X-Ray Diffraction and Morphology Studies of Sulfonated Polystyrene

and Maleated Natural Rubber Blend with PE-g-MA as

Compatibilished

Ahmad Nasir Pulungan

1,3

, Basuki Wirjosentono

, Eddiyanto

2,3

and Sunit Hendrana

Chemistry Postgraduate Study Programs, Universitas Sumatera Utara, Medan 20155, Indonesia

Department of Chemistry, Universitas Negeri Medan, Jl. Willem Iskandar Psr. V Medan Estate 20371, Indonesia

Department of Chemistry, Universitas Sumatera Utara, Medan 20155, Indonesia

Research Centre for Chemistry Indonesian Institute of Sciences,Kompleks Puspitek 452, Serpong, Banten 15314, Indonesia

Keywords: Sulfonated Polystyrene, Maleated Natural Rubber, Blend, X-Ray Diffraction, Morphology.

Abstract: The preparation of blend of sulfonated polystyrene (sPS) and maleated natural rubber (MNR) using the

Polyethylene-graft-maleicanhydride (PE-g-MA) as compatibilished has been done. The blending process

was done in dilute solution in each polymer, followed a steam and casting process at particular

temperatures. The composition of sPS and MNR was varied at 1:9; 2:8; 4:6 and 6:4 (w/w). The

characterization of membrane blend of sPS-MNR/PE-g-MA properties was determined by using X-ray

diffraction (XRD) and scanning electron microscopy (SEM). The data showed that the homogeneity and the

crystallinity of membrane were affected by the composition and process condition. The XRD data show that

the Membrane (sPS-MNR / PE-g-MA) with sPS: MNR ratio 2:8 produces diffraction patterns with higher

intensity and SEM images showed that membrane has a better homogeneous surface morphology than the

others.

1 INTRODUCTION

The formation of polymer blends generally aims to

produce new materials with superior properties

compared to each of the forming polymer materials

(Jhons and Rao, 2019). This method is widely

developed because of the low cost of processing and

short processing time to produce new polymeric

materials. The nature of the polymer blend is

determined mainly by the compatibility of the

polymer of the composition of the mixture, the

process parameters and the desired application

(Favis, BD, & Chalifoux, JP (1988). Polystyrene

(PS) is included in the thermoplastic group with an

extensive application, due to unique properties such

as transparent, high chemical stability, ease of

colouring and low cost (Ebewele, 2000), but the PS

also has limitations such as its fragile nature, low

heat deflection temperature and weak UV resistance

(Ozden, 2004). However, currently sulfonated

polystyrene (sPS) has been widely developed and

used as an electrolyte polymer membrane as an

alternative to the replacement of Nafion membrane

(Hendrana et al., 2016; Mulijani et al., 2014; Lee et

al., 2008), because it has a price conductivity

approaches Nafion. Therefore, the sPS membranes

require other polymeric materials to improve their

mechanical properties (elasticity).

Natural polymeric materials such as natural

rubber (NR) exhibit the best physical properties with

comprehensive industrial applications (Jhons and

Rao, 2008; Sanguansap et al., 2004). NR has

superior physical properties such as firmness, tensile

strength and high elasticity, abrasion and tear

resistance as well as good stickiness and are easy to

grind (Arroyo et al., 2007; Peng et al., 2007 and

Derouet et al., 2009). Therefore, these attracts many

researchers to produce various products for

industrial processes (Wirjosentono et al., 2018).

In this study, the sPS will be blended with the

NR, with the aim to improve the mechanical

properties (elasticity) of the membrane.

Compatibility is improved by modifying the NR to

form a maleated natural rubber (MNR) by grafting

maleic anhydride (MA) into the NR structure.

Nakason et al., (2004) studied grafting of MA onto

natural rubber. The use of maleic anhydride (MA) as

324

Pulungan, A., Wirjosentono, B., Eddiyanto, . and Hendrana, S.

X-Ray Diffraction and Morphology Studies of Sulfonated Polystyrene and Maleated Natural Rubber Blend with PE-g-MA as Compatibilished.

DOI: 10.5220/0008935003240328

In Proceedings of the 1st International Conference on Chemical Science and Technology Innovation (ICOCSTI 2019), pages 324-328

ISBN: 978-989-758-415-2

a coupling agent increases the adhesion and interface

properties of polymer composites (Cao et al., 2012;

Machado, 2000). Ismail et al., (2002), Wirjosentono

et al., (2008) and Wirjosentono et al., (2018)

reported an increase in adhesion of composite

Bamboo fibre with natural rubber; polypropylene

with cyclic natural rubber; and Oil palm empty fruit

bunch with polypropylene.

