An effect of OMMT on the anti‐reversion in NR/CR blend system

The influence of dispersed organomodified montmorillonite (OMMT) on curing behaviors of natural rubber (NR)/chloroprene rubber (CR) blend was investigated. The preparing procedure includes premixed rubber individually with its additives and then the two components were blended according to gum weight ratio for NR to CR is 75/25. Sulfur was chosen as the vulcanizing agent, and the research on vulcanization was carried through the rotor‐Rheometer at 143°C. Transmission electron microscopy showed the dispersion of OMMT in the rubber blends and detected little OMMT migrated into the NR phase. The scorch time (t₁₀), optimum vulcanizing time (t₉₀), and reversion phenomenon were both measured by the curing curve; meanwhile, the crosslinking densities and mechanical properties were determined through equilibrium swelling‐method, magnetic resonance crosslink density spectrometer, and tensile tests. By comparing the test results, an interesting phenomenon was discovered and furthermore was verified that the addition of OMMT can obviously modify the reversion resistance of the binary blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The influence of montmorillonite on the anti‐reversion in the rubber–clay composites

The influence of organically modified montmorillonate (OMMT) on the curing reversion of natural rubber (NR) and polychloroprene rubber (CR) blend has been demonstrated in this article. Characteristics of the NR/CR/OMMT hybrid composite were undertaken by combining the cure kinetics, thermal stability, and the detection of phase morphology. Compared to the neat rubber blend, thermal gravity analysis has shown improved thermal stability results during degradation for the nanofiller filled ones. Differential scanning calorimetry study has offered cure kinetic results; among which blending with NR has lifted the cure activation temperature of CR low toward. Meanwhile, transmission electron microscopy has shown the intercalation and immobilization of OMMT in the CR phase formed a barrier to NR phase. In addition, to discover the reversion source, infrared spectroscopy has been applied to trace the oxygenic function units in the neat NR vulcanizate. All of the experimental results and related analysis has offered us the base to explain the improvement of the anti‐reversion of the rubber blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A comparison of the properties of rice husk ash,silica, and calcium carbonate filled 75 : 25 NR/EPDM blends

The effects of incorporation of three different fillers, i.e., rice husk ash (RHA), silica, and calcium carbonate (CaCO₃), over a loading range of 0–60 phr on the curing characteristics, processability, mechanical properties, and morphology of 75 : 25 natural rubber (NR)/ethylene‐propylene‐diene monomer (EPDM) blends were studied using a conventional vulcanization system. Filler loading and type influence the processability of the blends in which RHA and CaCO₃ offer better processing advantage over silica. The best improvement in the tensile and tear strength and abrasion resistance of the 75 : 25 NR/EPDM blends with additional fillers was achieved when filled with silica. However, RHA and CaCO₃ were better in resilience property compared to that of silica. The RHA filled blends showed higher failure properties and abrasion resistance but lower ozone resistance than that containing CaCO₃. Scanning electron micrographs revealed that the morphology of the blend filled with silica is finer and more homogenous compared to the blend filled with RHA and CaCO₃. According to these observations, RHA can be used as a cheaper filler to replace CaCO₃ in rubber blends where improved mechanical properties are not so critical. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study on the milling behavior of chloroprene rubber blends with ethylene–propylene–diene monomer rubber,polybutadiene rubber,and natural rubber

The viscoelastic properties of the blends of chloroprene rubber (CR) with ethylene–propylene–diene monomer rubber (EPDM), polybutadiene rubber (BR), and natural rubber (NR) at different temperature were studied using rubber processing analyzer (RPA). Mooney viscosities of compounds were measured and tight milling and sheeting appearance were observed on a two‐roll mill. The results showed that Mooney viscosities and the elastic modulus of the blends decreased with the increase of the temperature from 60 to 100°C. And the decreasing trends of pure CR, pure NR, and CR/NR blend compounds were more prominent than that of pure EPDM, pure BR, CR/EPDM, and CR/BR blend compounds. For CR/EPDM blend compounds, the decreasing trend became slower with the increase of EPDM ratio in the blend. Compared with pure CR, pure NR and CR/NR blend compounds, pure EPDM, pure BR compounds, and the blend compounds of CR/EPDM and CR/BR showed less sensibility to temperature and they were less sticky to the metal surface of rolls and could be kept in elastic state at higher temperature, easy to be milled up and sheeted. At the same blend ratio and temperature, the property of tight milling of the blends decreased in the sequence of CR/EPDM, CR/BR, and CR/NR. With the increase of EPDM, BR, or NR ratio in CR blends, its property of tight milling was improved. POLYM. COMPOS., 28:667–673, 2007. © 2007 Society of Plastics Engineers     

