Chloroprene Research Articles

Study on the influence of carbon nanotube modification on the mechanical and magnetic properties of chloroprene rubber‐based magnetorheological elastomers

AbstractThis study explores the mechanical and magnetic properties of magnetorheological elastomers (MREs) based on chloroprene rubber, enhanced with carbonyl iron powder (CIP) as the primary filler. Carbon black serves as the primary reinforcing filler, with multi‐walled carbon nanotubes (CNTs) used as a secondary filler to strengthen the rubber matrix. The primary objective of this research is to examine the effects of the mixture of iron powder with reinforcing fillers and the interaction of these fillers with the rubber matrix on the mechanical and magnetomechanical performance of MREs. CNTs, tubular nanoscale carbon molecules, significantly enhance the tensile strength and fatigue resistance when combined with the MRE matrix. During mixing, CNTs form a network structure within the MRE matrix, promoting the dissipation of accumulated heat and reducing thermal fatigue loss. The addition of 20 parts of CNTs to the CR matrix significantly improved the tensile mechanical properties, with the 100% set elongation stress increasing by up to 260% and the magnetic responsiveness increasing by 30.6%. The addition of 10 parts of carboxylated CNTs most notably enhanced the magnetorheological effect, increasing the magnetic stress relaxation rate by 78%. These enhanced properties enable MREs to provide better vibration control and comfort in automotive suspension systems, improve energy absorption and damping effects in industrial damping systems, and enhance durability and sealing performance in sealant applications.Highlights Carbonyl iron powder, carbon black, and carbon nanotubes (CNTs) were used as fillers to strengthen the chloroprene (CR) matrix magnetorheological elastomers (MREs). CNTs formed a network structure, promoting the dissipation of accumulated heat and reducing thermal fatigue loss. The tensile mechanical property of MRE with 20 parts of CNTs has been significantly improved, with an increasing magnetic responsiveness of 30.6%. Magnetorheological effect of MRE with 10 parts of CNTs has notably enhanced, with the magnetic stress relaxation rate of 78%.

Interelastomer Reactions Occurring during the Cross-Linking of Hydrogenated Acrylonitrile-Butadiene (HNBR) and Chloroprene (CR) Rubbers Blends in the Presence of Silver(I) Oxide (Ag2O) and Mechanical Properties of Cured Products.

The purpose of this paper was to examine the possibility of producing new blends of hydrogenated acrylonitrile-butadiene and chloroprene rubbers (HNBR/CR) unconventionally cross-linked with silver(I) oxide (Ag2O), and to investigate the physicomechanical properties of the obtained materials. From the obtained results, it can be concluded that HNBR/CR composites were effectively cured with Ag2O, which led to interelastomer reactions, and the degree of binding of HNBR with CR was in the range of 14-59%. The rheometric and equilibrium swelling studies revealed that the cross-linking progress depended on the weight proportion of both elastomers, and the degree of cross-linking was greater with more content of chloroprene rubber in the tested blends. Interelastomer reactions occurring between HNBR and CR improved the homogeneity and miscibility of the tested compositions, which was confirmed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) analyses. The tensile strength and hardness of the obtained HNBR/CR/Ag2O vulcanizates proportionally increased with the content of CR, while the tear strength showed an inverse relationship. The obtained new, unconventional materials were characterized by significant resistance to thermo-oxidative factors, which was confirmed by the high aging factor.

Novel crystalline reduced graphene oxide/adhesive nanocomposites for enhanced electrical, thermal, dielectric properties and electromagnetic energy absorption application

At present times electromagnetic (EM) pollution is increasing due to a lot of progress and achievements in the electronics field. There is a dire need to develop materials that have greater EM energy absorption/emission properties. We report here the synthesis of a nanocomposite of carbonaceous material, reduced graphene oxide (rGO) with Chloroprene (CP) grafted polymethyl methacrylate (CP-g-pMMA), i.e. rGO/CP-g-pMMA. FTIR confirms the grafting of Chloroprene rubber and the presence of rGO. XRD shows the crystallinity of rGO alone and in the composites as well. SEM images showed smooth texture for neat polymer while nanocomposite showed a leafy appearance of the reduced graphene oxide (rGO). The viscosity of pure CP was 3740 cps while CP-g-pMMA was 1644 cps. A slight decrease was observed after the addition of rGO. Enhancement in thermal properties from 264 °C to 269 °C showed that the composites were thermally more stable than the virgin CP and CP-g-pMMA. The permittivity and alternating current conductivity were checked by Radio Frequency (RF) impedance and material analyzer in the range of (1–1000 MHz) X-band and (1–3 GHz) S-band. The nanocomposites showed the lowest percolation (0.32 vol. %) yet reported. The nanocomposites showed low real and absolute permittivity. The electrical and permittivity analysis of the rGO/CP-g-pMMA nanocomposites revealed that they can be potential candidates for their applications in electronic devices as an absorber.

