Malaysian Journal of Analytical Sciences Vol 19 No 4 (2015): 815 - 823

 

 

 

PHYSICOCHEMICAL CHARACTERISTIC OF PURIFIED LATEX (PL)

 

(Ciri Fisikokimia Lateks Tertulen (PL))

 

Nurulhuda Abdullah* and Siti Nor Qamarina Manaf

 

Rubber Research Institute of Malaysia,

Malaysia Rubber Board, 47000 Sg. Buloh, Selango, Malaysia

 

*Corresponding author: nurulhuda.a@lgm.gov.my

 

 

Received: 23 November 2014; Accepted: 27 June 2015

 

 

Abstract

Purified latex (PL) was prepared via urea incubation of commercial high ammoniated natural rubber latex (HA-NRL) in the presence and absence of sodium dodecyl sulphate (SDS) as surfactants. During this purification process, most of non-rubber substances presences in NRL including proteins, lipids, carbohydrates, are being removed especially at centrifugation stage. Effect of non-rubbers depletion was further elucidated by conducting a comparative study on HA-NRL and PL. Apparently from zeta potential analysis, negatively charged rubber surface over whole pH range and constant zeta potential value after pH 4 for PL suggesting the strong adsorption of surfactant on the surface of purified rubber. In the absence of surfactant, the surface charge of rubber particle also appeared to be a negatively charge but with a reduction trend in its zeta potential magnitude as pH increases attributed to urea residual. It is appeared that the occurrences of strong surfactant adsorption on the surface of rubber particles enable PL to retain their stability. Replacing the non-rubbers with surfactant has affect the rheological properties of PL as it experienced shear-thinning behaviour, increased in viscosity characteristic and distinctive linear viscoelastic region (LVR) manner in comparison to that of the HA-NRL. Obviously, an almost similar rheological characteristic was observed for PL in the absence of surfactant and HA-NRL.

 

Keywords: non-rubbers, purified latex, rheology, surfactant, zeta potential

 

Abstrak

Lateks tertulen (PL) telah disediakan melalui inkubasi urea terhadap lateks getah asli komersial tinggi ammonia (HA-NRL) dengan kehadiran dan ketiadaan natrium dodecyl sulfat (SDS) sebagai surfaktan. Semasa proses penulenan ini, kebanyakan bahan-bahan bukan getah yang hadir di dalam NRL termasuk protein, lipid, karbohidrat, dikeluarkan terutamanya pada peringkat pengemparan. Kesan penyusutan bahan bukan getah diperjelaskan dengan lebih lanjut dengan menjalankan kajian perbandingan ke atas HA-NRL dan PL. Jelas daripada analisis potensi zeta, permukaan getah yang bercas negatif terhadap keseluruhan julat pH dan nilai potensi zeta yang malar selepas pH 4 untuk PL mencadangkan penjerapan kuat surfaktan terhadap permukaan getah tertulen. Dalam ketiadaan surfaktan, cas di permukaan zarah getah juga muncul menjadi cas negatif tetapi dengan aliran pengurangan dalam magnitud potensi zeta apabila pH meningkat berpunca daripada sisa urea. Ia kelihatan bahawa keadaan penjerapan surfactant yang kuat pada permukaan zarah getah membolehkan PL untuk mengekalkan kestabilan mereka. Menggantikan bahan-bahan bukan getah dengan surfaktan memberikan kesan terhadap sifat-sifat reologi PL kerana ia mengalami kelakuan ‘shear-thinning’, peningkatan dalam ciri kelikatan dan perilaku rantau viskoelastik linear (LVR) tersendiri berbanding dengan HA-NRL. Jelas sekali, satu ciri reologi yang hampir sama diperhatikan untuk PL dalam ketiadaan surfactant dan HA-NRL.

 

Kata kunci: bahan-bahan bukan getah, lateks tertulen, rheologi, surfaktan, potensi zeta

 

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