Effect of fillers on morphological properties in NR/SBR blends for OTR tyres

Abstract

The blends of styrene butadiene rubber (SBR) and natural rubber (NR) are prepared using a two-roll mixing mill in the presence of different types of carbon blacks as reinforcing filler. The effects of fillers on cure characteristics and thermal, dynamic–mechanical, morphological properties of the blends are studied. The ISAF N231 type of carbon black shows a significant effect on tensile, tear and modulus properties by reacting at the interface between SBR/NR matrixes. The dynamic characteristics and storage modulus of SBR/NR with SAF N110 and SRF N774 types of carbon black show distinct characteristics in respect to all other blends in this system. The thermal stability of the rubber vulcanizates containing SAF N110 and SRF N774 types of carbon blacks is higher than other blend types. With the increasing percentage of SBR to NR, the thermal stability of the blend is increased. However, the heat buildup of the blends increases with the increase in SBR percentage.     

Thermal,morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) blends

The effect of the blend ratio on the thermal, morphological, and physicomechanical properties of (chlorinated polyethylene rubber)/(chloroprene rubber) (CPE/CR) blends was studied. Two distinct glass transition temperatures (T_g) of all blends were observed in differential scanning calorimetry curves, falling between the T_g of the two pure rubbers. Analysis of the blends by scanning electron microscopy showed both dispersed and continuous phase morphology that depended on the blend composition. Thermogravimetric analysis showed that all the compounds underwent two stages of thermal degradation. The Mooney viscosity and optimum cure times increased with the increase in CPE contents, whereas the scorch times decreased. The tensile strength and elongation at break decreased, whereas the 100% modulus, hardness, and compression set increased with the increase of CPE content; the tear strength had the lowest value for the 50/50 CPE/CR blend because of the poor miscibility. The results from thermal aging and oil resistance tests showed that pure CPE possessed better thermal aging property and oil resistance than those of pure CR. Thus, considerable improvement in oil resistance of the blend compounds was achieved with the increase of CPE content. J. VINYL ADDIT. TECHNOL., 21:18–23, 2015. © 2014 Society of Plastics Engineers     

Study on Tensile,Electrical, and Thermal Properties of Aluminium Particle Filled Natural Rubber (NR) and Ethylene-Propylene-Diene Terpolymer (EPDM) Composites

Comparative studies on the effect of aluminium particles in natural rubber (NR) and ethylene-propylene-diene terpolymer (EPDM) were conducted. The incorporation of aluminium particles in NR or EPDM composites increased the cure time, t ₉₀, and scorch time, t _S2 . At a fixed filler loading, EPDM composites exhibited longer t ₉₀ and t _S2 than NR composites. The results also indicate that the maximum torque, M _H of aluminium filled NR and EPDM composites increase with increasing filler loading. For tensile properties, EPDM composites show lower tensile properties than NR composites. Thermogravimetric analysis (TGA) results show that aluminium filled EPDM composites have better thermal stability than aluminium filled NR composites.

The results for electrical properties indicate that the electrical properties of aluminium filled NR and EPDM composites increase with increase in filler loading.     

轮胎胎面用新型橡胶的硫化特性研究

采用LH-Ⅱ硫化仪,研究了具有不同微观结构的轮胎胎面用国产乳聚SBR、BR、日本生产的八种牌号的溶聚SBR和乙烯基PBd及其与NR并用胶的硫化特性。结果表明,乙烯基含量越高,胶料的t_(90)越长,硫化返原性越好,而苯乙烯含量和顺、反式结构的影响较小。对于具有良好抗返原性的BR 1245和溶聚SBR SL 557,当它们与NR并用后,其并用胶抗返原性的改善程度较预计的大。返原性参数R值越小,胶料的抗返原性越好,R=(M_(max)-M_t)/M_(max)。BR1245的300％定伸应力随着硫化温度的提高和硫化时间的延长而明显增加。     

Research on Payne effect of natural rubber reinforced by graft‐modified silica

Silica (SiO₂) modified by in situ solid‐phase grafting was used for natural rubber (NR) reinforcement. The physical mechanical properties and Payne effect of natural rubber reinforced by SiO₂ and graft‐modified silica (G‐SiO₂) were analyzed systematically. The results showed the comprehensive performance of NR/G‐SiO₂ was better than that of NR/SiO₂. There was a proportional relationship between the filler loading and Payne effect. NR/G‐SiO₂ presented weaker Payne effect in comparison with NR/SiO₂. A qualitative analysis on the correlation of filler 3D network structure and filler loading was carried out according to the relationship between the bound rubber content and the shear modulus. The Payne effect mechanisms of rubber compounds differed according to the different filler loading. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43891.     