Preparation of polymer blend from the sPS and

MNR with PE-g-MA as compatibilities is expected

to produce a stable and homogeneous membrane

blend product. Thus, the membrane can be applied

as a proton exchange membrane. Therefore, it is

essential to investigate the properties of the polymer

blend. In this paper, an initial characterization of the

sPS-MNR / PE-g-MA blend by X-ray (XRD)

diffraction and scanning electron microscope (SEM)

will be carried out.

2 MATERIALS AND METHODS

2.1 Materials

Sulfonated polystyrene (sPS) were prepared

(Hendrana, 2013). High-ammonia concentrate

natural rubber (HANR) latex DRC 60% is from PT

IKN Medan-Indonesia. MNR were prepared

according to Pulungan et al. (2017). PE-g-MA is

from Aldrich (~0.5 wt. %). Methanol and toluene are

p.a., grade and all use from Merck.

2.2 Preparation of Membrane Blend of

sPS-MNR/PE-g-MA First Section

The blending process of sPS, MNR and PE-g-MA

polymer materials has been carried out in a very

dilute solution system, followed by a steam and

casting process at particular temperatures.

Comparison of sPS and MNR varied each: 1:90; 2:8;

4:6 and 6:4 (w/w) with the concentration of PE-g-

MA is 3% (w/w). In the initial stages the sPS were

dissolved in toluene: methanol with a ratio of 9:1 at

C and slowly stirred with a magnetic stirrer. The

MNR and the PE-g-MA were also dissolved in

toluene solvent and slowly stirred with a magnetic

stirrer at 45

C. The PE-g-MA solution was added to

the MNR solution, stirred until homogeneous.

Furthermore, the sPS solution was added slowly and

followed by the stirring process with a magnetic

stirrer at 45

C for 8 hours. The resulting blend

solution was cast and dried in an oven gear at 45

for 24 hours. The membrane obtained was dried in a

drying oven at 60°C for 8 hours.

2.3 Characterization of Membrane

Blend of sPS-MNR/PE-g-MA

The initial characterization of membrane blend

includes XRD analysis and morphology with SEM

as follows:

2.3.1 X-Ray Diffraction Studies

The XRD patterns of the membrane were recorded

with an X-ray diffractometer Shimadzu 6100, using

Cu Kα radiation, with a scanning rate of 2

min-1 in

a range from 7

to 70

(2θ). The operating voltage

and current of the tube kept at 40 kV and 30 mA

respectively.

2.3.2 Morphology Analysis

SEM analysis was performed to investigate the

morphology and homogeneity of the membrane

blend. The SEM images were obtained from SEM of

JSM-6510 LA. The surface of the membrane was

coating with gold before being measured under the

microscope.

3 RESULTS AND DISCUSSION

3.1 X-Ray Diffraction Studies

Figure 1: XRD diffractogram of (a) sPS, (b) MNR and (c)

PE-G-MA.

The XRD diffractograms of sPS, MNR and PE-g-

MA are depicted in Figure 1. The XRD

diffractograms crystalline polymers produce sharp

peaks, whereas amorphous polymers will produce

widening peaks. Figure 1 (a) shows the crystalline

X-Ray Diffraction and Morphology Studies of Sulfonated Polystyrene and Maleated Natural Rubber Blend with PE-g-MA as

Compatibilished

325

phase of PE-g-MA with a sharp peak intensity at 2θ

around 21.5

. While the sPS diffractogram shows an

amorphous phase with a peak widening at 2θ about

19.4

and the MNR shows a more amorphous phase

than the sPS at 2θ around 19.4

. Martin et al. (2003)

were reported that the sPS has amorphous properties

because the pure PS polymer is initially amorphous.

The sPS has a peak at 2θ around 19.8

and NR has

a peak at 2θ around 19

(Jhon and Rao, 2008).

The XRD diffractogram in Figure 2 provides

information about the structure of the polymer blend

from the sPS-MNR/PE-g-MA. The figure shows the

existence of a randomly mixed crystalline and

amorphous state, which illustrates the combined

characteristic peaks of MNR, sPS and PE-g-MA.

The sPS-MNR/PE-g-MA membrane with the

composition of sPS:MNR 2:8 produces the highest

intensity of the main peaks. While the sPS-

MNR/PE-g-MA membrane with the composition of

sPS:MNR 4:6 and 6:4 shows a decrease in the

intensity of the peak in the membrane. This shows

that the ratio of the composition of the membrane

blend gives an influence on the change in the

crystallinity phase. With increasing content of sPS,

the overall crystallinity of membrane blend

decreases. In the polymer material, if the degree of

crystallinity is getting smaller, the elasticity is

getting bigger, this is caused by the branch chain

that occurs, which causes the polymer material to be

more elastic.