Preparation and characterization of natural rubber–based new elastomers for high-damping base isolation systems

Natural rubber (NR)–based vulcanizates have been used as base isolation materials for many years. Combining good damping properties, low cost, and availability with acceptable mechanical and aging performance, these materials have always been the first choice for base isolation applications. In this research, we try to formulate a natural rubber base recipe with increased damping properties, which can fulfill mechanical and aging requirements of base isolation systems. For this purpose, a series of blends have been formulated by incorporating chloroprene (CR) or butadiene (BR) and acrylonitrile butadiene rubber (NBR) into the natural rubber base. Filler content accelerator type and vulcanization system have been chosen to optimize damping while maintaining a reference point. All vulcanizates have been tested for their mechanical properties. Moving die rheometer (MDR) and rubber process analyzer (RPA) have been used to obtain general cure data as well as storage (G′) and loss modulus and loss angle (η). Crosslink densities have been calculated using RPA and Lee and Pawlowsky’s Coran approach. Dynamic material tests have been performed to obtain dynamic shear properties, equivalent damping ratio, and shear modulus. The results indicated that NR/NBR and NR/CR compounds with viscous damping values of 10.4% and 8.9% at frequency of .5 Hz can lay bases for formulating high-damping rubber (HDR) materials for base isolation systems due to their increased damping and rather good mechanical and relaxation performance.

Studies on the curing, tensile and adhesion characteristics of cushion gum to carcass in truck retreaded tires: the effect natural rubber types

In order to improve the quality of truck retreaded tyres, the cushion gum (CG) plays an important role as an adhesion medium to bond the carcass of the new tread to the worn old tyre. This study investigates the effect of natural rubber types such as reclaimed skimmed latex (RSL), ribbed smoke sheet (RSS), chloroprene (CR) and RSS added 10 phr of carbon black (CB) towards its CG performance in cold cure systems. The CG was compounded based on ASTM D3182 with 10 phr of Cumaroun Resin, 5 phr of Calcium Silicate, and other chemicals. The 4 types of CG were tested its physical and tensile properties. To determine the curing time, the rheological was analysed. The results show that the addition of carbon black may improve physical and tensile properties, excluding the elongation at break. It is found that the curing time of cushion gum based on SL rubber has the shortest duration. Each CG was applied to retreat the same type of truck’s worn tyres (1000R20). After surface modification, 5 mm of CG was bonded new same carcass the old surface and continued by heating in the autoclave chamber for 3 hours with pressure at 2 atm. The results show that the adhesion strength of cushion gum based on RSL; RSS; CR; RSS/CB is as follows: 13.64; 8.21; 8.04; 8.01 kN/m respectively, while the adhesion strength of commercial cushion gum is 15,38 kN/m. The spectra FTIR of each cushion gum convince that the less dispersion matrix compared to commercial cushion gum. To sum up, the RSL-NR is the recommended polymer for cushion gum compounding. However, in order to improve its quality, it is suggested to do some pre-treatment and increase the number of tackifier and processing oil in the formulation

Studies on reinforcing effect of industrial nano silica in chloroprene vulcanizates containing carboxy-terminated liquid natural rubber

Maleic anhydride was chemically attached to depolymerized natural rubber, and the product was named as carboxy-terminated liquid natural rubber (CTNR). The CTNR can act as a potential plasticizer in chloroprene (CR) vulcanizates. This paper describes the use of commercial nano silica (NS) as a promising cost-effective filler, which can enhance the tensile properties and ageing resistance of the CR vulcanizates incorporated with CTNR (CR-CTNR). The enhancement in properties may be attributed to the increased bound-rubber content owing to the large surface area of the nano-sized filler. The characteristics of the NS-filled CR vulcanizates containing CTNR (NS CR-CTNR) were compared with those containing amorphous silica. The NS CR-CTNR vulcanizates showed superior ageing and oil resistance due to the finer rubber filler interaction modified by ionic cross linking.

