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The higher-order structure and the formations of SC and HC of the PLLA/PDLA blend melt-electrospun fibers collected on a rotating target were investigated. The diameter of the fiber decreased and the orientation factor increased with increasing take-up velocity. The formation of SC was promoted with decreasing fiber diameter and with increasing take-up velocity. The fiber collected on the fixed target was amorphous and did not show the molecular orientation to any particular directions indicating that the stretching of the fiber by the electrostatic force did not give much molecular orientation to the fiber. On the other hand, the stretching of the fiber by applying the mechanical taking-up gave a significant degree of the molecular orientation to the fiber direction. The crystalline orientation of HC of the annealed fiber was higher than that of SC.

Bis maleimide-terminated poly-L-lactide (M-PLLA-M) and bis furan-terminated poly-D-lactide (F-PDLA-F) were synthesized by isocyanate coupling reactions of mono maleimide-terminated PLLA (M-PLLA) and mono furan-terminated PDLA (F-PDLA) that had been prepared by the ordinary ring opening polymerization of L- and D-lactides with N-(2-hydroxyethyl)-maleimide and furfurylamine as the initiators, respectively. Both the M-PLLA-M and F-PDLA-F were dissolved in CH2Cl2 in 1:1 ratio and subjected to the ordinary electrospinning where the initial polymer concentration was increased up to 20 wt% because of the prepolymer state of the solute and the fiber diameter could be retained in nanometer to submicron size. The molecular weight of the polymers was found to have increased from 1.0 × 104 to 2.5 and 4.5 × 104 after the electrospinning and post annealing, respectively, due to the spontaneous chain extension taking place by the terminal Diels-Alder reaction of M-PLLA-M and F-PDLA-F to form a stereoblock polylactide. The as-spun fibers were amorphous or partially semi-crystalline, whereas the annealed fibers become fully crystalline due to the formation of the stereocomplex showing a melting temperature above 200oC.

Thin fibers having diameters ranging from 25 nm to 2 micro-m were successfully electrospun from solutions of polylactides (PLA) having different molecular weights both in entangled and aligned fiber forms. The latter aligned fibers were collected with a new target comprising a rotor around which several fins were attached. Low viscosity of the solutions resulted in formation of beads or beads-on-strings, while high viscosity gave homogeneous fibers at optimum conditions. The resultant aligned fibers were drawn to 2 - 3 times at various optimum temperatures. WAXD of the drawn fibers revealed smectic nature of the PLA chain arrangement in spite of crystal orientation supported. The mechanical properties of the PLA fibers were also improved after drawing.

Solution-spun PLLA⁄PDLA blend fibers were obtained by the laboratory size spinning machine. The fibers obtained were drawn to various ratios at temperatures ranging from 80 to 140°C and subsequently annealed at 200°C under tension. Solution-spun fibers were highly crystallized during the coagulation process in the solution spinning and only the a-form homo-crystal of PLLA and PDLA were detected. Drawing of the fiber at temperatures between 80°C and 160°C did not promote the stereocomplexation between PLLA and PDLA. The drawn fiber seems to have two homo-crystal phases, one easily transformed to the streocomplex upon annealing at an elevated temperature and the other stayed either homo-crystal or melted during annealing and froze into the amorphous phase. The fibers drawn to higher ratios at higher temperatures, which showed a large melting peak of the homo-crystal at higher temperature region, kept homo-crystal phase even upon annealing at 200°C. On the other hand, the fibers drawn to lower ratios at lower temperatures, which show the single melting peak of homo-crystal at a lower temperature region, changed the structure from oriented homo-crystal to the oriented stereocomplex upon annealing. Due to the small content of oriented stereocomplex crystal and larger content of unoriented amorphous phase, the fibers annealed at an elevated temperature have fairly poor mechanical property.

Poly(L-lactic acid) fibers were prepared by the melt electro-spinning process using CO2 laser irradiation. A grounded metallic flat plate and a grounded metallic rotating blade were used to collect the electrospun fibers. The fiber structure was investigated by polarizing optical microscopy, scanning electron microscopy and X-ray diffraction. The average fiber diameters were decreased with laser output power applied, and the fiber diameters collected on the flat collector were smaller than those collected on the rotating collector. The polarized light micrograph observation under crossed-nicol clearly showed an optical anisotropy of the as-spun fibers. The X-ray diffraction patterns of the annealed fibers showed a crystal orientation. Although the uniaxial drawing of the fibers up to x 2 enhanced the crystalline orientation, the crystal modification was unchanged.

Poly(lactic acid) (PLA) was blended with baked shell powder increasing the content up to 10wt%, and the influence of mixing the powder on the physical properties of the obtained PLA compounds were investigated. The measurements for storage modulus E' revealed that the settled powder will promote the crystallization of PLA. Moreover not only the thermal decomposition but also the biodegradation in compost system for PLA were enhanced by the mixing the powder.

Poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) with high molecular weights were melt mixed in a special procedure into a blend which produced the stereocomplex without indicating any trace of the occurrence of the homo-crystal. The granular blend with high stereocomplex content was obtained by mixing PLLA and PDLA at a temperature between Tms of the homo-crystal and the stereocomplex. This blend produced the stereocomplex consistently even in the repeated melting-solidifying processes. The formation of the block-copolymer of L- and Dlactic acids suspected to occur during the blending at high temperature may act as either the nucleating agent of the stereocomplex crystal or the compatibilizing agent for PLLA and PDLA. The blend obtained was melt-spun into amorphous fibers. Some of the drawn fibers showed very broad WAXD reflections from the alpha-form crystal, which immediately transformed to the stereocomplex in the annealing process at elevated temperatures without relaxing the molecular orientation. The annealing under tension seemed to extend the tie molecules between lamella of the stereocomplex and the change in the structure significantly reflected the mechanical property.

