PHB/Bentonite Compounds. Effect of Clay Modification and Thermal Aging on Properties

AUTOR(ES)

Almeida, Tatiara G., Costa, Anna Raffaela M., Wellen, Renate M. R., Canedo, Eduardo L., Carvalho, Laura H.

FONTE

Mat. Res.

DATA DE PUBLICAÇÃO

21/08/2017

RESUMO

Poly(3-hydroxybutyrate) (PHB) was compounded with three different Bentonite clays: natural, purified by ultrasound/sonicated and organically modified with hexadecyltrimethylammonium bromide. PHB/Bentonite masterbatches with 30% clay were prepared in a laboratory internal mixer and letdown with pure matrix to 1% and 3% w/w clay. Test samples were injection molded and characterized by x-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Increase in Bentonite hydrophobic character was evinced by FTIR for organoclays. XRD of composites showed increase in clay interlayer distance and peak broadening, suggesting formation of intercalated nanocomposites. DSC showed increase in crystallinity and crystallization rate for compounds, especially for PHB/organoclay formulations. Thermal aging was conducted by exposing specimens at 115ºC for up to 120 hours, and mechanical properties were measured according to ASTM standards. Elastic modulus increased and impact strength decreased with time and clay content; clay purification had little effect on the tensile properties. Tensile strength of thermal aged samples showed little variation, except for the organoclay nanocomposites, for which it significantly decreased with exposure time. SEM images displayed a whitened honeycomb structure and detachment of PHB/Bentonite layers which may be connected to cold crystallization and degradation processes taking place during thermal aging.

Documentos Relacionados

• Hydrolytic and Thermal Degradation of PCL and PCL/Bentonite Compounds
• Use of Copper Microparticles in SEBS/PP Compounds. Part 1: Effects on Morphology, Thermal, Physical, Mechanical and Antibacterial Properties
• Effect of thermal aging conditions on the corrosion properties and hardness of a duplex stainless steel
• Effect of heat cycling on melting and crystallization of PHB/TiO2 compounds
• Vitamin D compounds. Effect on clonal proliferation and differentiation of human myeloid cells.