Effect of butyl rubber type on properties of polyamide and butyl rubber blends

Polyamide‐12 was blended with butyl rubber, bromobutyl rubber, and chlorobutyl rubber with and without a sulfur curing system. Mechanical properties for dynamically vulcanized blends generally exceed those made with no vulcanization. Chlorobutyl‐containing blends prepared by dynamic vulcanization have higher tensile strength and elongation at break values in comparison to those made from other butyl rubbers. For a variety of polyamide/rubber blends made by dynamic vulcanization, there is very little effect of rubber percentage unsaturation and Mooney viscosity on the mechanical properties of the blends. In chlorobutyl‐containing blends prepared by dynamic vulcanization, the swelling index values attributed to the rubber portion decrease as rubber content decreases, and it is likely that the polyamide phase completely surrounds the rubber particles at compositions exceeding approximately 25% polyamide. Swelling index results can be correlated with elongation at break values for similar blends. The results of differential scanning calorimetry suggest that the polyamide phase is not a neutral component in high shear mixing with butyl rubbers with or without curing agents. Rheological studies indicate strong non‐Newtonian behavior for all blends of polyamide‐12 with butyl rubbers. Scanning electron microscopy on polyamide‐12/butyl rubber blends indicates compatibility for butyl rubbers in the order of chlorobutyl > bromobutyl > butyl rubber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1423–1435, 2004     

New smart conducting elastomer blends of Bi‐based superconductor ceramics nanoparticles reinforced natural rubber/low‐density polyethylene for double thermistors,antistatic protectors,and electromagnetic interference shielding effectiveness applications

A new conducting blend from natural rubber (NR), low‐density polyethylene (PE), and Bi‐based superconductor (BSCCO) nanoparticles was successfully formulated. Blends were prepared by means of an open two‐roll mill for five ratios (100/0, 90/10, 80/20, 70/30, and 60/40 NR/LDPE). The microstructures of the blends were examined in terms of scanning electron microscopy (SEM), bound rubber (BR), cross‐linking density (CLD), and Mooney viscosity (M₁₀₀). The mechanical properties like hardness (H) shore A, tensile strength (TS), and elongation at break (EB) of the blends were studied. The applicability of the blends as double thermistors, i.e., positive and negative coefficient of resistivity (PTCR/NTCR), was examined. The applicability of the blend for antistatic charge dissipation was also tested. Finally, electromagnetic interference response of conducting NR/PE‐filled BSCCO in the frequency range 1–12 GHz has been studied. Shielding effectiveness of the conducting blends in the microwave range 8–12 GHz shows an attenuation of 44–60 dB for PE ≤10 wt%. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Characterization and properties of LDPE/(ground tire rubber)/crosslinked butyl rubber blends

In recent years, interest in used rubber recycling, mainly focusing on the utilization of end‐of‐life tires, has heightened. This interest, is owing to the activities related to environmental protection and economic factors, which both stimulate companies to reuse the high‐quality rubber present in ground rubber scrap. In this study, the application of crosslinked butyl rubber in thermoplastic compositions of low‐density polyethylene and ground tire rubber (GTR) is presented. The static and dynamic mechanical properties and morphology of obtained products were studied. The addition of crosslinked butyl rubber to the investigated blends increased the compatibility between the low‐density polyethylene and the GTR particles. It was found that the mechanical properties of thermoplastic compositions containing higher amounts of elastomers (i.e., GTR and crosslinked butyl elastomer) displayed the same behavior, whereas the samples with GTR had worse respective parameters. Depending on their composition, the obtained new polymer blends can be applied to automotive parts, be adapted to pavement surfaces, and become parts of antivibration systems. J. VINYL ADDIT. TECHNOL., 20:237–242, 2014. © 2014 Society of Plastics Engineers     

Dynamic vulcanization of polyethylene‐based thermoplastic elastomer blends

In this investigation, the effects of blending with ethylene–propylene–diene terpolymer and subsequent dynamic curing with sulfur on the macromolecular structure and properties of pure low‐density polyethylene and high‐density polyethylene were studied. The crosslinking efficiency of polyethylene‐based ethylene–propylene–diene terpolymer blends upon dynamic curing was assessed with torque and gel content measurements. The curing of dispersed ethylene–propylene–diene terpolymer in a polyethylene matrix improved both the mechanical and thermomechanical properties as a result of the formation of a crosslink structure in the rubber phase. In view of the electrical applications of this cured blend material, the volume resistivity was measured. The thermal stability of vulcanized polyethylene/ethylene–propylene–diene terpolymer blends was found to be superior to that of unvulcanized blends. In scanning electron microscopy analysis, good interface bonding between the polyethylene matrix and dispersed ethylene–propylene–diene terpolymer was observed for the cured blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Failure properties of thermoplastic elastomers from polyethylene/nitrile rubber blends: Effect of blend ratio,dynamic vulcanization,and filler incorporation