Bacterial poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBH) highly oriented films were prepared by the combination of roll and uniaxial drawing processes. Compression molded films, which is rather brittle, turned to be ductile after roll drawing up to x 2, and the films were further uniaxially drawn to a draw ratio as high as 1000 %. The PHBH film with the tensile strength of 178 MPa and the modulus of 1.4 GPa were obtained. The roll drawn PHB film showed a slight crystalline orientation of Alpha-form. The orientation advanced with uniaxial draw ratio and the formation of Beta-form crystal was observed. Relations among the processing conditions, higher order structures and mechanical properties were investigated using wide-angle X-ray diffraction, differential scanning calorimetry, and tensile measurements.

Poly(butylene succinate) copolyesters with terephthalic acid (T) were melt-spun into monofilaments, subsequently were drawn with draw ratio of 2-6 times. The structure and properties of these drawn fibers were examined by wide angle X-ray scattering, differential scanning calorimetry, tensile test and scanning electron microscope (SEM). The enzymatic degradation of these fibers was performed in a buffer solution with Rhizopus delemar lipase at 37°C and evaluated by weight loss, SEM observation and tensile strength retention. The copolyester with 17 mol % of T component (T-17) fiber drawn with draw ratio of 6 times at 40°C showed the much higher degradation rate than poly(butylene succinate) and the copolyester with 52 mol % of T component (T-52) fibers. Tensile strength of T-17 fiber was decreased appreciably at the initial stage of the enzymatic degradation. The degradation rate of T-17 fiber was remarkably decreased with increasing the draw ratio of the fibers due to the increase in crystallinity and the development of orientation in the amorphous region.

High polymers of poly(butylenesuccinate) (PBS) and poly(butylenesuccinate-co-L-lactide) (PBSL) were melt-spun by the on-line spinning and drawing technique. The PBS fibers were drawn 4 - 12 times, while the PBSL fibers were drawn 4 - 40 times. The structcre and properties of these drawn fibers were studied by tensile test, WAXS, birefringence, and SEM. It was revealed that the tensile strength and modulus of the PBS and PBSL fibers mcreased with increasing craw rato while then tensile clongation was kept significantly high because of the low glass transition temperature of both polymers The molecular orientation of these fibers were comparable with that of the ordinary synthetic fibers such as Nylon 6 as judged by birefringence. Both PBS and PBSL fibers were found to be degraded quickly by enzymatic hydrolysis using a lipase originated from Pseudomonas, while they were little degraded in phosphate buffer (pH 7.0). The inclusion of a small amount of L-lactic acid units into the PBS sequences gave little effect on the degradability and mechamcal properties of these fibers.

Tranilast, N- (3, 4-dimethoxycinnamoyl) anthranilic acid), which suppresses the fibro blast hyperpalsia, and poly (e-caprolactone) (PCL), a biodegradable polyester with a low melting point, were blended and melt spun to produce the drug releasing biodegradable fibers.Thermal analyses, polarized optical microscope observation, and WAXD analyses revealed that tranilast existed as crystal in PCL solid at room temperature and dissolved in molten PCL at an elevated temperature. This tranilast acted either as a crystal nucleating agent or an impurity which obstracted the crystallization of PCL depending on the tranilast content and the thermal history.Melt-spun fibers of PCL/tranilast blends had mechanical properties which deteriorated with increasing tranilast contents. The drug release rate decreased with increasing draw ratio. This seems to be attributable to high crystallinity of drawn fibers.

Silicon monoxide (SiO) amorphous layer was deposited on the biaxially oriented nylon 6 films in a vacuum evaporator. This deposited layer tightly attaches to the nylon film. SiO deposited nylon 6 films thus obtained are transparent and show a high barrier to the water vapor and oxgen. Wettability of the SiO surface of the film to the water, ink, and the adhesives are satisfactory for the gravure printing and lamination with polyolefin films. It was found that the gloss of nylon film, which reflects the surface roughness of the film, affects the uniformity of SiO deposited layer on the nylon film and barrier property of the deposited films. Permeabilities of the water vapor and oxygen through the SiO deposited nylon films were fairly high just after the deposition, especially when the deposited layer was thin, and then decreased to lower equilibrium values. These equilibrium values are surprisingly low comparing with other high barrier films such as nylon and polypropylene films coated with poly (vinylidene chloride). Further the SiO vacuum deposition was continuously carried out on the running nylon film. We found that the thickness of the silicon oxide layer on the nylon film and the water permeability are strongly related to the running velocity of the nylon film and the applied electric current to the heater.

The chain conformations of polyethylene (PE), polypropylene (PP), poly (vinyl chloride) (PVC), polystyrene (PS), and poly (methyl methacrylate) (PMMA) were analyzed by MM2 (91) in which oligomeric model compounds composed of several repeating units were used as the initial structures. The optimized steric structures of the model compounds were found to correlate with those of the extended chains of the original polymers both in the crystalline and amorphous states. Therefore, these structures were used for estimating the values of birefringence of the polymers, for which a new program called MBES was newly developed. It was found that the resulting values of birefringence based on the structural data of MM2 are more reliable than those calculated by the conventional estimation method, especially for amorphous polymers.