Crystallization of randomly epoxidized trans-1,4-polyisoprene (original) (raw)
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Bulk crystallization of solution epoxidized trans-1,4-polyisoprene
Macromolecular Chemistry and Physics, 1994
Copolymers of trans-l,4-polyisoprene containing 2,2 mol-Vo, 5,O mol-Vo and 9,8 mol-Vo epoxidized units were crystallized from the melt at temperatures (T,) of 25 to 36 "C. The progress of the crystallization was monitored, and final crystallinities at T, and after cooling to 25 "C were measured using Fourier-transform infrared spectroscopy. The morphology of samples, treated with OsO, at 25 "C after crystallization was complete, was observed using scanning electron microscopy. The crystallinity decreases linearly with increasing epoxy content at T, = 25 "C and 30°C and shows marked deviations from linearity at T, = 36°C. Differences in morphology with epoxy content and T, were observed. The differences in crystallinity between solution and melt crystallized samples are discussed.
Journal of Polymer Science Part B: Polymer Physics, 1989
The crystallization of segmented block copolymers of trans-l,4-polyisoprene (TPI)/epoxidized TPI from solution was investigated. One preparation with an average TPI block length of 14.5 and an average epoxidized TPI block length of 10 was crystallized from 2-pentanol at 2O"C, 2-octanol at 2OoC, and 2-pentanone at 0°C. A second preparation with an average TPI block length of 18 and the same average epoxidized TPI block length was crystallized from 2-octanol at 20°C and 2-pentanone at 0°C. The crystallization products were epoxidized in suspension a second time and then characterized by carbon-13 solution NMR to determine the average noncrystalline traverse length and the average crystalline stem length. The crystallized products were also studied by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry to determine the morphology, the crystal form and crystallinity, and the melting point, respectively. The average noncrystalline traverse length was found to be highly dependent on the crystallization conditions and the crystalline stem length of the parent TPI lamellas; the composition of these traverses is discussed.
Morphology and properties of trans-1,4-polyisoprene crystallized from solution
Macromolecules, 1984
trans-1,4-Polyisoprene (TPI) fractions with Mn = 4.7 X lo3 to 2.5 X lo5 and Mw/M,, = 2.0-1.3 were crystallized from solutions, mainly at a concentration of 1 g/100 cm3, by cooling directly from 100 OC to an (apparent) TC of -15 to +32 OC, by precooling to 0 "C, redissolving a t 35-45 "C, and crystallizing at Tc, and by cooling to 0 OC and heating to 10,20, or 30 "C. Most of the structures obtained were characterized, while suspended in the crystallization liquid, by interference contrast microscopy and with crossed polaroids; the crystalline fraction from the density and the crystal form from X-ray diffraction and differential scanning calorimetry were determined for the dry products. The morphology obtained by direct crystallization was dependent on molecular weight, crystallization temperature, and solvent, with a-and 0-hedrites (sheaves), a-and 0-spherulites, and 0-aggregates of cup-shaped lamellas being found. The precooling method yielded overgrown lamellas in most cases; however, more complex morphologies developed when the thermal history was changed. The density depended on molecular weight, concentration, and crystallization temperature. The crystallinity was mainly a function of crystal form and molecular weight. The equation of Tseng, Herman, Woodward, and Newman was used to explain the molecular weight dependence of the crystallinity at low M, and to calculate the average number of monomer units per fold and interlamellar traverse. Epoxidation of some TPI structures suspended in amyl acetate a t 0 "C was carried out. At high concentrations of the epoxidizing agent, m-chloroperbenzoic acid, the fraction epoxidized approached or exceeded the noncrystalline fraction as obtained from density measurement.
Macromolecules, 1988
trans-1,4-Polyisoprene structures in the a and @ crystalline forms with various morphologies were prepared by using different crystallization procedures. The effects of molecular weight, crystallization temperature, and annealing treatment on the crystalline stem length and the noncrystalline traverse length were investigated by using epoxidation in suspension followed by carbon-13 solution NMR. Preliminary studies were carried out to determine the optimum conditions for quantitative reaction of the double bonds a t the lamellar surfaces. Results were obtained suggesting that for many liquids penetration of partially reacted lamellas can take place from the lateral surfaces; reactant concentration and time were also shown to be important and conditions were found that gave agreement between the fraction reacted and the noncrystalline fraction from infrared and density measurements. Interlamellar traverses were detected in multilamellar structures with the amount increasing with increasing molecular weight. The nature of chain folding in the trans-polydienes is discussed.
Infra-red spectroscopic investigation of bulk-crystallized trans-1,4-polyisoprene
Polymer, 1993
Crystallization from the melt of trans-l,4-polyisoprene was followed using Fourier-transform infra-red spectroscopy. The spectral subtraction factor versus time was obtained at the crystallization temperature and after cooling to 25°C for fractions and for the parent material. Crystallization of the/? crystal form was followed at 36 and 43°C and of the ~ form at 43 and 51 °C. Samples crystallized at 25°C and subsequently annealed at 43°C were also monitored. The amorphous fraction for prenucleated melt-crystallized :~-form-containing samples increased with molecular weight at the crystallization temperature and after cooling to 25°C. Samples containing the /~ crystal form showed a molecular-weight dependence at a crystallization/annealing temperature of 43°C that disappears upon cooling the sample to 25°C. The results are discussed in terms of lamellar surface disorder and lamellar thickness distribution.
