A small amount of poly(trimethylene succinate) (PTSu) were copolymerized or blended with poly(butylenes succinate) (PBSu) in this study. The range of intrinsic viscosity for PBSu and PBSu-enriched copolymers are between 1.62 and 0.97 dL/g; number-average molecular weights are in the range of 2.5x104 and 11.9x104 g/mol with polydispersity indices ranging from 1.52 to 3.94. Copolymer composition is calculated from 1H and 13C NMR spectra, and the distribution of BS and TS units in these copolymers are supported to be random from the evidence of a single glass transition temperature (Tg) and a randomness value close to 1.0. Tg of PBSu is -40.8 ¢XC. The Tg values of copolymers and blends increased with TS contents. The melting temperature (Tm) and the exothermic heat of crystallization of blends were not strongly affected by blending with PTSu. The values of Avrami exponent (n) for PBSu, copolymers and blends ranging from 2.3 to 3.1 indicate that heterogeneous nucleation with three-dimensional growth and homogeneous nucleation with two-dimensional growth might happen during the crystallization process. Multiple melting behavior was observed for PBSu, PBSu- enriched copolyesters and blends. Their peak temperatures are denoted as Tm1, Tm2 and Tm3 in order of increasing temperature. Tm1 corresponds to the melting temperature of the so-called annealing peak which might be resulted from the competition between continuous melting and re-crystallization. In contrast the peak at Tm2 is attributed to the melting of the primary crystals formed during isothermal crystallization. The peak at Tm3 may arise from the melting of re-crystallized primary crystals. Equilibrium melting temperatures were determined by the Hoffman-Weeks linear extrapolations which yield of 127.4 ¢XC for PBS, 125.7 ¢XC for PBTSA95/05, 120.6 ¢XC for PBTSu90/10, 128.6 ¢XC for PBSu/PTSu 98/02, 127.0 ¢XC for PBSu/PTSu 95/05 and 125.5 ¢XC for PBSu/PTSu 90/10. The thickness coefficient ( ) is located between 0.77 and 0.80. Three characteristics temperatures of thermal degradation, defined as temperature of thermal degradation at begining (Tstart), weight losses of 2% (Tloss2%) and maximum degradation rate (Tmax), were employed to characterize the thermal stability of polyesters and blends. The Tloss2% and Tstart values of PBTSu90/10 are higher than the values of the others because of its unusually high molecular weight. Wide-angle x-ray diffraction patterns were obtained after complete isothermal crystallization. Diffraction peaks are in the same positions, and these peaks become sharper and increase in intensity as the crystallization temperature increases. This indicates that during the heating process, only one crystal form appears and both of the crystallite size and perfect degree increase. The isothermal growth rate of PBSu spherulite increases from 0.01 £gm/sec at 103 ¢XC to 3.33 £gm/sec at 75 ¢XC. When the TS units increase, the spherulitic growth rates of PBTSu95/05 and PBTSu90/10 copolyesters decline dramatically. One of the reasons is that the incorporation of TS units into PBSu significantly inhibits the crystallization behavior of PBSu. Growth rates data were treated with Lauritzen-Hoffman secondary nucleation theory to find the regime transition. Using the Williams-Landel-Ferry (WLF) values, regime II to III transition is found at 95.1 ¢XC for PBSu, 84.4 ¢XC PBTSu95/05, and 77.1 ¢XC for PBTSu 90/10. All melt-crystallized specimens formed two dimensional axial-like spherulites with negative birefringence. Extinction bands were observed when PBSu, PBSu- enriched copolymers and blends specimens were crystallized at large undercooling.

