Thermal and Morphological Properties of Polyvinyl Alcohol-based

Hydrogel Containing Microcrystal Cellulose

Riski Aulia Hasibuan

, Diana Adnanda Nasution

and Basuki Wirjosentono

Postgraduate Chemistry Study Program, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara,

Jl. Bioteknologi No. 1 Kampus USU, Medan, Indonesia

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara, Jl. Bioteknologi

No. 1, Medan 20155, Indonesia

Keywords: Polyvinylalcohol, Microcrystal Cellulose, Acrylicacid, Interpenetrating-hydrogels.

Abstract: In this work, the PVA-based hydrogels containing various loading of microcrystal cellulose (MCC: 0; 0.2;

0.4; 0.6 and 0.8) g were prepared in a bench-scale reflux-reactor using water as a solvent in an optimized

condition. Other constituents added, i.e. acrylic acid (AA) and N’N-Methylene bisacrylamide (MBA) as

comonomers as well as ammonium persulphate ((NH4)2S2O8) as initiator was keeping their composition

ratio constant. Products of the interpenetrating-hydrogels were cast in plastic mold and cooled, and then

characterized. First of all, their absorption properties and were measured using swelling test to know

optimum conditions and the next will be characterized with FTIR, DSC, and SEM. Results showed that the

optimum composition ratio of PVA/AA/MCC/MBA/APS = 0.4/4/0.6/0.06/0.2 enhanced the water

absorption. FTIR analysis of the film specimen after exhaustive extraction in n-hexane still contained stable

AA-carbonyl (C=O) absorption peak at 1713 cm

-1

of hydrogel 1 and 1707 cm

-1

of hydrogel 4. The thermal

properties of the optimized composition of the hydrogel 1 showed its stable decomposition temperature

(thermal stability of 482.28

C). Morphological properties of the interpenetrating-hydrogel micro composites

also showed finely distributed of the micro filler, which is responsible for its improved mechanical and

thermal properties.

1 INTRODUCTION

Technological progress continues to increase. To

improve research in the field of polymers, new

technologies such as biopolymers are needed.

Biopolymers are one of the materials produced by

modifying a polymer. Modifications can be made by

combining polymers that function to improve the

properties of these polymers such as absorption,

elasticity, and mechanical strength that are

biodegradable, biocompatible, and non-toxic. This

modification can also affect the solubility of

polymers which can dissolve in water to be insoluble

like hydrogels (Sinha, 2018)).

Hydrogels are hydrophilic polymers with three-

dimensional structures that have cross bonds

(Ahmed, 2015). The three-dimensional structure of

the hydrogel formed through crosslinking makes the

hydrogel capable of absorbing and releasing water

reversibly (Ambrosio, Demitri, & Sannino, 2011).

The ability of a hydrogel to absorb water thousands

of times from its dry weight is influenced by a group

of hydrophilic functions found in three-dimensional

structures. This hydrophilic functional group can

hold large amounts of water (Ahmed, 2015, Maitra

& Shukla, 2014). The hydrophilic functional groups

contained in hydrogels such as carboxyl (-COOH),

hydroxyl (-OH), and amide (-CONH

) (Ha et al.,

2018). Hydrogels have several very important

properties, which are able to expand well in water,

insoluble in water (Burdick & Stevens, 2005),

softness, elasticity, and flexibility. Because of these

properties, hydrogels can be used in various

applications for food, agriculture, industry, medical,

medicine, and cosmetics (Kiatkamjornwong, 2007,

Anamica & P. P. Pande, 2017).

At present, a lot of research has been done

regarding the manufacture of hydrogels. Making

hydrogels that use polysaccharides such as starch,

chitosan, xanthan, and cellulose can be done through

polymerization reactions. The use of chitosan

polysaccharides with acrylic monomers is very

312

Aulia Hasibuan, R., Nasution, D. and Wirjosentono, B.

Thermal and Morphological Properties of Polyvinyl Alcohol-based Hydrogel Containing Microcrystal Cellulose.

