Laser light-scattering study of novel thermoplastics .2. Phenolphthalein poly(ether sulfone) (PES-C)

Five narrowly distributed fractions of phenolphthalein poly(ether sulfone) (PES-C) were studied in CHCl3 by both static and dynamic laser light scattering (LLS) at 25 degrees C. The dynamic LLS showed that the PES-C samples contain some large polymer clusters as in previously studied phenolphthalein poly(ether ketone)(PEK-C). These large clusters can be removed by a 0.1-mu m filter. Our results showed that [R(g)(2)](1/2)(z) = (3.35 +/- 0.13) x 10(-2) M(w)((0.52 +/- 0.03)) and [D] = (2.26 +/- 0.02) x 10(-4)M(w)-((0.54) +/- 0.03)) with [R(g)(2)](1/2)(z), M(w) and [D] being the z-average radius of gyration, the weight-average molecular weight, and the z-average translational diffusion coefficient, respectively. A combination of static and dynamic LLS results enabled us to determine D = (2.45 +/- 0.04) x 10(-4)M-((0.55 +/- 0.05)), where D and M correspond to monodisperse species. Using this scaling relationship, we have successfully converted the translational diffusion coefficient distribution into the molecular weight distribution for each of the five PES-C fractional The weight-average molecular weights obtained from dynamic light scattering have a good agreement with that obtained from static laser light-scattering measurements.

Laser light-scattering study of novel thermoplastics .1. Phenolphthalein poly(aryl ether ketone)

Five different molecular weight phenolphthalein poly(aryl ether ketone) (PEK-C) fractions in CHCl3 were studied by static and dynamic laser light scattering(LLS). The dynamic LLS revealed that the PEK-C samples contain some large polymer clusters. These large clusters can be removed by filtering the solution with a 0.1-mu m filter. We found that the persistence length of PEK-C in CHCl3 at 25 degrees C is similar to 2 nm and the Flory characteristic ratio, C-infinity is similar to 25. Our results showed that [R(g)(2)](1/2)(z) = (3.50+/-0.20) x 10(-2)M(w)(0.54+/-0.01) and [D] = (2.37+/-0.05) x 10(-4)M(w)(-0.55+/-0.01), with [R(g)(2)](1/2)(z), M(w), and [D] being the z-average radius of gyration, the weight-average molecular weight, and the z-average translational diffusion coefficient, respectively. A combination of static and dynamic LLS results enabled us to determine D = (2.20+/-0.10) x 10(-4)M(-0.555+/-0.015), where D and M correspond to monodisperse species. Using this calibration between D and M,we have determined molecular weight distributions of five PEK-C fractions from their corresponding translational diffusion coefficient distribution.

Surface roughness characterization of soft x-ray multilayer films on the nanometer scale

The soft x-ray reflectivity of multilayer films is affected by the surface roughness on the transverse nanometer scale. Scanning tunneling microscopy (STM) is an ideal instrument for providing high-lateral-resolution roughness measurements for soft x-ray multilayer films that cannot be obtained with other types of instruments on the transverse nanometer scale. The surface roughnesses of Mo/Si, Mo/C, and W/Si soft x-ray multilayer films prepared by an ion-beam-sputtering technique were measured with a STM on the vertical and transverse attributes. The film roughnesses and average spatial wavelengths added to the substrates depend on the multilayer film fabrication conditions, i.e., material combinations, number of layers, and individual layer thickness. These were estimated to lead to a loss of specular reflectivity and variations of the soft x-ray scattering angle distribution. This method points the way to further studies of soft x-ray multilayer film functional properties and can be used as basic guidance for selecting the best coating conditions in the fabrications of soft x-ray multilayer films. (C) 1996 American Vacuum Society.

Structural study on poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers

Structures of poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X-ray scattering and the one-dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (n(b)). When n(b) = 0.35, invariant Q, long period L, average thickness of crystal lamellae (d) over bar, electron density difference eta(c) - eta(a) and degree of crystallinity W-c,W-x assume minimum values.