Thermoplastic elastomers from blends of high‐density polyethylene and acrylonitrile butadiene rubber were prepared by a melt‐blending technique. The blends were dynamically vulcanized using sulfur, peroxide, and mixed curing systems. The peroxide concentration was varied to obtain samples of varying degrees of crosslinking. The peroxide system showed better mechanical properties. The crosslink density determination by the equilibrium swelling method revealed that the enhancement in properties can be correlated to the extent of crosslinking. It is observed that the effect of dynamic vulcanization on the property improvement is much more pronounced in rubber‐rich blends. To study the effect of filler incorporation on mechanical properties, fillers such as carbon black, silica, silane‐treated silica, and cork‐filled samples were prepared. All filled systems, except cork filled, exhibited superior mechanical properties. Scanning electron micrographs of selected fractured surfaces were analyzed to study the failure mechanism of the different compositions. Various theoretical models were applied to correlate the observed mechanical behavior with that of theoretically predicted values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2912–2929, 2006     

Dynamic vulcanization of recycled milk pouches (LDPE–LLDPE) and EPDM blends using dicumyl peroxide

The viability of thermomechanical recycling of post‐consumer milk pouches (blend of low‐density polyethylene (LDPE) and linear low‐density polyethylene (LLDPE)) and its scope for suitable engineering applications were investigated. The effects of blending with ethylene‐propylene‐diene monomer (EPDM) rubber and subsequent curing using dicumyl peroxide (DCP) on the macromolecular structure and properties of recycled polyethylene (PE) blends were studied. The crosslinking efficiency of recycled PE/EPDM blends and possible thermooxidative degradation of recycled polymer upon peroxide curing was assessed using torque and gel content measurements along with infrared spectroscopic analysis. Both the torque and gel content of the blends varied with DCP crosslinking reactions and also were affected by oxidative degradation. In view of the electrical application area of this recycled blend material, the dielectric breakdown strength and volume resistivity were measured. The mechanical performance and thermal stability of recycled PE/EPDM blends improved with progressive crosslinking by DCP but deteriorated somewhat at higher DCP dose. Scanning electron microscopy showed good interface bonding between recycled polymer and dispersed EPDM phase in the cured blends compared to the non‐cured blends. Copyright © 2007 Society of Chemical Industry     

Estimation of permeation rate of chemicals through elastometric materials

Elastometric materials are used as barriers to protect workers against exposure to chemicals. The effectiveness of a polymer as a chemical protective material therefore depends on the rate of the permeation of chemicals through it. The permeation rate depends on the solubility and the diffusion coefficient of chemicals in the materials. The diffusion coefficient itself is a strong function of concentration of the chemicals in the polymeric material. Permeation rates can be measured directly using a permeation cell or they can be calculated from the solubility and the diffusion coefficient data. Sorption/desorption experiments can be used to determine solubility and an expression for the diffusion coefficient in terms of concentration. Experiments were conducted for the sorption and desorption of ethyl acetate in three glove (one butyl and two neoprene materials) and two garment (neoprene and chlorinated polyethylene) materials. The data collected were used to estimate the steady‐state permeation rates of ethyl acetate through the materials. The results of the experiments show that the solubility of ethyl acetate in butyl rubber is 0.795 g/cm³, and the steady‐state permeation rate is 0.32 μg cm⁻² s⁻¹. The solubility of the chemical through the three neoprene materials is in the range of 2.25–5.31 g/cm³, and the steady‐state permeation rates vary from 27 to 43 μg cm⁻² s⁻¹. The solubility of ethyl acetate in the chlorinated polyethylene is 7.14 g/cm³, and the steady‐state permeation rate is 62.43 μg cm⁻² s⁻¹. The experimental method is very simple to use and it requires a small sample of the material (less than 1 cm²) and only a few milliliters of the chemical. Sorption/desorption experiments can also provide information on the amount of additives extracted from an elastomeric material during contact with a chemical. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1265–1272, 2001     

Oil resistant thermoplastic elastomers of nitrile rubber and high density polyethylene blends

Different grades of oil resistant thermoplastic elastomers (TPE) based on blends of nitrile rubber (NBR) and high density polyethylene (HDPE) have been developed. Chemical treatment of HDPE to evolve compatibility with NBR and dynamic vulcanization with different curatives have been studied. Determination of physico‐mechanical and thermal properties and relative crystallinity of these blends have been carried out. Oil resistance characteristics of the blends have been evaluated in different commercially used oils and fuels for applications as a substitute for NBR/polyvinyl chloride (PVC) blends.     