DOI: 10.5220/0008932403120318

In Proceedings of the 1st International Conference on Chemical Science and Technology Innovation (ICOCSTI 2019), pages 312-318

ISBN: 978-989-758-415-2

efficient in making hydrogels (Mahdavinia,

Zohuriaan-Mehr, & Pourjavadi, 2004). Initially, the

hydrogel was made from cellulose and polyvinyl

alcohol which have a hydrophilic group and have a

high affinity for water. This type of hydrogel has

several disadvantages including absorption capacity

is relatively small, less stable to changes in pH,

temperature and physical properties that are not

good (Swantomo, Megasari, & Saptaaji, 2008).

The manufacture of polyvinyl alcohol (PVA) and

polyacrylic acid (PAA) hydrogels with xanthan gum

polysaccharides which can be applied as drug

delivery control through cross-linked polymerization

using N’N-methylene bisacrylamide (MBA) as a

crosslinking agent and ammonium persulfate (APS)

as the initiator. The best water absorption results are

shown in hydrogels containing low MBA, namely

0.010 g (Bhattacharya et al., 2012).

Polyvinyl alcohol (PVA) is one of the most

promising synthetic polymers for the development of

biomaterials (Teodorescu, Bercea, & Morariu, 2018).

PVA is a water-soluble polymer, easily degraded

(Chiellini, Corti, D’Antone, & Solaro, 2003), has high

tensile strength and flexibility, elastic, non-toxic, and

biocompatible polymer. So it can be used in many

applications make PVA a hydrogel which is widely

used in the textile, adhesive, food, medicine, paper,

packaging, and cosmetics industries (Peresin et al.,

2010, Vieira et al., 2009).

Manufacture of semi-IPN hydrogels based on

MCC from cellulose pulp for biomedical applications.

MCC was dissolved in PEG / NaOH solvents with

acrylic acid monomers, crosslink N’ N-

methylenbisacrylamide by free radical

polymerization. Increased crosslink concentration

causes a decrease in water absorption. The increasing

number of crosslinks will affect the polymer chain,

thereby reducing the incoming water and causing the

chain to become stiff (Bajpai & Swarnkar, 2014).

Manufacturer hydrogels from Polyacrylic acid (PAA)

with micro-crystal cellulose amplifier (MCC) carried

out through acrylic acid polymerization using UV

light. Addition of 1% MCC (1% of the weight of

acrylic acid) caused an increase in water absorption

capacity in the hydrogel of 122 g water / g hydrogel

(from 427 to 549 g water / g hydrogel). The water

capacity of the hydrogel matrix network increases

because the formed hydrogels have a porous structure

and have increased surface area in the hydrogels (Ni,

Wen, & Liu, 2015).

The addition of cellulose has many advantages,

including from plants with available widely (Anah &

Astrini, 2015), cheap, and not toxic. Also, the

addition of micro-sized cellulose such as

microcrystalline cellulose to the polymer matrix can

increase the physical strength of the formed

hydrogels (Spagnol et al., 2012). MCC is an

available widely commercial material (Brinchi,

Cotana, Fortunati, & Kenny, 2013) which can be

used as fillers, additives, cosmetics, tablets, and food

products (Ioelovich & Leykin, 2006).

Based on the description above the researchers

were interested in research on the thermal and

morphological properties of a polyvinyl alcohol-based

hydrogel containing microcrystalline cellulose (MCC)

using N'N-Methylene bisacrylamide as a crosslinking

agent and ammonium persulfate as initiator.

2 MATERIALS AND METHODS

2.1 Materials

Commercial Cellulose Microcrystalline (Avicel PH

101 50 μm), Acrylic Acid (Merck Schuchardt from

Germany), Polyvinyl Alcohol, as initiator has used

Ammonium Persulfate (≥ 98% from China), N'N-

Methylene bisacrylamide (Sigma Aldrich) was used

as a crosslinking agent.