Miscibility and crystallization behavior of thermosetting polyimide thermoplastic polyimide blends

Compatibility, morphology, crystalline structure and mechanical properties of the blends of a thermosetting polyimide with thermoplastic polyimides consisting of dianhydrides of different lengths have been studied by the use of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) techniques. The results of our research show that the blends change from compatible to semi-compatible when the difference between the length of the dianhydrides of the two components increases. Addition of a thermoplastic polyimide inhibits the crystallization of the thermosetting component. However, this effect decreases with increasing length of the dianhydrides and the distribution of the molecules of the thermoplastic polyimide component changes from interlamellar to interfibrillar. Impact strength and morphology of the fractured surfaces indicate that among the semiinterpenetrating polymer networks (semi-IPN) obtained the toughening effect of the partially compatible one is the best. The results are discussed in terms of charge transfer interaction between imide group and p-phenylene group.

THE INFLUENCE OF GAMMA-RADIATION ON POLYAMIDE-1010 AGGREGATE STRUCTURES

The influence of gamma-radiation on polyamide 1010 aggregate structures and crystal damage were examined by using wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) techniques. The results revealed that some structural parameters of the aggregated state, the density differences and the degree of crystallinity W-c,W-x, essentially decreased with increasing radiation dose, but the specific surface O-s increased. Crosslinking and scission of irradiated polyamide 1010 samples occurred mainly in amorphous and interphase regions, and crystal damage and amorphization induced by gamma-radiation spread from the interphase and extended into the crystal phase with increasing radiation dose. This result also indicated that the (010) reflection with the hydrogen bond was more susceptible to the action of radiation.

THE CHAIN STRUCTURE AND LIGHT-SCATTERING-STUDIES FOR ACRYLAMIDE-SODIUM ACRYLIC-ACID (AM-AA) COPOLYMERS

A set of AM-AA copolymer samples with the same comonomer content and different average molecular weight have been characterized by C-13 NMB and light scattering methods in this paper. The chemical composition (comonomer AA, mole content 16.9 +/- 1.1%) of these samples is uniform. the sequence of AA in the macromolecular chain is of alone and random distribution and the light scattering theory from polyelectrolyte in added-salt solutions is suitable for the AM-AA copolymers-0.12 mol/L NaCl water systems. The actual values of M(w), the second Virial coefficient A(2) and the mean square radius of gyration (R(2)), for the studied samples have been obtained. The relationships between the molecular parameters are as follows: A(2)=0.0619 ($) over bar M(w)(-0.24), < R(2) >(1/2)(t)= 0.0210 ($) over bar M(w)(0.54).

STUDIES ON MORPHOLOGY OF SOLUTION-CAST FILMS OF IPP/APP BLENDS

Morphologies of solution-cast films of iPP/aPP blends have been studied by means of electron microscopy and X-ray scattering techniques. Microscopic observation showed that solution-cast film of iPP consists of two kinds of structural regions, cross-hatched and lath-liked structures. The addition of small amount of aPP (less than or equal to 30%) into iPP did not change iPP's characteristic crystallization behavior. It is noticed that when the content of aPP in its blend was over 80%, iPP formed a very loosely woven-like network composed of very long lamellae with wide-angle lamellar branchings. The X-ray data showed that aPP did not cocrystallize with iPP.

A DYNAMIC LASER LIGHT-SCATTERING STUDY OF CHITOSAN IN AQUEOUS-SOLUTION

The solution behavior of four chitosans (91% deacetylated chitin) with different molecular weights in 0.2M CH3COOH/0.1M CH3COONa aqueous solution was investigated at 25 degrees C by dynamic laser light scattering (LLS). The Laplace inversion of the precisely measured intensity-intensity time correlation function leads us to an estimate of the line-width distribution G(Gamma), which could be further reduced to a translational diffusion coefficient distribution G(D). By using a combination of static and dynamic LLS results, i.e. Mw and G(D), we were able to establish a calibration of D = k(D)M(-alpha D) with k(D) = (3.14 +/- 0.20) X 10(-4) and alpha(D) = 0.655 +/- 0.015. By using this calibration, we successfully converted G(D) into a molecular weight distribution f(w)(M). The larger alpha(D) value confirms that the chitosan chain is slightly extended in aqueous solution even in the presence of salts. This is mainly due to its backbone and polyelectrolytes nature. As a very sensitive technique, our dynamic LLS results also revealed that even in dilute solution chitosan still forms a small amount of larger sized aggregates that have ben overlooked in previous studies. The calibration obtained in this study will provide another way to characterize the molecular weight distribution of chitosan in aqueous solution at room temperature. (C) 1995 John Wiley & Sons, Inc.

