Research in the area of biological renewable materials has shown that the main building blocks of life – carbohydrates, fats, proteins, and their derivatives - could substitute products from traditional nonrenewable sources. However its realization will need significant and continuous improvement of those materials. Problems of applications of bioplastics arise not only from the (price) competition with the highly developed synthetic polymers but also from their, up to now not sufficient property levels. Possibilities to decrease the hydrophilicity and to increase the values of mechanical properties so far are: i) application of hydrophobic coating(s); ii) blending with different, biodegradable synthetic polymers (polyesters) and iii) new ways of reactive extrusion of natural. A new possibility in this direction is seen in the creation of composite materials of thermoplastic organic biopolymer and nanoscopic inorganic particles incorporated on a molecular scale.

This paper will show the results of the first experiments to get nano-scale starch/clay composites. The starch will be fully gelatinized and the modified clay can be dispersed homogeneously on a truly nanoscale. Therefore all requirements of a significant increase in mechanics and a decrease in permeability of this composite material are present.

Abstract We compare for multiblock copolymers the results of mean field calculations with those from Monte Carlo simulations based on the bond uctuation method and experimental results from scattering data. The application of Leibler's [1] theory for copolymers and the results of Monte Carlo simulations indicate that the microphase separation transition occurs at larger xN as the number of blocks is increased beyond two (i.e., beyond diblock), and that the characteristic length scale of the emerging morphology decreases as the number of blocks increases. The latter is in qualitative agreement with published experimental results [2] for model multiblock poly(styrene-isoprene) systems and recent results [3] for a segmented poly(ester-urethane).

Thin films of aromatic polymers such as polyimide (PI) and polyethersulfone (PES) find an extensive use in aerospace and electronic applications, in particular, as sensitive to moisture and gas uptake layers for bimorphic sensors. In this work, a complex investigation of the film composition, microstructure and physical properties of ion beam modified polymer films was carried out to optimize the moisture uptake. To modify thin films of polyimide and polyethersulfone 50, 130 and 180 keV boron ions with irradiation doses between 1013 and 1016 B+/cm2 were implanted. It could be shown, that partly destruction of chemical bonding under ion bombardment leads to the creation of new amorphous and graphite-like structures, which increase the modified surface film conductivity by several orders of magnitude and enhances the sensitivity of these nanocomposite films to moisture uptake.

Random cross-linking in rubbers produces local variations in the elasticity of the network. These variations, whose characteristic size lies in the range 1-100 nm, are revealed when the rubber is swollen in a low molecular weight solvent, owing to the competition between the osmotic pressure of the solvent and the local elastic constraints, which affects the local polymer concentration. Such concentration fluctuations can be measured by small angle X-ray or neutron scattering (SAXS or SANS) as well as by dynamic light scattering.

In filled elastomers, the filler modifies the distribution of the polymer and of the elastic constraints. Swelling these systems in a solvent in which the deuteron/proton ratio can be varied permits the different components in the scattering function of the polymer and of the filler to be separated. Observations on silica particles in a poly(dimethyl siloxane) (PDMS) rubber yield measurements not only of the surface area of the particles but also of the fraction of the surface area occupied by the polymer. Analysis of the dynamic light scattering response of these systems gives confirmation of the validity of the procedure.

Coherent X-ray scattering measurements, combined with dynamic light scattering measurements of the filled uncross-linked polymer melts in the absence of solvent reveal that the structural relaxation process that follows an external mechanical perturbation is a diffusioncontrolled process.

The influence of shear on viscoelastic polymer-clay solutions was investigated by means of small-angle neutron scattering (SANS) under shear. SANS measured the shearinduced orientation of polymer and platelets. With increasing shear rate an anisotropic scattering pattern developed. At higher shear rates, the scattering anisotropy increases due to the increased orientation of the clay platelets in the shear field. Cessation of shear leads to fast recovery demonstrating the system to be highly elastic. As a result of drying, these solutions produce translucent nanocomposite films with a microporous membrane character. Depending on the preparation and degree of polymer-clay film dispersion, it is possible to modify the morphology and elastic properties of nanocomposite materials. Atomic Force Microscopy (AFM) reveals the network character and the development of morphology as a function of polymer concentration. Preliminary SANS experiments on the films will be correlated to morphologies obtained from AFM.

