Simultaneous differential scanning calorimetry (DSC), small-angle (SAXS) and wide-angle X-ray scattering (WAXS) measurements were adopted for more precise determination of the equilibrium melting temperatures (Tm*) of a and b phases in bulk-crystallized syndiotactic polystyrene. On the basis of Kratky-Porod approximation, a new method for determining crystalline lamellar thickness from SAXS profiles obtained at high temperatures where there are only limited number of discrete crystalline lamellae dispersed in the melt matrix was developed. This method is shown to be reliable as it gave comparable results obtained from the conventional 1D correlation function method for SAXS profiles obtained at lower temperatures where lamellae are closely stacked. Results of the subsequent Gibbs-Thomson analysis indicated that the trigonal a phase is the entropically favored high temperature phase with Tm* = 355 oC whereas the b phase is enthalpically favored at lower temperatures, with Tm* = 314 oC. Compared to previous held contention in the temperature-dependent phase stability of these two phases, the current phase stability assignment is more consistent with both the density and the symmetry of the corresponding crystal structures. It also explains various observations reported previously on the competition between the two polymorphs during crystallization and during melting.

Crystallization kinetics and melting behavior of PEEK were studied by differential scanning calriometry (DSC) and modulated differential scanning calriometry (MDSC). The isothermal crystallization was performed in DSC between 290 and 320¢XC. The Avrami constants (n1, n2) and the level off time were determined from the Avrami analysis. The n1 values varied from 1.50 to 2.98, and the n2 values were between 0.52 and 1.37. The minimum induction time required for the occurrence of double melting peaks was obtained by increasing the isothermal crystallization time in a interval per minute. It was found that the minimum time was always longer than the level off time, which cannot be used as the delimitation for the occurrence of single or double melting peaks. To study the melting behavior and the mechanisms of double melting peaks, the samples after melting at 400¢XC for 15 min were crystallized isothermally between 200 and 320¢XC for 10 or 60 min, and then they were heated to 380¢XC at 10 or 2 ¢XC/min, respectively. From the MDSC results of crystallization temperatures between 280 and 310¢XC, it is found that two different morphologies and melting-recrystallization phenomenon coexisted. As the isothermal crystallization temperature increased from 280 to 310¢XC, the contribution of melting-recrystallization to the upper melting peak gradually decreased. In the case of 320¢XC, the mechanisms of double melting peaks were dominated by two different morphologies only. Quasi-isotropic composites in the stacking sequence of [0/¡Ó45/90]2s were fabricated by a modified diaphragm forming apparatus. Three different processing conditions were used to prepare AS4/PEEK composites with the same crystallinity but different transcrystallinity. The morphology before and after the long-term tensile-tensile tests was observed by means of scanning electron microscope. The transcrystallinity has no significant effect on the short-term tensile test. This was due to the fibers in the 0¢X plies of [0/¡Ó45/90]2S laminates dominated the failure at high stress for the short-term tensile test. However, as the transcrystallinity increased, the failure cycles for the long-term tensile test became longer. This expressed that the delay of damage initiation in the 90¢X and ¡Ó45¢X plies of [0/¡Ó45/90]2s led to a longer failure cycles in the long-term tensile tests.

This thesis contains two parts of materials characterization. Part I is a poly(butylene succinate) copolymer with minor amount of 2-methyl-propylene succinate. In the second part, six kinds of implant crowns made from five dental casting alloys and one Zircoina ceramic are studied. Copolyester was synthesized and characterized as having 89.0 mol% butylene succinate units and 11.0 mol% 2-methyl-propylene succinate units in a random sequence, revealed by NMR. Isothermal crystallization kinetics was studied in the temperature range (Tc) from 75 to 91 ¢XC using differential scanning calorimeter (DSC). The melting behavior after isothermal crystallization was studied by using DSC by varying the Tc, the crystallization time and the scanning rate. DSC curves showed triple melting peaks. Multiple melting behaviors indicate that the upper melting peaks are associated with the primary and the recrystallized crystals, or the crystals with different lamellar thickness. As the Tc increases, the contribution of recrystallization slowly decreases and finally disappears. A Hoffman-Weeks linear plot gives an equilibrium melting temperature of 118.4 ¢XC. The spherulitic growth rates of this copolyester were measured at Tc between 69 and 91 ¢XC using an optical microscope equipped with a CCD camera. The kinetic analysis of the growth rates gave a regime II-III transition temperature at about 77.2 ¢XC. Rectangular specimens of 10 ¡Ñ 9 ¡Ñ 4 mm were made of five kinds of casting alloys, separately. They were treated in the same procedures as crowns did. Their surfaces after oxidation were analyzed using x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Rectangular specimens after applying porcelains were ~5.5 mm thick. The cross-section areas were studied by electron probe micro analyzer (EPMA). Standardized maxillary premolar crowns were fabricated with five different alloys and one Zircoina ceramic. The crown specimens were positioned in a custom testing apparatus and vertically loaded on the middle of the occlusal surface with a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. Mean values of load at fracture were calculated in each alloy and compared with a one-way analysis of variance and Tukey test (£\=0.05). The fracture surfaces were examined using SEM. The results of XPS, SEM and EPMA indicate that on the surface there was an oxidation layer (or interface between metal and ceramic) of indium (or/and tin, zinc, etc.). The concentration of oxide metal increased, whereas that of precious metal decreased, from bulk to interface. The fracture strength and the fracture path of the crowns were correlated with the metal-ceramic interface of the rectangular specimens that was characterized using XPS, SEM and EPMA.

