Abstract
Behavior studies of thermoplastic polymers during non-isothermal crystallization are extremely important since most of their properties are influenced by degree of crystallinity and the crystallization process. In general, an approach based on a model-fitting method is used to perform crystallization kinetic studies. Due to their inability to uniquely determine the reaction mode, many studies have used the isoconversional method, where it is not necessary to assume a crystallization model to obtain the kinetic parameters. Therefore, in this work, the influence of acid and octadecylamine functionalized carbon nanotubes (CNTs) in the crystallization kinetic of polyethylene (PE) was studied using an isoconversional method with differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The kinetic parameters and the crystallization model were determined. The incorporation of functionalized and non-functionalized CNTs into PE did not change the Johnson-Mehl-Avrami crystallization model. However, the CNTs increased the crystallization temperature and reduced the activation energy for crystallization. In addition, the Avrami coefficient values were lower for the nanocomposites when compared to pure PE. The incorporation of CNTs accelerated the crystallization of PE, reducing the crystallite sizes and modifying their morphology.
Highlights
The use of plastics in several areas became widespread after World War II, rapidly increasing the production and even surpassing the commercialization of most other materials, especially metals
The high-density polyethylene (HDPE) pellets used in this study were obtained from Brasken (IG58, ρ = 0.956 gcm3)
The multi-walled Carbon nanotubes (CNTs) used as a nanofiller to prepare HDPE nanocomposites were provided by INPEBrazil and prepared by the chemical vapor deposition method (CNT–P) [46]
Summary
The use of plastics in several areas became widespread after World War II, rapidly increasing the production and even surpassing the commercialization of most other materials, especially metals. PE presents interesting properties, such as chemical inertness, low permeability, corrosion resistance, good stiffness, low density, and excellent electrical resistance. These qualities along with its low cost and easy processability make PE the choice material for a vast number of applications, especially for food packaging, storage containers for liquids, and chemical storage tanks [3]. CNTs remarkable properties, such as high Young’s modulus and tensile strength, chemical stability, biocompatibility, and excellent thermal conductivity, make them attractive for reinforcing polymer matrix, increasing the mechanical, biological, and thermal properties of the nanocomposite [8,9,10]
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