Interfacial adhesion evaluation in (low‐density polyethylene)/elastomer blends

Low‐density polyethylene (LDPE) with different elastomers at a ratio of 50/50 wt% blends was prepared by using a co‐rotating twin‐screw extruder. Three kinds of elastomers were used: ground tire rubber (GTR), partially crosslinked butyl rubber (Kalar^®), and styrene‐butadiene‐rubber block copolymer (SBS; Kraton^®). For better characterization of interaction between polyethylene and elastomer, influence of the type of elastomer on the properties of compositions LDPE/elastomer was determined. In the studies, two types of partially crosslinked butyl rubber (differing over filler content and Mooney viscosity) and two types of SBS (differing over structure: linear/branched) were used. The influence of kind and type of elastomer on static mechanical properties (tensile strength, elongation at break, hardness), dynamic mechanical properties, thermal properties, and morphology of obtained compositions were characterized. LDPE/linear SBS copolymer blend had the best mechanical properties, as a result of better compatibility in comparison with other investigated blends. The reason for improved compatibility was an increase of mobility of chain segments in the amorphous phase of polyethylene associated with their partial plasticization by flexible polybutadiene blocks present in SBS copolymer. J. VINYL ADDIT. TECHNOL., 22:492–500, 2016. © 2015 Society of Plastics Engineers     

Electrical and mechanical behaviors of carbon nanotube‐filled polymer blends

Four carbon nanotube (CNT)‐filled polymer blends, i.e., CNT‐filled polyethylene terephthalate (PET)/polyvinylidene fluoride, PET/nylon 6,6, PET/polypropylene, and PET/high‐density polyethylene blends, have been injection‐molded and characterized in terms of their microstructures, electrical conductivities, and mechanical properties. The distribution of CNTs in the polymer blends has been examined based on their wetting coefficients and minimization of the interfacial energy. The electrical conductivity and mechanical properties have been related to the cocontinuous polymer blends, the conductive path formed by CNTs, the CNT distribution, and the intrinsic properties of the constituent polymers. It is found that to obtain a CNT‐filled polymer composite with both high electrical conductivity and good mechanical properties, it is preferred that most CNTs distribute in one polymer phase, while the other polymer phase(s) remain neat. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 477–488, 2006     

Influences of blend proportions and curing systems on dynamic,mechanical, and morphological properties of dynamically cured epoxidized natural rubber/high‐density polyethylene blends

Thermoplastic elastomers (TPEs) based on dynamically cured epoxidized natural rubber/high‐density polyethylene (ENR/HDPE) blends were prepared. Influence of the process oil, blend proportion, and curing systems were investigated. It was found that the oil‐extended thermoplastic vulcanizates (TPVs) exhibited better elastomeric properties and improved ease of the injection process. Increasing the proportion of ENR caused increasing elastic response of elongation at break, tension set properties, and tan δ. It was also found that the TPV treated with phenolic resin exhibited superior mechanical properties and the smallest vulcanized rubber domains. The TPV treated with the conventional peroxide co‐agent curing system showed superior strength properties but had poor elastomeric properties. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Optimization of accelerators on curing characteristics,tensile, and dynamic mechanical properties of (natural rubber)/(recycled ethylene‐propylene‐diene‐monomer) blends

