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The pollution due to non-degradable material such as plastics, has led to studies about the development of environmental-friendly materials. Because of natural sources-based materials and their biodegradability, polylactid acid (PLA) and ijuk fiber are interesting to be modified into a composite. Furthermore this study is also expected to reduce the impact of environmental problems. Surface modification of ijuk fiber through alkalinization, was aimed to enhance compatibility between the ijuk fiber and the PLA, in order to improve properties of the composite such as crytallinity and thermal behavior. To investigate in detail about this modification, this research also studied effect of the alkalinized ijuk fiber and the PLA composition to the crystallinity and the thermal behavior of the composites. The experimental results were investigated by FTIR to qualitatively analyze compounds content in the ijuk fiber before and after alkalinization, DSC and TGA to study crystallinity and thermal stability behavior of the composite, respectively and FE-SEM to observe morphological behavior like compatibility between the ijuk fiber and the PLA. The FE-SEM observation showed that alkalinization of the ijuk fiber led to wettability enhancement between the ijuk fiber and the PLA. This may be caused by annihilating lignin and hemicellulose. Furthermore this treatment leads to expose micro-fibril cellulose (MFC) in the ijuk fiber and then to enhancement of bonding affinity with the PLA. This phenomenon gives a possibility for the PLA in the composite to increase its crystallinity due to nucleating effect of crystalline parts in the MFC. DSC measurements show that addition of the alkalinized ijuk fiber tends to increase the crystallinity of PLA in the composites.Keywords: alkalization, Arenga Pinnata, compatibility, crystallinity, PLA, thermal stability

The main purpose of the research is to investigate the effect of thermal treatment through commercial pressure cooker (5, 25, and 60 min) on thermal and crystallinity properties of stalk sweet sorghum fibres. Crystallinity index and thermal stability of the fibers have been studied by using X‐ray diffraction (XRD) and simultaneous thermal analysis (STA) characterization, respectively, compared to untreated fibers. The result of this study shows that this treatment increased crystallinity index and thermal stability properties of the fibers. This result also shows that sorghum fiber can be used for a reinforcement candidate in thermoplastic matrix.

View the article online for updates and enhancements. Abstract. Polypropylene (PP) is usually added to bitumen to improve its mechanical properties, however, both of them have different chemical properties. To achieve best mechanical properties of the mixture, coupling agent such as lignin is importantly required. Lignin is an amorphous biopolymer, has bipolar characteristic due to its distinct chemical function which has carbonyl, carboxyl, hydroxyl and phenol chemical function. Otherwise, bitumen and PP have polar and nonpolar characteristic, respectively. In the previous research, it is found that lignin is potential to be used as coupling agent. In order to confirm the potential of lignin as a coupling agent, there are various compounds of lignin on PP-bitumen mixtures used in this research. This experiment consists of several stages, ranging from sample preparation, characterization of raw materials, mixing, and characterization of the PP-Modified Bitumen. This experiment used hot melt mixing to mix lignin, PP, and bitumen. The result of this experimental was analyzed by using FTIR and FESEM. The addition of lignin make Polymer Modified Bitumen (PMB) getting better mixing and increase mechanical properties. Furthermore, FESEM characterization indicated that the addition of lignin gave better mixing of PP-Bitumen. FTIR showed a new chemical structure due to the addition of lignin. From this experiment, the addition of lignin can improve mixing between PP and Bitumen. So, we can use lignin as coupling agent.

This work was aimed to investigate the effect of alkalization treatment on the fiber-matrix interfacial interaction and hence their compatibility. Kenaf fiber was treated using a 6% NaOH solution for 8 hours. The composites were produced by mixing the treated fiber with PP at various temperatures, duration, and fiber composition. Alteration on the surface chemistry of the fiber was identified by performing FTIR analysis. The surface energy of the treated fiber was mathematically derived from the contact angle measurement results. The compatibility level between treated fiber and PP matrix was visualized through FESEM analysis. Tensile strength tests were also conducted to obtain data necessary for exploring the relationship between the thermodynamic aspects of the fiber-matrix interfacial interaction and the mechanical properties of the composites. The FTIR spectra show that there was significant increase in the %transmittance at wavelength range of 3100-3600 cm-1 indicating that O-H groups were degraded during treatment. However, the polar component of the surface energy for treated fiber was instead higher compared to the untreated one. The SEM images show that there are no noticeable reduction in the size of the treated fibers as expected. On the other hand, the tensile strength of the PP-treated fibers composites reached its highest value when the matrix were loaded with fibers at the lowest percentage i.e. 5%.