A new development of modified dipping process of the prevulcanized natural rubber latex films: Investigation on the tensile and swelling properties

• Main Author: Noor Marlyna, Ismail
• Format: Thesis
• Language: English
• Published: Universiti Malaysia Perlis 2011
• Subjects: Natural rubber latex; Latex; Prevulcanized natural rubber latex films; Dipping process; Latex manufacturing
• Online Access: http://dspace.unimap.edu.my/xmlui/handle/123456789/12829
• Institution: Universiti Malaysia Perlis

Prevulcanized natural rubber latex films were produced by modified dipping process and their tensile and swelling properties were investigated. Two type of natural rubber latex which is high ammonia (HA) and low ammonia (LA) latex. This research study is divided into three main parts. The first part of this research is mainly to determine the most suitable maturation time for the latex compound. Therefore, each type of latex was matured into three different maturation time, i.e., 1 hour, 3 hour and 24 hour. The latex compounds were further matured in water bath at temperature of 70°C until chloroform number 3 is achieved, in which indicates that coagulum is a non-tacky agglomerates. At this stage, the latex compound is considered moderately vulcanized. Then, the latex compounds were underwent coagulant dipping process and followed by curing/ drying at room temperature, stripping and testing. Results of the tensile test show that tensile strength and tensile modulus (M100 and M300) is increase whereas elongation at break decrease with increasing filler loading, with maturation parameter at 24 hour has shown the highest value for all tensile properties, followed by 3 hour and 1 hour. At similar filler loading, HA latex shows better tensile properties than LA latex. The second part involves the investigation on different curing time and temperature of the latex. The latex compounds were prepared as same method as in the part one with maturation time is 3 hour. The 3 hour maturation was chosen because the process is become more effective in term of time consuming. After that, the dipped compounds were vulcanized in the oven at two different processes. The first oven was set at lower temperature than the second oven, and variables with time. From the tensile test results, this part exhibits that the curing temperature at 70°C and 80°C for Oven A and Oven B, respectively, with curing time of 10 minutes for each oven shows better properties than other curing parameters. For last part, every sample in part one and two were underwent leaching process. The leached latex samples were then tested their tensile properties. At the same time, the vulcanized latex also prepared by modified dipping process in which the dipped compounds were vulcanized in the oven and then proceed with the vulcanization in the water bath. Finally, the cured-leached latex samples were dried at room temperature for 25 hours before testing. The results of modified dipping process latex samples show better tensile properties than samples in part one (vulcanized at room temperature) and part two (vulcanized in oven). Overall, crosslink density increases/ higher with increasing filler loading, maturation time and by using HA latex. The crosslink density is also higher for samples that vulcanized by modified dipping process than vulcanized at room temperature and in the oven.