Study on the Curing Mechanism and Characterization of Low-temperature Cured Natural Rubber Latex using Bifunctional Aldehyde as Curing Agent

Abstract

This thesis focuses on studying the curing mechanism and characterization of low-temperature cured natural rubber (NR) latex using bifunctional aldehydes as curing agents. The research is divided into four main parts, each addressing specific aspects of the study. In the first part, the influence of protein content in NR latex on the properties of cured NR using glutaraldehyde (GA) is investigated. The results reveal that higher levels of protein content in NR latex lead to significant improvements in the overall properties of NR vulcanizates. This indicates that GA not only crosslinks NR molecular chains but also forms crosslinks with proteins present in NR latex. The second part explores the properties of GA-cured grafted-NR with different acrylic monomers. The vulcanizates of grafted-NR exhibit enhanced overall properties, demonstrating the efficacy of the grafting process. Additionally, it is found that the chemical interaction between GA and rubber can facilitate crosslinking through the active ester groups of grafted-NR molecules. In the third part, the properties of NR vulcanizates using different types of bifunctional aldehyde curing agents are studied. The findings highlight that the molecular structure of the bifunctional aldehyde plays a significant role in determining the properties of NR vulcanizates. Furthermore, the use of phthaldialdehyde (PA) as a curing agent results in the production of transparent NR films, showcasing its potential applications. Lastly, the fourth section investigates the properties of NR latex mixed curing systems with varying ratios of sulfur (S) and GA. The study reveals that the S70/GA30 ratio yields superior mechanical properties, while higher levels of GA content in NR vulcanizates exhibit enhanced thermal properties. This suggests that tailoring the composition of the curing system enables the attainment of desired material characteristics. Overall, this thesis provides comprehensive insights into the curing mechanism and characterization of low-temperature cured NR latex using bifunctional aldehydes. The findings emphasize the importance of protein content, grafted-NR, molecular structure of curing agents, and curing system ratios in determining the properties of NR vulcanizates. These results offer promising opportunities for the application of low-temperature cured NR latex using bifunctional aldehydes in various rubber industries.