This review first describes organic-inorganic composites which have been prepared using techniques similar to those employed in the new sol-gel approach to ceramics. Organometallics such as silicates, titanates, and aluminates are hydrolyzed in the presence of polymer chains (for example polysiloxanes and polyamides) that typically contain hydroxyl groups. The functional groups are used to bond the polymer chains onto the silica, titania, or alumina being formed in the hydrolysis, thus forming novel organic-inorganic composites. When the polymer chains are present in excess, they constitute the continuous phase, with the ceramic-type material appearing as reinforcing particles. When present in smaller amounts, the polymer is dispersed in the continuous ceramic phase, to give a polymer-modified ceramic. Under some conditions,bicontinuous systems are obtained.

The second part addresses one of the major unsolved problems in the area of rubberlike elasticity, specifically a molecular understanding of the mechanisms by which the mechanical properties of elastomers are improved by the incorporation of particulate fillers such as carbon black or silica. Theoretical work on the reinforcement thus obtained is illustrated by some Monte Carlo calculations on one aspect of the problem, namely excluded volume effects of the filler particles on the network chain configurations. The resulting end-to-end distributions are then used in standard molecular models to generate stress-strain isotherms, which document the nature of the reinforcement obtained.

The final part provides an overview of the specific papers presented at this symposium, and attempts to place them into the broad general context of “Filled and Nanocomposite Polymer Materials”.

Composites in which fibres or fillers are incorporated into a polymeric component exhibit improved mechanical strength compared to the polymer matrix. This reinforcement effect strongly depends on the properties of the interphase and the specific interactions between the polymer and the reinforcing additive.

A wide range of experimental methods have been used to assess the effect of active fillers on the mobility of the polymer chains. The experimental results from NMR, dielectric spectroscopy and dynamical thermal analysis reveal that the mobility of chain units adjacent to the adsorbed surface differs considerably from the bulk.

We have used quasielastic neutron scattering to investigate the dynamic properties of poly(dimethyl siloxane) (PDMS) filled with silica particles. This technique which probes the motion of the hydrogen atoms has been extensively used to study the local dynamics of polymeric materials. In this paper we show that QENS provides detailed information on the reduced mobility of chain segments in polymer-filler systems.

QENS measurements were carried out on PDMS filled with hydrophilic Aerosil with different specific surface area (average diameter 7 and 20 nm). Detailed data analysis indicates that the QENS spectra of the polymer-filler composites can be described by the sum of two contributions: (a) a quasielastic component due to chains not affected by the presence of the fillers and (b) an elastic term from those chain segments strongly affected by the presence of fillers. The latter depends on the specific surface area of the particles and their weight fraction in the composite.

A critical need in the fundamental understanding of reinforcement in filled polymers is the characterization of the polymer-filler interface and the dynamics of the polymer in this interfacial regime. In carbon black filled polymers, one of the central themes in the mechanism of reinforcement is that of “bound” polymer. Understanding the dynamics of this bound polymer may be key to arriving at an understanding of reinforcement mechanisms in filled polymers. The interactions between polymers and filler surfaces are also key in the development of more advanced nanocomposite materials.

We have previously utilized inelastic neutron scattering methods to examine the variation of bound polymer dynamics as a function of carbon black type for a single, initial carbon black concentration. An apparent change in the distribution in backbone motions was observed in the bound polymer compared with the pure polymer. In this study, we extend our prior work to examine the bound polymer dynamics as a function of the type of carbon black and the initial concentration of carbon black. The results suggest that two types of dynamic behavior are observed as a function of the initial carbon black concentration. This critical cutoff concentration may be related to the percolation threshold of the carbon black and suggests that quantifying the amount of bound polymer is insufficient for understanding the relationship between mechanical behavior and bound polymer content.

