The starch (7 wt %) was gelatinized at 80 °C in a neck flask
for 3 h, while PVA was dissolved in deionized water at 90 °C
for 3 h. The resultant solutions were homogenized using a sonicator
(HD 2200, Bandelin electronic Co., Berlin, Germany) at 72% power for
10 min. Similarly, kraft lignin (7 wt %) and citric acid (7 wt %)
were dissolved in deionized water for 3 h and 15 min, respectively.
The lignin solution was homogenized using a sonicator at 72% power
for 15 min. The starch-soluble, PVA, and lignin solutions were centrifuged
at 11 000 rpm to remove undissolved particles. To prepare the
H-SCL slurry, starch, citric acid, and lignin were mixed in a ratio
of 51:9:40, while the H-PCL slurry was synthesized by blending PVA,
citric acid, and lignin in a ratio of 45.5:24.5:30. The solutions
were mixed using a magnetic stirrer for 1 h, then homogenized at 72%
power for 10 min, and finally degassed. The degassed slurry was cast
on a glass substrate using a doctor blade and partially dried to form
a flexible film that could be easily rolled into straws on a Teflon
rod. The partially dry films can easily be bonded at the edges without
needing binders and adhesives. The films and rolled straws were fully
dried in a dry oven and cured in a vacuum oven at 180 °C to form
esterified straws and films.
for 3 h, while PVA was dissolved in deionized water at 90 °C
for 3 h. The resultant solutions were homogenized using a sonicator
(HD 2200, Bandelin electronic Co., Berlin, Germany) at 72% power for
10 min. Similarly, kraft lignin (7 wt %) and citric acid (7 wt %)
were dissolved in deionized water for 3 h and 15 min, respectively.
The lignin solution was homogenized using a sonicator at 72% power
for 15 min. The starch-soluble, PVA, and lignin solutions were centrifuged
at 11 000 rpm to remove undissolved particles. To prepare the
H-SCL slurry, starch, citric acid, and lignin were mixed in a ratio
of 51:9:40, while the H-PCL slurry was synthesized by blending PVA,
citric acid, and lignin in a ratio of 45.5:24.5:30. The solutions
were mixed using a magnetic stirrer for 1 h, then homogenized at 72%
power for 10 min, and finally degassed. The degassed slurry was cast
on a glass substrate using a doctor blade and partially dried to form
a flexible film that could be easily rolled into straws on a Teflon
rod. The partially dry films can easily be bonded at the edges without
needing binders and adhesives. The films and rolled straws were fully
dried in a dry oven and cured in a vacuum oven at 180 °C to form
esterified straws and films.