Studies on xanthate/dithiocarbamate accelerator combination in NR/BR blends

Zinc butyl xanthate [Zn(bxt)₂] was prepared in the laboratory. The effect of this xanthate with zinc diethyl dithiocarbamate (ZDC) on the vulcanization of natural rubber (NR), polybutadiene rubber (BR), and NR/BR blend has been studied at different temperatures. The amounts of Zn (bxt)₂ and ZDC in the compounds were optimized by varying the amount of ZDC from 0.75 to 1.5 phr and Zn (bxt)₂ from 0.75 to 1.5 phr. The cure characteristics were also studied. HAF filled NR, BR, and NR/BR blend compounds were cured at different temperatures from 60 to 150°C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density and elongation at break, compression set, abrasion resistance, etc. were evaluated. The results show that the mechanical properties of 80NR/20BR blends are closer to that of NR vulcanizates, properties of 60NR/40BR blends are closer to BR vulcanizates, while the 70NR/30BR blends show an intermediate property. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3516–3520, 2007     

Interaction of silica and carbon black fillers with natural rubber/poly(ethylene‐co‐vinyl acetate) matrix by swelling studies

The interaction of a black filler and a white filler, which are extensively used in the rubber industry, with natural rubber/poly (ethylene‐co‐vinyl acetate) (NR/EVA) blends vulcanized by DCP has been examined by equilibrium swelling technique. Blends loaded with intermediate super abrasion furnace black (ISAF) and those with silica (SiO₂), of same loading, have been used. The silica incorporated blends sorbed a higher amount of aromatic solvents, compared with the ISAF filled blends, when NR was the continuous phase. However, the silica filled systems showed lower sorption characteristics when EVA became the continuous phase. This has been explained in terms of the differences in the interaction between the filler particles and the blend components. The swelling coefficient, diffusion coefficient, and molar mass between crosslinks have been computed to complement the experimental observations. POLYM. COMPOS., 28:705–712, 2007. © 2007 Society of Plastics Engineers     

Bentonite as a reinforcing and compatibilizing filler for natural rubber and polystyrene blends in latex stage

Bentonite clay was used as a reinforcing and compatibilizing filler for natural rubber/polystyrene (NR/PS) blend via latex blending process. The reinforcing and compatibilizing performance of bentonite clay in the NR/PS blends were evaluated. The improvement of the mechanical properties of NR/PS blends with the weight ratios of 90/10, 80/20, and 70/30 was found with the addition of 3 and 5 parts per hundred rubber (phr) clay. The characterization by using Fourier transform infrared spectroscopy and X‐ray diffraction (XRD) gave the evidence that the silicate layer was intercalated by NR and PS molecular chains. The morphology of tensile fracture surface by scanning electron microscope showed the separated phase boundaries of PS and NR blend and gradual disappearance with the bentonite content. This could be implied that the bentonite contributes to the compatibilization between PS and NR. The compatibilization action of the bentonite clay was also reflected by the shift of glass transition temperature (T_g) of NR to higher temperatures than those of the blends. These results suggested that the tensile and tear properties of the blends were controlled by compatibility between NR and PS. The most enhanced properties of blends were found with the addition of 3 phr bentonite clay. POLYM. ENG. SCI., 54:1436–1443, 2014. © 2013 Society of Plastics Engineers     

Effect of filler loading on cure time and swelling behaviour of SMR L/ENR 25 and SMR L/SBR blends

The effect of filler loading on the cure time (t₉₀) and swelling behaviour of SMR L/ENR 25 and SMR L/SBR blends has been studied. Carbon black (N330), silica (Vulcasil C) and calcium carbonate were used as fillers and the loading range was from 0 to 40 phr. Results show that for SMR L/ENR 25 blends the cure time decreases with increasing carbon black loading, whereas silica shows an increasing trend, and calcium carbonate does not show significant changes. For SMR L/SBR blends, the cure time of carbon black, silica and calcium carbonate generally decreases with increasing filler loading. The percentage swelling in toluene and ASTM oil no 3 decreases for both blends with increasing filler loading, with calcium carbonate giving the highest value, followed by silica‐ and carbon black‐filled blends. At a fixed filler loading, SMR L/ENR 25 blend shows a lower percentage swelling than SMR L/SBR blends. © 2003 Society of Chemical Industry     

A study about the structure of vulcanized natural rubber/styrene butadiene rubber blends and the glass transition behavior

