1. Synthesis and characterization of biodegradable PVA/starch composite films reinforced with cellulose nanocrystals
Bianca-Ioana Dogaru1, 2, Carmen-Mihaela Popescu1,
Mirela Goanta2, Daniel Timpu1, Maria-Cristina Popescu1
1Petru Poni Institute of Macromolecular Chemistry of the Romanian Academy, Iasi, Romania
2 Al. I. Cuza University, Faculty of Chemistry, Iasi, Romania

2. Why PVA?
Increasing government initiatives to support green packaging coupled with the biodegradable nature of PVA films is expected to drive demand over the next years.
Polyvinyl alcohol (PVA) is a biodegradable synthetic polymer, non-carcinogenic, has good biocompatibility and excellent film-forming properties.
A material with high technological potential as an water processable and melt-processable material
PVA water-soluble film has good air barrier and resistance to oil. It could preserve food for longer time and keep fresh.

3. Water soluble PVA films are used for packaging in various industries; and over 66% of them are used for detergent and agrochemicals. Other applications may include :
Water Soluble Laundry Bag
Food packing
Commodity packaging
Chemical packing
Packaging of Infection Control
Agriculture Usage

4. Why Starch?
Starch is economically competitive with polymers derived from petroleum for manufacture of packaging materials.
Starch has been widely used in different industries due to its low cost, biodegradability and renewability.
It is use to improve the properties of food such as viscosity, texture, thickness etc.
However the starch granules hydrate easy, swell rapidly, lose viscosity, and produce weak bodies which create a very stringy and cohesive paste.
The combination of the properties of the starch/PVA films make them one of the most popular biodegradable blend. However, some of their physical properties (mechanical properties and water resistance) are still lower than those of other synthetic polymers made from petroleum resources. Many researchers tried to resolve these problems by ultraviolet irradiation [1], by adding crosslinking agents [2], or different types of nanoparticles [3]

5. Materials 90% PVA/10 % S 75% PVA/25% S 50% PVA/50% S 5% CNC 10 % CNC
water
glycerol
water
90% PVA/10 % S
75% PVA/25% S
50% PVA/50% S
5% CNC
10 % CNC
15% CNC

6. PVA/Starch films
90 %PVA/10% S
0 % CN % CNC 15% CNC

7. IR Spectroscopy
3300 cm-1 stretching vibration of free and bonded OH groups
1640 cm-1 bending vibration of O-H groups
The bands at 1240 and 1082 cm-1 are attributed to the stretching vibration of C–O in C–O–H groups, and the band at 1020 cm-1 is related to the C–O stretching vibration of C–O–C groups of the glucose unit in starch
The absorption bends appearing at 1425, 1373, and 845 cm-1 are due to the starch only and this is an ideal reference frequency to monitor starch content in the films.

8. deformation vibration of CH groups
1427 cm-1, 1324 cm-1, 1279 cm-1
deformation vibration of CH groups
1158 cm-1
stretching vibration of COC groups
1053 cm-1, 1000 cm-1
stretching vibration of CO groups

9. WAXD analysis of composite films
Precursors films after dewatering:
Red = S
Black = CNC
Blue = PVA
(90% PVA / 10 % S) % CNC /
5 % CNC / 10 % CNC / 15 % CNC
the increase of the signal intensities from  22.5 and  15.3  (2 theta degree) is in correlation with the increase of the CNC content
the modification of the signal from 19.7 is the combinated contribution of PVA and S

10. AFM cross section 3D 2D hystogram phase contrast
75%PVA / 25% S surface
cross
section 3D 2D
hystogram
phase contrast

11. (90% PVA/ 10% S) + CNC
0 % CNC
5 % CNC
15 % CNC
10 % CNC

12. Standard parameters statistics
Amount of sampling
Max nm
Min nm
Peak-to-peak, Sy nm
Ten point height, Sz nm
Average nm
Average Roughness, Sa nm
Second moment
Root Mean Square, Sq nm
Surface skewness, Ssk
Coefficient of kurtosis, Ska
Entropy
Redundance
Standard parameters statistics
- square area side: 0.5 / 1 / 2 / 5 / 10 / 20 / 50 um
- 256256 pixels resolution
3 different investigation zones on the same film
totally 21 data set / every film surface
l (um)
mean
0.5
2.97
2.10
1.85
2.31 1
2.93
8.77
6.04
5.92 2
4.59
10.93
9.35
8.29 5
23.10
27.45
25.11
25.22 10
40.13
41.26
40.05
40.48 20
55.19
64.66
46.90
55.58 50
81.98
90.31
65.01
79.10
Root Mean Square, Sq

13.  Root Mean Square, Sq increases with the percent of CNC
Sq (nm)
15 % CNC
10 % CNC
5 % CNC
0 % CNC
l (m)
(90% PVA + 10 % S) + % CNC
 Root Mean Square, Sq increases with the percent of CNC

14. Water vapor sorption
RH %
T=25 oC

15. Water vapor sorption

16. Water vapor sorption

17. Conclusions PVA/Starch/CNC composite films were prepared
The interactions between the components were evidenced by infrared spectroscopy
AFM indicated the surface morphology of composite films
The statistical analysis evidenced the modifications in the mean rugosity as a function of composite film composition and/or CNC concentration
The water vapor sorption decreased with CNC content, indicating the formation of intermolecular bonds involving OH groups between starch and PVA molecules

18. Thank you for your attention!