P3DDT (3-dodecylthiophene-2,5-diyl) and PCBM( [6,6]-phenyl C61-butyric acid methyl ester) were fabricated to the active layer of Bulk Heterojunction Organic Solar Cells .We obtained the device efficiency was 0.64 % by evaporating solvent at room temperature. We measured Thermal decomposition Temperature (Td) of P3DDT was 487¢J. But operational temperature was over 90¢J, it could affect the roughness of thin film and make efficiency to be 4¡Ñ10-3(%). For results of experiments, we know that roughness changed by the crystallization of side chain and exciton dissociation modified by the morphology between P3DDT and PCBM. Thin film solar cell has a large effect on the formation of active layer, such as heat treatment, choices of solvents, composition ratio, and speed of spin coating. The efficiency of solar cell has been shown to be highly sensitive to the size, composition and crystallization of the formed domains. We studied two kinds of conjugated polythiophenes with the same main chain but different side chain. When the number of carbon atoms of alkyl side chains is more than 10, some orderly arrangements will occur for side chains between the layers. We tried to explain the crystallization caused by long alkyl side chains determined which intrinsic phenomena are the most evident for altering the PCE of solar cell. After recrystallization, the layered structures of P3DDT can be improved, but those orderly degrees of the arrangements with PCBM are further aggregated. The main point for low PEC and Jsc by heat treatment is the unfavorable and roughened morphology. Charge transfer only occurs at the boundary ,which is interfacial area between donor and acceptor materials, hence, the low Jsc could be caused by poor charge transfer between P3DDT and PCBM. The redistributed arrangement of P3DDT domains exclude PCBM from original space, and it makes PCBM to aggregate large particles, from nanophase to mesophase scales, which reduce mutual solubility to be the source of PCE and Jsc reduction.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 135-138).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1972. / Includes bibliographical references (leaves 156-162).

No description available.

No description available.