MISCIBILITY, MICROSTRUCTURE, AND DYNAMICS OF BLENDS CONTAINING BLOCK-COPOLYMER .2. MICROSTRUCTURE OF BLENDS OF HOMOPOLYSTYRENE WITH STYRENE-BUTADIENE BLOCK-COPOLYMERS

The microstructures of styrene-butadiene triblock (SBS) and styrene-butadiene four-arm star block (SB-4A) copolymers and their blends with homopolystyrene (PS) of different molecular weights, MPS, have been investigated by means of small-angle X-ray scatt

EFFECT OF IRRADIATION ON CRYSTALLINITY AND MECHANICAL-PROPERTIES OF ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE

Ultrahigh molecular weight polyethylene (UHMWPE) has been irradiated (0-40 Mrad) with a Co-60 source at room temperature under vacuum. The crystallinity has been investigated by differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). The mechanical properties have been determined at room temperature. A significant increase of heat of fusion can be seen at low irradiation doses, which is attributed to crystallization, caused by chain scission during the process of irradiation. It is also observed that the thickness of the lamellae changes with irradiation dose. The Young's modulus has been improved significantly after irradiation at low doses. (C) 1993 John Wiley & Sons, Inc.

STUDY ON STRUCTURE-PROPERTY RELATIONSHIP OF POLYIMIDE BLENDS .2. STRUCTURE AND MISCIBILITY OF POLYIMIDE PBPI-E/PTI-E BLENDS

The structure and miscibility of polyimide PBPI-E/PTI-E blends were studied by wide- and small-angle X-ray scattering and dynamic mechanical analysis, where PBPI-E is a biphenyl-dianhydride-based polyimide, and PTI-E is a polyimide from 4,4'-thiodiphthalic anhydride and 4,4'-oxydianiline. The results obtained show that there exists a paracrystalline structure in the blends with high content of PBPI-E, but this does not affect the miscibility of the blends. The blends are miscible over the entire composition range, since only one T(g) was observed for each blend. Meanwhile, the segregation of PTI-E during crystallization of PBPI-E in the blends is interlamellar.

STRUCTURE OF MESOMORPHIC FORM OF ISOTACTIC POLYPROPYLENE

The structure of quenched isotactic polypropylene (iPP) films, including samples etched with fuming nitric acid (FNA), has been studied by infrared (IR) spectra, wide-angle x-ray diffraction (WAXD), small-angle x-ray scattering (SAXS), and differential scanning calorimetry (DSC) measurements. The changes of IR, SAXS, DSC, and WAXD results induced by annealing for etched samples have been compared with those for unetched ones. The IR absorbance spectrum of the quenched iPP etched by FNA did not change. In addition, the SAXS intensity did not increase when these samples were annealed, indicating that the total (IR) crystallinity (i.e., the content of chain segments in the helical conformations) of the etched samples does not increase. However, WAXD patterns of the samples changed in a manner similar to those of the unetched one, from the original two blurred diffraction peaks to the sharp crystal patterns of alpha-form iPP, suggesting that the mesomorphic (or liquid crystal-like) phase has reorganized to alpha-form crystals. It is concluded that the change of WAXD of quenched iPP films during annealing results mainly from transformation of order in the mesomorphic phase, rather than only from an increase of crystal size. In other words, mesomorphic-form iPP is not constituted by any known crystals (such as alpha or beta crystals) in small sizes; its WAXD pattern reflects truly the degree of order in the mesomorphic phase.

THE RING-BANDED SPHERULITE STRUCTURE OF POLY(EPSILON-CAPROLACTONE) IN ITS MISCIBLE MIXTURES WITH POLY(STYRENE-CO-ACRYLONITRILE)

The structure of the PCL spherulite in poly(epsilon-caprolactone)/poly(styrene-co-acrylonitrile) (PCL/SAN) blends was investigated by optical microscopy and small angle light scattering. The spherulite structure with a Maltese cross has been observed in pure PCL. Similar PCL/SAN blends exhibited not only spherulites with a Maltese cross, but also distinct extinction rings. The H(v) light scattering pattern especially caused diffraction rings in PCL/SAN blends but not in pure PCL. The spherical symmetry of spherulite PCL becomes more incomplete and the twist of the lamella becomes more irregular with increasing SAN content. It is found that the spherulite structure of PCL/SAN blends is dependent on the crystallization temperature and the concentration of SAN in PCL/SAN blends.