Development of biocompatible natural rubber latex film incorporated with vegetable oil microemulsion as plasticizer: Effect of curing conditions

Abstract

The development of vegetable oil mircoemulsion has attracted great attention due to its relatively low cost in production and usable for many applications. However, reports on the application of vegetable oil microemulsion as plasticizers in biocompatible natural rubber (NR) latex film are scanty. In this study, the vegetable oil microemulsion of coconut kernel oil (CKO) and soybean oil (SBO) with the ratio of 7:3 was prepared by the phase inversion temperature method. The particle size and zeta potential of the oil microemulsion were measured as 10.43 nm and -6.09 mV respectively. About 2.5 phr microemulsion was blended with NR latex to produce latex films that were cured at different temperatures (80°C, 100°C & 120°C) and durations (30 min, 1 h & 2 h). The results showed that the tensile strength of all latex films incorporated with oil microemulsion (NR/ME) were obviously lower than the tensile strength of the control latex film but the tensile strengths of these films could be improved as the curing temperature and duration increased. CKO/SBO microemulsion was found to be compatible with the NR latex as the contact angles of all films did not exceed 90°, signifying no oil blooming onto the surface of latex films. In a nutshell, the CKO/SBO microemulsion had the potential to be utilized as a plasticizer to produce the biocompatible latex film.