Manganese and Nickel Acetylacetonates as Curatives for Chloroprene Rubber Based on Heck’s Reaction

The commonly used curing system for chloroprene rubber (CR) is a combination of two metal oxides, such as magnesium oxide (MgO) and zinc oxide (ZnO). Application of MgO and ZnO enables to obtain a good balance between processability of rubber compounds and mechanical properties of the vulcanizates. Despite high activity in crosslinking reactions, ZnO is classified as ecotoxic to aquatic organisms, thus environmental legislation requires its quantity in technology to be limited. In our studies more environmentally friendly curing systems were applied, which enabled eliminating ZnO from CR compounds. These curing systems consisted of manganese acetylacetonate (Mn(acac)) or nickel acetylacetonate (Ni(acac)) and triethanolamine (TEOA) used as a base necessary to perform Heck’s reaction. Both metal acetylacetonates exhibited high activity in crosslinking reactions, which was confirmed by a great torque increment during rheometric measurements and high degree of elastomer crosslinking. The type of metal acetylacetonate and the amount of TEOA seemed to have less influence on the efficiency of the curing system than the filler used. Rubber compounds filled with carbon black (CB) were characterized by definitely shorter optimal vulcanization times and higher degree of crosslinking compared to CR composites filled with nanosized SiO2. Moreover, application of the proposed curing systems allowed to obtain CR vulcanizates with mechanical properties comparable with the benchmarks cured with metal oxides.

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Influence of different curing regimes on properties of new copolymer of chloroprene and acrylonitrile

Journal of Elastomers & Plastics ◽

10.1177/00952443211038667 ◽

2021 ◽

pp. 009524432110386

Author(s):

Mousumi De Sarkar ◽

Takashi Sunada ◽

Atsunori Kondo

Keyword(s):

Stable State ◽

Industrial Applications ◽

Vital Role ◽

Product Families ◽

Compression Set ◽

Rubber Compounds ◽

Chloroprene Rubber ◽

Ethylene Thiourea ◽

Curing Regimes ◽

Curing Systems

The curing system plays a vital role in designing rubber compounds for various industrial applications. Therefore, it is paramount to establish viable curing strategies for any new elastomer to explore its application potentials and commercial significance. Impacts of different curing regimes on the properties of a recently developed copolymer of chloroprene and acrylonitrile (acrylonitrile-chloroprene rubber, NCR) are reported here. Several primary accelerators (four from thiourea- and one from thiazolene product families) were used for curing the new rubber along with fixed loadings of zinc oxide (5 phr) and magnesium oxide (4 phr). Besides, curatives based on sulfur and peroxide were also evaluated. The influence of different curing systems on the rheological and physical properties of the copolymer was explored. It has been seen that the properties of the copolymer are considerably influenced by the different curing systems used. While ethylene thiourea (ETU) and propylene thiourea (PTU), as primary accelerators, provide the highest state of cure but may cause scorch. The use of trimethyl thiourea (TMU), on the other hand, results in the fastest rate and the most stable state of cure, good scorch safety, bin stability, and an overall good balance of properties. The sulfur-based crosslinking system induces good mechanical properties but causes limited bin stability, poor high-temperature compression set, and impaired heat resistance properties. As a curing agent, peroxide delivers the best bin stability in the rubber stocks but yields higher stiffness and limited aging resistance in the vulcanizates.

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METAL COMPLEXES AS NEW PRO-ECOLOGICAL CROSSLINKING AGENTS FOR CHLOROPRENE RUBBER BASED ON HECK COUPLING REACTION

Rubber Chemistry and Technology ◽

10.5254/rct.19.81465 ◽

2019 ◽

Vol 92 (3) ◽

pp. 589-597 ◽

Cited By ~ 2

Author(s):

Anna Dziemidkiewicz ◽

Martyna Pingot ◽

Magdalena Maciejewska

Keyword(s):

Metal Complexes ◽

Metal Oxides ◽

Reference Sample ◽

Coupling Reaction ◽

Industrial Applications ◽

Rubber Blends ◽

Crosslinking Process ◽

Chloroprene Rubber ◽

High Degree ◽

Crosslinking Agents

ABSTRACT The influence of new pro-ecological curing agents on the crosslinking process of chloroprene rubber (CR) was examined. The proposed curing system used a simpler recipe (no need to apply harmful products such as zinc oxide and ethylene thiourea) and cost less than standard metal oxides. It was expected that the mechanism of crosslinking would be similar to that of Heck-type reactions. Heck-type reactions are powerful tools for the creation of new C=C bonds. They provide the simplest and most efficient way to synthesize a variety of important compounds used in many areas, such as pharmaceuticals, antioxidants, ultraviolet absorbers, and industrial applications. However, despite their wide application, Heck-type reactions have not been used in the rubber industry so far. Rubber blends containing acetylacetonates with different transition metals as new crosslinking agents were filled with fumed silica Aerosil 380 or carbon black Corax N-550. It was found that metal complexes are active crosslinking agents of the CR composites. The obtained vulcanizates were characterized by a high degree of crosslinking and good mechanical properties. Considering the high tensile strength and degree of crosslinking, iron acetylacetonate was the most effective curing agent of the used metal complexes. Compared with the reference sample cured with metal oxides, the CR samples crosslinked using metal acetylacetonates had a higher activity.

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Cure Characteristic and Mechanical Properties of Epoxidized Natural Rubber/Chloroprene (ENR/CR) Blends

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.93-94.631 ◽

2010 ◽

Vol 93-94 ◽

pp. 631-634

Author(s):

Chanchai Thongpin ◽

Piyaporn Niltui ◽

Piyapong Sornwaneenawakhun ◽

Tossaporn Maneeprom ◽

Saovaros Malithong ◽

...

