Preparation of High-Performance Polyethylene Nanocomposites with Oleic Acid-Siloxene-Supported Ziegler-Natta Catalysts.

The addition of two-dimensional inorganic nanomaterials can effectively enhance the properties of polyethylene (PE). In the present study, a series of high-performance PE/oleic acid (OA)-siloxene nanocomposites were prepared by in situ polymerization using OA-siloxene-supported Ziegler-Natta catalysts. Compared with the conventional Ziegler-Natta catalyst, the polymerization activity of the OA-siloxene-supported Ziegler-Natta catalyst was enhanced to 100 kg/mol-Ti•h, an increase of 56%. The OA-siloxene fillers exhibited excellent dispersion within the PE matrix through the in situ polymerization technique. Compared to pure PE, PE/OA-siloxene nanocomposites containing 1.13 wt% content of OA-siloxene showed 68.3 °C, 126%, 37%, and 46% enhancements in Tdmax, breaking strength, modulus, and elongation at break, respectively.

Synthesis of Long Alkyl and Fluoroalkyl Substituted Siloxane Copolymers for the Water Repellency of Rammed Earth Walls.

Rammed earth in a built environment has vapor diffusion characteristics and humidity control abilities, each of which is respectively attributed to the porous structures and the hydrophilic properties. Indeed, these structures and properties allow for the easy absorbance of water particles, hence affecting the durability of a rammed earth wall. This paper presents the water-repellency method for rammed earth walls, which utilizes siloxane copolymers containing fluorine. The water-repellent properties are investigated by measuring the contact angle, water absorption rate, and compressive strength after spray-coating with the synthesized siloxane copolymers on the surface of the rammed earth specimens under study. The water contact angle of the specimen, coated with a siloxane copolymer containing 10 mol.% of a silane monomer with a fluorine group, is about 140°. The water absorption of the specimen obtained after immersing in water for 24 h is low, at about 3.5 wt.%. In addition, the compressive strength remains more than 80% of the corresponding strength of the specimen which is not immersed in water. It is confirmed that the use of a 10% by volume of the siloxane copolymer containing the fluorine group may enhance the water-repellent performance and economic competitiveness.