Browsing by Author "Weerakoon, A.D."

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Automotive Windshield Wiper Blade from Incorporating RSS/Skim Rubber Blend in the EPDM Formulation.
(Faculty of Computing and Technology, University of Kelaniya, Sri Lanka., 2017) Weerakoon, A.D.
Ethylene-propylene-diene rubber (EPDM) is one of the highly demanded synthetic rubber to manufacture automotive windshield wiper blades. In order to Sulphur vulcanizing of EPDM, powerful synergistic systems are needed to cope with the low level of unsaturation in the EPDM rubber. Blending natural rubber in the form of ribbed smoked sheets (RSS) and skim rubber is an obvious method of taking advantage of the relatively low price of skim rubber whilst minimizing its disadvantages, not least that possible variability. In addition, the vulcanization characteristics of skim rubber better due to presence of higher amount of non-rubber ingredients in skim, which act as co-accelerator activators for the vulcanization reaction. Hence skim rubber is used for increasing the rate of vulcanization of SBR. Similarly, non-rubber ingredients present in skim rubber can act as co-accelerator activators for the vulcanization of EPDM also. Optimum amount of skim rubber that can be used as an additive to improve cure characteristics and physicomechanical properties of EPDM lies are around 5 phr with TMTD/TBBS accelerator system. This research was focused to investigate the potential of EPDM/RSS /skim rubber composite to manufacture automobile windshield wiper blades. The used blend ratios of EPDM/RSS /skim rubber composites were 30/70/0, 30/65/5, 30/60/10, 30/55/15, 30/50/20 and 30/45/25 and the composites were prepared according to the ISO 4097-1980 (E) formulation with TMTD/TBBS accelerator system. Optimum cure time of the composites progressively has decreased from the first composite to the last composite. Torque difference of the composites has increased with the increment of skim rubber content up to 15 phr and after that it has decreased. However, scorch safety has gradually increased when increasing the skim rubber quantity of the composite. Cure characteristics after 30/55/15 ratio implies the decrement of crosslink density of the composites due to decreasing the number of cross linking sites in the composites. Highest hardness value (61 IRHD) and the lowest compression set % (27) was also obtained with the 30/55/15 composite. The overall results of this study shows that even though the amount of non-rubber ingredients increases with the increment of skim rubber, the number of cross linking sites available for the Sulphur vulcanization has been decreased. This research study concludes EPDM/RSS/skim rubber composite of 30/55/15 ratio can be used to manufacture automotive windshield wiper blades.
Facilitating an E-Learning Platform Beyond the Lectures: Digital Natives Become Active Learners.
(Faculty of Computing and Technology, University of Kelaniya, Sri Lanka., 2017) Weerakoon, A.D.
The traditional lecturing can't inspire the digital natives towards the engagement in active learning to succeed them in the university environment and beyond in the real world context. In 2004, Romiszowski declared that e-learning presents an entirely new learning environment for students, thus requiring a different skill set to be successful. In 2008, Markus stated that e-learning is a learning process created by interaction with digitally delivered content, network-based services and tutoring support. E-learning is also called web-based learning, online learning, distributed learning, computer assisted learning, or internet based learning. This study was focused to explore the impact of a poster exhibition project on the active learning of digital natives by providing an e-learning environment. This study was carried out with Level 2 Polymer Engineering Technology students and four consecutive annual poster exhibitions has been conducted with four different batches. Each poster exhibition project was a one-month project. The students were grouped into 12 teams of 2 students in each group and each group had to prepare one poster after finalizing a theme for the poster exhibition project and the topics for the individual posters. The theme and the topics were selected to cover more than the 75% of the syllabus content of DPT 207 Polymeric Materials subject. In preparation of the posters, each group had to write a report in prior to create the rough skeletons for the poster by referring relevant articles including journal articles through the internet and each group was asked to email that report to the researcher before the given deadline. Through the constructive feedback the students had to modify the rough skeletons several times and finally came up with amazing posters. At the end of the poster exhibition project the students were given a questionnaire with both open-ended and close-ended questions. Descriptive statistical results reveal the facilitation of e-learning helps the students to learn actively, motivationally and to enhance self-monitored learning along with the collaborative learning. By enabling learners to be more active participants, a well-designed-e-learning experience can motivate them to become more engaged with the subject content and further develop them as lifelong learners.
