Master of Science in Polymer Technology

Permanent URI for this collectionhttp://192.248.9.226/handle/123/27

Browse

Browsing Master of Science in Polymer Technology by Author "Amarasinghe, ADUS"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    item: Thesis-Abstract
    Characterization and evaluation of starch xanthide encased powdered natural rubber
    Maduwage, S; Amarasinghe, ADUS; Subramaniam, K
    Rubber as a free-flowing powder, is essential in order to stream line the manufacturing processes of rubber goods. The previous works noted the importance of using powdered rubber as a competitive raw material for continuous processing in rubber industry. However, in most of these works, the study was continued to the synthetic rubbers and only a few had been reported on the natural rubber. Sri Lanka which is an agricultural based country, has a bulk quantity of natural rubber field latex at a low price. Hence, it is worthwhile to produce a value-added product like powdered rubber using field latex. Encapsulation is a common process in preparing powdered natural rubber. In this process, starch xanthate, SX, which acts as a diluent/reinforcing filler, behaves as an encapsulating agent for latex particles. The level of encapsulation as well as the properties of the resulting powder is highly dependent on the strength and the amount of the SX solution. The present work investigates these effects with varying strength of SX by changing the degrees of substitution, DS, of the SX solution and also the loading of the SX. The lower and the upper limits of DS of SX examined were 0.07 and 0.35 and the results suggested that the intermediate DS levels were more promising. The physical properties of the final vulcanizates were found to be satisfactory and were comparable with the rubbers available in the market. Study on drying techniques established the necessity of water washing step for natural rubber powders to remove non-rubber substances and the applicltion of an anti-cake agent to prevent agglomeration during drying. The effect of different anti-cake agents such as zinc stearate, talc powder and whiting was examined and zinc stearate was found to be the best out of the anti-cake agents used. Highly friable crumbs that ground readily to give powders were obtained with oven drying rather than with sun drying.
  • Thumbnail Image
    item: Thesis-Abstract
    Synthesis and characterization of alkyd resins using blend of soya beans oil and karawila seed oil
    De Silva, SHUI; Amarasinghe, ADUS; Premachandra, BAJK
    This research is based on synthesizing an air drying long oil alkyd resin using a blend of semi drying soya bean (Glycine max -Pb I) oil and fast drying karawila (Momodica charantia -MC43) seed oil. The alkyd resin was synthesized with the aim of obtaining a varnish without standing film properties, especially drying characteristics enhance by significant amount of a-eleostetic acid (ctt,9,11,13-18:3), where is having conjugated double bonds, presence in karawila seed oil. A series of alkyd resins were prepared maintaining 65% oil length by changing the ratio of karawila seed oil from 0-50% (by w/w%). The other constituents of alkyd resins werepentaerythritol, phthalic anhydride, xylene and sodium methoxide as catalyst. Due to the lowacid values of the seed oils monoglyceride process was selected and obtained accept able standard for transesterification and polye sterification reactions and 240°C temperature was maintained at transesteritication and esterification stages. Patton constant and the ratio of OH:COOH groups were maintained closer to 1.00 when preparing alkyd resins. In addition, the alkydresins were prepared by maintaining final acici. value below 20 mg/g to make sure the extent of polymerization was in the range of 90 % to 95 %. Physicochemical properties of these alkydresin solutions were examined to see the effect with the increase of karawila seed oil in the resin. The solid content was adjusted to 50% and cobalt octate with lead octate were used as driers to prepare varnish from these alkyd resins. The film properties of the alkyd resins were examined to find the optimum ratio of karawila oil to soya bean oil. Mechanical properties, chemical resistant properties and drying properties of these films were examined and evaluated in this regardThe alkyd resin blended with 30% karawila seed oil showed the best film properties in the oil blended series and it also render lower set to touch drying time and dry to touch drying time, better scratch hardness, adhesion and better gloss. In addition, better resistance to water, acid, solvent and corrosion was observed.
  • Thumbnail Image
    item: Thesis-Abstract
    Synthesis and characterization of stoving alkyd resin based on oil blends of Karawila seed oil and Coconut oil
    Vitharana, DKB; Amarasinghe, ADUS
    Synthetic resins are used as binders in protective coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called Baking enamel or Stoving enamel cured through functional groups of resin. Mostly these stoving alkyds are short oil alkyd type and synthesized from coconut oil. This research project describes synthetic resins of the alkyd type and synthesize of such resins. Also this research focused on novel modified stoving alkyd resins having improved properties such as Drying time, Film hardness, Adhesion and Gloss which are synthesized using blends of coconut oil and karawila seed oil. Fatty acid distribution of Coconut oil shows that it is having saturated fatty acids in major quantity and very small amount of oleic and linoleic acids present in the mixture. Coconut oil has an acid value of 3.22 mg g -1and saponification value of 251.9 mg g -1. on the other hand karawila seed (MC43/ oil is havig an acid value of 2.87 mg g-I and saponification value of 203.94 mg g-I. Karawila seed oil consist conjugated trienoic acid in large quantity and shows good drying properties compared to other drying oils. Blending is done to improve the film properties and to monitor air drying ability of alkyd synthesized by oil blends. , Both the oils are having low acid values and this leads to the selection of monoglyceride process as the method of manufacturing. Better film properties could be obtained when a mixture of Propylene Glycol and Pentaerythritol was used as polyols with excess OH. Film properties were compared by gradually increasing the karawila oil -content to a maximum of 10%, since the yield ofkarawila seed oil is 24%1 while maintaining the oil length at 45%. Excellent film properties were shown for the oil percentage of karawila seed oil in the total mixture is 10%.