Development of Novel Magnetic Responsive Intelligent Fluid, Hybrid Fluid (HF), for Production of Soft and Tactile Rubber

For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic polymerization, we proposed a novel magnetic responsive intelligent fluid, Hybrid Fluid (HF). HF is structured with water, kerosene, silicon oil having Polydimethylsiloxane (PDMS) and Polyvinyl Alcohol (PVA) as well as magnetic particles and surfactant. The state of HF changes as jelly or fluid by their rates of the constituents and motion style. In the present paper, we presented the characteristics of HF: the viscosity and the magnetization are respectively equivalent to those of other magnetic responsive fluids, MF and their solvents. For the structure, HF is soluble simultaneously with both diene and non-diene rubbers. The diene rubber such as Natural Rubber (NR) or Chloroprene (CR) has a role in the feasibility of electrolytic polymerization and the non-diene rubber such as silicon oil rubber (Q) has a role in defense against deterioration. Therefore, the electrolytically polymerized HF rubber by mixing NR, CR as well as Q is effective for the artificial soft and tactile skin. It is responsive to pressure and has optimal property on piezoelectricity in the case of the mixture of Ni particles as filler. HF is effective in the production of the artificial soft and tactile skin made of rubber.

Flame retardant and durable chloroprene rubber and styrene-butadiene rubber blends crosslinked with copper(I) oxide

The purpose of this work was to investigate the effect of application of copper(I) oxide (Cu2O) as an unconventional crosslinking agent of chloroprene (CR) and styrene-butadiene (SBR) rubber compositions. The use of Cu2O arises from the need to limit the application of ZnO as a CR crosslinking agent. The obtained results indicate that CR/SBR blends crosslinked with Cu2O are characterized by good mechanical properties and a high degree of crosslinking The results show that the proportion of both processing rubbers, as well as the amount of copper(I) oxide, influence the crosslinking of CR/SBR blends and the properties of the vulcanizates. Performing FTIR analysis has allowed the development of a crosslinking mechanism. Crosslinking presumably takes place according to the mechanism of Friedel–Crafts alkylation reaction. Silica, chalk, china clay and nanofiller (montmorillonite modified with quaternary ammonium salt containing hydroxyl groups) were applied as fillers. Among the fillers, silica had the greatest impact on improving the properties. It is arisen from silica activity, unlike other used fillers. The AFM analysis allowed us to determine the miscibility of the rubbers and dispersion of fillers. Thermal analysis was performed to determine the changes occurring as a result of material heating. The low intensity of the peaks corresponding to the crosslinking of the CR/SBR blends may indicate a small amount of bonds formed during heating, or possibility is the formation of connections between chains with a low binding energy. The use of chalk, china clay or silica increases the thermal stability of the vulcanizates. Obtained vulcanizates were characterized by increased incombustibility. The study of combustion time in the air showed that the prepared vulcanizates did not support the burning.

Use of Carboxy Terminated liquid Natural Rubber (CTNR) as a reactive polymeric plasticizer in chloroprene vulcanizates

Maleic anhydride was chemically attached to depolymerized natural rubber by a photochemical reaction. The product is named as Carboxy Terminated liquid Natural Rubber (CTNR). This paper describes the use of CTNR as a reactive polymeric plasticizer for chloroprene (CR) vulcanizates, which can improve the tensile properties and ageing resistance of the chloroprene vulcanizates, due to similarity in polarities. The efficiency and permanence of this polymeric plasticizer were compared with that of conventional plasticizer in silica and carbon black filled CR vulcanizates. It is found that CTNR could replace the conventional plasticizer either partially or fully. A combination of the conventional plasticizer and CTNR could improve the ageing and oil resistance of the chloroprene vulcanizates.

Studies on Physical Chemistry of Rubber-Rice Husk Ash Composites

Nowadays an alternate source of filler from renewable and plant derivatives are being thought of in rubber industries due to their reliability, environmental and economic benefits. Rice Husk Ash (RHA) a byproduct of the rice milling industry is obtained on partial and as well as full combustion of the rice husks. This ash is a good source of silica, silicates and needle shaped carbon and hence can be used as filler for cements. In the present study, a detailed investigation was carried out to understand the RHA as reinforcing material using mechanical properties and fractography using SEM. The rubbers studied were natural rubber (NR), poly chloroprene (CR) and ethylene propylene diene monomer (EPDM). Interestingly, the RHA added NR stock on open mill mixing generated considerable amount of static charges. The properties of NR were found to be as good as regular formulations. EPDM compounds behaved well during mixing. But the properties were found to be poor. CR- RHA compounds were found to result in higher viscosity and the properties were not as good. The SEM studies showed surprisingly cohesive failure as evidenced with the presence of flow lines and the fibrous filler (RHA) remains embedded in the matrix regardless of the chemistry of the repeating unit, NR, EPDM and the chlorine containing monomer inCR.