A new approach to the synthesis of a novel silicon-containing polyester by noncarbothermal method directly from SiO2 was studied. At first, a high reactive pentacoordinate organic silicon compound (KSi(OCH2CH2O)2(OCH2CH2OH)) was prepared by the reaction of the fumed silica with ethylene glycol (EG) and KOH. Then, a novel double hydroxy tetracoordinate silicon monomer (OCH2CH2O)Si(OCH2CH2OH)(OCH2CH2OCH2CH2OH) was synthesized by the reaction of ClCH2CH2OH with reactive pentacoordinate silicon compound. Finally, a silicon-containing polyester was synthesized by low temperature solution condensation between tetracoordinate silicon compound and p-phthaloyl chloride in dimethyl sulfoxide (DMSO). The product was characterized by FTIR, TG, GPC, etc. The IR spectra of polyester exhibited a characteristic strong absorption band for ester carbonyl in the 1722.2cm-1. IR spectra also showed absorption at 1124.6cm-1 due to the O-Si-O group. TG analysis showed its good thermal stability. GPC analysis showed that the number average molecular weight of this siliconcontaining polyester was about ninety thousand.

Producing nanofiber-diameter polymeric fibers presents an attractive and robust approach toward the processing of nanocomposites, with applications ranging from clear optical components to toughened structural materials. In this work, we are examining the electrospinning process for the production of nanometer-diameter polymer fibers, giving particular attention to the following key features: jet-initiation, fiber architecture, and fiber distribution. A wide range of polymer systems and polymer-solvent combinations were studied in order to broaden the applicability of our conclusions to other systems. Specifically, a dimensional analysis was applied to jet-formation data obtained by quantifying the conditions required for the expulsion of fibers from a charged capillary to a grounded collection plate. The relationships between various dimensionless groups were compared with the expressions for the critical voltage that have been proposed for electrospinning of polymer solutions.

A new experimental technique for determining mechanical properties of the polymer-metal interface was developed by replacing conventional mechanical testing machine with a piezoelectric actuator. Using this technique, fatigue crack growth behavior of epoxy/aluminum interface was studied as a function of electric field, crack length and cyclic frequency. The crack growth rate was found to depend on the magnitude of the applied electric field and decrease with testing frequency.

A mathematical analysis of surfaces may help to understand how the carbon black is dispersed into polymer. Rubber samples are broken out, and the rupture interface is scanned with a prolometer. The roughness is detected at the micron scale. Roughness functions are dened, measuring the average oscillations of the surface. The roughness behaviour is “fractal” for small scales until around 10 microns, then become linear. A roughness ratio is defined, depending both on the scale and on the mixing time. There is evidence to suggest that the roughness ratio does not depend on the polymer, but only on the dispersion of the filler. A dispersion factor is derived, and results are shown on three diserent compounds.

Rheological data are reported for a series of fumed silica filled PVAc samples, using fillers of different specific surface areas and surface treatments. Data at the glass transition temperature and 45 C above Tg are presented. The addition of filler systematically increases Tg, and all samples obey time-temperature superposition. However, temperature normalized and frequency normalized plots of loss modulus indicate that there is no change in the dispersion of the glass transition, with the only exception being a surface modified with covalently bonded polymer chains. Thus, contrary to expectations, an increase in filler content or change in surface treatment has no effect on the relative shape of the relaxation time spectrum at the glass transition. At 45 C above Tg, different behavior is observed. The filler concentration has a major effect on the nonlinearity of dynamic moduli vs. strain amplitude, with higher filler content reducing the strain amplitude at which nonlinear behavior is observed. Specific filler surface treatments result in major changes in the shape of the loss factor versus strain amplitude relationship. These results suggest that interfacial interactions strongly modify the far-field polymer behavior with respect to chain entanglement slippage at large strains.

The effect of silica nano-particle filler on poly(ethylene-co-hexene)/xylene gels has been investigated using mainly small angle neutron scattering and rheological measurements. Both non-filled and filled polymer gels show same characteristics in the structure factor and mechanical properties during melting and gelation. These observations suggest that particle interaction is screened by the absorbed polymers and the effect of the silica filler is mainly softening the gelation transition by introducing defects to the crosslinking microcrystals.

Films of deuterated polystyrene (dPS) and poly(methyl methacrylate) (PMMA) blends, as well as dPS and PMMA and poly(ethylene-co-propylene) (PEP) blends have been spin-cast from toluene solution and annealed at temperatures above their glass transition temperatures for up to 72 hours. Surface topography of the cast and annealed films was measured by atomic force microscopy (AFM). Dynamic secondary ion mass spectrometry (SIMS) was used to study microphase segregation of the polymer films. A series of two-dimensional (2D) images of the films were acquired during sample sputtering. A reconstruction of the sample three-dimensional (3D) structure from 2D data was performed. Spatial distributions of H, D, C, O, and higher mass fragments revealed microphases with dimensions on the order of a few microns. We describe the method that corrects height distortion to 3D SIMS images. After sputtering, AFM is used to produce a topographic image of the area analyzed by SIMS. The surface height variation array from SIMS data was compared with that observed by AFM. A limitation of the correction method is discussed.

