A closed form solution for the vulcanization prediction of NR cured with sulphur and different accelerators

Self Cite

A comprehensive experimental and numerical analysis aimed at investigating the rheometer behavior of Natural Rubber (NR) vulcanized with sulfur and two accelerators [N,N‐diphenylguanidine (DPG) and N‐terbutyl, 2‐benzothiazylsulfenamide (TBBS)] is presented. To fit experimental data, the general reaction scheme proposed by Han and co‐workers for vulcanized sulfur NR is re‐adapted and suitably modified, taking into account DPG and TBBS single contributions. An ad hoc interactive software based on GUI technology is utilized to fit experimental data, allowing estimating kinetic constants also by unexperienced users. Chain reactions initiated by the formation of macrocompounds responsible for the formation of the instable crosslinked polymer are accounted for. In the presence of two accelerators, reactions are assumed to proceed in parallel, making the hypothesis of negligible interactions, being their concentrations rather similar. From the kinetic scheme adopted, a closed form solution is found for the crosslinking density, with the only limitation that the induction period is excluded from computations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43519.

Section: Introductionmentioning

confidence: 92%

“…Excluding K 0 , it has been recently shown that the crosslinking percentage

α

admits a closed form solution as follows:

\begin{matrix} left \\ α = r_{1} + r_{2} = β true{\frac{K_{1}}{K_{1} + K_{2}} true[1 - e^{- true(K_{1} + K_{2} true) true(t - t_{i} true)} true] + \frac{K_{2}}{K_{1} + K_{2} - K_{3}} true[e^{- K_{3} true(t - t_{i} true)} - e^{- true(K_{1} + K_{2} true) true(t - t_{i} true)} true] true} \\ + true(1 - β true) true{\frac{K_{1}^{'}}{K_{1}^{'} + K_{2}^{'}} true[1 - e^{- true(K_{1}^{'} + K_{2}^{'} true) true(t - t_{i} true)} true] + \frac{K_{2}^{'}}{K_{1}^{'} + K_{2}^{'} - K_{3}^{'}} true[e^{- K_{3}^{'} true(t - t_{i} true)} - e^{- true(K_{1}^{'} + K_{2}^{'} true) true(t - t_{i} true)} true] true} \end{matrix}

…”

Section: The Kinetic Approach Proposedmentioning

confidence: 99%

“…Hereafter, the simplifying hypothesis

β = 1

Section: The Kinetic Approach Proposedmentioning

confidence: 99%

“…or eq. are negligible from a practical point of view, especially in this particular dataset, as shown by Milani et al …”

Section: Numerical Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

Combined experimental and numerical kinetic characterization of NR vulcanized with sulfur, N‐terbutyl, 2‐benzothiazylsulfenamide, and N,N‐diphenylguanidine

Hanel

Donetti

Milani³

2016

Self Cite

“…As known in rubber processing, it is a necessity to add curing agents such as sulfur or peroxide, activator, and accelerator in order to enhance the mechanical properties of the rubber products. Though, sulfur is used in the vulcanization system due to low cost and toxicity, accelerator, and activator chemicals that are necessarily used in the sulfur vulcanization system have disadvantage connected with the formation of nitrosamine and the containing heavy metals, respectively . Pire et al .…”

Section: Introductionmentioning

confidence: 99%

Self‐crosslinkable hydroxylated natural rubber/carboxymethyl starch blend and its properties

Chooprayoon

Boochathum

2018

Self‐crosslinkable hydroxylated natural rubber (HNR) and carboxymethyl starch (CMS) was successfully prepared via in situ mixing of CMS slurry in HNR latex. The purpose of this work was to study the crosslinking of HNR using CMS as a novel crosslinker in order to reduce the use of sulfur vulcanizing agent and other toxic chemicals such as accelerator. Two systems with different HNR:formic acid:hydrogen peroxide ratios were prepared: 1:0.25:0.25, designated as HNR025, and 1:0.35:0.35, designated as HNR035. Well dispersion and distribution of CMS in the HNR025 matrix were obvious as imaged in scanning electron microscope micrographs. The resulting interfacial combination and ester bonding between HNR and CMS molecules were believed to enhance the mechanical properties and thermal stability of the HNR/CMS blends. It was remarkable that the determined crosslink densities of the HNR/CMS blends increased with the CMS loading and were corresponding to the improved mechanical properties. This self‐crosslinkable blend between HNR and CMS without using any vulcanizing agents would be of interest for the preparation of the green biodegradable rubber products in the future. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47271.

UV‐activated hydrosilylation of (Me‐Cp)Pt(Me)₃: Enhanced photocatalytic activity, polymerization kinetics, and photolithography

et al. 2019

Hydrosilylation is commonly known as a thermally induced addition reaction between unsaturated bonds and Si H bonds to synthesize or crosslink organosilanes and organosilicones, while it has emerged that it can also be activated under the coaction of UV irradiation and specific platinum catalyst. For higher photopolymerization conversion, excessive platinum catalyst is always required; however, this inevitably causes the significant increase of production cost and decrease of operation time. In this study, traces of trimethyl(methylcyclopentadienyl) platinum (IV) (Me-Cp)Pt(Me) 3 catalysts is combined with different photosensitizers (PSs) to efficiently promote the UV-activated hydrosilylation. Naphthalene is found to be the most applicable PS, because it improves the photopolymerization conversion from about 70 to 100% for the crosslinking of silicone rubbers. This UV-activated hydrosilylation is more likely to follow the first-order reaction kinetics, and its activation energy is 30.9 kJ mol −1 . The mechanical properties and thermostability of UV-crosslinked silicone rubbers are also enhanced with the incorporation of naphthalene. Moreover, this UV-activated hydrosilylation of silicone rubbers reveals a potential role to prepare complicated geometry shapes by photolithography.