Minor amounts of monomers or homopolymer of poly(butylene succinate) (PBS) were copolymerized or blended with monomers or homopolymer of poly(ethylene succinate) (PES). PEBSA 95/05 represents a copolymer synthesized from a feed ratio of 95 mol% ethylene glycol and 5 mol% 1,4-butanediol with 100 mol% succinic acid. Copolymers PEBSA 90/10 and 50/50 were also synthesized. Blends of PES and PBS were prepared in solution with ratios of PES/PBS: 98/02, 95/05 and 90/10. Molecular weights of homopolymers and copolymers were measured using capillary viscometer and gel permeation chromatography. The results indicate that polyesters used in this study have high molecular weights. The chemical composition and the sequence distribution of co-monomers in copolyesters were determined using 1H NMR and 13C NMR. The distribution of ES and BS units in these copolyesters was found to be random from the evidence of a single Tg and a randomness value close to 1.0 for a random copolymer. Thermal properties of polyesters and blends were characterized using differential scanning calorimeter (DSC), temperature-modulated DSC (TMDSC) and thermogravimeter. For copolymers, melting point of PES significantly decreases from 100.9 to 94.5 to 89.8 oC with an increasing in BS units from 0 to 5 to 10 mol%. Blends keep the intrinsic melting points of PES and PBS homopolymers. There is no significant difference or no trend about the thermal stability of these polyesters and blends. Wide-angle X-ray diffractograms (WAXD) were obtained for specimens after complete isothermal crystallization. Diffraction peaks indicate that the crystal structure of PES is dominated in PES-enriched copolymers. However, PEBSA 50/50 displays weak diffraction peaks of the characteristic peaks of PBS homopolymer. Isothermal crystallization of copolyesters and blends were performed using DSC. Their crystallization kinetics and melting behavior after complete crystallization were analyzed. The n1 values of the Avrami exponent for copolyesters increased from 2.54 to 2.84 as the isothermal temperature (Tc) increased. The Hoffman-Weeks linear plots yielded an equilibrium melting temperature of 111.1 and 107.0 oC, respectively, for PEBSA 95/05 and 90/10. Homopolymer PES has an equilibrium melting temperature of 112.7 oC. For blends, the n1 value has a minimum at Tc of 40 oC then it increases with an increase in Tc or in PBS. At the same Tc, n1 increases slightly and the rate constant (k1) decreases when the ratio of PBS in blends increases. All of these blends gave an equilibrium melting temperature of 113.1 oC. Multiple melting behavior involves melting-recrystallization-remelting and various lamellar crystals. As Tc or BS unit in copolymer increases, the contribution of recrystallization slowly declines. Acetophenone was used a diluent for PES homopolymer. Five concentrations were used to estimate the melting point depression, and the heat of fusion of PES was obtained to have a value of 163.3 J/g according to Flory equation. Spherulitic growth rates of copolymers were measured at Tc between 30 and 80 oC using polarized light microscope (PLM). Maximum growth rates occurred at Tc around 50 oC. It is found that the growth rate of copolymer decreases significantly after randomly incorporating BS units into PES. Non-isothermal method at a cooling rate of 2, 4 or 6 oC/min was used to calculate the isothermal growth rates of copolymers. These continuous data fit very well with the data points measured isothermally. Growth rates data are separately analyzed using the Hoffman-Lauritzen equation. A regime II-III transition is found at 59.4 and 52.4 oC, respectively, for copolyesters PEBSA 95/05 and PEBSA 90/10. The results of DSC and PLM indicate that blend PES/PBS 98/02 not only retains the melting point and the crystallinity of PES homopolymer, but also increases the nucleation rate of this blend. The effect of blending 2 mol% PBS with PES on the biodegradability of PES is deserved to be investigated furthermore.

No description available.

No description available.

none

NO ENGLISH ABSTRACT.

