Referencia Apresentador Autores
Ademir José Zattera Dias, R.R.(Universidade Federal do Rio de Janeiro); Piazza, D.(Universidade de Caxias do Sul); Pereira, I.M.(Centro Tecnológico do Exército); Zattera, A.J.(Universidade de Caxias do Sul); Soares, B.G.(Universidade Federal do Rio de Janeiro); The material studied is a nanostructured thermoplastic film developed to function as matrix in polymer composite. High density polyethylene (HDPE)/montmorillonite (MMT) 0.06 mm blown films were successful produced with 3% wt MMT, Cloisite 20A, content. Films were produced, initially, by mixing and extruding, in a laboratory single-screw extruder (diameter 16 mm, L/D = 26), HDPE and MMT at 40 rpm and 120° C from feed zone to die. After pelleting, blown films were obtained using a single-screw extruder with annular die and film take-up device (diameter 40 mm, L/D = 32) at screw rotation of 50 rpm and temperature profile of 170 ºC to 200 ºC. The orientation, morphology and property of both films were investigated by applying techniques such as: step scan differential scanning calorimetry (SDSC), small angle x-ray diffraction (SAXS), Fourier transform infrared spectroscopy (FTIR), tensile test. To evaluate the adhesive strength, pelling tests were applied to a woven lamina manufactured with aramid (Kevlar) and the blown films. To investigate the film’s morphology, DSC and SAXS results were used. The crystallization kinetics showed that the addition of MMT increased both the crystallization rate and the isothermal Avrami exponent. The reversing heat flow (Cp) and the non-reversing heat flow signal (IsoK) showed that modified and unmodified specimens presented samples with double melting peaks. Higher melting temperature was observed for MMT samples, suggesting thicker lamellae structure for the obtained materials. Cp-SDSC curve studied the crystal distribution of the structures formed. IsoK signal curves was employed to calculate the degree of crystallinity. Both materials presented isotropic 2D SAXS pattern. The lamellar structure of pure HDPE and HDPE/MMT blow films originates a peak around q = 0.265 nm-1 and a bump next to 0.6 nm-1. No extra peak was observed, suggesting complete exfoliation. The inter-domain repeat distance was calculated as 27.70 nm. HDPE/MMT scattering particle presented a distorted intermediate shape between a rod and a plane with ~37 nm radius of gyration. One-dimensional correlation function was calculated and the thickness of crystalline lamellae and thickness of amorphous layer obtained. Infrared spectrum of both films presented the characteristic CH2 bands. HDPE/MMT also presented a low intensity band at 1060 cm-1, which coincides with the stretching Si-O-Si functional group band. In tensile tests, each material exhibited similar properties in machine direction (MD) and transverse direction (TD), confirming that the chosen process parameters lead to isotropic properties. Peel test suggested that composite using HDPE/MMT film as matrix present superior resistance to delamination. Therefore, the HDPE/MMT films achieved biaxial properties, obtaining a globally isotropic morphology and exfoliated structure, which allowed it to be efficiently employed as a polymer composite.
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