Thermal Decomposition of Brominated Butyl Rubber

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates, while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31 to 228.13 kJ·mol−1 at various heating rates. The non-isothermal degradation was found to be a first-order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggest that brominated butyl rubber has excellent thermal stability. This study can indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

Thermal Decomposition of Brominated Butyl Rubber

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31–228.13 kJ·mol-1 at various heating rates. The non-isothermal degradation was found to be a first order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggested that brominated butyl rubber had excellent thermal stability. This study will indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

Determination of Antioxidant 264 in the Butyl Rubber Stopper and the Compatibility with Recombinant Potent Antitumor and Antivirus Protein Injection

Objective. To establish a method for extraction and determination of antioxidant 264 (2,6-di-tert-butyl-4-methylphenol) in the brominated butyl rubber stopper for injection and migration study in recombinant potent antitumor and antivirus protein injection (Novaferon). Methods. Dichloromethane-ethanol was adopted as the extraction solvent during the process of reflux extraction of antioxidant 264 in the brominated butyl rubber stopper. High-performance liquid chromatography (HPLC) was used for the determination of the migration of antioxidant 264 to Novaferon. The mobile phase consisted of acetonitrile-water (80 : 20, v/v). The flow rate was 1.5 mL/min. The detection wavelength was 280 nm. Results. The linearity range was from 4.003 to 200.150 μg/mL (r2 = 0.99996), and the average recovery of antioxidant 264 was 97.8%. The applicability of the methodology was good, which can be used for the determination of antioxidant 264. The results indicated that antioxidant 264 was not detected in Novaferon after the accelerated test and three months of long-term test. Conclusion. The established validated method in this study can be used for the determination of antioxidant 264 in the rubber stopper, and the brominated butyl rubber stopper has good compatibility with Novaferon.

Thermal analysis of halogenated rubber cured with a new cross-linking system

The aim of this work was to examine the influence of new curing agents proposed for brominated butyl rubber (BIIR) on the cross-linking process of rubber compounds and the thermal behavior of the vulcanizates. Rubber blends that were filled with carbon black and contained acetylacetonates of different transition metals in the presence of triethanolamine (TEOA) as new cross-linking agents were prepared. The performed studies showed that metal acetylacetonates (Me(acac)) are effective cross-linking agents for BIIR, which was confirmed by high values of the torque increment (∆M) and significant cross-linking degree of the vulcanizates (α(T)). The most active curing agent seems to be iron acetylacetonate (Fe(acac)). Its application results in a shorter optimal vulcanization time, lower onset vulcanization temperature and similar vulcanization enthalpy compared to the BIIR cured with a sulfur curing system. The BIIR vulcanizates cured with Me(acac) reveal good mechanical properties with tensile strengths in the range of 9–14 MPa and better damping properties comparing to the sulfur-cured rubber. The proposed curing agents do not significantly affect the thermal stability of the BIIR vulcanizates.

Preparation and Properties of Rubber Blends for High-Damping-Isolation Bearings

To improve the energy dissipation capacity of rubber isolation bearings, it is important to find a new rubber material with good applicability and high damping properties. Two types of blends were prepared using nitrile rubber (NBR), brominated butyl rubber (BIIR) and ethylene-vinyl acetate copolymer (EVA): NBR/BIIR and NBR/BIIR/EVA. The vulcanization, mechanical and damping properties of the blends were analyzed. The results show that both blends exhibit excellent vulcanization plateaus and mechanical properties. For NBR/BIIR, as the BIIR content increases, the complementary effects of NBR and BIIR afforded by blending are enhanced. Two damping peaks appeared in the tanδ-T curve and shifted toward lower and higher temperatures, respectively, which clearly widened the effective damping temperature range. However, the damping value in the valley of the tanδ-T curve was as low as 0.39. For NBR/BIIR/EVA, the addition of EVA greatly increased damping in the valley of the tanδ-T curve to approximately 0.54. EVA was observed to be the optimal polymer for improving the compatibility of the NBR/BIIR blend. Moreover, hot air thermal aging tests showed that both blends demonstrated good stability.

INSIGHTS INTO THE CURE CHEMISTRY OF BROMINATED BUTYL RUBBER

ABSTRACT The importance of dehydrobromination to the cure chemistry of brominated butyl rubber (BIIR) is demonstrated through a combination of cure rheometry studies and model compound experiments. These data show that, while HBr elimination to give an exomethylene conjugated diene is inevitable, subsequent reactivity is highly sensitive to acidity within the mixture. As a result, formulations containing acid scavengers such as epoxides or MgO produce cure dynamics and yields that differ markedly from those of unstabilized analogues. These differences in allyl cation reaction pathways underlie much of the known behavior of BIIR + ZnO compounds and have a substantial effect on the progress of sulfur-based cure formulations. In this report, allyl cation fragmentation and electrophilic addition mechanisms are developed from 1H nuclear magnetic resonance (NMR) and mass spectrometry analysis of model compounds, and their implications for sulfur, ZnO, and sulfur + ZnO vulcanization chemistry are detailed.

Facile and Eco-Friendly Preparation of GO/BIIR Composite for Gas Barrier Applications

Owing to weak interfacial bonding and incompatibility between graphene and polymer, there are several challenges in the fabrication of graphene-based polymer composites with an effective gas barrier. Hence, it is necessary to enhance the affinity between polymers and graphene. We selected graphene oxide (GO) as filler and brominated butyl rubber (BIIR) as a substrate to prepare GO/BIIR composites via the simple latex mixed route. The tortuous path of diffusion of helium molecules is extended after insertion of GO nanosheets, thus improving the gas barrier of composites. GO/BIIR composite with the GO content of 0.3[Formula: see text]wt.% exhibits favorable barrier efficiency to helium with a helium gas transmission rate of 12.79[Formula: see text]cm3 cm m[Formula: see text] day[Formula: see text] bar[Formula: see text].