Synthesis of poly(chloroprene)-based block copolymers by RAFT-mediated emulsion polymerization

Chloroprene (CP)-based block copolymers were synthesized via the RAFT-mediated emulsion polymerization of CP using polyacrylate macro-chain transfer agents (CTAs) via a one-pot (in-situ), two-step process. The quantitative formation of hydrophobic macro-CTA in the latex in the first step and subsequent incorporation of CP monomer into the latex using a high internal phase emulsion (HIPE) in the second step were observed to be crucial for producing poly(CP)-based block copolymers. The formation of poly(CP)-b-poly(n-butyl acrylate)s were confirmed by an evident shift in the SEC traces and the 1H and DOSY NMR measurements. The block copolymers exhibited microphased structures composed of the poly(CP) matrix with low Tg (−30 °C) and the poly(nBA) spherical phase with lower Tg (−50 to −60 °C), as revealed by dynamic mechanical analysis (DMA) and transmission electron microscopy (TEM). This study represents the first report of the controlled synthesis of poly(CP)-based block copolymers by RAFT-mediated emulsion polymerization using HIPE.

Characterization and evaluation of a novel renewable plant product (RPP) gum as a flame retardant additive in chloroprene and natural rubber

With an objective to search a new class of polymer / rubber additives specially flame retardant (FR) from the plant origin as a suitable substitute of conventional FR additive Sb2O3, an attempt was made to explore the effectiveness of a renewable plant product (RPP), collected as a gum from an Indian local plant, Spondias dulcis, Anacardiaceae family, as a flame retardant additive in chloroprene (CR) and natural rubber (NR) vulcanizate. FTIR spectra were recorded and the relevant functional groups present in RPP gum were assigned. TGA and DSC were registered to study the thermal response of the gum. The crystalline behaviour was judged by XRD followed by evaluation of surface elemental composition by EDX. Compound formulations containing 10 wt% of RPP were prepared with CR and NR separately along with the control with and without Sb2O3. Flame retarding property of all the filled vulcanizates was monitored by limiting oxygen index (LOI) test and some tensile properties viz., 200, 300 % modulus, tensile strength and elongation at break are measured to study the effect of RPP on physico-mechanical properties of vulcanizates. In a preliminary study LOI value was found to increase by ~17 and ~12 % for CR and NR respectively in the formulations containing RPP in comparison with that of the control without Sb2O3. The flame retarding property of RPP was justified with TGA and DSC results. No significant change of the tensile properties was observed on incorporation of RPP in the formulations.

Iodoform‐mediated free radical emulsion polymerization of chloroprene

AbstractThe free radical emulsion polymerization of chloroprene (CP) is carried out at 9°C using different amounts of iodoform as the chain transfer agent. The molecular weight of polychloroprene (PCP) can be regulated effectively by CHI3. PCP suitable for use as an adhesive is obtained with 0.22–0.28 wt % CHI3 and reaches even higher monomer conversion than when mercaptan is used as the chain transfer agent. The emulsion polymerization of CP with high amounts of CHI3 (1.0–3.0 wt %) proceeds in a living polymerization manner. The molecular weight increases in proportion to the monomer conversion in the range of the whole polymerization process even up to very high monomer conversion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Controlled radical polymerization of conjugated 1,3-dienes with methyl 1,3-butadiene-1-phosphonate

Preparation of new tailor-made phosphorus-containing polydiene materials via controlled radical copolymerization of dimethyl 1,3-butadiene-1-phosphonate (BPMe) with chloroprene (CP) or isoprene (IP), by using, respectively, AIBN or an alkoxyamine derivative as initiator, is reported. The corresponding materials have been microstructurally characterized by 1H and 31P NMR spectroscopies.

Mechanical properties of swelled vulcanizates of polar diene elastomers

AbstractRubber elements, which usually form a major part of different isolators of vibrations, are generally easily swelled by oils, greases, or fuels. This leads to meaningful changes of their mechanical characteristics and shortening of durability of rubber components in service. The influence of the semisynthetic motor oil on mechanical and, particularly, dynamic properties of swelled vulcanizates of the polar diene rubber, chloroprene (CR) and acrylonitrile‐butadiene (NBR), is estimated in this article. These elastomers, as is widely known, are resistant to the mineral oils absorption. However, our investigations showed that even a small degree of swelling of the vulcanizates causes decrease of their mechanical properties and considerable changes of the dynamic characteristics of the samples. The obtained results have shown the need to take into account the environment in which isolators of vibrations and dampers have worked, while designing the suitable composition of rubber compounds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

Compósitos de borracha natural ou policloropreno e celulose II: influência do tamanho de partícula

