Influence of Thermal Treatment on Mechanical and Morphological Characteristics of Polyamide 11/Cellulose Nanofiber Nanocomposites

Denis Mihaela Panaitescu,Adriana Nicoleta Frone,Raluca Augusta Gabor,Eugeniu Vasile

doi:10.1155/2015/136204

Abstract

Nanocomposite films were prepared from polyamide 11 (PA11) and cellulose nanofibers (CN) by melt compounding and compression molding. The impact of thermal treatment on the morphology and mechanical behavior of PA11 and nanocomposite films was studied using dynamic mechanical analysis, tensile tests, X-ray diffraction (XRD), and peak force (PF) QNM technique. Slightly higher storage modulus values were obtained for nanocomposites compared to the matrix before the treatment, but a noticeable increase was observed after the treatment. Although CN addition determined increased tensile strength and modulus both before and after the treatment, the increase was much more significant in the case of treated films. The best mechanical properties were shown by treated PA11 films containing 5 wt% CN, with 40% higher Young’s modulus and with 35% higher tensile strength compared to the matrix. Some of the changes pointed out by static and dynamic mechanical tests were explained by the morphological changes determined by the thermal treatment and emphasized by PF QNM and by the increase of XRD crystallinity. A transition from lamellar stack morphology to one involving spherulites was highlighted by AFM. Thermal treatment has proved a valuable method for improving the mechanical properties of PA11/CN composites.

Highlights

Promotion of environmental protection has determined intensive research to develop high performance materials by the exploitation of renewable resources [1,2,3,4,5,6]
Treated polyamide 11 (PA11)/CN5, an increase of Young’s modulus with more than 40% and of tensile strength with 35% compared to the matrix being obtained
Thermal treatment has a significant impact on the morphology and mechanical properties of PA11 and nanocomposite films containing different amount of cellulose nanofibers (CN)

Summary

Introduction

Promotion of environmental protection has determined intensive research to develop high performance materials by the exploitation of renewable resources [1,2,3,4,5,6]. In an attempt for taking full advantage of nature potential, PA11 was modified by cellulose nanofibers (CN) [14] Because of their renewability, biodegradability, and remarkable mechanical properties, CN were successfully tested for improving the mechanical properties of various polymers [4, 6, 15,16,17,18,19]. Encouraging results were reported for polyamide 11 reinforced with CN, an increase of both yield strength and elastic modulus being observed from 1 to 5 wt% CN in nanocomposites [14]. Flexible bio-based polymer films with good mechanical properties, thermal stability, and chemical resistance are increasingly required in the design of lightweight and flexible electronics and robotics as well as in automotive or packaging applications. Dynamic mechanical analysis (DMA), XRD, tensile tests, and peak force QNM (quantitative nanomechanical mapping), an AFM technique, were used to quantify the influence of both CN and annealing on the morphology and mechanical properties of PA11 matrix

Materials and Methods

Results and Discussion

Conclusions