Durability of LDPE Nanocomposites With Clay, Silica, and Zinc Oxide II. Weatherability of the Nanocomposites Halim Hamid Redhwi, 1 Mohammad Nahid Siddiqui, 2 Anthony L. Andrady, 3 Hussain Syed 4 1 Chemical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia 2 Chemistry Department and Center of Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia 3 Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27607 4 Dhahran Techno-Valley, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia Three LDPE nanocomposites based on the nanoscale fillers, montmorillonite clay, silica, and zinc oxide were studied to determine if the reinforcement they imparted was accompanied by any change in the weatherability of the nanocomposite. Changes in weathering behavior were monitored in samples exposed to natural weather- ing outdoors over a period of 24 months of exposure. Because of superior light-shielding afforded by the high specific surface area of nanofillers a stabilization effect might be anticipated. Alternatively chemical effects may enhance weatherability. In all three nanocomposites studied, the weatherability compared to unfilled LDPE did not significantly change due to the presence of 5 wt% of the nanofillers. The efficient reinforcement afforded by the nanofillers is not accompanied by a loss or enhancement in durability of the material. POLYM. COMPOS., 00:000–000, 2013. V C 2013 Society of Plastics Engineers INTRODUCTION Industrial and research interest in thermoplastic nano- composites stems from the expectation that nanoscale fill- ers potentially impart dramatically improved properties at low loading. This is reasonable because of the high particle densities (10 6 210 8 particles per sq. micron), the exceptionally high interfacial area generated (10 3 210 4 m 2 ml 21 ) and proximity of particles in the matrix [1]. Increased interphase volume at the same volume fraction of filler is particularly advantageous as it is this volume that yields the superior properties of any composite [2]. The specific surface area is particularly large in lay- ered silicate clays including Montmorillonite clay (MMT) that are superior nanofillers especially when the polymer is intercalated between the plate-like morphology. This is easily achieved in the laboratory with in situ polymeriza- tion or template synthesis [3] in the matrix [4–8]. How- ever, industrial applications are likely to rely on melt- intercalation, often with the use of a compatibilizer [9– 11]. The blending is carried out usually in a compounding extruder. Melt compounding is more likely to break-up aggregates and facilitate good dispersion with simple nanoparticles. This is particularly true of layered silicate nanofillers such as MMT. Nanoparticles, having no lay- ered structure have relatively lower specific surface area, but are relatively easier to disperse in the polymer matrix. Successful incorporation of nanomaterials into thermo- plastics has been reported in the literature. Melt blending of clay and silica with polyethylene can be successfully achieved [6,7,12]. Sanchez-Valdez et al. [11] for instance studied polyethylene/MMT nanocomposites films pre- pared by melt blending: low-density polyethylene (LDPE) with MMT using maleic anhydride grafted polyethylene (LDPE-g-MA) as a compatibalizer. In this study we compare the nanocomposites obtained at constant weight fraction of three fillers with very Correspondence to: Halim Hamid Redhwi; e-mail: hhamid@kfupm.edu.sa Contract grant sponsor: Deanship of Scientific Research (DSR) at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia; contract grant number: IN100021. DOI 10.1002/pc.22594 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2013 Society of Plastics Engineers POLYMER COMPOSITES—2013