O objetivo deste trabalho foi o desenvolvimento de compósitos claros com propriedades de interesse tecnológico utilizando elastômeros com diferentes polaridades. Para que este objetivo fosse atingido, celulose II em pó foi usada como carga, em borracha natural (NR) ou policloropreno (CR). A celulose II foi obtida por coagulação da solução de xantato de celulose em meio ácido, sob agitação constante e à temperatura ambiente, constituindo uma nova forma de obtenção deste tipo de carga. Compósitos com 10 phr de celulose II com NR e CR, respectivamente, foram desenvolvidos tendo como variável o tamanho de partícula da carga. As propriedades mecânicas e os aspectos microscópicos dos diferentes compósitos foram avaliados e comparados com aqueles das formulações sem carga. Os resultados permitiram identificar o compósito como o de melhor resultado, influenciado pela polaridade da matriz elastomérica e pelo tamanho de partícula da carga, conseqüência das condições de moagem usadas.

Relative reactivity of chloroprene and methyl methacrylate toward initiator radicals

The relative rates of addition of chloroprene (CP) and methyl methacrylate (MMA) toward small model radicals structurally similar to the poly(MMA), poly(methacrylonitrile) and poly(styrene) radical was investigated following the method of Bevington and Huckerby [J Polym Sci Polym Chem 20 (1982) 2655]. Results indicate that these small radicals are significantly more selective toward CP than the corresponding polymer radicals, consistent with earlier reports that penultimate unit effects may be important in the copolymerisation of CP with MMA and styrene. As previous investigations of substituted dienes by the end-group method have given similar results for polymer radicals and small model radicals, this may constitute evidence for a penultimate unit effect that is predominantly electronic rather than steric in origin.

Point mutations of K- ras and H- ras genes in forestomach neoplasms from control B6C3F1 mice and following exposure to 1,3-butadiene, isoprene or chloroprene for up to 2-years

1,3 Butadiene (BD), isoprene (IP) and chloroprene (CP) are structural analogs. There were significantly increased incidences of forestomach neoplasms in B6C3F1 mice exposed to BD, IP or CP by inhalation for up to 2-years. The present study was designed to characterize genetic alterations in K- and H- ras proto-oncogenes in a total of 52 spontaneous and chemically induced forestomach neoplasms. ras mutations were identified by restriction fragment length polymorphism, single strand conformational polymorphism analysis, and cycle sequencing of PCR-amplified DNA isolated from paraffin-embedded forestomach neoplasms. A higher frequency of K- and H- ras mutations was identified in BD-, IP- and CP-induced forestomach neoplasms (83, 70 and 57%, respectively, or combined 31/41, 76%) when compared to spontaneous forestomach neoplasms (4/11, 36%). Also a high frequency of H- ras codon 61 CAA→CTA transversions (10/41, 24%) was detected in chemically induced forestomach neoplasms, but none were present in the spontaneous forestomach neoplasms examined. Furthermore, an increased frequency (treated 13/41, 32% versus untreated 1/11, 9%) of GGC→CGC transversion at K- ras codon 13 was seen in BD-, and IP-induced forestomach neoplasms, similar to the predominant K- ras mutation pattern observed in BD-induced mouse lung neoplasms. These data suggest that the epoxide intermediates of the structurally related chemicals (BD, IP, and CP) may cause DNA damage in K- ras and H- ras proto-oncogenes of B6C3F1 mice following inhalation exposure and that mutational activation of these genes may be critical events in the pathogenesis of forestomach neoplasms induced in the B6C3F1 mouse.

The Influence of Interphase Condition on Mechanical Properties of Short-Fiber Reinforced Rubber

The mechanical and curing properties of short nylon66 fiber reinforced Chloroprene rubber have been investigated as functions of interphase conditions and fiber content. The tensile strength exhibits a dilution effect at a low fiber content in each interphase. It is found that the interphase conditions have an important affect on the dilution ratio and critical fiber content. Double coatings of bonding agent 402 and rubber solution become the best interphase model in this study. The yield strength, tensile modulus, tear strength and fracture toughness at rupture, Jr are significantly improved due to fiber concentration

Synthesis of chloroprene and α-cyanoethyl acrylate copolymer and its characterization

The radical copolymerizations of chloroprene (CP) and α-cyanoethyl acrylate (CEA) were carried out in toluene at 45°C in moisture free atmosphere by use of dry nitrogen. Microstructures in the copolymers have been examined by 1H and 13C nuclear magnetic resonance and Fourier transform infra-red spectroscopy. They showed that the copolymer, whose composition ratio was nearly CP/CEA = 1/1 (mol), possessed predominantly-(CP-CEA)-repeating unit in which CP had the 1,4 unit. A reaction mechanism by way of Diels-Alder intermediate was discussed for this regular copolymerization. © 1997 Elsevier Science Ltd.