On the potential of organoclay with respect to conventional fillers (carbon black,silica) for epoxidized natural rubber compatibilized natural rubber vulcanizates

Onium modified montmorillonite (organoclay) was compounded with natural rubber (NR) in an internal mixer and cured by using a conventional sulfuric system. Epoxidized natural rubber with 50 mol % epoxidation (ENR 50) in 10 parts per hundred rubber (phr) was used as a compatibilizer in this study. For comparison purposes, two commercial fillers: carbon black (grade N330) and silica (grade vulcasil‐S) were used. Cure characteristics were carried out on a Monsanto MDR2000 Rheometer. Organoclay filled vulcanizate showed the lowest values of torque maximum, torque minimum, scorch, and cure times. The kinetics of cure reaction showed organoclay could behave as a cocuring agent. The mechanical testing of the vulcanizates involved the determination of tensile and tear properties. The improvement of tensile strength, elongation at break, and tear properties in organoclay filled vulcanizate were significantly higher compared to silica and carbon black filled vulcanizates. In terms of reinforcing efficiency (RE), organoclay exhibited the highest stiffness followed by silica and carbon black filled vulcanizates. Scanning electron microscopy revealed that incorporation of various types of fillers has transformed the failure mechanism of the resulting NR vulcanizates compared to the gum vulcanizates. Dynamic mechanical thermal analysis (DMTA) revealed that the stiffness and molecular relaxation of NR vulcanizates are strongly affected by the filler–rubber interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2438–2445, 2004     

Synthesis and aging properties of reactive antioxidant NAPM in natural rubber vulcanizates

The rubber antioxidant N‐(4‐anilinophenyl) methacrylamide (NAPM) was synthesized by a two‐step reaction using thionyl chloride (SOCl₂) with methacrylic acid (MAA) and consequently 4‐aminodiphenylamine (ADPA) as precursors. NAPM was characterized by IR, ¹H NMR and elemental analysis. Thermal stability, aging property of NAPM and mechanical properties of natural rubber (NR) vulcanizates containing NAPM were investigated and compared with two other commercial antioxidants N‐isopropyl‐N′‐phenyl‐p‐phenylene diamide (4010NA) and N‐(1, 3‐dimethyl butyl)—N′‐phenyl‐p‐phenylene diamide (4020). It was found that NAPM was an effective antioxidant with a better thermal stability and higher antiaging resistance than unreactive antioxidants 4010NA and 4020. And unsaturation level of NR vulcanizates containing NAPM was lower than that of 4010NA and 4020. Moreover, an antiaging resistant mechanism of a surface reaction between NAPM and cis‐1, 4‐polyisoprene in NR was proposed to explain the better properties of NAPM based on the IR and SEM analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study of mangosteen (garcinia mangostana) peel powder as antioxidant in natural rubber compound

Mangosteen peel powder (MPP) was used as an antioxidant in natural rubber (standard Malaysian rubber [SMR] L). Natural rubber compounds with various types of antioxidants (i.e., MPP; N‐isopropyl‐N'‐phenyl‐P‐phenylenediamine [IPPD]; 2,2,4‐trimethyl‐1,2‐dihydroquinoline [TMQ], and 2,6‐di‐tert‐butyl‐p‐cresol [BHT]) were prepared. The SMR L compounds were cured at 150°C according to their cure time. Curing characteristics, tensile and aging properties, thermal behavior, and morphological properties of the SMR L compounds were studied. Curing and tensile properties obtained by SMR L compounds with MPP are comparable to SMR L compounds with commercial antioxidants. It was found that the addition of MPP into SMR L compounds improved the aging property of the compound. J. VINYL ADDIT. TECHNOL., 23:86–92, 2017. © 2015 Society of Plastics Engineers     

甲基丙烯酸固态原位接枝改性炭黑对天然橡胶和顺丁橡胶性能的影响

考察了固态原位接枝改性制备的甲基丙烯酸接枝改性炭黑对天然橡胶(NR)和顺丁橡胶。(BR)静态力学性能、动态力学性能的影响。结果表明。甲基丙烯酸改性炭黑比普通商品炭黑填充的NR硫化胶具有更好的静态力学性能;甲基丙烯酸改性炭黑曼有利于降低NR和BR硫化胶的滚动阻力。同时,有利于提高NR硫化胶的抗湿滑性。     

