The Effects Of Various Additives On Mechanical And Rheological Properties Of Polystyrene/Polvpropylene Blend

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THE EFFECTS OF VARIOUS ADDITIVES

ON MECHANICAL AND RHEOLOGICAL PROPERTIES

OF POLYSTYRENE

I

POLVPROPYLENE BLEND

by

HALlMATUDDAHLIANA

Thesis submitted in fulfillment ofthe

requirements for the degree

of Master of Science

November 2001

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ACKNOWLDGEMENT

Bismillaahirrahmaanirrahiim,

I would like to express my heartiest appreciation and deep gratitude to my supervisors

Prof Madya Dr.

Hanafi

Ismail and Prof Madya Dr. Mohd Nasir Zainal Arif. Your guide,

encouragement, constructive remarks and criticisms are one of paramount importance to

the foundation of

this

research work. Your willingness in revising in the

final

part of the

thesis will alwaysbe appreciated.

I am grateful to the dean and

alI

the staff in School of Industrial Technology for their

co-operation and help. I am pleased to appreciate the various help and assistance provided

by the laboratory assistants and technicians: En. Mohd Noor,

Mr

Segaran, En. Md

Zandar,En. Mohd Hassan, Pak Syed, En. Azhar, and

Kak

Jamilah.

I also would like to extend my deepest thanks to my "sisters": Salmah, Hamidah,

MauIida and Lilis, my ''brothers'': Indra and Dian and

my

"Ibu" Jenimar, I

thank

you all.

To my friends: Mariatti, Hao, Susantha, ZuIkitli, Ibrahim, Prerna, ,

Razaina,

Zurina, Ong,

BihNi, Shahnon, Ragi, Pipit and

alI

the numerous friends whose names have not been

mentioned, it was nice knowingyou

alI.

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ABSTRACT

Studies on mechanical and rheological properties of polystyrene/polypropylene (PSIPP)

blends with and without the addition of various additives were carried out. Blends of 20180,

50/50 and 80/20 (wt%) were prepared through melt blending in a single screw extruder at a

screw speed of 40 rpm. The blending temperature of 200°C

was

determined by the

consideration of the most suitable melt temperature of the homopolymers. Four types of

additives

viz. polystyrene-block-poly

(ethylene-butylene)-block-polystyrene (SEBS),

surlyn, ethylene vinyl acetate (EVA) and sodium salt hydrate of 4 styrenesulfonic acid

(ssh-4-ssh) were used in this study. The concentration of the additives is 7.Swt%. Tensile

strength, elongation at break, Young's modulus and impact strength of the blends with and

without additives at different blend composition were compared. Flow behavior, which was

measured at various shear stresses (from 11762 to 46144 Pa) was carried out to determine

the dependencies of melt viscosity on the blend composition and the addition of additives

using melt flow indexer as a rheometer. For mechanical properties, the results indicate that

all blend compositions exhibit extremely poor properties. The blends containing SEBS and

EVA showed a positive effect to the elongation at break and the impact strength of the

blend. In the presence of surlyn the tensile strength and Young's modulus of the blend

slightly increased, whereas for ssh-s-ssa showed the negative effect to the blend properties.

For non additive blend, all blend compositions exhibit a reduction in melt viscosity, but the

incorporation of EVA, surlyn and SEBS produced more resistance system to flow and

increased the melt viscosity. However, in the presence of ssb-l-ssa a reduction in melt

viscosity was observed, indicating easier for blend to flow. The morphological study

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exhibits different micrograph surfaces of the blends for both with and without additives.

These results indicating a multiphase system of the PSIPP blend. At PP-rich blend and

intermediate blend composition, PP forms the continuous phase and PS remains as

dispersed phase, whereas at PS-rich blend both of the phases seem to remain as continuous.