The migration of sulfur from natural rubber (NR) compound to the ground waste ethylene‐propylene‐diene monomer (EPDM) rubber phase may have caused the cure incompatibility between these two rubbers. Optimization of accelerators had been adopted to overcome the cure incompatibility in NR/(R‐EPDM) blends as well as to get increased curative distribution. In this study, blends of NR and R‐EPDM were prepared. The effect of accelerator type on curing characteristics, tensile properties, and dynamic mechanical properties of 70/30/NR/(R‐EPDM) blend was investigated. Four types of commercial accelerators were selected [ie, N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , N‐cyclohexyl‐benzothiazyl‐sulfenamide (CBS), tetramethylthiuram disulfide, and 2‐mercaptobenzothiazol]. It was found that the tensile strength of the blends cured in the presence of CBS was relatively higher than the other three accelerators. Scanning electron micrographs of CBS‐cured NR/(R‐EPDM) blends exhibited more roughness and cracking path, indicating that higher energy was required toward the fractured surface. The high crosslinking density observed from the swelling method could be verified from the storage modulus (E′) and damping factor (tan δ) where (tetramethylthiuram disulfide)‐cured NR/(R‐EPDM) blends provided a predominant degree of crosslinking followed by N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , CBS, and 2‐mercaptobenzothiazol, respectively. J. VINYL ADDIT. TECHNOL., 21:79–88, 2015. © 2014 Society of Plastics Engineers     

Effect of Crosslinking on the Flow Behavior and Morphology of Crosslinkable Polyethylene and Crosslinked Butyl Rubber Blends

Effects of degree of crosslinking in butyl rubber on the flow behavior and morphology of crosslinkable polyethylene (XLPE) and butyl rubber blends have been studied as a function of shear rate and processing temperature. Viscosity, flow activation energy, and rheological parameters have been studied with reference to the effect of blend compositions. Low-crosslinked butyl rubber showed higher normal stress difference than the highly crosslinked butyl rubber in the blend. As evidenced from extrudate swell, melt compliance, and Reynolds number, phase reversion in low-crosslinked butyl rubber occurred within a narrow composition range whereas in highly crosslinked butyl rubber blends, the change occurred over a wide composition range. Change of phase has also been confirmed by SEM examination. Highly crosslinekd butyl rubber showed higher elastic response than low-crosslinked rubber.     

Study of some properties of waste LDPE/waste butyl rubber blends using different compatibilizing agents and gamma irradiation

Blends of waste low‐density polyethylene with waste butyl rubber of equal quantities containing reactive compatibilizing agents, namely: maliec anhydride; glycidyle methacrylate, divinyl benzene, tetraethyleneglycoldimethacrylate and diethyleneglycoldimethacrylate were preparedand exposed to different γ‐irradiation doses up to 400 kGy. The swelling behavior in organic solvent of the gel and soluble fractions and the degree of crosslinking were investigated. The mechanical properties, namely tensile strength and elongation at break were also studied. Thermal properties using thermo gravimetric analysis and differential scanning calorimetry analysis follow analyses have been followed up to follow the change of the structure for the irradiated and nonradiated blends. Results obtained indicated improvement in physical, mechanical and thermal properties on irradiation of the prepared blends which incorporate compatibilizing agents, but with varying degrees. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

IIR/CIIR共混胶硫化特性的研究

研究了影响丁基橡胶／氯化丁基橡胶(IIR／CIIR)共混胶硫化特性的因素．包括并用比、硫化体系、补强剂和硅炕偶联剂。研究结果表明：随着IIR／CIIR共混胶中CIIR含量的增加，硫化速度加快，是大转矩值减小：用硫磺硫化的共混胶硫化速度比用树脂硫化的快，且共混胶起始转矩值也较高。在选用的几种补强剂中，添加N220补强的共混胶硫化速度较快，T90时间较短，添加活性沉淀白炭黑(WCB)补强的共混胶最大转矩值较高。加入硅烷偶联剂会使共混胶的T90时间延长，最大转矩值变高。     

Non‐isothermal crystallization kinetics and segmental dynamics of high density polyethylene/butyl rubber blends

Non‐isothermal crystallization kinetics and dynamics of polymer blends are important to both theory and applications. In this work, we studied the morphology, crystal structure, non‐isothermal crystallization kinetics and dynamics of high density polyethylene/butyl rubber (HDPE/IIR) blends. The non‐isothermal crystallization kinetics is analyzed by Mo's model and the dynamics behavior is analyzed by a linear method. The results of morphology, non‐isothermal crystallization kinetics and dynamics show that the condensed structure of HDPE/IIR blends has a marked influence on their non‐isothermal crystallization kinetics and segmental dynamics. © 2015 Society of Chemical Industry     

Effect of dicumyl peroxide and phenolic resin as a mixed curing system on the mechanical properties and morphology of TPVs based on HDPE/ground tire rubber

