Sulfur-Free Prevulcanization of Natural Rubber Latex by Ultraviolet Irradiation in the Presence of Diacrylates

Abstract

Natural rubber (NR) latex was prevulcanized by ultraviolet (UV) irradiation in the presence of different diacrylate coagents. Prevulcanization was affected by the aliphatic hydrocarbon chain length of the coagents. The following diacrylate coagents with increasing aliphatic hydrophobic chain lengths were used: 1,4-butanediol diacrylate (BTDA), 1,6-hexanediol diacrylate (HDDA), and 1,9-nonanediol diacrylate (NDDA). Oxygen inhibition of the freeradical reactions of prevulcanization and the effects of the inert CaCO 3 filler (concentration range = 0−40 parts per hundred rubber) on properties of the prevulcanized NR films were investigated. The hydrocarbon chain length of the coagent influenced its hydrophobicity and therefore its affinity toward NR, and this affected the prevulcanization outcomes. HDDA showed the greatest affinity for NR and thus was the most suitable coagent for prevulcanization of NR. Prevulcanization via UV irradiation was insensitive to oxygen and the filler tested. The CaCO 3 filler proved to be satisfactory and could be added either before or after UV irradiation.

Compositing prevulcanized natural rubber with multiwalled carbon nanotubes to make antistatic films

“…As a consequence, the swelling ratio of the Treatment 3 films was around 95% of the average value for the films of Treatments 1 and 2. Swelling ratio and crosslink density are known to be interlinked 4 and swelling ratio typically declines with increasing crosslink density, as in the present work. Furthermore, a higher crosslink density further led to $12% higher tensile strength of Treatment 3 films compared to the average for the other two treatments (Table 3).…”

“…Natural rubber (NR) is often preferred to other rubbers for making rubber gloves, but it needs to be vulcanized before use, 4 to crosslink the rubber chains to increase the strength of the objects that are eventually made from it. For vulcanization for glove making, the NR latex is simply mixed with additives, including a vulcanizing agent (e.g., sulfur), and vulcanization occurs at room temperature.…”

“…Although thiol coagents are effective for prevulcanizing NR latex via UV irradiation, they are difficult to use because of their unpleasant odor and poor storage stability 11 . The thiols‐associated problems can be avoided by using a diacrylate coagent, although the resulting films have a low tensile strength (~12 MPa) 4,12 . Therefore, UV‐based prevulcanization needs to be optimized using a diacrylate coagent to establish conditions for forming films with the necessary strength.…”

“…11 The thiols-associated problems can be avoided by using a diacrylate coagent, although the resulting films have a low tensile strength ($12 MPa). 4,12 Therefore, UV-based prevulcanization needs to be optimized using a diacrylate coagent to establish conditions for forming films with the necessary strength.…”

The effects of the cross‐linking mechanism of low doses of gamma irradiation on the mechanical, thermal, and viscoelastic properties of the natural rubber latex/poly(styrene‐block‐isoprene‐block‐styrene) block copolymer blend

“…The C-C bond was also described in previous NR-cross-linked studies. [22,65] Based on the FTIR analysis, the probable chemical mechanism of the cross-linking is obtained in the irradiated NRL/SIS polymer blend and is illustrated in Scheme 1. Scheme 1A shows the chemical structure of the NRL and SIS blend.…”