2.2 Preparation of Hydrogel

Microcrystalline cellulose was heated with 25 mL

aquadest at 60

C and stirred for 30 minutes until

homogeneous. Polyvinyl alcohol is heated at 85

added to microcrystalline cellulose and stirred. 0.06 g

Ammonium Persulfate is added to the polymer

mixture at a temperature of 60-70

C and stirred for 30

minutes. 4 g of acrylic acid which has been added

with 10 mL of aquadest and has been neutralized with

NaOH 17.5% until pH = 5 is added to the polymer

mixture. 0.2 g of N'N-Methylene bisacrylamide was

added to the mixture and stirred. The reaction was

finished at 70

C after the reaction has been running

for 30 minutes. The product is released in hot

conditions. The hydrogel was washed with water then

the hydrogel is dried in the oven at 60

C. After the dry

hydrogel is inserted into the desiccator. MCC and

PVA variations can be seen in Table 1.

Table 1: Variation of MCC and PVA.

MCC (g)

PVA (g)

0.0

1.0

0.2

0.8

0.4

0.6

0.4

0.8

0.2

Thermal and Morphological Properties of Polyvinyl Alcohol-based Hydrogel Containing Microcrystal Cellulose

313

2.3 Swelling Test

Three or four replicas of each dried hydrogel were

swollen in deionized water at room temperature for

3 days to achieve equilibrium swelling. The degree

of swelling of hydrogels were measured after 5 min,

10 min, 20 min, 0.5 h, 1.5 h, 1 day, 2 days and 3

days. Completely three replicas were measured, the

standard deviations were marked with error bars in

the swelling profile charts. The degree of swelling

was calculated as the following Yang (2012)

equation:

Degree of swelling = [(Wet weight – Dry

weight) / Dry weight] ×100%

(1)

2.4 Functional Group Analysis

Detection of functional group, was analyzed by a

Perkin Elmer-Fourier transform infrared and

transmission was measured in the range of 4000–600

-1

2.5 Morphological Analysis

Changes in the surface morphology of the hydrogel

were analyzed by scanning electron microscopy

(SEM). The micrographs of samples were taken

using a Hitachi TM3000 scanning electron

microscopy (SEM).

2.6 Differential Scanning Calorimetry

Differential scanning calorimetry (DSC) was

performed using a DSC-60 Plus Shimadzu

containing nitrogen gas and its flow rate was 30

mL/min. Hydrogel samples and Al

comparison

materials were weighed and heated at room

temperature to 600

C at a heating rate of 15

C /

minute.

3 RESULTS AND DISCUSSION

3.1 Preparation of Hydrogel

The manufacture of polyvinyl alcohol-based

hydrogels containing microcrystalline cellulose with

acrylic acid monomer, N’N-Methylene

bisacrylamide as a crosslinking agent and

ammonium persulfate as initiator. Polyvinyl alcohol

and cellulose microcrystal were varied to produce

five hydrogels can be seen in Figure 1.

Figure 1: Hydrogel with varied microcrystal cellulose.

3.2 Swelling Test

Swelling test is done by determining the percent

swelling ratio. The percentage of the hydrogel

swelling ratio can be seen in Figure 1. Based on

Figure 1. It can be seen that at 5 and 10 minutes.

Hydrogel 3 has the highest percent swelling. At 20

minutes the hydrogel 5 has the highest percent

swelling. The highest swelling percentage at 30 and

90 minutes was shown in hydrogel 1. On the first,

second, and third days hydrogel 4 had the highest

percent swelling. It can be assumed that the hydrogel

4 has the highest percent swelling of around 3245%.

Water absorption from hydrogel 4 has increased.

This is because the addition of the amount of MCC

0.6 g to the hydrogel 4 affects the percent swelling

ratio in the hydrogel. The addition of MCC will

increase the percent swelling ratio but the addition

of 0.8 g MCC percent swelling ratio decreases which

occurs in hydrogel 5. Water absorption will decrease

too.

The addition of 0.2 g MCC of Hydrogel 2 and

0.4 g MCC of hydrogel 3 had lower percent swelling

compared to hydrogel 1 without the addition of

MCC.

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314

Figure 2: Degree of swelling (minutes).

Figure 3: Degree of swelling (days).

3.3 Analysis of FTIR

Functional group analysis using FTIR is a qualitative

analysis used to interpretation absorption peaks from

the infrared spectrum. This analysis can show

various areas of hydrogel absorption that are

produced so that the resulting functional group

changes can be produced. Data analysis of

functional groups using FTIR is presented in

graphical form in Figure 4 and Table 2.

