Influence of nanodispersed organoclay on rheological and swelling properties of ethylene propylene diene terpolymer

Revealing nanocomposite filler structures by swelling and small-angle X-ray scattering

Polymer nanocomposites are used widely, mainly for the industrial application of car tyres. The rheological behavior of such nanocomposites depends in a crucial way on the dispersion of the hard filler particles – typically silica nanoparticles embedded in a soft polymer matrix. It is thus important to assess the filler structure, which may be quite difficult for aggregates of nanoparticles of high polydispersity, and with strong interactions at high loading. This has been achieved recently using a coupled TEM/SAXS structural model describing the filler microstructure of simplified industrial nanocomposites with grafted or ungrafted silica of high structural disorder. Here, we present an original method capable of reducing inter-aggregate interactions by swelling of nanocomposites, diluting the filler to low-volume fractions. Note that this is impossible to reach by solid mixing due to the large differences in viscoelasticity between the composite and the pure polymer. By combining matrix crosslinking, swelling in a good monomer solvent, and post-polymerization of these monomers, it is shown that it is possible to separate the filler into small aggregates. The latter have then been characterized by electron microscopy and small-angle X-ray scattering, confirming the conclusions of the above mentioned TEM-SAXS structural model applied directly to the highly loaded cases.

Investigating Thermal Stability and Flame Retardant Properties of Synthesized Halloysite Nanotubes (HNT)/Ethylene Propylene Diene Monomer (EPDM) Nanocomposites

In this work, Halloysite Nanotube (HNT) was synthesized, using a modified method, from kaolin clay. The scanning electron microscopy (SEM) of the synthesized HNT revealed that many of the nanotubes were tubular; however, spherical and semi-spherical, platy and semi rolled structures were also observed. Fire retardant EPDM compounds composed of typical flame retardants (FR), deca-bromo diphenyl oxide (DBDPO), antimony oxide (Sb2O3), talc and carbon black were prepared. Three elastomer compounds, with 5, 10 and 20 wt.% of synthesized HNT, and one more compound with 10 wt.% of synthesized HNT and 10 wt.% of conventional flame retardants were prepared and formed by a two roll mill. A TEM micrograph was presented to prove the well dispersion of HNT in polymer matrix. The flammability, thermal stability and tensile strength of the compounds were compared to that of typical fire retarded EPDM. The results showed that the typical flame retardants diminish the tensile strength and elongation at break of EPDM elastomers; in addition, these compounds showed the lowest thermal stability among the typical formulations. The extent of flammability of the compounds was characterized using the cone calorimetry technique. The compound containing 5 wt.% HNT showed the highest tensile strength, the least flammability and the highest thermal stability compared to the other compounds. This was related to the good dispersion and also on the tubular structure of the synthesized nanotubes. The peak of heat release rate (PHRR) and total heat release (THR) as well as the amount of hazardous gas emission for the sample having the highest mechanical response was smaller than those with conventional micro-filler flame retardants.

Effects of High Energy Radiation on Mechanical Properties of PP/EPDM Nanocomposite

Nanocomposites are the materials that are created by introducing nanoparticulates that always referred to as filler into the matrix. Blends of polypropylene (PP)/ethylene propylene diene monomer (EPDM)/Montmorillonite (MMT) were treated by compatibilizer MAPP and irradiation of electron beam. The effects on mechanical properties for both samples were compared with the untreated nanocomposites. Because each samples used different portion of clay loading, the effects of clay loading on mechanical properties is also observed. The sample is characterized by using Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), tensile test and impact test.