Effect of Deproteinized Methods on the Proteins and Properties of Natural Rubber Latex during Storage

Abstract

Summary: Three different methods of deproteinization, i.e. saponification, surfactant washing and enzymatic treatment were employed to unravel the effect of deproteinized on the properties of natural rubber (NR) latex. The cleavage of proteins in NR latex was found to proceed with concomitant formation of low molecular weight polypeptides. This results in a lowering in gel formation of the enzyme‐treated latex, indicating modification of the remaining proteins at the rubber chain‐end. Washing NR latex with surfactant would efficiently reduce and remove proteins from NR latex particles through denaturation and transferring them to the serum phase. The relatively stable gel formed during storage of surfactant‐washed NR latex is an indication of the absence of branch formation of proteins at the rubber molecule terminal. Saponification by strong alkali would hydrolyze the proteins and phospholipids adsorbed on the latex particle surface. The reason of the significantly higher gel formed in saponified NR latex is still not clear. The present study shows that deproteinization treatments result in modification of the proteins at the surface of NR latex particles and also those freely‐suspended in the serum. The cleavage or the denaturation of the rubber proteins during purification by washing has a profound effect on the properties of the deproteinized NR latex upon storage, in particular the thermal oxidative aging properties of the rubber obtained.

Characterisation of macrogel composition from industrial natural rubber samples: Influence of proteins on the macrogel crosslink density

“…This gel phase is composed of an insoluble fraction called 'macrogel' [11,12], and of microaggregates dispersed in the soluble fraction, called 'microgel' [13,14] (Figure 1). Some non-isoprene compounds of NR, such as lipids (1.5-4% w/w) [4,[15][16][17], proteins (1-3.5% w/w) [4,[17][18][19], and minerals (0.2% w/w) [4,20], are assumed to be responsible for the existence of this gel phase. For example, macrogel can be eliminated by transesterification or deproteinization of NR.…”

Influence of nonrubber components on properties of unvulcanized natural rubber

“…In addition, in Table 4, the quantity of lipids was also reduced after the alkaline treatment. Therefore, the breakdown of lipids to smaller molecules forming sodium salts of lipids also took place, as schematically illustrated in Figure . These solubilized lipids (ie, free fatty acids and their esters) in NR could be easily eliminated by the acetone extraction …”

Katalitik transfer hidrogenasi lateks karet alam dengan senyawa diimida pada skala semi pilot

“…Terbentuknya fraksi gel disebabkan oleh adanya interaksi antara senyawa non karet yaitu protein dan fosfolipid yang berada di ujung-ujung setiap rantai molekul karet melalui pembentukan ikatan silang selama masa simpan yang lama (Nawamawat et al, 2010;Nimpaiboon et al, 2014). Hasil perhitungan kadar gel karet terhidrogenasi ditampilkan pada Gambar 5.…”