A study of the thermal behavior of cured elastomeric blends of natural rubber (NR) and styrene butadiene rubber (SBR) prepared by solution blending in toluene is presented. Binary blends with different compositions of NR/SBR were produced using a conventional cure system based on sulfur and TBBS (n-t-butyl-2-benzothiazole sulfonamide as accelerator. The compounds were vulcanized at 433 K up to an optimum time of cure determined by rheometric tests. From swelling tests, the crosslink densities of the compounds were obtained and compared with those obtained in similar blends prepared by mechanical mixing. The results were analyzed in terms of the disentangling of the chain structures of the SBR and NR phases and the achieved cure state of the blend. Using differential scanning calorimetry, the glass transition temperature T_g of each blend was measured. In most compounds, the value of T_g corresponding to each phase of the blend was determined, but in some blends a single value of T_g was obtained. The variation of T_g with the composition and cure level in each phase was analyzed. On the other hand, a physical mixture of two equal parts of NR and SBR vulcanized was measured and the results were compared to those of the NR50/SBR50 cured blend. Besides, to analyze the influence of the network structure, pure NR and SBR unvulcanized samples were measured. On the basis of all the obtained results, the influence of the interphase formed in the blend between SBR and NR phases is discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of ultrasonically aided extrusion of NR/BR blends on structure and properties of silica‐filled compounds and vulcanizates

Ultrasonic extrusion of NR/BR blends at amplitudes up to 7.5 μm was carried out. Silica or silica/silane at loading of 60 phr was incorporated into blends to prepare compounds and vulcanizates. Effect of ultrasound on molecular structure of rubber blends, rubber–filler interaction of compounds and crosslinking structure of vulcanizates was studied. No gel was generated in NR/BR blends upon ultrasonic treatment, while earlier studies on treatment of BR alone have shown generation of gel. This finding provides means to significantly improve filler dispersion and minimize deterioration of vulcanizate properties. Processing‐structure‐properties relationship was established. Die pressure and ultrasonic power consumption were recorded. Imposition of ultrasound reduced die pressure providing potentials to increase extrusion output. No polymer degradation observed during treatment at amplitudes of 3.5 and 5 μm. A slight degradation was found at 7.5 μm leading to a decrease of storage and loss moduli of the blend, and an increase of loss tangent. Treated blends compounded with silica showed more bound rubber content, better rubber–filler interaction, reduced filler–filler interaction and less flocculation. M100 and tensile strength of NR/BR/Silica 5 μm vulcanizate was increased. In contrast, ultrasonic treatment showed little effect on NR/BR/Silica/Silane blends. The predictions related to tire performance was discussed. POLYM. ENG. SCI., 59:E261–E270, 2019. © 2018 Society of Plastics Engineers     

Reclaiming of rubber by a renewable resource material (RRM). III. evaluation of properties of NR reclaim

Sulfur‐cured filled natural rubber (NR) is successfully reclaimed by using a renewable resource material (RRM) and diallyl disulfide (DADS), which is the major constituent of RRM. Reclaiming of NR vulcanizate was carried out at 60°C for 35 min in an open two‐roll mixing mill. Evaluation of the properties of NR reclaim was carried out by mixing it with virgin rubber in various proportions. The cure characteristics and mechanical properties of the virgin NR/ reclaim NR blend were studied. With increase in the proportion of reclaim rubber (RR) in virgin NR/ reclaim NR blend scorch time and optimum cure time decrease. To increase scorch time N‐cyclohexylthiophthalimide as prevulcanization inhibitor (PVI) was added in NR/RR (50/50) blend. It was found that use of 40% NR reclaim with virgin rubber resulted 83% retention of tensile strength of that of the virgin NR vulcanizate. Effect of carbon black loading was studied in NR/RR (50/50) blends. Tensile properties and swelling value of different NR/RR blends were evaluated before and after aging. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1493–1502, 2000     

Influence of incorporation methods of ATH on microstructure,elastomeric properties,flammability, and thermal decomposition of dynamically vulcanized NR/PP blends

Flame‐retardant thermoplastic vulcanizates (TPVs) of natural rubber (NR)/polypropylene (PP) (60/40 wt %) blends filled with alumina trihydrate (ATH) were prepared with an internal mixer. To increase the properties of flame‐retardant NR/PP TPV, the new mixing method, stepwise masterbatch mixing (SMB) method was adopted. The effects of SMB method along with different ATH loadings on microstructure and properties of NR/PP TPVs were investigated. Conventional one‐step mixing (CV) method was also studied for comparison. Transmission electron microscopy analysis showed that different processes led to a variation in microstructural homogeneity, which imposed various effects on blend properties. The mechanical properties of TPVs changed with ATH loading, and the strength of the samples obtained from SMB method was higher than those of CV method. LOI and cone calorimetry tests revealed that the flame retardancy of NR/PP blends dramatically increased at higher ATH loading. Furthermore, the increment level of flame retardancy was accelerated in the blends produced particularly through SMB method, resulting from homogeneity of local ATH distribution in NR/PP blend. Greater combustion resistance of blends prepared from SMB route were confirmed by thermogravimetry and pyrolysis‐gas chromatography–mass spectrometry techniques. Finally, a burning mechanism between filler structure and flammability of NR/PP TPVs obtained from CV and SMB methods was discussed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46231.     

