Effects of the crystallization temperature on crystal structure and its melting behavior poly (l-lactic acid) (PLLA) have been investigated by means wide-angle (WAXS) small-angle (SAXS) X-ray scattering, optical microscopy, differential scanning calorimetory (DSC). PLLA was found to crystallize as α form when Tc higher than 120 °C, while significant change in lattice parameters seen for Tc's below °C. The ratio a- b-axis lengths begins decrease with °C is 31/2 90 which suggests a new...

Effects of the addition PDLA on crystallization behavior PLLA was investigated by means differential scanning calorimetry, wide-angle X-ray diffraction, melt rheology, and polarized optical microscopy. Nonisothermal isothermal including low (l-PDLA) high molecular weight (h-PDLA) were studied. PLLA/PDLA asymmetric blends form stereocomplex (SC) crystal stay unmelted at 200 °C in melt. measurement from showed monotonous rise temperature for PLLA/h-PDLA blend, while peculiar concentration...

We performed small-angle neutron and X-ray scattering (SANS SAXS) measurements on an elongated blend of low molecular weight deuterated polyethylene (PE) high hydrogenated one (97.2/2.8) in a very wide range vector 1 × 10-4−3 Å-1 to elucidate hierarchic structure the so-called shish-kebab. Comparing SANS SAXS data, we found that PE formed large long object aligned along elongation direction. The data were analyzed terms multicore−shell cylinder model, oriented had radius ∼1 μm length ∼12...

Abstract The nucleation event of amyloid fibrils is one the most crucial processes that dictate timing and rate pathology diseases; however, information regarding how protein molecules associate to produce fibril nuclei currently limited. In order explore this issue in more detail, we performed time-resolved small angle X-ray scattering (SAXS) measurements on insulin fibrillation, combination with additional multidirectional analyses thioflavin T fluorescence, FTIR spectroscopy, light...

Aiming to clarify the mechanism of crystal nucleation polymers, we have made a quantitative investigation about conformational change syndiotactic polystyrene (sPS) during induction period (ca. 30 min) when crystallized at 120 °C, 25 K above glass transition temperature Tg = 95 from glassy state, i.e., for so-called crystallization by time-resolved Fourier transform infrared (FT−IR) spectroscopy. It was found that even in period, absorbance trans conformation bands begins increase and it...

The crystallization process of isotactic polypropylene (iPP) by heating from the prequenched mesomorphic phase has been studied using wide-angle X-ray diffraction, small-angle scattering, and optical microscopy. Mesomorphic iPP as quenched shows well-known nodular structure ca. 100 Å. In nodules grew larger keeping self-similarity, with partially transforming into crystalline inside nodules. After reaching isothermal process, stopped to grow at a certain quasi-equilibrium size depending on...

The thermal expansion behavior of polystyrene (PS) thin films was investigated using x-ray reflectivity, focusing on ultrathin below 10 nm. It found that the glass transition temperature T(g) decreases with thickness as reported by many researchers while it is almost independent and constant at 354 K for approximately dependence well reproduced a two-layer model consisting mobile surface layer 354.5 bulklike 373 ( =bulk ), suggesting so-called immobile dead near substrate negligible or very...

We performed neutron reflectivity measurements on multilayered polymer thin films consisting of alternatively stacked deuterated polystyrene (d-PS) and hydrogenated (h-PS) layers ∼200 Å thick as a function temperature covering the glass-transition T(g), we found wide distribution T(g) well thermal expansivity α within films, implying dynamic heterogeneity along depth direction. The reported anomalous film thickness dependences were reasonably understood in terms distributions, showing that...

Preparation of strong fiber with ultrahigh strength and modus is a dream polymer scientists engineers. It believed that shish-kebab the structure origin modulus fiber. This article presents our investigation on inner precursor isotactic polystyrene in μm scale formed by shear flow above nominal melting temperature Tm using microbeam wide- small-angle X-ray scattering (WAXS SAXS). The WAXS experiments indicated included crystallites degree crystallinity ∼0.15%, which had higher than normal...