Improvement of Rubber to Steel Adhesion in Press-on Solid Tyres by Varying the NR/BR Ratio in the NR/BR Composite Bonding Layer.
(Faculty of Computing and Technology, University of Kelaniya, Sri Lanka., 2017) Weerakoon, A.D.; Jayawarna, J.C.
Press-on solid tyres are typically made from a tread compound and a bonding layer as a composite on to the pretreated and adhesive (primer and cement) coated steel band. The so called intermediate bonding layer is a NR/BR composite. A significant problem in solid tyres is the loss of adhesion between steel and rubber with time. This limits the ultimate useful lifetime of the reinforcement and hence, of tires. This research was focused to investigate the improvement of the rubber to steel adhesion by varying the NR/BR ratio in the NR/BR composite bonding layer. In 1984 M.G. Huson et.al reported, even though NR and BR are differing little in either polarity or degree of unsaturation NR/BR blends have been shown to suffer uneven crosslink distributions in Sulphur vulcanizates and effects the physico-mechanical properties of the NR/BR blends. D. Freitas (2003) showed in preparation of NR/BR rubber blends, the addition sequence with which the components of the formulation are mixed does have influence on the behavior of the final material. Fluctuation of the prices of NR and BR in the market also significantly affect to the cost of NR/BR composite. In this study, NR/BR composites were prepared by varying the NR/BR ratio from 100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 and 0/100. Curing characteristics and the physico-mechanical properties including the adhesion value were measured in each prepared NR/BR composites. The best adhesion value obtained with the 50/50 NR/BR composite and it was 25.61 KN/m and that was in the excellent level according to the figures given for levels of adhesion for rubber to metal in ISO 813 peel test. The best tensile strength, hardness and the rebound resilience values also obtained from the 50/50 NR/BR composites and those values were 22.6 MPa, 63 IRHD and 55%. These properties together with cure characteristics and the ageing properties also were the best in the 50/50 NR/BR composite. Adhesion values were higher than the adhesion value obtained from the currently utilizing NR/BR composite. The results further concluded that the so called properties including rubber to steel adhesion properties obtained from 50/50 NR/BR composite is better than the currently existing NR/BR composite which is with 70/30 NR/BR ratio.
A Novel Approach to Enhance Students' Attention Span: A Digital Framework Among the Polymer Engineering Technology Students.
(Faculty of Computing and Technology, University of Kelaniya, Sri Lanka., 2017) Weerakoon, A.D.
In higher education, retention of the digital natives' attention span throughout the lecture is a challenging task. Gibbs (1992) found a drop in attention between 10 and 30 minutes into the lecture, which has been associated with the passive nature of the standard format, and has consequences for learning approaches and outcomes. Usually Institute of Technology of University of Moratuwa (ITUM) offers 120-minutes lengthy lectures. Because of the monotonous nature of the lecture, the students tend to sleep or talking each other without concentrate into the lecture content. So lengthy lectures should be punctuated with periodic activities by introducing lecture breaks to retain the students' attention. This study was focused to investigate the potential of a digital framework as a lecture break. The implemented digital framework was "kahoot". Kahoot is a web programme and it is a game based response platform. This user friendly website gives the ability to create quizzes and surveys about any subject area. In ITUM, the computer room is the next door to the lecture room. All the students were facilitated with individual computers with the internet facility. After 30 minutes of the lecture, students were allowed to respond for the quiz (5 questions) accessing through kahoot. Depending on answer choice and speed, kahoot give students a score. The students enjoy playing kahoot because it is fast paced, visual, and energetic. Active engagement of the students for two to four minutes through kahoot helped them to become re-energized for the next 15 to 20 minutes mini-lecture. Three to four quizzes were conducted for one lecture period. Descriptive statistics of the students' responses for the close-ended questionnaire emphasized the new digital framework helped them to actively engage in the lecture, ability to judge their knowledge level and to enhance time management skill, knowledge retention, language skill and further helped them to practice as self-directed learners. This study concludes that a simple digital framework, kahoot can act as effective lecture breaks by enhancing students' attention span while facilitating the development of graduate attributes.