A quantitative review of Canadian university researchers in evolution and ecology shows that, in 1993, the median researcher worked in a small laboratory, consisting of a principal investigator and two associates. The median total support for these laboratories was Can$51 000/year, of which a Natural Sciences and Engineering Research Council research grant represented about Can$27 000. A few laboratories sometimes enjoyed more support, but many were surviving with less. The median laboratory had graduated two master's and one doctoral student in the previous 6 years, and the vast majority of these graduates found positions that made productive use of their training. This median laboratory also produced two or three papers a year, plus occasional reviews, book chapters, and books. Both productivity and impact rose with funding, but grant size explained much less than half of the variation among publication and citation rates. Although typical Canadian grants were less than half the size of those in other countries, available indices of national achievement in evolution and ecology place Canadian research among the world's best. From 1981 to 1992, Canada was the second most active nation in the fields of environment, ecology, and aquatic sciences in terms of both publications and citations.

AbstractThe occurrence of transcrystallinity in polypropylene in the presence of glass fibres under stress was studied. An experiment was designed on a hot‐stage polarizing microscope in which it was found that slight mechanical stress at the fibre polymer interface gives rise to surface nucleation and growth of transcrystalline regions. Composites of polypropylene with various concentrations of glass fibres were prepared by injection molding. The observed transcrystalline regions in the injection molded samples were attributed to the availability of sufficient inherent internal stresses. Moreover, an increase in fibre concentration was found to enhance transcrystallinity. This indicated that the internal stresses were increased with increasing fibre population.

AbstractHigh‐density polyethylene up to about 30% by weight was melt‐mixed with polypropylene and short‐glass‐fiber‐reinforced polypropylene. The presence of high‐density polyethylene and glass fibers in the polypropylene matrix affects its crystallization characteristics, which were studied with the help of differential scanning calorimetry. The blend and composite samples have a large number of polypropylene domains apparently due to an abundance of surface nuclei; as a result, the tensile strength, tensile modulus, and toughness are enhanced. The temperature dependence of shear modulus and logarithmic decrement indicate that high‐density polyethylene can have plasticizing effect below the glass transition temperature of polypropylene. The scanning electron micrographs of fractured ends show the presence of dispersed domains in the composite samples.

Journal of the Society of Dyers and ColouristsVolume 98, Issue 12 p. 432-436 The Influence of Fibre Structure on the Adsorption of Basic Dyes by Acrilan R H Peters, R H Peters University of Manchester Institute of Science and Technology Sack ville Street Manchester M60 1QDSearch for more papers by this authorH. Wang, H. Wang †Feng Chia University Taichung TaiwanSearch for more papers by this author R H Peters, R H Peters University of Manchester Institute of Science and Technology Sack ville Street Manchester M60 1QDSearch for more papers by this authorH. Wang, H. Wang †Feng Chia University Taichung TaiwanSearch for more papers by this author First published: December 1982 https://doi.org/10.1111/j.1478-4408.1982.tb03616.xCitations: 10 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume98, Issue12December 1982Pages 432-436 RelatedInformation

AbstractThe rate of acid hydrolysis of a basic dyeable polyester in water, before and after heat‐setting, has been investigated. Intrinsic viscosity measurements and chemical analysis have been used to establish experimental conditions under which the hydrolysis is inhibited. It is suggested that the critical stage of the hydrolysis mechanism is the exchange of sodium ions from the sulphonate groups in the fiber for hydrogen ions.

AbstractA series of copolymers based on poly(tetramethylene terephthalate) containing poly(tetramethylene oxide) blocks whose molecular weights ranged from 1000 to 5000 in concentrations from 10 to 30% by weight was prepared. The polymers were melt spun into fibers and the undrawn fibers dyed with a disperse dye at three temperatures. The equibrium adsorption and diffusion coefficient of the dye increased with both the molecular weight and concentration of the polyether. The equilibrium adsorption varied linearly with both the molecular weight and concentration. It has been assumed that the equilibrium dye partition coefficient KM gives a parameter of the accessibility, V, of the fiber for dye. If the diffusion coefficient DM is given by DM = VDo/τ, where Do is the diffusion coefficient of the dye in the amorphous regions and τ is a tortuosity factor, a good correlation can be obtained between KM and DM, suggesting that changes in Do/τ vary in a systematic fashion.

The exchange of the sodium ions of the sodium sulphonate group in anionically modified polyester fibers has been measured. The accessibility of the sulphonate groups in the polymer is greatly improved by plasticization and is independent of the size of the exchanging ion.

AbstractFibers were prepared from tetramethylene terephthalate–polytetrahydrofuran (PTHF) random block copolymers, containing the latter in the range of molecular weights 1000–5000 with up to 30% by weight incorporation, using a conventional melt spinning technique. The spinnability of the copolymer and the mechanical properties of these undrawn fibers were evaluated. The changes in mechanical properties brought about by the incorporation of PTHF groups in 4GT units were related to the PTHF block size and content in the copolymer. X‐ray diffraction data are also discussed briefly in terms of the structural differences.

Random block copolymers of tetramethylene terephthalate and polytetrahydrofuran (PTHF) were prepared by melt polycondensation. Five different molecular weights of PTHF were used in the polymerizations with up to 30% by weight incorporation. The copolymers so obtained were characterized in terms of their molecular weight by means of endgroup analysis and solution viscometry. Compositions were established by nuclear magnetic resonance spectroscopy. Thermal properties were studied by differential scanning calorimetry and dynamic mechanical methods. Melting and glass transition temperatures are discussed in terms of the structural differences, particularly the effect of polyether composition and block size on chain flexibility.

