine)s with 1,5‐ or 2,6‐substituted naphthalene moiety in the main chains were prepared in aprotic polar solvents or m‐cresol under various reaction conditions. In the polymerization of 1,5‐diaminonaphthalene with terephthalaldehyde, the polymer that synthesized in (HMPA/DMSO) at room temperature for 24 h by adding 5 wt % of calcium chloride and a very small amount of p‐toluenesulfonic acid showed the highest reduced viscosity in all of the polymers from 1,5‐diaminonaphthalene. The reduced viscosity of poly(azomethine)s synthesized from 2,6‐diaminonaphthalene with 2,6‐diformylnaphthalene in m‐cresol and with terephthalaldehyde in HMPA/DMSO were ηred = 0.35 and 0.36, respectively. The thermal analysis showed the poly(azomethine)s had high thermal stability and the glass‐transition temperatures of these polymers are about 250 °C. The X‐ray diffraction showed that they are partially crystalline. They could be polymerized again by second stage polycondensation in polyphosphoric acid. The reduced viscosities of the obtained polymers were about 2–5 times as high as that of the pristine polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1064–1072, 2000

SbstractThis work aims at studying not only the rheological behavior of natural rubber-based compositions by making use of different contents of fluoromica or ME 100 synthetic mica in a natural rubber (NR) matrix, but also the different filler-filler and matrix-filler interactions before and after curing. The ME 100 content in NR varied from 0 to 10 phr (parts per hundred parts of resin) and the results enabled to conclude on the influence of the mineral filler on the curing parameters, as well as on the limit amount of ME 100 for the best performance resulting from the best filler distribution/interaction in the polymer matrix. All data were compared with those of the unfilled composition. Based on complex viscosity, curing parameters, dynamic modulus and Payne effect tests it was concluded that the mica content limit for the best performance was 7 phr.

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SynopsisPhotosensitivity of cyclized polydienes such as cis-1,4-polybutadiene, 1,2-polybutadiene, and polypentenamer having pendent cinnamate groups has been studied in terms of the influence of polymer structure. The photosensitivity, which was based on the photodimerization of cinnamate groups in these polymers, was greatly affected by the mobility of the cinnamate groups. The observed rates (k&) could be estimated by using the reciprocal of the difference between an irradiated temperature (T) and a standardized temperature ( T g -501, at which the free volume of the polymer could be considered as zero by taking the glass transition temperature (T,) of the polymer as a standard. Furthermore, the photosensitivity of the cyclized rubber decreased with an increase in the amount of the cyclized units in the polymer. The overall rate of the photodimerization did not linearly correlate with the amount of the incorporated cinnamate groups, because the glass transition temperature of the cyclized rubber was not dependent on the small amount of the incorporated cinnamate groups, but on the amount of the cyclized units in the polymer. Theoretical treatment of the photodimerization reaction in the solid polymer was carried out, which was consistent with experimental results.