Modified Yttrium Hydroxide/MC Nylon Nanocomposites and Scaling Effects in Multilayer Polyethylene Films

In this thesis, monomer casting (MC) nylon was synthesized. MC nylon could replace nonferrous metals in certain applications, including gears, wheels, and other moving parts. However, compared with metals, MC nylon products have poor strength and stiffness, and crack easily, especially at low temperatures. In addition, the dimensional stability of MC nylon is poor, especially in the large casting nylon products, causing significant internal stresses due to shrinkage. Thus, MC nylon cracks easily when cast and molded. The yttrium hydroxide particles were modified by stearic acid and dispersed in the caprolactam. The polymerization time was short due to fast anionic polymerization. Copolymerization with different ratios of yttrium hydroxide particles can be used to prepare the copolymer. The effects of different amounts of yttrium hydroxide on the performance of the monomer casting nylon were studied. The products were characterized using X-ray diffraction, impact, and tensile testing. When the percentage of modified yttrium hydroxide is 0.3 wt %, the composite exhibits the maximum impact strength, thus the 0.3 wt % of modified yttrium hydroxide is the suitable percentage to enhance the impact strength of MC nylon.;Transparency and color of polyethylene film layered packages change with the number of layers. When polyethylene layer thickness is between 50 microm and 200 microm, each additional subsequent layer in the package leads to an abrupt change of color and transparency. Polarized light optical effects can be used to manufacture packaging films and labels with forgery protection. A significant influence of the scaling factor on the latent effect and optical properties of the film package is demonstrated for 1 to 6 layers with the total thickness of 200+/-50 microm. Prior thermal treatment of individual layers before they are assembled into a package or assembled package heat treatment change the laminate color. This allows hidden marking and recording text or graphics on the multi-layer films, not visible under normal lighting conditions, but appearing when viewed in polarized light, or through the polarizer.