AbstractThe mode of action of carriers in augmenting the rate of dyeing of disperse dyes with acrylic and polyester fibers is discussed in terms of the plasticizing action of the carrier. It is shown that the effectiveness of a carrier is determined by its ability to reduce the glass transition temperature of the fiber and not by the fiber swelling. The rate of dyeing as measured by the diffusion coefficient of the dye is shown to be uniquely related to the difference between the dyeing temperature and the glass transition temperature (T – Tg). In the light of these results, some aspects of carrier action in dyeing from perchlorethylene are discussed. Treatment of polyester fibers with carrier also increases crystallinity. Changes in diffusion for a series of copolyesters have been correlated with the long spacing obtained from small angle X‐ray scattering (SAXS).

Tetramethylene terephthalate–tetramethylene sebacate copolymers containing up to 20 mol % sebacate have been prepared and characterized. Molecular weights and distributions have been evaluated using viscometry and gel-permeation chromatography. Compositions have been established by NMR spectroscopy. Thermal properties have been studied by differential scanning calorimetry and dynamic mechanical methods. Melting and glass-transition temperatures and moduli are discussed in terms of the structural differences, particularly the effect of composition on chain flexibility. Density and thermal methods of crystallinity determination are critically discussed for these systems.

Drawn and undrawn fibers of tetramethylene terephthalate–tetramethylene sebacate copolymers, containing up to 20 mol % of the latter, have been dyed in an infinite dyebath with a disperse dye. The dyeing process has been interpreted in terms of the equilibrium dye absorption, the half-time of dyeing, and the diffusion coefficient. Increasing sebacate content has been found to have a marked effect on the rate and level of dye uptake. Deviations from Fickian behavior have been observed for the drawn fiber and related to presence of voids.

The Donnan distribution of sodium and chloride ions has been measured between wool and aqueous solutions, in the pH range 3 to 10, following treatment with either sulphuric or peracetic acids. Changes in the sorption isotherms at 25°C were found to depend upon the concentrations of the acids used, and they have been interpreted in terms of the formation of ionizable groups within the wool fiber.

The melting and crystallization behavior of poly(tetramethylene terephthalate) and its copolymers with tetramethylene sebacate (≯ 20 mol %) has been studied using differential scanning calorimetry (DSC). The effect of the sebacate concentration on equilibrium melting temperature and crystallization behavior is discussed in terms of the theory of equilibrium crystallization of random copolymers. The multiple-melting behavior of these systems is described and interpreted in terms of the theory of equilibrium melting of chain-folded crystals, together with molecular fractionation during crystallization and melting and recrystallization during the DSC scan.

The glass-transition temperatures (Tg) of a series of polytetramethylene terephthalate/polytetramethylene isophthalate, copolyesters have been measured by a variety of methods including differential thermal analysis, dilatometry, and broad- line nuclear magnetic resonance. The values measured for Tg are discussed in relation to differences in copolymer com position, sample crystallinity and the method used in the measurement of Tg. An increase in the isophthalate content of the copolyester has been found to decrease T g, whereas annealing and increasing the test frequency have both been shown to raise Tg. Values calculated for the apparent activation energy of the glass-transition (Δ ETg) for the series of copoly esters are also reported. In addition, the influence of water on the Tg of polyesters has been investigated.

Fibers have been prepared from tetramethylene terephthalate–tetramethylene sebacate copolymers, containing up to 20 mol % of the latter, using a conventional melt-spinning technique. The mechanical properties of these undrawn fibers and of highly oriented fibers prepared from them have been evaluated. The changes in mechanical properties brought about by the introduction of sebacate groups in poly(tetramethylene terephthalate) have been related to the glass-transition temperatures of the copolymers and to the flexible nature of the sebacate unit. The formation of voids during a continuous drawing process and during mechanical testing is discussed.

A density balance has been used to measure the crystallization isotherms of poly(ethylene adipate) and copolymers which were prepared by extending the polyester with four different diisocyanates. The occurrence of extensive secondary crystallization processes precluded satisfactory interpretation in terms of the Avrami theory and further analysis could only be based on the half-time for crystallization. This parameter has the advantage that it is determined directly and is independent of any theoretical analysis. The presence of very small concentrations of diisocyanate units can have a profound effect on the rate of crystallization if they are very different structurally from the parent polyester, e.g. a molar concentration of about 5% of 2,4-tolylene diisocyanate increases the half-time by a factor of 20 whereas the same concentration of hexamethylene diisocyanate has an insignificant effect. The temperature dependence of the half-times is discussed in relation to several theories of crystallization.

The dyeing of Acrilan with C.I. Basic Green 4 from water containing benzyl alcohol and benzyl alcohol containing water has been examined. Benzyl alcohol in water acts as a plasticizing agent for the fibre. The plasticizing action of small quantities of water in benzyl alcohol has also been detected and in both systems the rate of diffusion of dye into the fibre is related to the plasticizing action. The equilibrium absorption is a function of the difference between the dyeing temperature (T) and the glass transition temperature (Tg) of the fibre. The differences in the behaviour of the dye in the aqueous and benzyl alcohol dyebaths are related to the degree of dissociation of the dye and the mechanical properties of the fibres.

AbstractComparison of the various solubility parameters of different plasticizing agents has shown that their plasticizing action on Acrilan filaments is governed by polar interactions. The diameter swelling of the filaments appears to decrease with increasing efficiency of the plasticizing agent. The diffusion of a disperse day through the plasticized fiber is not related to the fiber swelling and is controlled by the plasticizing action of the dyebath.