Autoclaved aerated concrete waste (AACW): An alternative filler material for the natural rubber industry

Material waste from the production of autoclaved aerated concrete, a porous material, should be considered as a valuable byproduct for use as a filler material for the rubber industry. Natural rubber (NR) composites filled with different loading (over the range of 0–60 phr) of autoclaved aerated concrete waste (AACW) as a new eco‐friendly material were produced using two roll mills and then were studied for their cure characteristics, mechanical and aging properties, and morphology, and also compared with commercial fillers, calcium carbonate (CaCO₃), and silica (SiO₂). In most cases, the cure characteristics and mechanical and aging properties of the SiO₂‐filled NR composites were significantly better than those of the AACW‐ and CaCO₃‐filled NR composites. However, these properties for AACW‐filled composites appeared to be higher than CaCO₃‐filled composites. The reason for this could be due to a larger surface area which is both porous and of an irregular shape of the AACW filler used. Scanning electron microscope images showed that the morphology of the rubber filled with SiO₂ was finer and more homogenous compared with the rubber filled with AACW or CaCO₃. Overall results revealed that the reinforcement ability of AACW‐filled NR composites was generally better when compared with CaCO₃‐filled NR composites; therefore, AACW can be used effectively as a cheaper filler for production of rubber products where end‐use properties of a rubber product is specifically required. POLYM. COMPOS., 36:2030–2041, 2015. © 2014 Society of Plastics Engineer     

Effect of surface modification of silicon carbide nanoparticles on the properties of nanocomposites based on epoxidized natural rubber/natural rubber blends

Improvement of the properties of rubber nanocomposites is a challenge for the rubber industry because of the need for higher performance materials. Addition of a nanometer‐sized filler such as silicon carbide (SiC) to enhance the mechanical properties of rubber nanocomposites has rarely been attempted. The main problem associated with using SiC nanoparticles as a reinforcing natural rubber (NR) filler compound is poor dispersion of SiC in the NR matrix because of their incompatibility. To solve this problem, rubber nanocomposites were prepared with SiC that had undergone surface modification with azobisisobutyronitrile (AIBN) and used as a filler in blends of epoxidized natural rubber (ENR) and natural rubber. The effect of surface modification and ENR content on the curing characteristics, dynamic mechanical properties, morphology and heat buildup of the blends were investigated. The results showed that modification of SiC with AIBN resulted in successful bonding to the surface of SiC. It was found that modified SiC nanoparticles were well dispersed in the ENR/NR matrix, leading to good filler‐rubber interaction and improved compatibility between the rubber and filler in comparison with unmodified SiC. The mechanical properties and heat buildup when modified SiC was used as filled in ENR/NR blends were improved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45289.     

Effect of carbon black loading on curing characteristics and mechanical properties of waste tyre dust/carbon black hybrid filler filled natural rubber compounds

Curing characteristics, tensile properties, fatigue life, swelling behavior, and morphology of waste tire dust (WTD)/carbon black (CB) hybrid filler filled natural rubber (NR) compounds were studied. The WTD/CB hybrid filler filled NR compounds were compounded at 30 phr hybrid filler loading with increasing partial replacement of CB at 0, 10, 15, 20, and 30 phr. The curing characteristics such as scorch time, t₂ and cure time, t₉₀ decreased and increased with increment of CB loading in hybrid filler (30 phr content), respectively. Whereas maximum torque (M_HR) and minimum torque (M_L) increased with increasing CB loading. The tensile properties such as tensile strength, elongation at break, and tensile modulus of WTD/CB hybrid filler filled NR compounds showed steady increment as CB loading increased. The fatigue test showed that fatigue life increased with increment of CB loading. Rubber–filler interaction, Q_f/Q_g indicated that the NR compounds with the highest CB loading exhibited the highest rubber–filler interactions. Scanning electron microscopy (SEM) micrographs of tensile and fatigue fractured surfaces and rubber–filler interaction study supported the observed result on tensile properties and fatigue life. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011