Preparation and properties of melt‐mixed metallocene polyethylene/silica nanocomposites

Abstract

Metallocene polyethylene (mPE)/silica nanocomposites were prepared via melt mixing. Two types of commercial fumed nanosilica, bare silica (A200) and organic modified silica (R974), were incorporated to improve the mechanical properties of the nanocomposites. Transmission electron microscopy, atomic force microscopy, and scanning electron microscopy revealed that the modified silica was dispersed slightly better within the mPE matrix. No distinct effects on the thermal behaviors of the fast‐crystallizing mPE matrix were observed with variations in both the silica dosages and types. Thermal stability was enhanced through the addition of nanosilica, with or without surface treatment. The surface‐modified silica system showed slightly higher tensile strength and Young's modulus compared with the bare silica system, as evidenced by a rheological study using a Cole‐Cole plot to assess enhanced polymer matrix‐dispersed silica interactions, especially for high dosages of organic modified silica. A limited increment in the dynamic storage modulus for modified silica cases, completely opposite of that observed for bare silica cases, was due to the low‐aspect ratio of smaller agglomerates from highly dispersed organic modified silica within the mPE matrix. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.

Preparation and properties of melt blended metallocene polyethylene/silica nanocomposites: modifier effects

“…mPE/silica (1 phr) nanocomposites at a different process condition in our other study were not intended for comparison with the current condition here [7] . LLDPE-g-MA modifi ed cases were listed for typical examples as they showed the highest enhancement in Young ' s modulus unless otherwise stated.…”

“…Afterwards, the sample was cooled to -40 ° C with a cooling rate of 10 ° C/min for crystallization. The melting temperature ( T m ) was obtained at a heating rate of 10 ° C/min from -40 ° C to 140 ° C. The crystallinity was calculated by taking the heat of crystallization divided by the actual resin content and the enthalpy required for 100 % crystallinity, equal to 289 J/g [7] . The glass transition temperature ( T g ) was determined via a dynamic mechanical analyzer DMA (Perkin Elmer, Pyris Diamond, Waltham, MA, USA) under a tensile mode at a frequency of 1 Hz at a heating rate of 5 ° C/min from -80 ° C to 30 ° C. Thermogravimetric analysis TGA (Perkin Elmer, Pyris 1, Norwalk, CT, USA) was employed to evaluate the thermal stability of the nanocomposites with a heating rate of 20 ° C/ min from 40 ° C to 800 ° C in a nitrogen environment.…”

“…EOC grafted with vinyltriethoxysilane confi rmed the improved fi ller dispersion through the formation of covalent bonds between the VTEOS and the hydroxyl groups on silica surface. We recently reported the effects of hydrophilic or hydrophobic silica dispersion on the mechanical and rheological properties of metallocene PE/silica nanocomposites [7] . Suryadiansyah and Azhari [8] have investigated the effects of two compatibilizers, i.e., ethylene diamine dilaurate (EDD) and maleic anhydride grafted polypropylene (PPMA), on the mechanical properties, water absorption, morphology, and thermal properties of silica-fi lled polypropylene composites.…”

“…There are literature studies that indicate the possible interfacial modifi cation between hydroxyl groups on inorganic silicate surface and maleic anhydride groups on the organic modifi ers [8, 15 -17] . As the organically modifi ed silica was chosen to have a good interaction with the matrix based on our previous study [7] , the modifi ers would be expected to have a limited effect on the dispersion of silica. This design allowed us to compare the modifi er effects on other properties under similar silica dispersion.…”

Development of environmentally friendly cellular polymers for packaging and structural applications: Study of the relationship cellular structure-mechanical properties

“…These materials are gaining special attention due to the industrial interest in using PP for automotive applications in which lightweight materials with high stiffness and strengths are required [63,64,65] . The mechanical property improvement is not only associated with the intrinsic reinforcing effect of nanofillers but also with the morphological changes induced in the polymer because nanoparticles can act as nucleating agents during the crystallization process [66,67,68 This thesis has been mainly focused on how the cellular structure and consequently, the mechanical properties of PP-based foams are modified by the presence of nanoclays within their cell walls, edges and vertexes, which is a very complex task due to the multifunctional effect of nanoparticles during the foaming process. More details about these aspects will be given in section 2.6.3.…”