In order to determine the adhesion of filler particles to polymeric matrix a set of tests on the tensile strength of composite materials based on CFD and PPS has been performed. The best results were observed for composites with nanosized amorphous fillers Mo and MoO2. The strength of composites filled with such fillers increased up to 2 times compared to the pure polymer value. The effect of using fine-ground mineral fillers is less – about 1.5 times. Coarse fractions of mineral fillers (50μm) do not have positive effect on the composite tensile strength. Thus, the effect of fillers on the mechanical properties of polymer-based composites depends heavily on the nature and dispersivity of the filler and is apparently determined by the behavior of chemical and mechanical bonds occurring on the phase boundaries. The large number of bonds for nanosized fillers is promoted by the high specific (to surface area) number of radicals on their surface, which results in strong bounding of particle to matrix, besides the polymeric material close to the phase boundary gains additional properties.

Since the size of nanoparticles is proportional to the thickness of interphase boundary layer, the considerable portion of the composite material transforms to a boundary interphase state, which properties, being different from both filler and polymer properties, determine the new characteristics of the composite material.

Blends of PS/HDPE and PS/PP were investigated for synergism in flexural modulus with varying composition. The evolution of blend morphology was studied and related to the improvement in flexural modulus around the co-continuous composition. DSC studies were conducted to study crystallinity variations in the semi-crystalline component of the blend. We found that co-continuous morphologies help in developing strong mechanical bonds between the components. Crystallization is inhibited in the co-continuous region and is related to the spatial constraints during the solidification process.

The effect of blending polycarbonate (PC) with an amorphous copolyester (PCTG) and a crystallizable polyester (PBT) on the environmental stress cracking (ESC) resistance was studied. The determination of the ESC resistance for the blend was accomplished through tensile testing in a fluid environment utilizing an Eyring-type activated process to describe ESC. It was found that the miscible blend, PC/PCTG, displayed a rule of mixtures for ESC resistance to all fluids tested except ether resistance. The immiscible blend, PC/PBT, displayed a significant negative deviation from the rule of mixtures for ESC resistance, except for ether resistance, which has been attributed to the development of stress sites for craze initiation at the interface between the blend components on the surface of the test sample. The differences in ether resistance compared to the trends found for the fluid ESC resistance in this study were attributed to possible changes in crystallization for the samples tested in ether. The data suggests that strongly swelling fluids, e.g. diethyl ether in the presence of PC, may cause densification from polymer crystallization resulting in voids that facilitate in the initiation and growth of crazes.

Porous microspheres of poly(styrene-co-divinylbenzene) (SD) have been synthesized by suspension polymerization. They present a narrow porosity gap (21–24%) and a mean pore-radius range (106–117 Å). The mesoporous voids are then made use as the polymerization reactor for ethyl acrylate (EA), and as a result of the embedded polymerization, linear EA formed is trapped inside the individual particles (SD-EA), and its Tg is brought up to as high as the ambient temperature. Two specific loadings of EA were attained: 11% and 28% by weight. The acoustic absorption behaviors of SD-EA and SD microspheres are assessed by the attenuation coefficient (a = IAttenuated/IIncidence), in which the incident acoustic waves are two arbitrary audio frequency bands, 100–1000 Hz and 4000–5000Hz. In contrast to porous SD microspheres, SD-EA microspheres apparently relax the incident frequencies and attenuate more effectively the higher frequency sound waves. The maximum attenuation level (a) of SD-EA absorbent is about 80% (dB). It was found that the higher EA loading could improve rather slightly the attenuation level in the higher frequency range.

The complexation behaviour of linear DNA (negatively charged) with surface functionalised sub-micron latex spheres is studied by dynamic light scattering (DLS), small-angle neutron scattering (SANS), small-angle x-ray scattering (SAXS), and micro rheology. The complexes are measured in solution as a function of component concentration (CDNA, CSPH) and added salt concentration (Cs). In the absence of salt, measured radius increases with CDNA (CSPH held constant) up to a plateau value. The presence of salt causes a decrease in the measured complex radius, which may be due either to increased flexibility of the chains allowing them to form a more compact layer on the sphere surface, or dissociation of the two components due to screened electrostatics. More detailed experiments to determine this are underway.

We characterize the electric properties of single-walled carbon nanotube (SWNT) dispersed in the polymethyl methacrylate (PMMA) composites. In the melt-blended sample, the SWNTs – originally semiconducting – became predominantly metallic. The interaction of the PMMA and SWNT is investigated by the polarized Raman studies. The structure changes in the PMMA and SWNT shows that the anisotropic interactions play important role in SWNT electronic density of states (DOS) changes. The increased metallic SWNT percentage is confirmed by the conductivity and dielectric constant measurements of composite and neat PMMA.

Electric field induced phase transition has been used to explain the high strain response in some PVDF-based EAP. However, it is hard to understand some features (such as the relationship between the strain and the preload) of elastomers - an important type of EAPs. In this paper, we reported the study of recrystallization on high-energy-electron irradiated P(VDF-TrFE) copolymer. The morphology and structure as well as the structural transformation in the recrystallized copolymers were studied by means of X-ray diffraction, DSC, FTIR, and polarization measurements. The effect of crosslinking induced by the irradiation is discussed. The results suggest that a new interface layer existed in the recrystallized polymers. The partially ordered interfacial layer is a novel micro-origin of a high polarization obtained in an EAP. Based on this concept, the effect of preload on the E-M performance of the elastomers can be well explained. A new method to develop high performance electroactive polymer is outlined by using the interface state.

The effects of chain extension and branching on the properties of nanocomposites produced from recycled poly (ethylene-terephthalate) and organically modified clay were investigated. As the potential chain extension/branching agent, maleic anhydride (MA) and pyromellitic dianhydride (PMDA) were used. The nanocomposites were prepared by twin-screw extrusion, followed by injection molding. Recycled poly (ethylene-terephthalate) was mixed with 2, 3 or 4 weight % of organically modified montmorillonite. During the second extrusion step, 0.5, 0.75 or 1 weight % of MA or PMDA was added to the products of the first extrusion. The effects of the sequence of addition of the ingredients on the final properties of the nanocomposites were also investigated. X-Ray Diffraction analysis showed that, the interlayer spacing of Cloisite 25A expanded from 19.21 Å to about 28–34 Å after processing with polymer indicating an intercalated structure. PMDA content, MA content and screw speed did not have a significant effect on the expanded interlayer distance. In the first extrusion step, nanocomposites containing 3% organoclay content gave significant increase in Young's modulus and decrease in elongation at break values indicating good interfacial adhesion. After the addition of anhydrides, it was observed that, in general PMDA improved the mechanical properties of the nanocomposite owing to the branching and chain extension effects that increase the molecular weight. However, MA did not significantly improve the properties, since in this case the chain scission seemed to be more dominant.