摘要:

AbstractPolystyrene (PS) (1)/Poly (n‐butyl acrylate (BA)/amide type functional monomer) (2) structured latex particles were prepared through emulsion polymerization varying the hydrophilicity of the functional monomer employed. The second‐stage polymerization kinetics, the size and morphology of latex particles, and the location of the functional groups in the final latexes were studied, in order to relate them to the thermomechanical properties of films cast from these latexes. It has been shown that, as expected, increasing the hydrophobicity leads to a better homogeneity in the copolymer formed during the second‐stage polymerization, while the more hydrophilic functional monomer partly homopolymerizes in a separate phase. However, the functionalization by all the monomers used in this work, prevents the PS seed particles to form a continuous skeleton (percolated network). Further heat treatments at 140°C do not lead to the formation of a continuous PS phase as for pure BA/pure PS two‐stage particles. In addition, some thermally induced crosslinking effects are discussed in relation with the functional monomer location within the particles. © 1995 John Wiley&

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331101

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIt has been shown in this study that the effects of particle size distribution or molecular weight distribution on selected physical properties can be related by a generalized blending approach that involves similar equations. The blending equations developed involve differentz‐fractions wherez= 3 for volume blending of spherical particles, orz= 2 for surface blending of spherical particles, orz= 1 for the weight blending of molecular weights. This new analysis approach addresses the magnitude of the ratios of particle size averages,Dx/Dy, or ratios of molecular weight averages,Mx/My, as well as the location of this maximum, the level of distribution information available for the starting materials, and the type ofz‐fraction blending. To illustrate this approach suspension viscosity/concentration data was used to show how theDx/Dyratio could be introduced successfully to analyze latex volume blending wherez= 3. In addition, the maximum steady‐state elastic compliance,Je, as a function of weighted blends (z= 1) of two different molecular weights of polyisobutylene was shown to fit the simple equationJe= 1.187 (M3/M2) (M4/M1) reasonably well. © 1995 John Wiley&Son

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331102

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe multiplet formation in calcium partially neutralized poly(acrylamidocaproic acid) was studied by using differential scanning calorimetry and Fourier transform infrared spectroscopy. At 20 mol % of neutralization of acid groups, the ionic groups started to aggregate to form multiplets. The hydrogen bonding of amide group was destroyed during multiplet formation due to the reduction of the motional freedom of the side chain. The extension of the short side chain started to be loosened at the neutralization of 44 mol %. In this state, the multiplets could be formed without severe side chain stretching due to the proximity of the ionic groups. It is expected that the more stable multiplet is formed with increasing the degree of neutralization. © 1995 John Wiley&Sons, Inc

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331103

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe C 1s, N 1s, and O 1s excitation spectra of model methylenediphenyldiisocyanate (MDI) polyurethanes with well known structures have been recorded using electron energy loss spectroscopy (EELS) in an electron microscope. These spectra are compared to the core excitation spectra of selected small molecule analogue species (recorded by gas phase EELS) in order to identify transitions characteristic of various structural components found in polyurethanes. A more detailed report on the small molecule analogue spectra is presented in the following article. Spectral features characteristic of the different structural components in polyurethanes are identified in the spectra of the model polymers. These can be used as the basis for chemical studies of micron or submicron sized segregated phases in flexible polyurethane polymers. © 1995 John Wiley&Sons, Inc

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331104

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCore excitation spectra of selected small molecule analogue species have been acquired to assist interpretation of the core excitation spectra of model methylenediphenyldiisocyanate (MDI) polyurethane polymers. Oscillator strength spectra for C 1s and O 1s core excitation of diethyl ether and diisopropyl ether; C 1s, N 1s, and O 1s core excitation of urea,N‐phenyl urea,N, N′‐diphenyl urea, ethyl carbamate,N‐phenyl carbamate,N‐phenylN‐methyl carbamate, and benzyl carbamate have been derived from gas phase electron energy loss spectra (EELS). Extended Hückel Molecular Orbital (EHMO) calculations are used to assist assignment and to interpret the effect of π‐electron delocalization on the gas phase spectra. Functional group identification by core excitation is explored for the purpose of using core excitation spectra for microanalysis of polyurethane polymers. © 1995 John

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331105

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractDiffusion of aqueous and nonaqueous coagulants into lyotropic/nematic solutions of poly(phenylene benzobisoxazole) in polyphosphoric acid using fluorescence microscopy is reported. The fluorescence microscopy technique offers advantages in that the experiment is independent of the coagulant and the experiments can be performed in a front surface mode so that optically thin samples are not required. The diffusion process is modeled as Case II diffusion as described by Crank and Park. The apparent diffusion coefficients are found to range from ∼ 2 × 10−6cm2/s to ∼ 2 × 10−7cm2/s for aqueous and nonaqueous coagulants. The apparent diffusion coefficients can be varied by several orders of magnitude (e.g., down to ∼ 3 × 10−10cm2/s) by varying the concentration of polyphosphoric acid in the coagulant. © 1995 John

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331106

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA simple thermodynamic model, based on an extension of Flory‐Huggins theory, is applied to temperature rising elution fractionation (TREF). Dependence of the fractionation process on melting temperature, melting enthalpy, average crystallinity, average crystallizable sequence length, and polymer‐solvent interaction parameter is predicted. Results from the model fit experimental TREF data, and correctly predict number‐average branch points for TREF fractions. © 1995 John Wiley&Son

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331107

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractFluorescence of several new polyimides in which neighboring imides are linked by aN‐Nbond was examined in chloroform solutions. For the naphthalene‐containing polyimide1, analysis of the emission, excitation, and absorption spectra at different concentrations showed the existence of a ground‐state intermolecular charge transfer (CT) complex due to chain association and aggregation. For the perylene‐containing polyimides3‐6, the fluorescence was characterized by a low energy band superimposed on the normal perylenediimide bands. This was interpreted as arising from a CT interaction between electron donor‐acceptor pairs on the polymers backbone of the same chain, revealing certain degrees of chain coiling of these polymers in solution. © 1995 John Wil

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331108

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPolymer‐solvent interaction parameters are reported for poly(vinyl acetate)‐acetone, poly(vinyl acetate)‐toluene, and poly(dimethyl siloxane)‐toluene systems using different techniques. Results obtained by osmotic deswelling are compared with those from quasi‐elastic light scattering and small‐angle neutron scattering (SANS). In gels, the latter techniques involve separation of the time‐dependent from the static component of the scattered radiation+ Separation is achieved in quasi‐elastic light scattering through the heterodyning properties of the light, and in SANS by subtracting an appropriate static structure factor. The interaction parameters obtained by different separation procedures are consistent with measurements using the osmotic method. © 1995 John

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331109

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe elastic modulusElof the crystalline regions of cellulose polymorphs in the direction parallel to the chain axis was measured by x‐ray diffraction. TheElvalues of cellulose I, II, IIII, IIIII, and IVIwere 138, 88, 87, 58, 75 GPa, respectively. This indicates that the skeletons of these polymorphs are completely different from each other in the mechanical point of view. The crystal transition induces a skeletal contraction accompanied by a change in intramolecular hydrogen bonds, which is considered to result in a drastic change in theElvalue of the cellulose polymorphs. © 1995 John Wiley&Sons, I

ISSN:0887-6266    

DOI:10.1002/polb.1995.090331110

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY