ORIGINAL CONTRIBUTION Effect of poly(amid–imide)/Al 2 O 3 hybrid with various ratios on the physicochemical properties of poly(vinyl alcohol) nanocomposites films Shadpour Mallakpour & Elham Khadem Received: 30 April 2014 /Revised: 19 May 2014 /Accepted: 20 May 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract To study the effect of the various ratios of poly(amide–imide)/Al 2 O 3 nanocomposites (PANC)s on the mechanical and thermal properties of nanocomposites films, poly(vinyl alcohol) (PVA)/PANCs based on various ratios of 2, 4, and 6 wt% were prepared and characterized. In the first step, the surface of alumina nanoparticles was treated with 15 wt% of biosafe diacid and consequently, about 10 wt% of these modified nanoparticles were load- ed into the poly(amide–imide) matrix. Then, various con- tents of the obtained PANCs were incorporated into a PVA solution using a sonochemical treatment. The effects of PANC on the structure and morphology of PVA matrix were studied using powder X-ray diffraction, field emis- sion scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy (AFM), and thermal gravimetric analysis (TGA). The results show that the tensile strength and decomposition temperature were improved as the portion of PANC into PVA matrix are increased from 2 to 6 wt%. Also, AFM pictures of the fracture surfaces of PVA/PANCs showed a significantly rougher surface than the neat PVA. Keywords Alumina nanoparticle . Poly(amide–imide) nanocomposite . Poly(vinyl alcohol) . Mechanical properties . Ultrasonic irradiation Introduction Nanocomposites (NC)s containing natural and synthetic hy- drophilic polymers as poly(vinyl alcohol) (PVA) have re- ceived signification attention from the scientific viewpoint [1, 2]. Hydrophilic PVA as semicrystalline polymer was adopted by polymerization of vinyl acetate to poly(vinyl acetate), and then hydrolysis to the PVA macromolecule [3, 4]. Contrary to full carbon backbone of PVA, it was recognized as one of the most suitable biocompatibility and biodegradable synthetic macromolecules [5]. This polyhy- droxy polymer, due to unique chemical and physical proper- ties such as adhesive properties and excellent chemical resis- tant, has good film-forming and high hydrophilic properties, high tensile strength, and flexibility, is successfully used in extensive range of industrial fields and consumer products [6–8]. However, its properties depend on humidity, and there- fore, PVA as a soluble polymer cannot be used in wide application. Accordingly, in order to elevate its performance and ameliorate its properties, various additives such as nano- particles and salts [9–11] as filler are usually added to the PVA matrix. However, maximal PVA properties and performance can be attained when the nanofillers are dispersed homoge- neously in the matrix via a strong interaction at the interface between the filler and the matrix. Also, filler chemical natural and its interaction way with the matrix, in alter the PVA properties are important [12]. Polymer NCs due to having structure in the nanometric size and also existing oxygen- containing functional groups including hydroxyl can be used as reinforcement in the PVA matrix. Aromatic poly(amide– imide)s (PAI)s are an important class of alternative polymers S. Mallakpour (*) : E. Khadem Department of Chemistry, Organic Polymer Chemistry Research Laboratory, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran e-mail: mallak@cc.iut.ac.ir S. Mallakpour e-mail: mallak777@yahoo.com S. Mallakpour e-mail: mallakpour84@alumni.ufl.edu S. Mallakpour Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran Colloid Polym Sci DOI 10.1007/s00396-014-3281-1