The FTIR spectrum of hydrogel 1 and hydrogel 4

produced showed several absorption peaks is

hydrogel 1 absorption at 3340, 2924, 2181, 1713,

1565, and 1404 cm

-1

, and hydrogel 4 absorbed at

3336, 2945, 2167, 1707, 1558, and 1402 cm

-1

The FTIR spectrum of hydrogels 1 and 4 is a

wide absorption peak at 3340 and 3336 cm

-1

wavenumbers which shows the presence of vibrating

O-H groups from microcrystalline cellulose,

polyvinyl alcohol, and acrylic acid so the absorption

appear wide (Sunardi, Irwan, Nurjannah, &

Istikowati, 2013). The absorption peak at 2924 and

2945 cm

-1

on hydrogel 1 and hydrogel 4 showed the

presence of C-H stretching. Also, there is an

absorption peak at wave number 2181 and 2167 cm

-1

which shows CH

in crosslinks (Saragih, Tamrin,

Marpongahtun, Nasution, & Abdillah, 2018).

The presence of a functional group C = O of

acrylic acid at the absorption peak was 1713 and

1707 cm

-1

. Curved absorption sharp peaks at

wavenumber 1565, 1404 cm

-1

from hydrogel 1 and

absorption peaks at wavenumber 1558 and 1402

-1

from hydrogel 4 showed symmetrical and

asymmetrical stretches of carboxylic anions (COO-)

(Bajpai & Swarnkar, 2014).

The results of FTIR data obtained can be

concluded that there was not significant change in

functional groups on hydrogel 1 and hydrogel 4.

This is because hydrogels only occur physical

interactions on hydrogen bonds between O-H

functional groups of MCC, carboxylates, and

polyvinyl alcohol.

Figure 4: FTIR spectra of Hydrogel 1 and Hydrogel 4.

Table 2: Functional group of hydrogel.

Wavelength (cm

-1

)

Functional Groups

3340 and 3336

O-H

2924 and 2945

C-H

2181 and 2167

CH2

1713 and 1707

C=O

1565 and 1558

COO-

1404 and 1402

COO-

3.4 Differential Scanning Calorimetry

The DSC of the hydrogel is shown in Figure 5. The

DSC thermogram of Hydrogel 1 obtained 4 peaks.

At the first peak, there was an endothermic reaction

Thermal and Morphological Properties of Polyvinyl Alcohol-based Hydrogel Containing Microcrystal Cellulose

315

from a temperature of 162.31

C to a temperature of

177.48

C which required the energy of -111.12 mJ

or equivalent to -26.55 mcal. The second peak of

Hydrogel 1 has an endothermic reaction from a

temperature of 176.21 to a temperature of 190.02

which requires the energy of -343.73 mJ or

equivalent to -82.11 mcal. Hydrogel 1 experienced

melt at 167.95

C and the perfect melt occurred at

177.53

C. At the third peak, an exothermic reaction

occurs. Hydrogel 1 began to increase in temperature

from 253.96

C to a temperature of 308.97

C which

released the energy of 260.47 mJ or equivalent to

62.22 mcal. At this peak of hydrogel 1 is degraded at

296

C where the tissue arranged in the hydrogel

begins to weaken the bonds with each other. At the

fourth peak, an exothermic reaction occurs.

Hydrogel 1 experienced an increase in temperature

from 445.51

C to 507.40

C which released the

energy of 2.94 J or equivalent to 702.34 mcal. At

this time the three-dimensional network structure on

hydrogel 1 experienced decomposition. It means the

composition of hydrogel has burned to be ash and

water vapor. We can see the fourth peak in figure 4.

Hydrogel 1 has good thermal stability occurs at a

temperature of 482.28

The DSC thermogram from Hydrogel 4 obtained

3 peaks. At the first peak, there was an endothermic

reaction from a temperature of 60.69

C to a

temperature of 223.40

C which required the energy

of -1.49 J or equivalent to -356.69 mcal. Hydrogel 4

experienced melt at 134.02

C. The second Hydrogel

4 peak exothermic reaction occurs.

Figure 5: Thermogram of Hydrogel 1 and Hydrogel 4.

