Structure and properties of injection-molded nanocomposites of biobased polyamide 11 and fibrous sepiolite or layer-like montmorillonite nanofillers
Polymer Materials
Final Report Abstract
In this project, the effects of addition of nanofillers and injection molding conditions on the crystallization behavior and on properties of the biobased polyamide 11 (PA 11) were investigated. Two different morphological and structural nanofillers, organo-modified sheet-like OMMT (Cloisite 30B) and needle-like sepiolite (Pangel S9) were successfully dispersed in the biobased PA 11 by twin-screw-extrusion compounding. TEM-images indicated full delamination and dispersion of the nanofillers within the PA 11 matrix at a concentration of 2.5 m%. Both sepiolite and OMMT nanofillers at 2.5 m% act as a nucleating agent to increase the crystallization rate of PA 11, in particular on rapid cooling/high supercooling which is relevant to processing conditions. Addition of nanofillers with loadings higher than 2.5 m% led to ineffective nucleation due to incomplete exfoliation of nanoparticles. OMMT and sepiolite nanocomposites showed an increase in storage modulus, tensile strength, and hardness due to classical reinforcement and due to an increase of the crystallinity of the PA 11 matrix. Structure formation in injection molding was investigated in detail and resulted in the development of a new concept for predicting structural gradients. This new concept is based on the simulation of the cooling-rate profile in all regions of the molding as a function of the temperature of the melt, and forecasting the corresponding temperatures of crystallization based on non-isothermal quiescent-melt crystallization experiments performed independently. It appears by observation of similar semicrystalline morphologies in the various regions of the injection moldings with that in samples crystallized from the relaxed melt at comparable conditions that the suggested approach of predicting the structural gradient via estimating crystallization temperatures in injection moldings is reliable and does not necessarily need to account for shear-induced crystallization effects for this particular polymer. The approach was found worth to be re-published by the Society of Plastic Engineers (SPE).
Publications
- (2018) Flame retarding polyamide 11 with exfoliated vermiculite nanoflakes. Polym Eng Sci (Polymer Engineering & Science) 58 (10) 1746–1755
Macheca, Afonso D.; Focke, Walter W.; Kaci, Mustapha; Panampilly, Bindu; Androsch, René
(See online at https://doi.org/10.1002/pen.24775) - Crystallization kinetics of polyamide 11 in the presence of sepiolite and montmorillonite nanofillers. Colloid and Polymer Science 2016, 294, 1391–1391
Jariyavidyanont K, Focke W, Androsch R
(See online at https://doi.org/10.1007/s00396-016-3874-y) - Supercooling-controlled heterogeneous and homogenous crystal nucleation of polyamide 11 and its effect onto the crystal/mesophase polymorphism. Polymer 2016, 106, 29–34
Rhoades AM, Wonderling N, Schick C, Androsch R
(See online at https://doi.org/10.1016/j.polymer.2016.10.050) - Crystallization of polyamide 11 during injection molding. Polymer Engineering and Science 2017
Jariyavidyanont K, Williams J, Rhoades AM, Kuehnert I, Focke W, Androsch R
(See online at https://doi.org/10.1002/pen.24665)
