Browsing by Author "Roshanie, LKS"

Now showing 1 - 2 of 2

item: Thesis-Full-text
A Study on the effect of aeration on mechanical stability of concentrated natural rubber latex upon maturation
Roshanie, LKS
ABSTRACT The ever innovation of rubber products in diversified fields have made it necessary to find suitable quality latex rubberfordifferentproducts.Because,manufacturesofrubberproductsareinsistingoncertain range of mechanical stability ( usually in the range of 500 -1000 seconds), there is a continuous research going on to find suitable test method to asses a such quality of latex It is been found that volatile fatty acid number (VFA No:), Alkalinity and Mechanical Stability Time (MST) test for quality control test proved to be a sui tabl e methods for making quality products. The objective of this research to simply give a alternative mclhod to develop mechanical stability without adding soap because previous studies shows that when soap level is high the quality of the latex was low. Current studies consist of analyzing the MST variation of centrifuged latex with aeration level and maturation. And also analyze the variation of other properties such as Alkalinity, VF A No:, Viscosity , to nductivity and pH. The latex used for this study were obtained from a centrifuged plant, accordingly a special request was made to them to supply latex with minimum addition of soap. Aeration was supplied in different levels to different sample. Following properties was investigated at intervals: MST, Alkalinity, VFA No:, Viscosity, pH and Conductivity Out of the whole investigated properties; response to the aeration level was remarkable in MST, with maturation results suggest that MST is increases with higher the aeration level. Other properties such as a VF A, Alkalinity are not much effect with the air quantity. Therefore supply of air is not destroying the quality of the latex. VF A increment is not much significant. Viscosity is decreases up to some significant level with air quality. pH of the samples show some storage patterns not a trend pattern. Variation in MST is due to the air supplied to the sample; promote hydrolysis of proteins and phospholipids in the latex. Finally former fatty acids anions, phosphate anions are observed at the ... particle interface and enhance the stability of latex Further more results show that the highest aeration level is not the optimum aeration level . so • further studies should be carried out to find an optimum aeration level and how minimize the space of vessel which is required for aeration.
item: Article-Abstract
Effect of different aeration levels on natural rubber latex upon maturation
Roshanie, LKS; Walpalage, S
Mechanical Stability (MS) of Natural Rubber Latex (NRL) is practically important to the latex producer and consumer whenever latex is handled. MS of fresh NRL is very low and fresh NRL cannot be directly used for manufacturing processes. Thus, freshly tapped NRL is kept for maturation and MS naturally develops and achieve steady level around 21 days. Water soluble fatty acid soap is used as an accelerator for the MS development and excess soap is added by NRL manufacturers to cut-down the maturation time. Appearing tiny pin holes on dipped latex films is one the major drawback due to excess soap in NRL. The main aim of this research was to find the alternative method to accelerate the MS development process without adding excess soap. Aeration of NRL was selected as an alternative technique and NRL samples were matured with different levels of air quantity and minimum soap content which is needed only to centrifuge. It was found that Mechanical Stability Time (MST), Volatile Fatty Acid (VFA) Number, Alkalinity, Conductivity and Viscosity changed with the air quantity. At minimum soap level, time duration to obtain standard MST was changed with air quantity. VFA number was slowly increased as air quantity increase, but it was not very significant.