Modificação da interface de compósitos de polipropileno com fibras de vidro pela técnica Layer-by-Layer

Abstract

The properties of glass fiber-reinforced polymer composites are closely related to the performance of the interface between fibers and polymer matrices. Many interfacial treatments have been developed and used to improve the mechanical properties of the composites. However, the goal of these treatments is usually limited to enhance interfacial adhesion. In the present work, the Layer-by-Layer (LbL) technique was introduced to build a novel interface in polymer composites that could have multiple functions, such as to improve the stiffness and toughness, but also to encapsulate special active components. The LbL technique was used to modify the surface of glass fibers (GFs) that were further incorporated into a polypropylene matrix. Different numbers of bilayers of poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) were deposited on the surface of woven glass fibers (0°/90°). Moreover, carbon nanotubes were also incorporated within the deposited layers to test the hypothesis that the LbL technique could allow the incorporation of active nanocomponents potentially useful to improve stiffness, thermal properties and electrical conductivity in the interface of polymer composites. Polypropylene composites containing the modified GFs were prepared by compression molding. Thermogravimetric analysis and SEM images proved that multilayers of polymers could be deposited on GFs by the LbL technique. Results obtained from Raman spectroscopy showed that the carbon nanotubes were successfully incorporated within the modified surfaces of GFs. Mechanical tests revealed that composites with modified fibers display an increase in Flexural Modulus, reaching higher values after deposition of 20 bilayers. The overall results of this work proved the hypothesis that the LbL technique can be used to construct interfaces in polymer composites with different structures and compositions. These designed interfaces can perform many different tasks, such as to improve the stiffness of composites and to encapsulate active nanocomponents, among others. LbL technique could provide a new way to improve or create specific properties on GFs which traditional sizing doesn`t reach.