Η ανάπτυξη πρωτεϊνικών κρυστάλλων, κατάλληλων για κρυσταλλογραφία ακτίνων-Χ, είναι γνωστό ότι είναι το βασικό στοιχείο του προσδιορισμού της πρωτεϊνικής δομής. Οι κρυσταλλογράφοι αντιμετωπίζουν σε καθημερινή βάση προβλήματα όπως η ποσότητα της πρωτεΐνης, η διαθεσιμότητα της υψηλής ποιότητας κρυστάλλων πρωτεΐνης και ο έλεγχος του μεγέθους του κρυστάλλου. Πολλές προσπάθειες έχουν γίνει για να βελτιωθεί η διαδικασία κρυστάλλωσης με τη χρήση των μαγνητικών πεδίων, της ηλεκτρό-εστίασης, και των εσωτερικών ή εξωτερικών ηλεκτρικών πεδίων. Τα ηλεκτρικά πεδία αποτελούν μια σημαντική μεθοδολογική πρόοδο και έχουν χρησιμοποιηθεί προκειμένου να ενισχυθεί η δημιουργία και ανάπτυξη πυρήνων κρυστάλλωσης. Σε αυτή την εργασία διερευνήθηκε η επίδραση της ασύρματης μεταγωγής ρεύματος κατά την κρυστάλλωση της λυσοζύμης, της ριβονουκλεάσης Α και της ινσουλίνης χρησιμοποιώντας μια πρωτότυπη συσκευή παραγωγής ιόντων. Η μέθοδος διάχυσης ατμών χρησιμοποιήθηκε σε όλες τις πειραματικές διατάξεις. Η ποιότητα των κρυστάλλων και η τρισδιάστατη δομή των πρωτεϊνών που καλλιεργήθηκαν με και χωρίς την επίδραση του ηλεκτρικού πεδίου αναλύθηκαν μέσω της περίθλασης ακτίνων-Χ. Οι κρύσταλλοι εμφανίστηκαν νωρίτερα στα δείγματα που εκτέθηκαν στο ηλεκτρικό πεδίο σε σχέση με τα μη εκτεθειμένα δείγματα κάτω από ταυτόσημες συνθήκες. Επιπλέον, οι κρύσταλλοι πρωτεΐνης που ελήφθησαν σε μικρότερους χρόνους ήταν μεγαλύτεροι σε μέγεθος. Αρκετά ενδιαφέρον ήταν ότι η ποιότητα των κρυστάλλων που αναπτύχθηκαν στις εκτεθειμένες σταγόνες ήταν η ίδια, αν όχι καλύτερη από, εκείνη των κρυστάλλων που αναπτύχθηκαν στις μη εκτεθειμένες σταγόνες σε κάποιο ηλεκτρικό πεδίο. Η διαδικασία πυρήνωσης φαίνεται να διαφέρει μετά από την έκθεση σε κάποιο ηλεκτρικό πεδίο από ότι η μη έκθεση σε αυτό υπό ταυτόσημες συνθήκες. Η χρήση της πρωτότυπης συσκευής ασύρματης μεταγωγής ρεύματος φαίνεται να επάγει τον προσανατολισμό των πολικών μορίων της πρωτεΐνης, ευνοώντας έτσι την κρυστάλλωση. Η χρήση της συσκευής προσφέρει το πλεονέκτημα ότι παρέχει φορτισμένα σωματίδια πάνω σε ολόκληρη την εκτεθειμένη επιφάνεια του διαλύματος κρυστάλλωσης, ενώ ταυτόχρονα ελαχιστοποιεί τον κίνδυνο μόλυνσης. Επίσης, η συσκευή αυτή είναι πολύ απλούστερη και ευκολότερη στη χρήση από ό,τι άλλες συσκευές με κλασικά ηλεκτρόδια. / The growth of protein crystals, suitable for X-ray crystallography is known to be the basic element of the protein structure determination. Crystallographers face problems such as the amount of the protein, the availability of high-quality protein crystals and the control of the crystal size in a daily basis. Many efforts have been made to improve crystallization process with the use of magnetic fields, electro–focusing, and internal or external electric fields. The electric fields consist a significant methodological advancement and have been used in order to enhance nucleation and crystal growth. In this work, the influence of a non-contact current transfer upon the crystallization of Lysozyme, Rnase A and Insulin was investigated using a prototype ion-generator device. The vapor diffusion method was used in both hanging and sitting drop setups. The crystal quality and the three-dimensional structure of lysozyme grown with and without the EF influence were analyzed by means of X-ray diffraction. Crystals appeared earlier in samples exposed to NCCT than in non-exposed samples under identical conditions. Furthermore, protein crystals that were obtained after shorter times were larger in size when grown after exposure to NCCT device. More interestingly, the quality of the crystals grown in NCCT-exposed drops was the same as, if not better than, that of the crystals grown in the control drops. The nucleation process after exposure to NCCT differs from that after exposure to an ion-free gas stream under identical conditions. The use of the NCCT prototype device appears to induce the orientation of the polar protein molecules, thereby favoring crystallization. The use of NCCT offers the advantage of delivering charged particles onto the entire exposed surface of the crystallization solution, while at the same time minimizes the risk of contamination. Also, the use of this device is much simpler and easier to use than other devices with classic electrodes.

Kimberlite hosts two populations of olivine that are distinguished on the basis of grain size and morphology; the populations are commonly described genetically as xenocrysts and phenocrysts. Recent studies of zoning patterns in kimberlitic olivine phenocrysts have cast doubt on the actual origins of the smaller olivine crystals. Here, we elucidate the nature and origins of the textural and chemical zonation that characterize both populations of olivine. Specifically, we show that both olivine-I and olivine-II feature chemically distinct overgrowths resulting from magmatic crystallization on pre-existing olivine xenocrysts. These results suggest that the total volume of olivine crystallized during transport is substantially lower (≤5%) than commonly assumed (e.g. ~25%), and that crystallization is dominantly heterogeneous. This reduces estimates of the Mg# in primitive kimberlite melt to more closely reconcile with measured phenocryst compositions. Several additional textures are observed in olivine, and include: sealed cracks, healed cracks, phases trapping in cracks, rounded grains, overgrowths and phase trapping in overgrowths. These features record processes that operate in kimberlite during ascent, and from these features we create a summary model for kimberlite ascent: • Olivine is incorporated into kimberlitic melts at great depths as peridotitic mantle xenoliths. • Shortly after the incorporation of these xenocrysts the tensile strength of the crystals within xenoliths is reached at a minimum of 20 km from its source. Disaggregation of mantle xenoliths producing xenocrysts is facilitated by expansion of the minerals within the xenoliths. • The void space produced by the failure of the crystals is filled with melt and crystals consisting of primary carbonate (high-Sr), chromite and spinel crystals. The carbonate later crystallizes to produce sealed fractures. • Subsequent decompression causes cracks that are smaller than the sealed cracks and are preserved as healed cracks that crosscut sealed cracks. • Mechanical rounding of the xenocrysts post-dates, and/or occurs contemporaneously with decompression events that cause cracking. • Saturation of olivine produces rounded overgrowths on large xenocrysts, euhedral overgrowths on smaller xenocrysts, and a volumetrically minor population of olivine phenocrysts. Olivine growth traps fluid, solid and melt inclusions. Calculations based on these relationships suggest that the melt saturates with olivine at a maximum depth of 20 km and a minimum depth of 7 km.