We studied crystallization process of isotactic polypropylene (iPP) under shear flow as a function rate using time-resolved wide-angle X-ray scattering (WAXS), small-angle (SAXS), depolarized light (DPLS), and polarized optical microscopy (POM) to elucidate the formation mechanism so-called shish-kebab structure in wide spatial scale from 0.1 nm several tens μm. In DPLS, SAXS, WAXS measurements we observed processes shish-like structure, kebab crystalline lattice (mostly kebab),...

The effect of isotacticity on the mesomorphic phase-forming properties isotactic polypropylene (iPP) is reported. Only iPP having high (iPP-HT) can form phase by a rapid quench, but low (iPP-LT) cannot though it crystallizes same quenching rate. These results suggest that closely related to stereoregularity polymer chain. in iPP-HT shows longer regular 3/1 helices than crystalline iPP-LT. structure and formation mechanism are considered analogous those liquid crystals since average length...

We performed small-angle X-ray scattering (SAXS) measurements on crystallization processes of polyethylene blends low molecular weight and ultrahigh components with various blending ratios in order to clarify effects component shish-kebab structure formation. Anisotropic patterns due kebab formation were observed above a certain concentration polyethylene. The critical was about ∼0.1 wt % independent the temperature below 125 °C, while it increased °C. Analyzing correlation between more...

A phase transition is observed between a one-phase disordered and an ordered with multilamellar (onion) structures in off-critical mixture of ${\mathrm{D}}_{2}\mathrm{O}$ 3-methylpyridine (3MP) containing 85 mM salt the absence surfactant. The consists hydrophilic cations hydrophobic anions that interact asymmetrically solvent composition fluctuations inducing mesophases. structure factor distribution obtained from small-angle neutron scattering has peak at intermediate wave number multiple...

Extensive studies on polymer thin films to date have revealed their interesting but unusual properties such as film thickness dependence of glass transition temperature Tg and thermal expansivity. Recent shown that the lower is not always related higher mobility in films, which contradicts our current understanding process. In this work, we report results inelastic neutron-scattering measurements polystyrene using two spectrometers with different energy resolutions well ellipsometry...

Time-resolved light scattering measurements were performed on gelation processes of poly(vinyl alcohol) (PVA) solutions at 25 °C in mixtures dimethyl sulfoxide (DMSO) and water (H2O) with volume ratios 60/40 80/20. It was found that the profile I(Q) from a (DMSO/H2O) solution has maximum whose position Qm is independent time intensity Q = increases exponentially time. These observations agree theoretical predictions for initial stage spinodal decomposition (SD) type phase separation, while...

We report x-ray reflectivity measurements on polystyrene thin films supported silicon wafer. In annealing experiments, we found fast and slow contraction processes in the above glass transition temperature. The former is normal relaxation (annealing) process observed bulk, latter unexpected enhanced below approximately 20 nm. addition, extremely reexpansion glassy state. These very are discussed terms of lateral expansion driven by entropic changes at interfaces difference expansivities between

We studied the distribution of glass transition temperature (${T}_{\mathrm{g}}$) through neutron reflectivity in a poly(methyl methacrylate) (PMMA) thin film supported on silicon substrate with five-layered PMMA consisting deuterated-PMMA and hydrogenated-PMMA. The depth ${T}_{\mathrm{g}}$ was successfully observed film. Compared to previously reported polystyrene film, presence long-range interfacial effect, supposedly caused by an interaction between substrate, is considered be responsible...

We have studied the glass transition temperature (${T}_{g}$) and molecular mobility of polystyrene (PS) thin films near interface between polymer film substrate with bilayer consisting surface hydrogenated PS (h-PS) bottom deuterated (d-PS) using neutron reflectivity. With decreasing thickness d-PS layer, ${T}_{g}$ increased compared to bulk a drastic increase was observed for layer 155 \AA{} thick. The orientation chains at is supposed be related substrate. chain decreased even no...