The major inorganic component of the rice husk (RH) is silica (∼20%)[1]. In the past, the utilization of RH mainly concentrated on the ash of the rice husk, such as using rice husk ash (RHA) as filler in plastics, especially in polypropylene (PP). In this work, RH was directly used as filler in PP. Some treatments were applied to the RH. PP composites of different filler loadings were compounded using a laboratory size two-roll mixer at a temperature of 180° C for a period of 5 minutes. The tensile strength of the RH-PP composites increased steadily with increasing filler loading until about 20% loading. The impact strength of the composites decreased with the increasing filler loading. Torques and melt index (MI) of composites with various filler loadings were investigated. The MI of the composite decreased with the increasing filler loading. RH showed more potential than RHA as PP filler.

A composite based on exfoliated graphite (EG) and polystyrene was prepared by polymerization-filling technique. With the argument of the amount of filled EG, the molecular weight of polystyrene in the resulting composite increased and the molecular weight distribution decreased. The glass transition temperature of the polystyrene was determined by dynamic mechanical analysis (DMA) and showed the glass temperature of polystyrene increasing to 123.74°C. The thermal degradation behavior was studied using thermogravimetry (TG) and showed higher thermal stability of the composite than that of pure polystyrene and polystyrene//EG composite prepared by melt-blending. Four-probe instrument and high resistivity meter were used to measure the volume conductivity of the composites. Composites prepared by both polymerization-filling technique and melt-blending exhibit increased electrical conductivity, while composite prepared by polymerization-filling technique has a conductive percolation threshold lower than 2.5wt%.

Polymethylmethacrylate (PMMA) nanocomposites were synthesized by free radical polymerization in the presence of various weight percentages of alumina (Al2O3) nanoparticles. The resulting nanocomposites show an average increase of 600% in strain-to-failure and the appearance of a well-defined yield point. Concurrently, the glass transition temperature (Tg) of the composites decreased 20°C, while the ultimate strength and the Young's modulus decreased by 20% and 15%, respectively.

Carbon black is widely used as a filler in order to modify the mechanical or the electrical properties of polymers. Such composites display significant non-linear effects. Moreover, examination of the large number of papers devoted to the physical properties of carbon black filled polymers indicates that each composite, even composites apparently consisting of similar matrixes and similar carbon blacks, may behave differently when prepared by different mixing methods. The present work aims to show that these particular behaviors can be related to the fact that carbon blacks used for composites are mass fractals of low dimensionality (Df ˂2) that are able to interpenetrate each other to an extent that depends on the filler-matrix surface interaction and on the volume fraction of filler.

Small-angle X-ray scattering (SAXS) is a convenient method for studying disordered systems at length scales ranging between a few tenths and a few hundred nm. SAXS is therefore particularly advantageous for exploring the morphology of carbon black aggregates and their degree of interpenetration when dispersed in a matrix. Furthermore, the use of an area detector yields two-dimensional images and hence information about anisotropy of the arrangement of scatterers. It is shown that this arrangement profoundly influences the physical properties of the composites.

Analysis of SAXS curves obtained for a rubber grade carbon black (N330) and for composites prepared by dispersing it into polyethylene or EPR will be presented. As an example, the temperature and frequency dependence of the electrical conductivity will be discussed and compared to theoretical models. Finally, the mutual consistency of the electrical and mechanical behavior, theoretical models and information deduced from the scattering curves will be shown.

Intercalated nanocomposites of modified montmorillonite clays in a glassy epoxy were prepared by crosslinking with commercially available aliphatic diamine curing agents. These materials are shown to have improved Young's modulus but corresponding reductions in ultimate strength and strain to failure. These results are consistent with most particulate filled systems, The macroscopic compressive behavior is unchanged, although the failure mechanism in compression varies from the unmodified samples. The fracture toughness of these materials is investigated and improvements in toughness values of 200% over unmodified resis are demonstrated. The fracture surface topology is examined using SEM and tappin-mode AFM and showm to be related to the clay morphology of the system.