Because CFC-11 and CFC-12 are extremely stable and purely anthropogenic and the CFCs enter the ocean through air-sea exchange at the sea surface, they serve as good tracers for studying the oceans. Since CFCs and tritium share similar characteristics such as their anthropogenic production, inertness to biological activities, a tritium box model applied to the North Atlantic Ocean by J. L. Sarmiento in 1983 is used to study the distribution of CFCs in the Northwest Pacific. This thesis attempts to use this model to calculate the past concentrations of CFCs in the atmosphere assuming equilibrium distribution between the surface ocean waters and the atmosphere in the source region of the oceans. The results may allow us to check the history of CFCs in the atmosphere. The data used in this thesis are those reported by NOAA from three cruises: CO2-87 and CGC92 along 165oE and CO2-88 along 170oW, all from 40o to 10oN. This latitude range avoids the complex gyres and the sea-ice which may limit the air-sea exchange in the North, and also avoids the upwelling in the equatorial region. The outcrop of the 26.0 sq water is located at longitude about 52o-53oN along 165oE, but is located at about 40oN along 170oW. The outcrop will move southward in winter. The vertical distribution pattern of CFCs is similar to that of oxygen. Concentrations of CFCs in ocean water increase as potential temperature and salinity decrease. High latitudes of low temperature and salinity have high CFC solubility and high air-sea exchange rates, and are presumably the major areas for input of CFCs into the seawater. As the CFCs in the air increase over the years the concentrations of CFCs in the surface ocean water also increase but decrease with water depth. The solubility, F, of CFCs is a function of both temperature and salinity, but temperature prevails. The F values for CFC-11 and CFC-12 from 10o to 50oN along 165oE are 5.86-16.0 and 1.70-4.15 mmole/kg/ atm, respectively. The values along 170oW are, respectively, 6.60-22.2 and 1.89-5.55 mmole/kg/atm. The solubility of CFC-11 is about four times as large as that of CFC-12. The solubility of CFCs along 170oW is about 1.4 times along 165oE because of temperature and salinity differences. The exchange rate in the time scale for =1 year ranges 0.85-1.3 yr-1, CFC-11 has a mean of 0.99 yr-1, CFC-12 has a mean of about 1.04 yr-1. Along the isopycnal surface of sq=26.0, the highest exchange rate between two boxes is 2.34 yr-1, the lowest 0.06 yr-1. Based on the calculated concentrations of CFCs in the surface seawater from the atmospheric value in the past, apparent ages of the Mode Waters are similar for both CFC-11 and CFC-12. The apparent age along 165oE at 10oN is about 17 years on the defined isocypnal surface, and it is about 15 years along 170oW at 10oN. The spreading rate of CFCs in the Northwest Pacific is thus about 172-221 km/yr. During the 17 years, the annual increase in influx to the seawater is about 0.12 pM/kg/yr for CFC-11, and about 0.059 pM/kg/yr for CFC-12. The error in calculating atmosphere CFCs in the past is about 11 % for CFC-11, and 6 % for CFC-12.

The effects of work¡¦s surface wavelength on the ultimate surface roughness are considered in this study. Both the experimental and theoretical studies will be done in this study. In the experimental study, the relationships between ultimate surface roughness and various operating parameters will be examined. In the theoretical study, a mathematical model relating the machining rate and various machining parameters are proposed. In the mathematical model, qualitative and quantitative properties of machining rate under various surface geometric condition are obtained by the aid of computer simulation. For the experimental study, a series of experiments will be done to investigate the effects of various factors on the ultimate surface roughness of different work¡¦s surface wavelength.The factors may include the the tool speed, the tool¡¦s surface irregularity, and the particle density of slurry. The comouter simulation indicates that the removal rate is non-linear proportional to tool speed and normal load. Besides, results also showed that the difference of removal rate between peak and valley of surface profile always decreases as the work¡¦s surface wavelength increases. The experimental study confirmed that the relationship between ultimate roughness and wavelength does exist in the specific range of work¡¦s surface wavelength . The model appears to be consistent with currently available experimental data.

None

Customer load characteristics provides very critical information for power system operation. The accuracy of load forecasting and the effective cases of system generation and network planning can be enhanced by the investigation of customer load characteristics. In this thesis, the intelligent meters have been used to collect the power consumption within each 15 minutes of study customers, which have been selected by stratified sampling method. The typical load patterns of each customer class have been derived. The load composition and the power system load profile of Fengshan District in Taipower have been solved by the typical load patterns and the power consumption of each custom class. To investigate the distribution system reliability, the service territory of Fengshan district is divided into six service areas. The forecasting of yearly peak loadings for each area over the future 20 years is performed by the time series method based on the historical load data and load characteristics. By using the forced outage rate ¡]FOR¡^ of main transformers in the substations, the loss of load expectation¡]LOLE¡^ which corresponds to yearly peak loading of each service area is solved. By this way, the capacity expansion planning of main transformers to meet the service reliability can therefore be derived. To further enhance the distribution system planning, the capacity transfer capability of main transformers and the tie line flow capacity between different areas are considered too. It is found that the expansion planning of main transformers by the proposed methodology can provide better cost effectiveness of transformer investment to satisfy the service reliability as well as the system peak loading.