RESUMEN
The use of natural fibres for polymer composite applications has been widely researched due to the biodegradable and lightweight nature of natural fibres. To achieve good adhesion and compatibility between the matrix and the fibre filler, prior modification of the fibre surface via the use of various methods has been found to be effective. The natural fibres have been modified using chemical, physical, radiation, grafting and biological methods. The current study aims to evaluate the effect of sodium hydroxide-treated waste pineapple leaf fibres (PALF) content on the chemical, thermal, and morphological properties of polybutylene succinate (PBS) composites. PBS-PALF composites with fibre content ranging from 0 to 20 wt% were prepared using an internal mixer and their properties were studied using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and Scanning electron microscope (SEM). The FTIR results showed no noticeable functionality differences among the composites, however, carbonyl groups from PBS polymer at â¼1700 cm-1 and hydroxyl groups from PALF at â¼3000 cm-1 were observed in the composites. The water absorption uptake of the composites increased with fibre content due to the hydrophilic nature of the PALF fibres and the highest water absorption percentage achieved was â¼30 %. The incorporation of the fibres into the PBS matrix decreased the crystallinity of the composites as shown by the XRD peaks at 2Ï´ = 22 and 30°. SEM images of the composites with 20 wt% exhibited morphologies where the fibres protruded out from the polymer matrix, and this was ascribed to the agglomerated fibres which were poorly mixed with the matrix at the higher fibre content. Overall, the incorporation of high PALF content in the composites disrupted the crystallinity and thermal stability of the PBS matrix. The composites have potential in industrial agricultural mulching film applications due to their sustainability characteristics.
RESUMEN
A propylene-ethylene random copolymer was fractionated by preparative temperature rising elution fractionation (TREF). The structural heterogeneity of the bulk sample and its TREF fractions was studied by high temperature liquid chromatography with a solvent gradient elution from 1-decanol to 1,2,4-trichlorobenzene. HPLC alone cannot resolve those propylene-ethylene copolymers with high ethylene content in the bulk sample, due to their low weight fractions in the bulk sample and a small response factor of these components in the ELSD detector, as well as their broad chemical composition distribution. These components can only be detected after being separated and enriched by TREF followed by HPLC analysis. Chemical composition separations were achieved for TREF fractions with average ethylene contents between 2.1 and 22.0mol%, showing that copolymers with higher ethylene contents were adsorbed stronger in the Hypercarb column and eluted later. All TREF fractions, except the 40°C fraction, were relatively homogeneous in both molar mass and chemical composition. The 40°C fraction was rather broad in both molar mass and chemical composition distributions. 2D HPLC showed that the molar masses of the components containing more ethylene units were getting lower for the 40°C fraction. HPLC revealed and confirmed that co-crystallization influences the separation in TREF of the studied propylene-ethylene copolymer.