Preparação e funcionalização de nano fibras (whiskers) de quitina e sua aplicação como agente de recuperação de propriedades em polímeros reciclados

Abstract

Polymers usually show reduction in mechanical properties due to recycling processes. In this work, the hypothesis that both the incorporation of nanocomponents and the control of their interaction with polymers could allow the recovery of some properties of the recycled polymers was tested. Chitin whiskers were produced from commercial chitin by acid hydrolysis processes and had their surfaces chemically modified by grafting methoxy polyethylene glycol (mPEG) with different molar masses and acetic acid. Successful production and modification of these whiskers were confirmed by infrared spectroscopy, transmission and scanning electron microscopy, atomic force microscopy, x-ray diffraction, light scattering, thermogravimetric analysis and dynamic scanning calorimetry. Films of neat and recycled PP and neat and recycled ABS having the prepared whiskers were produced, characterized and submitted to mechanical tensile tests and dynamic mechanical analyses (DMA). A novel procedure to incorporate the whiskers within ABS, consisting in the dissolution followed by fast precipitation of thepolymer in contact with the whiskers, was developed. This procedure was successful in producing films containing 0.5 wt.% of whiskers in ABS without the presence of large aggregates. It was shown that the incorporation of chitin whiskers in polypropylene led to reductions in mechanical properties similarly to what often happe ns when conventional fillers were added to polymers. DMA results revealed that the presence of whiskers in recycled PP was able to reproduce the dynamic mechanical behavior observed for neat PP. In the ABS based system, the incorporation of 0.5% of whiskers modified with highermolar mass methoxilated PEG and acetate groups led to substantial improvements in strength, stiffness and strain at failure in relation to recycled ABS, demonstrating that they could be used to recover the properties of recycled polymers.