The incorporation of SEBS on

20/80

PSIPP blend, a finer dispersion degree of particles

together with morphological evidence of interfacial adhesion was found. On the other hand,

the addition of EVA showed a plastic deformation, whereas surlyn showed a finer phase

domains. However, the presence of ssh-l-ssa into

20/80

PSIPP blend, the interface does not

change so much compared to the non additive blend.

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KESAN PELBAGAI BAHAN PENAMBAH KE ATAS SIFAT MEKANIK. DAN

.REOLOGI BAGI ADUNAN POLISTIRENAIPOLIPROPILENA

ABSTRAK

Kajian terhadap kesan bahan penambah ke atas sifat mekanik

dan

reologi bagi adunan

polistirenalpolipropilena

(PSIPP)

telah dijalankan. Adunan 20/80, 50/50 dan 80/20

(berdasarkan berat) telah disediakan melalui pencampuran leburan dengan menggunakan

ekstruder skru tunggal pada kelajuan skru 40 rpm. Subu peleburan adunan iaitu 200°C telah

ditentukan oleh subu peleburan homopolimer (PS

dan

PP) yang paling sesuai. Empat jenis

bahan penambah pada peratusan 7.5% berdasarkan jumlah berat adunan telah digunakan

iaitu polistirena-blok-poli-(etilena-buti1ena)-blok-polistirena (SEBS), surlyn, etilena vinil

asetat (EVA) and sodium salt hydrate of 4 styrenesulfonic acid (ssh-4-ssa). Kekuatan tensil,

pemanjangan pada takat putus, modulus Young dan kekuatan hentaman bagi adunan

PSIPP

tanpa

atau dengan bahan penambah pada komposisi adunan berbeza telah dibandingkan.

Sifat aliran

pada pelbagai kadar ricih (daripada 11762 hingga 46144 Pa) untuk menentukan

kebergantungan nilai kelikatan terhadap komposisi adunan dan penggunaan bahan

penambah telah dijalankan dengan menggunakan indek aliran lebur (MFI). Bagi sifat

mekanik, keputusan menunjukkan bahawa untuk semua komposisi adunan sifat yang

diperolehi adalah tidak baik. Adunan yang mengandungi SEBS

dan

EVA menunjukkan

kesan positif terhadap pemanjangan takat putus campuran. Penambahan surlyn pula

meningkatkan kekuatan tensil dan modulus Young adunan tetapi dengan penambahan

ssh-4-ssa menunjukkan kesan negatif terhadap sifat adunan, Bagi adunan tanpa bahan

penambah, kesemua komposisi adunan menunjukkan penurunan kelikatan, tetapi dengan

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penambahan EVA, surlyn dan SEBS didapati kelikatan adunan

PSIPP

untuk semua

komposisi

bertambah.

Walaubagaimanapun, kehadiran ssh-s-ssa telah menurunkan

kelikatan peleburan adunan

PSIPP

dan memudahkan leburan untuk mengalir. Kajian

morfologi menunjukkan keputusan permukaan mikrografyang berbeza bagi adunan

PSIPP

tanpa ataupun dengan bahan penambah. Keputusan ini menunjukkan sistem multi fasa bagi

adunan

PSIPP.

Bagi komposisi

20/80

dan

50/50,

PP membentuk fasa selanjar dan PS

membentuk fasa terselerak. Bagi adunan

80/20

kedua-dua PS dan PP membentuk fasa

selanjar. Bagi adunan

20/80

penambahan SEBS ke dalam adunan PSIPP, menghasilkan

darjah keselerakan partikel yang lebih baik dan bukti morfologi bagi perekatan antaramuka

telah diperhatikan. Sementara itu, penambahan EVA menunjukkan deformasi plastik,

sedangkan surlyn menunjukkan domain fasa yang lebih

baik,

Walaubagaimanapun

kehadiran ssh-4-ssa ke dalam adunan

20/80

tidak menunjukkan sebarang perubahan yang

ketara berbanding dengan adunan tanpa bahan penambah.

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