Synthesis and characterization of palm-oil-based polymeric surfactant as biocompatible additives for natural rubber latex film / Heng Yi Xin

Heng , Yi Xin (2022) Synthesis and characterization of palm-oil-based polymeric surfactant as biocompatible additives for natural rubber latex film / Heng Yi Xin. Masters thesis, Universiti Malaya.

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Abstract

Natural rubber (NR) is the preferred material in the glove industry with its outstanding characteristics of tensile strength, elasticity and tear resistance. Surfactants are commonly added in latex glove manufacturing to maintain latex stability, wet formers for coagulant dipping and assist smooth film deposition on the former. However, these surfactant molecules tend to migrate to the film surface during drying process and diffuse into the water during leaching process. This will raise the concern of polluting the environment and endangering the aquatic life. Hence, this study focuses on the development of biocompatible polymeric surfactants as an additive to natural rubber (NR) latex and production of dipped films thereafter.In this work, two polymeric surfactants, anionic and non-ionic polymeric surfactants, namely APS and NPS were synthesized from palm oil using polyesterification method. Physicochemical properties of these surfactants were determined. Both APS and NPS were compounded into NR latex to produce latex films. The physical properties of the NR latex films were subsequently studied. Both surfactants are liquid at room temperature and APS has higher viscosity (6750 cps) compared to NPS (1500 cps). Gel permeation chromatography (GPC) result shows that NPS has greater molecular weight but a lower glass transition temperature, -67.11 °C than those ofAPS surfactant. Both surfactants have reasonably good thermal stability with decomposition temperature well above 200 oC, suggesting its suitability to be used in latex compounding for sulfur vulcanization system. In the antimicrobial study, both surfactants shown antibacterial efficacy on Gram-positive bacteria at low concentration but insignificant growth inhibition for Gram-negative bacteria. The outcome of cytotoxicity study is very encouraging with both surfactants exhibited low cytotoxicity at high concentrations, 50 and 100 μg/mL for the first 24 hours, particularly in human keratinocytes and fibroblast cells. Prior to incorporation of the surfactant into the NR latex, surfactants need to be dissolved in water to form solution to reduce its viscosity for better miscibility with NR matrix. The surfactant solutions exhibited excellent wetting property with contact angle < 90°, low critical micelle concentration (CMC) value, low foaming ability and reasonable stable upon storage up to 6 months at storing temperature 40 °C. The results of physical testing demonstrated that the tensile strength of the APS film was about 35 % stronger than control and the low modulus at 300 % elongation also reflected an excellent softness of the film. In the event of thermal aging, both surfactant films exhibited anti-aging properties with no apparent depreciation in the mechanical properties after heat treatment. Collective result from all the tests carried out has demonstrated that APS is an innovation with great potential for NR latex applications, particularly in glove applications such as surgical gloves.

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