To investigate the effect of membrane

composition, the interaction between the sPS and

MNR on the membrane is observed based on the

crystal size change approach. The X-ray diffraction

scattering pattern can provide information about the

configuration of the chain in crystallites, the

estimated crystallite size and the comparison of the

crystalline region with the amorphous region (degree

of crystallinity) of the polymer material. Crystal size

can be determined through the approach of the

FWHM value (full width at half maximum) using

the Debye-Scherrer equation (Kumar and Raji,

2011) as follows:

D = 0.9 λ / B Cos θ (1)

Where:

D = Average Size Crystal

λ = wavelength of XRD (0.15406 nm)

θ = Braag Diffraction angle

B = FWHM value in radian

The results of the calculation of the crystal size of

each membrane are summarized in Table 1.

Table 1: The Average Size Crystal of membrane

sPS-MNR/PE-g-MA.

2θ (º) D (nm)

sPS:MNR (1:9) 19.49 1.49

21.59 5.37

23.97 4.82

sPS:MNR (2:8) 19.31 2.13

21.49 6.97

23.82 3.85

sPS:MNR (4:6) 19.37 1.54

21.49 4.76

23.82 5.12

sPS:MNR

(

6:4

)

19.32 1.65

21.63 5.46

23.86 3.52

Based on the data in table 1, it can be seen that

an increase in the sPS concentration to the sPS:

MNR (2:8) increases the crystal grain size at 2θ

around 19.4

but the crystal grain size gets smaller at

the sPS:MNR ratio of 4:6 and 6:4. This is because in

the sPS:MNR 2:8 the diffraction peak width is

narrower so that the half peak width value (FWHM)

is smaller, and the crystal grain size is increasing.

However, at the sPS: MNR 4:6 and 6:4, the FWHM

value is enlarge which shows that the width of the

diffraction peak widened as well due to the

increased concentration of sPS in the membrane.

These data indicate that the effective interaction of

the polymer blend is at the ratio of SPS: MNR 2:8

(w/w). The higher number of sPS actually disturbs

the effectiveness of the interaction between sPS and

MNR. This resulted in interactions that occurred

between sPSS and NMR being dominated by

sulfonate groups from sPS.

Figure 2: XRD diffractogram of sPS-MNR/PE-g-MA

membrane with sPS: MNR composition: (a) 1: 9; (b) 2: 8;

ICOCSTI 2019 - International Conference on Chemical Science and Technology Innovation

326

3.2 Morphological Measurement using

SEM

The surface morphology of each membrane is given

in Figure 3.

Figure 3: SEM images of sPS-MNR/PE-g-MA membrane

with sPS: MNR composition ratio (a) 1: 9; (b) 2: 8; (c) 4:

6 and (d) 6: 4 (w /w).

In Figure 3, it can be seen that the sPS-

MNR/PE-g-MA membrane with a sPS:MNR 2:8

composition ratio shows a more homogeneous

surface compared to other membranes. In

membranes with a composition ratio of sPS:MNR

2:8 produces a dense and homogeneous surface even

though the presence of grainy components of the

sPS is not completely dissolved with the MNR. This

is due to the increase in adhesion between the sPS

and MNR. While on membranes with a greater sPS

composition ratio, i.e. on the sPS: MNR 4:6 and 6:4

membranes, it appears that the presence of grainy

components from sPS forms larger sPS cluster

groups as a result of the increasing number of sPS

that are not completely dissolved with the MNR.

From this data, information is obtained that the

optimum blending composition is produced at the

sPS:MNR ratio = 2:8 (w/w). This is due to the

reduced adhesion force because the interactions that

occur are dominated by sulfonate groups from sPS.

Increased sPS concentrations do not provide better

membrane compatibility. Concentration plays a role

but not a high concentration of Sps.

4 CONCLUSIONS

Based on XRD data, membranes with the

composition of sPS:MNR with ratio 2:8 produce the

highest peak intensity diffractogram, as a result of

the most effective interaction between sPS and

MNR. This is also supported by SEM of the

membrane surface with a more homogeneous

surface morphology compared to that of the

membrane surface with the composition of sPS:

MNR 4:6; 6:4 and 1:9 respectively. The composition

ratio plays a role to produce compatible sPS-MNR /

PE-g-MA membrane.

ACKNOWLEDGEMENTS

The authors would like to thank University of

Sumatera Utara and Universitas Negeri Medan for

funding this work through research program of

“Penelitian Disertasi Doktor tahun 2017”, also to

P2F LIPI, Chemistry Laboratory of The Department

of Chemistry and Material Laboratory of The

Department of physics, Universitas Negeri Medan

for providing facilities of the work.

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