Morphology of trans -1, 4-polyisoprene crystallized in thin films
Journal of Materials Science, 1977
The development of melt-grown crystalline morphology in thin films of trans-1,4-polyisoprene (TPI) was studied by optical and electron microscopy. The crystalline morphologies observed are explained in terms of thin chainfolded lamellar crystals which would grow (if unrestricted) to a diamond shape. The electron diffraction patterns obtained can be indexed using the unit cells proposed by Fisher [3]. The preferred growth faces for the low melting form crystals (LMF) are the (120) planes and probably the (110) planes for the high melting form crystals (HMF). LMF crystals are exclusive to LMF spherulites and HMF crystals are exclusive to HMF spherulites. At large supercoolings both LMF and HMF spherulites nucleate as bundles of lamellar crystals and grow by extensive, twisting, branching and spawning. LMF spherulites grown at small supercoolings develop as hedrites/axialites, or as splayed groups of large crystals differing in orientation with respect to the electron beam. The frequen...
Macromolecules, 2003
The crystallization behavior of three double crystalline diblock copolymers containing poly-(-caprolactone) and poly(p-dioxanone) has been studied via differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray scattering (WAXS). Crystallization and melting temperatures and enthalpies are compared among copolymers and to those of the corresponding homopolymers. Only one crystallization exotherm was observed for the diblocks. DSC and WAXS indicated that during isothermal crystallization PPDX crystallized first, followed by PCL. POM revealed a transformation of crystalline morphologies at around 50°C, from granular aggregates at high temperature (where only PPDX is crystalline) to banded spherulites at lower temperature, where both blocks were crystalline. The kinetics of crystallization were studied in detail via spherulite growth rates obtained from POM, and it was found that PPDX crystallization in the diblocks occurred much more slowly than in the homopolymers, this being responsible for the observed coincident crystallization of the two blocks during DSC cooling scans. On the other hand, the crystallized PPDX acts to nucleate the PCL block, so that heterogeneous crystallization was always observed even in copolymers containing a minority of this component (23%), for which "confined" crystallization might be expected. The crystallization kinetics of the PCL in the copolymers is accelerated by the presence of the crystalline PPDX block.
ACS Applied Polymer Materials
1. Materials and Methods Materials. The description of most of the materials for the syntheses of PEO 11-TR-(CH 2) n-TR-PEO 11 (with n = 2-4) can be found elsewhere. 1 Additionally, 1,8-nonadiyne (98%), 1,7dibromoheptane (97%) and 1,8-dibromooctane (98%) were purchased from Sigma Aldrich and used as received. 1,9-Decadiyne (≥ 98%) was purchased from TCI Chemicals and also used as received. Acetone and ethyl acetate were purchased from VWR International. For the syntheses of the ,-bis(1-methyl-1,2,3-triazole-4-yl)alkanes (TR-(CH 2) n-TR, n = 2-6), dichloromethane (≥ 99.9%), N,N-dimethylformamide (≥ 99.8%), sodium azide (≥ 99%) and sodium sulfate (≥ 99%) were acquired from Carl Roth. Iodomethane (≥ 99%), 1,7-octadiyne (98%), 1,8-nonadiyne (98%) and bromotris(triphenylphosphine)copper(I) (98%) were purchased from Sigma Aldrich. 1,5-Hexadiyne (> 95%) and 1,6-heptadiyne (> 98%) were obtained from TCI Chemicals and 1,9-decadiyne (97%) was bought at Alfa Aesar. Differential Scanning Calorimetry. A Mettler Toledo DSC 822 e module recorded the DSC traces under continuous flow of nitrogen (10 mL min-1). The polymers were heated to T = 100 °C, held there for 5 min. Then, they were cooled to T =-40 °C with a rate of 1 K min-1. Finally, the polymers were heated to T = 60 °C with a heating rate of 1 K min-1. The model compounds were heated to 200 °C, held at this temperature for 5 min, and cooled down to 25 °C. After 5 min at this temperature, the samples were heated to 200 °C again. The heating rate was 5 K min-1. The melting temperatures and enthalpies were determined from the second heating cycle.
Thermal properties and crystalline structure of poly(10-undecene-1-ol)
European Polymer Journal, 2011
Thermal properties and crystalline structure of liquid crystalline (LC) poly(ethylene terephthalate-co-2(3)-chloro-1,4-phenylene terephthalate) [copoly(ET/ CPT)] were investigated using differential scanning calorimetry (DSC), thermogravimetry (TGA), limiting oxygen index (LOI) measurement, electron dispersive X-ray analysis (EDX), X-ray diffractometry, and infrared spectrometry (IR). The thermal transition temperatures of copoly(ET/CPT) were changed with the composition. Copoly(ET/ CPT) showed two thermal decomposition steps and the residues at 700°C and LOI values of copoly(ET/CPT) were almost proportional to its chlorine content. The activation energy of thermal decomposition of LC units was very low compared to that of poly(ethylene terephthalate)(PET) units. Crystal structure of copoly(ET/CPT) (20/80) was of triclinic system with the lattice constants of a ϭ 9.98 Å , b ϭ 8.78 Å , c ϭ 12.93 Å , ␣ ϭ 97.4°,  ϭ 96.1°, and ␥ ϭ 90.8°, which is very close to that of poly(chloro-pphenylene terephthlate) (PCPT) with the lattice constants of a ϭ 9.51 Å , b ϭ 8.61 Å , c ϭ 12.73 Å , ␣ ϭ 96.8°,  ϭ 95.4°, and ␥ ϭ 90.8°. When copoly(ET/CPT)(50/50) was annealed at 220°C in vacuum, crystallization induced sequential reordering (CISR) was not observed but the heat of fusion was slightly increased due to the increase of the trans isomer content in PET units.