Preparation and property assessment of eco-friendly composite based on polyvinyl alcohol and lignin extracted from biomass
TNU Journal of Science and Technology
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- Figure 1.
- 3.3. Mechanical property of the composite film
- TNU Journal of Science and Technology
| TNU Journal of Science and Technology
226(06): 3 - 9 http://jst.tnu.edu.vn 6 Email: jst@tnu.edu.vn at 3282 cm -1 and C-OH groups at 1085 cm -1 , (Figure 1c). In the composite sample (PL3) (Figure 1b), due to interaction with lignin, a redshift appeared from 3282 cm -1 to 3290 cm -1 for hydroxyl of PVA and a similar phenomenon occurred for C-OH groups which shifted from 1085 cm -1 to 1097 cm -1 . This redshift revealed the appearance of hydrogen bonding interactions between hydroxyl groups in PVA and polar groups in lignin, enhancing composite properties. Figure 1. FTIR of lignin (a), PVA/lignin composite (PL3) (b), and PVA (c) 3.2. Surface morphology of PVA/lignin composite films The surface morphology of composite film with 25 wt% lignin was observed by scanning electron microscopy (Figure 2). Figure 2. SEM image of composite film (PL3) In the SEM image (Figure 2), it could be seen that the lignin was the discontinuous phase with particles size less than 500 nm and the PVA was the continuous phase. In addition, the result also showed that the sample surface had a uniform distribution and dispersion of lignin. 3.3. Mechanical property of the composite film The effect of lignin content on the mechanical properties of PVA/lignin composite was illustrated in Figure 3. With the addition of lignin amount, the tensile strength of the composite increased gradually until the lignin content gained 25 wt%. Then, the tensile strength began to decrease when the lignin amount continued to be added. Therefore, the tensile strength of the sample reached the highest value of 62 MPa with the lignin content of 25 wt%, an increase of TNU Journal of Science and Technology 226(06): 3 - 9 http://jst.tnu.edu.vn 7 Email: jst@tnu.edu.vn about 35 MPa compared to the tensile strength of PVA film. It could be seen that lignin played a role as a filler in the composite, leading to an increase in the tensile strength of the film significantly. One of the reasons was that lignin obstructed the movement of PVA molecules under the impact of external forces, increasing the durability of the composite film. Another significant reason was because the bond between hydroxyl functional groups on lignin and PVA molecules created intermolecular hydrogen bonds in the composite structure, enhancing the tensile strength of the film. However, with more lignin content was added to the composite, only a part of the lignin tightly bound with PVA, the rest of the lignin poorly dispersed into the PVA matrix, leading to a decrease in the strength of the film. tải về 0.53 Mb. Chia sẻ với bạn bè của bạn:
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