Small-angle neutron scattering was used to measure the influence of temperature on the radius of gyration in the melt of atactic polypropylene and poly(1-butene). The chain dimension temperature coefficient, d In (RZ)ddT, was found to be respectively -0.1 X and 0.4 X le3 degl. These values, with one exception, disagree with the rotational isomeric state predictions as well as with thoee values obtained via intrinsic viscosity measurements either at 8 conditions or in perceived athermal solvents. Conversely, excellent agreement was obtained with the values available from both thermoelastic and rheological measurements on atactic poly(1-butene).

The structure of porous TiO 2 films and TiO 2 :poly(Nvinylcarbazole) (PVK) composite films is investigated with time-offlight grazing incidence small-angle neutron scattering (TOF-GISANS). The TiO 2 films have been prepared by application of a sol-gel process with a diblock copolymer as structure directing agent, and the conductive polymer PVK is infiltrated in the porous network by spin coating and solution casting. The films show a hierarchical pore structure with mesopores 52 nm in size and additional large macropores with a diameter of about 180 nm. By matching the scattering contrast of the TiO 2 with the polymer information about the penetration of the polymer in the pores is determined. Whereas in the PVK film prepared by solution casting the pores are filled to a high degree; in the spin coated film, PVK wets only the TiO 2 pore walls and forms a solid overlying layer.

No abstract

No abstract

The sections in this article are Introduction General Considerations General Course of an Isothermal Precipitation Reaction Thermodynamic Considerations–Metastability and Instability Decomposition Mechanisms: Nucleation and Growth versus Spinodal Decomposition Thermodynamic Driving Forces for Phase Separation Experimental Techniques for Studying Decomposition Kinetics Microanalytical Tools Direct Imaging Techniques Scattering Techniques Experimental Problems Influence of Quenching Rate on Kinetics Distinction of the Mode of Decomposition Precipitate Morphologies Experimental Results Factors Controlling the Shapes and Morphologies of Precipitates Early Stage Decomposition Kinetics Cluster‐Kinetics Approach Classical Nucleation–Sharp Interface Model Time‐Dependent Nucleation Rate Experimental Assessment of Classical Nucleation Theory Non‐Classical Nucleation–Diffuse Interface Model Distinction Between Classical and Non‐Classical Nucleation Diffusion‐Controlled Growth of Nuclei from the Supersaturated Matrix The Cluster‐Dynamics Approach to Generalized Nucleation Theory Spinodal Theories The Philosophy of Defining a ‘Spinodal Alloy' —Morphologies of ‘Spinodal Alloys' Monte Carlo Studies Coarsening of Precipitates General Remarks The LSW Theory of Coarsening Extensions of the Coarsening Theory to Finite Precipitate Volume Fractions Other Approaches Towards Coarsening Influence of Coherency Strains on the Mechanism and Kinetics of Coarsening–Particle Splitting Numerical Approaches Treating Nucleation, Growth and Coarsening as Concomitant Processes General Remarks on the Interpretation of Experimental Kinetic Data of Early Decomposition Stages The Langer and S chwartz Theory ( LS Model) and its Modification by K ampmann and W agner ( MLS Model) The Numerical Model ( N Model) of K ampmann and W agner ( KW ) Decomposition of a Homogeneous Solid Solution General Course of Decomposition Comparison Between the MLS Model and the N Model The Appearance and Experimental Identification of the Growth and Coarsening Stages Extraction of the Interfacial Energy and the Diffusion Constant from Experimental Data Decomposition Kinetics in Alloys Pre‐Decomposed During Quenching Influence of the Loss of Particle Coherency on the Precipitation Kinetics Combined Cluster‐Dynamic and Deterministic Description of Decomposition Kinetics Self‐Similarity, Dynamical Scaling and Power‐Law Approximations Dynamical Scaling Power‐Law Approximations Non‐Isothermal Precipitation Reactions Acknowledgements