Hydrogel 4 began to experience an increase in

temperature from 246.24 to 289.79

C which released

the energy of 215.50 mJ or equivalent to 51.48 mcal.

At this peak of hydrogel 4 are degraded at a

temperature of 275.97

C where the tissue composed

of hydrogels begins to experience weakening of each

other bonds. At the third peak, an exothermic

reaction occurs. Hydrogel 4 experienced an increase

in temperature from 443.14 to 535.98

C which

released the energy of 3.73 J or equivalent to 890.16

mcal. At this time the three-dimensional network

structure on hydrogel 4 has experience

decomposition. It means the composition of

hydrogel has burned to be ash and water vapor. We

can see the third peak in Figure 5. The thermal

stability of hydrogel 4 occurred at 473.79

C. From

the picture above it can be seen that the thermal

stability in hydrogel 1 is greater than the thermal

stability of the hydrogel 4. Thermal stability

decreases with the addition of 0.6 g MCC.

3.5 Scanning Electron Microscopy

The results of the surface morphology analysis of

Hydrogel 1 without the addition of MCC, Hydrogel 4

with the addition of 0.6 g MCC, and Hydrogel 5 with

the addition of 0.8 g MCC. These results provide

information relating to the surface of the hydrogel

with homogeneity. The surface morphology of

hydrogels was analyzed with 500x magnification.

SEM micrographs of the surface of hydrogel 1

without the addition of MCC in Figure 6 show a

homogeneous, smooth, flat surface without pores. It

can be concluded that PVA has been distributed to

all hydrogel 1 networks.

Figure 7 surface of the hydrogel 4 with the

addition of 0.6 g MCC shows a slightly coarse

surface, and a surface that looks deep and dark so it

looks slightly porous. MCC spreads well in

hydrogels. Higher absorption occurs due to the

irregular shape of the hydrogels and pores (Saragih

et al., 2018).

Figure 6: SEM micrographs of Hydrogel 1 without using

MCC.

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316

Figure 7: SEM micrograph of Hydrogel 4 using 0.6 g

MCC.

Figure 8: SEM micrograph of Hydrogel 4 using 0.8 g

MCC.

Figure 8 the surface of hydrogel 5 with the

addition of 0.8 g MCC shows the surface of the

hydrogel is not homogenous, coarse, and it looks a

lot porous. Lots of porous because the shape of the

surface looks a lot in the inner and dark areas.

4 CONCLUSIONS

From the research that has been done on the thermal

and morphological properties of polyvinyl alcohol-

based hydrogels containing microcrystalline

cellulose, it is undeniably about making optimal

mixtures in the manufacture of hydrogels from PVA,

MCC and acrylic acid using the ammonium

persulfate initiator and crosslinking, N'N-Methylene

bisacrylamide by involving (0,4: 0,6: 4: 0,06: 0,2) g.

As much as 0.6 g MCC has the highest swelling

ratio of 3245% in Hydrogel 4. The higher the

swelling ratio, the more optimal absorption.

Hydrogels that have absorbency are characterized

optimally using FTIR, SEM, and DSC. The results

of FTIR data obtained can be concluded that there

was not a significant change in functional groups on

hydrogel 1 and hydrogel 4. This is because

hydrogels only occur physical interactions on

hydrogen bonds between O-H functional groups of

MCC, carboxylates, and polyvinyl alcohol. Thermal

stability decreased with the addition of MCC 0.6 g

from a temperature of 482.28

C to a temperature of

473.79

C. It means the addition of 0.6 g MCC can

increase absorption and decrease the thermal

stability. The Surface morphology of hydrogel 1

looks homogeneous, smooth and has no pore. When

the addition with 0.6 g MCC the surface of the

hydrogel slightly coarse, and has a slight porous.

The porous on the surface of the hydrogel increases

when additing of 0.8 g MCC and decreases

absorption

ACKNOWLEDGEMENTS

The authors would like to thank to The Higher

Education Directorate, Ministry of Research,

Technology and Higher Education for granting the

research fund to carry out this work through:

“Penelitian Tesis Mahasiswa, DRPM RISTEKDIKTI

2019 0f Universitas Sumatera Utara”.

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