Keyword(s):

Mechanical Properties ◽

Natural Rubber ◽

Epoxidized Natural Rubber ◽

Maximum Torque ◽

Tear Strength ◽

Rubber Compounds ◽

Cure Time ◽

Chloroprene Rubber ◽

Cure Characteristic ◽

Two Phases

Epoxidized Natural rubber (ENR) with the epoxide content of 40 % was prepared and blended with various contents of chloroprene rubber (CR) and 50 phr of carbon black. The cure characteristic, mechanical properties and the effect of gasohol E-85 on the mechanical properties of the rubber vulcanizate were studied. It was revealed from cure characteristic results, tested by Moving Die Rheometer (MDR), that minimum torque of the rubber compounds increased with the content of CR whereas maximum torque tended to increase at the content of 10 phr and decrease after this content, of which the values agreed well with the modulus at 100% elongation in rubber vulcanizates. Considering characteristic scorch and cure time, the values increased with the CR contents. It was clear from the result that at the ENR:CR ratio of 90:10, modulus of 100% elongation and tear strength exhibited the highest values. It was also found that the mechanical properties of the blend vulcanizates were slightly suffered by gasohol E85 except for tear strength. It was understood that this must be because of the effect of the phase continuity and crosslinking that occurred differently in two phases. The phase morphology of the blends were also investigated and reported in the research.

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Specification for chloroprene rubber compounds

10.3403/00044663 ◽

1982 ◽

Keyword(s):

Rubber Compounds ◽

Chloroprene Rubber

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Specification for chloroprene rubber compounds

10.3403/00229407u ◽

2015 ◽

Keyword(s):

Rubber Compounds ◽

Chloroprene Rubber

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Chloroprene rubber compounds. Specification

10.3403/02833347 ◽

2003 ◽

Keyword(s):

Rubber Compounds ◽

Chloroprene Rubber

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Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Polymers ◽

10.3390/polym13071085 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1085

Author(s):

Patricia Castaño-Rivera ◽

Isabel Calle-Holguín ◽

Johanna Castaño ◽

Gustavo Cabrera-Barjas ◽

Karen Galvez-Garrido ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Black ◽

High Performance ◽

Rubber Matrix ◽

Butadiene Rubber ◽

X Ray Diffraction ◽

X Ray ◽

Rubber Blends ◽

Ft Ir ◽

Chloroprene Rubber

Organoclay nanoparticles (Cloisite® C10A, Cloisite® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

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Rheometer Evidences for the Co-Curing Effect of a Bismaleimide in Conjunction with the Accelerated Sulfur on Natural Rubber/Chloroprene Rubber Blends

Polymers ◽

10.3390/polym13091510 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1510

Author(s):

Marek Pöschl ◽

Shibulal Gopi Sathi ◽

Radek Stoček ◽

Ondřej Kratina

Keyword(s):

Mechanical Properties ◽

Natural Rubber ◽

Tensile Properties ◽

Crosslinking Agent ◽

Alder Reaction ◽

Diels Alder ◽

Ene Reactions ◽

Rubber Blends ◽

Diels Alder Reaction ◽

Chloroprene Rubber

The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has been introduced as a co-crosslinking agent for a 50/50 blend of NR and CR in conjunction with accelerated sulfur. The delta (Δ) torque obtained from the curing curves of a blend with the addition of 1 phr MF was around 62% higher than those without MF. As the content of MF increased to 3 phr, the Δ torque was further raised to 236%. Moreover, the mechanical properties, particularly the tensile strength of the blend with the addition of 1 phr MF in conjunction with the accelerated sulfur, was around 201% higher than the blend without MF. The overall tensile properties of the blends cured with MF were almost retained even after ageing the samples at 70 °C for 72 h. This significant improvement in the curing torque and the tensile properties of the blends indicates that MF can co-crosslink between NR and CR via the Diels–Alder reaction.

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Utilization of Solid Waste from Brick Industry and Hydrated Lime in Self-Compacting Cement Pastes

Materials ◽

10.3390/ma14051109 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1109

Author(s):

Mati Ullah Shah ◽

Muhammad Usman ◽

Muhammad Usman Hanif ◽

Iqra Naseem ◽

Sara Farooq

Keyword(s):

Mechanical Properties ◽

Solid Waste ◽

Manufacturing Industry ◽

Setting Time ◽

Hydrated Lime ◽

Pozzolanic Reaction ◽

Early Age ◽

Cement Pastes ◽

Brick Powder ◽

High Degree

The huge amount of solid waste from the brick manufacturing industry can be used as a cement replacement. However, replacement exceeding 10% causes a reduction in strength due to the slowing of the pozzolanic reaction. Therefore, in this study, the pozzolanic potential of brick waste is enhanced using ultrafine brick powder with hydrated lime (HL). A total of six self-compacting paste mixes were studied. HL 2.5% by weight of binder was added in two formulations: 10% and 20% of waste burnt brick powder (WBBP), to activate the pozzolanic reaction. An increase in the water demand and setting time was observed by increasing the replacement percentage of WBBP. It was found that the mechanical properties of mixes containing 5% and 10% WBBP performed better than the control mix, while the mechanical properties of the mixes containing 20% WBBP were found to be almost equal to the control mix at 90 days. The addition of HL enhanced the early-age strength. Furthermore, WBBP formulations endorsed improvements in both durability and rheological properties, complemented by reduced early-age shrinkage. Overall, it was found that brick waste in ultrafine size has a very high degree of pozzolanic potential and can be effectively utilized as a supplementary cementitious material.

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