Morphology multiphase

The characteristics of the crystallization behaviors of thermotropic longitudinal PLCs can be summarized as (1) small and imperfect lamellae about lO-lOOnm in size (2) limited crystallinity (3) an increase of lamellar thickness, improvement of lateral correlation and transformation of the lattice resulting from annealing and (4) formation of high-melting crystals in the partially molten state. 

Important issues concerning the crystallization behaviors of PLCs which should be further explored include the crystallization mechanism, the relation of crystal lamellae to the microfibrils and the effect of crystallites on mechanical properties. 

The heterogeneous morphology and microphase separation process of block PLCs are closely related to the processing history and the molecular structures. For PET/PHB PLCs, PET-rich and PHB-rich phases are detected by SEM observation of etched samples [41,42]. When the PHB content is lower than 50 mol%, the PET-rich phase is continuous, and vice versa when the PHB content is higher than 60 mol%. The size of the PET-rich phase was found to be 10-20 pm with 40mol% PHB and 3-6 pm with 80 mol% PHB. In addition, the phase dimension will be influenced by the thermal and mechanical history. Joseph et al. have reported [41,42] that in an injection molded plaque of PET/PHB PLCs, PHB was richer in the skin while PET was richer in the core. However, there is controversy concerning this observation [3]. 

Multiphase structures of two wholly aromatic blocky copolyesters with a composition similar to Xydar have been observed in our laboratory [43]. Compact spherical domains with a diameter of about 

Kwolek, S.L., Morgan, P.W. and Shaefgen, J.R. (1992) High Performance Polymers Composites, p. 416. 

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Hedrick et al. reported imide aryl ether ketone segmented block copolymers.228 The block copolymers were prepared via a two-step process. Both a bisphenol-A-based amorphous block and a semicrystalline block were prepared from a soluble and amorphous ketimine precursor. The blocks of poly(arylene ether ether ketone) oligomers with Mn range of 6000-12,000 g/mol were coreacted with 4,4,-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in NMP in the presence of A - me thy 1 morphi 1 i nc. Clear films with high moduli by solution casting and followed by curing were obtained. Multiphase morphologies were observed in both cases. 

Development of Multiphase Morphology Sequential Interpenetrating Polymer Networks... 

Multiphase morphology of roughly spherical shape that comprises alternating layers of different polymers arranged concentrically, all layers being of similar thickness. 

Multiphase morphology in which dispersed phase domains of one polymer contain and completely encapsulate many phase domains of a second polymer that may have the same composition as the continuous phase domain. 

Their non-linear and often synergistic mechanical behavior which arises from their above mentioned multiphase morphology. Thus, both impact resistant plastics and thermoplastic elastomers have been bom. 

In the present study we have used a relatively new technique to study the morphology of these systems. Application of an alternating electric field to a multiphase morphology results in a frequency-dependent electric-field distribution due to the different permittivities and conductivities of dissimilar phases. Measured permittivity increases with decreasing frequency v = 0)/2ir, approaching a low frequency limit eQ as the field distribution transits from permittivity dominated to conductivity dominated. 

Furthermore, anionic polymerization will lead to well-defined multicomponent multiblock copolymers. A plethora of novel multiphase morphologies will be hopefully discovered. The potentialitiy of these multi-component multiblock copolymers to be used as multifunctional smart materials is enormous. 

Several papers report about properties of ternary blends with iPP as the main component. The majority of the ternary blends possess a multiphase morphology, and adequate mechanical and physical properties are correlated to the dimension of the particles of the dispersed phase. The compatibility could be related to the modihcation of the interfacial properties of the blend. 

There has been increasing interest in polymer- polymer interfaces from both an academic and an applied point of view. Because most of the industrial relevant polymer blend systems have a multiphase morphology, the understanding of interfaces is essential to achieve desired product properties. Therefore, theoretical interest in polymer-polymer interfaces has increased recently and simultaneously a number of experimental methods to study them have been developed. Neutron reflectivity has an excellent depth resolution of about 0.2 nm but requires deuterated samples which are often not available for engineering... 

Another aspect of multiphase rheometry is related to the interrelations between the flow field and system morphology. In the present context, the term morphology will refer to the overall physical stmcture and/or arrangement of the components, usually described as a dispersed phase (particles or domains), co-continuous lamellae, fibrils, spherulites, etc. Furthermore, multiphase morphology deals with the distribution and orientation of the phases, the interfacial area, the volume of the interphase, etc. Flow may induce modifications of morphology, such as concentration gradients and orientation of domains. 

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