BIODEGRADABILITY OF MODIFIED NATURAL RUBBER BLENDS WITH MODIFIED CASSAVA STARCH

A. A. Falomo, A. K. Akinlabi, S.O. Sojinu, I. A. Osinuga, F. Akinwunmi, A. M. Mosaku, K. A. Fasina, D. Malomo

Abstract


Polymeric materials are widely used packaging materials, they are not easily biodegradable hence their disposability is of major concern. Recently researches are being geared towards the development of biodegradable polymeric materials from natural resource as alternatives to petroleum-derived polymeric materials. This study was carried out to assess and establish the biodegradability of the blends of modified natural rubber (epoxidized (ENR), deproteinized (DPNR) and depolymerized (DPLNR)) and modified cassava starch via acetylation. The natural rubber (NR) latex used was first characterised via total solid content, dry rubber content, ash content volatile matter and mechanical stability test before modification.  The modified natural rubber (MNR) and acetylated starch (AS) were prepared and characterised using Fourier Transform Infrared Spectrophotometer (FTIR). Biodegradable polymer blends were prepared by blending the modified starch (from acetylated cassava starch) with each of the modified natural rubbers in the presence of glycerol as plasticizer using solution casting method. Biodegradability of the blends were then investigated via water absorption, solubility, mechanical analysis, thermal tests and soil burial test for twelve weeks. The progress of biodegradation under soil burial test was determined through weight loss measurement at two weeks interval. The results obtained showed that NR and MNR did not show any significant weight loss while starch and acetylated starch showed appreciable weight loss during the period of the test. Also observed was an increase in the biodegradability of the blends as the percentage of AS was increased with blend containing 30% ENR and 70% AS (ENRAS30) having the highest weight loss of 82.4%. The blends containing epoxidized natural rubber were also found to have the highest percentage weight loss. All the blends were found to be soluble in the following solvents; toluene, chloroform, petrol and kerosene used in this study. The tensile strength of the MNRs were found to be higher than that of the NR while those of the various blends were found to be lower than that of NR. The MNR have lower elongation at break than the NR. The elongation at break of the blends were also found to decrease with increase in the percentage of starch or acetylated starch in the blends. The study showed that blending NR, ENR, DPNR and DPLNR with AS will increase the rate of their biodegradability.

KEYWORDS: Natural rubber, epoxidized, depolymerized, deproteinized, acetylated, biodegradability.


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Chemical Society of Nigeria