Thermoplastic vulcanizates (TPVs) are a special group of thermoplastic elastomer with the characteristic that consists of rubber elasticity and the processability of thermoplastic polymers. TPVs based on high density polyethylene (HDPE)/ground tire rubber (GTR) with phenolic resin (HY‐2045) and dicumyl peroxide (DCP) as vulcanizing agents are prepared through dynamic vulcanization in this article. The blends consisting of 40/60 HDPE/GTR are melt‐mixed in an internal mixer and then pressed with a compression molding machine. The aim of this experiment is to study the influence of a compound curing agent system on the mechanical properties of the HDPE/GTR composites. The results indicate that the mechanical properties of the HDPE/GTR blends are improved significantly by adding 4 phr HY‐2045 and 0.3 phr DCP than those of TPVs without any vulcanizing agents after dynamic vulcanization. The X‐ray photoelectron spectroscopy study and the FTIR‐ATR analysis confirmed that the crosslinking phenomenon occurred in the preparation of TPVs; and the gel fraction analysis indicates that the GTR components and the HDPE components of the HDPE/GTR blends are all moderately crosslinked. In addition, the morphology of the HDPE/GTR blends has been investigated by scanning electron microscopy. POLYM. COMPOS., 36:1907–1916, 2015. © 2014 Society of Plastics Engineers     

A study of dynamic vulcanization for polyamide‐12 and chlorobutyl rubber

Polyamide‐12 and chlorobutyl rubber were blended by dynamic vulcanization in a high shear environment using curing systems based on sulfur, dithiocarbamate/ZnO, and 4,4‐methylenebiscyclohexylamine/MgO. As expected, all blends with curing agents show increased tensile strength and elongation at break in comparison to blends without curing agents. Maximum mechanical properties are obtained at relatively low levels of curing agent in all systems. Hexane extraction of the mixtures and measurement of percentage of insolubles along with the swelling index of the rubber phase confirm that a high level of cure is achieved at low levels of curing agent. Although the curatives are designed for the rubber phase, differential scanning calorimetry results indicate that both phases are affected during the dynamic vulcanization process, with polyamide‐12 showing a reduced melting temperature that is indicative of molecular weight reduction, structure changes, or reaction with the rubber phase. Scanning electron microscopy results indicate that phase size is reduced with increased blending time and level of curing agent. Rheological studies indicate that blends containing curing agents exhibit non‐Newtonian behavior to a greater extent than polyamide or nonvulcanized polyamide/chlorobutyl rubber blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 871–880, 2003     

A dynamic mechanical and thermal study of various rubber–bitumen blends

Blends of a Nynas 100 penetration‐grade bitumen with a cis‐polybutadiene, a butyl rubber, three polyisobutylenes of different molecular weights, a chlorinated‐polyethylene, polychloroprene in latex form, and a polyurethane rubber (scrap Lycra) were prepared using a Z‐blade masticator mixer at a temperature of about 180°C. The blends contained between 10 and 40 pph (i.e., 9 and 29%) by weight of rubber. They were characterized by fluorescence optical microscopy, differential scanning calorimetry, and dynamic mechanical thermal analysis. The bitumen‐rich phases provided the matrix in most of these systems, polymer‐rich extensive phases being formed with butyl rubber, and low‐ and moderate‐molecular‐weight poly(isobutylenes) when the proportion rose above 30 pph, and for the poly(cis‐butadiene) and chlorinated polyethylene system only when the proportion rose above 40 pph, according to the tan δ plots. Only glass transitions were associated with polymer‐rich phases, and there were some melting transitions from paraffinic wax components ejected from the bitumen‐rich phases. Below room temperature the modulus of blends of polybutadiene, chlorinated polyethylene, and the polyurethane rubber were similar to that of the bitumen; but those of the other polymers were stiffer by a factor of 50, perhaps because of a rearrangement of the asphaltenes. The softer blends, particularly the first two named above, had loss processes (with tan δ > 0.5) ranging over 200°C or more. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 586–601, 2000     

硅橡胶／EPDM／ⅡR共混的研究

研究了硅橡胶/三元乙丙橡胶/丁基橡胶的共混技术与硫化体系。对增容剂、共混比例等对共混胶的力学性能的影响进行了探讨。KH570适宜于作为共混增容剂;共混胶宜于采用DCP硫化,也可以采用硫黄硫化,随着丁基橡胶含量的增加,其力学性能有大幅度提高,并出现最佳值点。