Moshe Narkis

This research presents a generic fabrication method for tailoring polymer/carbon nanofillers composites with controlled architecture and composition. Two types of common carbon nanofillers, i.e. multi‐walled carbon nanotubes (MWNTs) and graphene nanosheets, are finely dispersed in an aqueous dispersion of polyacrylate followed by a microfiltration process. The second step allows preserving the high dispersion level of the nanofillers within the polymer matrix in the resulting solid films/layers. This study aims to investigate the structure–property relationship of the polyacrylate/nanofiller films, fabricated by the combination of latex technology and microfiltration. The polyacrylate/MWNTs system is studied over the entire MWNTs composition (0 to 100 wt%) and is shown to exhibit a structural transition; from a nanocomposite structure, in which the nanotubes are dispersed within a continuous polymer matrix, to a porous MWNTs macrostructure containing segregated polymer domains. This structural transition is corroborated with the films‐specific surface area values and the mechanical properties versus the MWNTs content. The percolation threshold of the studied polyacrylate/MWNTs systems is obtained at MWNTs content of ~0.04 wt%, an order of magnitude lower compared with cast films, fabricated by conventional latex technology. Polyacrylate/graphene nanosheet nanocomposites that are fabricated using the same method also demonstrate a structural transition from nanofiller/polymer composite material to graphene macrostructures. Copyright © 2014 John Wiley & Sons, Ltd.

Electrically conductive elastomeric nanocomposites containing carbon nanotubes (CNT) and polyaniline (PANI) are reported in the present investigation. The synthesis procedure included an in situ inverse emulsion polymerization of aniline doped with dodecylbenzene sulfonic acid (DBSA) in the presence of CNT and dissolved styrene‐isoprene‐styrene (SIS) block copolymer. The PANI synthesis step was carried out by applying ultrasonic energy. The dispersions obtained were processed by two methods: a recently developed precipitation‐filtration procedure, and a conventional drop‐cast procedure. The techniques developed resulted in homogeneous exfoliated PANI coated nanotubes within the elastomeric matrix. The presence of CNT/PANI in the SIS elastomeric matrix affects thermal, mechanical, and electrical properties of the nanocomposites. The formation of continuous three‐dimensional CNT/PANI networks prepared via the precipitation‐filtration method enhances the nanocomposite properties. Contrarily, the intermittent three‐dimensional network prepared by conventional drop‐cast method leads to inferior properties. Nanocomposites produced by both techniques are observed by HRSEM. The two processing techniques result in different structures, which affect the physical properties of the materials produced. A relatively low percolation threshold for both methods was determined. The Young's modulus of the SIS/CNT/PANI significantly increased in the presence of CNT. The precipitation‐filtration technique yields an improved nanocomposite product compared to the drop‐cast route. POLYM. COMPOS., 35:788–794, 2014. © 2013 Society of Plastics Engineers

Transparent plastic films are widely used in agriculture as greenhouses covering and in the food industry as packaging films. The films are usually prepared by hydrophobic low polarity thermoplastics such as polyethylene (PE). In a greenhouse, the temperature and humidity are usually higher than the outside temperature and fog will appear on the inner surface of the PE film. Anti‐fogging (AF) additives are tensoactive materials, mainly nonionic surfactants, equalizing the PE and water surface tensions, thus creating a thin, continuous film of water rather than discrete droplets. In the present work, a new method of controlled migration of AF is described, by grafting AF molecules to the surface of submicron inorganic particles. Glycerides and fatty acids are used as AF. During the grafting reaction two fractions are formed: attached AF fraction to the inorganic particles' surface, a fraction which cannot be detached by extraction, and an unreacted, thus unattached AF fraction. Solvent extraction, FTIR and TGA measurements have confirmed the existence of the grafted AF molecules to the inorganic particle's surfaces. Aging tests, developed in the present work, have shown a significant decrease of the AF migration rate, thus confirming an extended duration of the anti‐fog's activity. POLYM. ENG. SCI., 54:2023–2028, 2014. © 2013 Society of Plastics Engineers

This work describes an empirical study of in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of nine different types of carbon nanotubes (CNT) in toluene. The polymerization method described in this work is simple and very fast (5 min) compared to the other literature reports (3–12 h). During polymerization, CNT are coated with polyaniline (PANI) forming a core‐shell structure of nanowires as evidenced by transmission electron microscopy (TEM) and high‐resolution scanning microscopy (HRSEM). HRSEM images and surface resistivity imply that PANI coating of CNT leads to a remarkable improvement in separation and dispersion of CNT in toluene, which otherwise would have rapidly coagulate and settle. Two of the nine different CNT studied have shown the lowest surface resistivities. Films of uniform thickness were successfully produced (HRSEM of cross‐sections). The effect of film thickness on conductivity and optical properties is reported in the work. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013