铁系乙烯基丁二烯橡胶/天然橡胶共混物的性能

研究了铁系乙烯基丁二烯橡胶(FVBR)与天然橡胶(NR)以50/50(质量比)共混硫化胶的物理机械性能和黏弹特性,并与溶聚丁苯橡胶(SSBR)与NR共混胶进行了对比。结果表明,FVBR与NR有良好的相容性,共混胶只存在1个玻璃化转变温度。FVBR/NR的混炼行为良好,但必需添加操作油,否则难以获得理想的硫化胶性能。FVBR/NR与SSBR/NR相似,不仅具有良好的拉伸和撕裂性能,而且具有高抗湿滑性;其生热和滚动阻力以及热老化性能优于后者,但耐磨性略逊于SSBR/NR。     

A comparative study of aging characteristics and thermal stability of oil palm ash,silica, and carbon black filled natural rubber vulcanizates

Filler‐filled natural rubber (NR) vulcanizates were prepared by conventional laboratory‐sized two roll mills and cured using sulfuric system. The effect of thermal aging on physical properties and thermogravimetric analysis (TGA) of oil palm ash (OPA) and commercial fillers (i.e., silica vulkasil C and carbon black N330)‐filled NR vulcanizates at respective optimum loading and equal loading were studied. Before aging, the OPA‐filled vulcanizates showed comparable optimum strength as carbon black‐filled vulcanizates. The hardening of aged filler‐filled NR vulcanizates happened after aging, thereby tensile strength and elongation at break reduced while the modulus increased. Fifty phr carbon black‐filled vulcanizates showed better retention in tensile properties as compared to silica (10 phr) and OPA (1 phr). This was attributed to the addition of different filler loading and this finding was further explained when equal loading of filler‐filled vulcanizates was studied. Fourier transform infra‐red analysis showed chemical structure had changed and tensile fractured surface exhibited smooth appearance due to the deterioration in tensile properties after aging. TGA also denoted the thermal stability was depending on the amount of filler loading. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4474–4481, 2013     

Preparation,structural characterization,and antioxidative behavior in natural rubber of antioxidant GM functionalized nanosilica

To restrain the migration and extractability of the antioxidants and improve the dispersion of nanosilica in natural rubber (NR), antioxidant 2‐tert‐butyl‐6‐(3‐tert‐butyl‐2‐hydroxy‐5‐methylbenzyl)‐4‐methyphenyl acrylate (GM) functionalized nanosilica was prepared using antioxidant coupling agent (KH590‐GM) as functional modifier, which was first synthesized through thiol‐ene reaction between the mercapto group of γ‐mercaptopropyl trimethoxysilane (KH590) and the CC double bonds of antioxidant GM. Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance confirmed the structure of KH590‐GM and GM functionalized nanosilica. Thermogravimetry analysis indicated that the grafting rate of GM functionalized nanosilica reached 13.4%, and the antioxidant had good thermal stability. Scanning electron microscope and mechanical properties measurement showed GM functionalized nanosilica was dispersed uniformly in NR vulcanizates, and helpful for the increase of the tensile strength and tensile stress of NR vulcanizates. Based on the study of the antioxidative behavior and extraction resistance of the NR vulcanizates, it was found that in contrast to NR vulcanizates with GM, the ageing coefficient and oxidation induction time of that with GM functionalized nanosilica increased to 0.66 and 39 min from 0.58 and 30 min, respectively. Furthermore, the NR vulcanizates with GM functionalized nanosilica also exhibited excellent extraction resistance. POLYM. COMPOS., 38:1241–1247, 2017. © 2015 Society of Plastics Engineers     

Hydrogenated natural rubber blends: Aspect on thermal stability and oxidative behavior

Hydrogenated natural rubber (HNR) prepared from natural rubber (NR) is a new sustainable elastomer with excellent thermal properties. This study reports on the effect of vulcanization system and blend ratio on the thermal and oxidative resistance of HNR/NR vulcanizates. The various HNR/NR ratios vulcanized by peroxide and sulfur donor system exhibited the highest retention of tensile strength after thermal aging due to the formation of zinc‐dimethyldithiocarbamate (ZDMDC) which is an efficient antioxidant. The results from thermogravimetric analysis (TGA) indicated that the saturated structure of HNR had higher decomposition temperature and activation energy to enhance the thermal stability of HNR/NR vulcanizates. The initial and maximum decomposition temperatures of NR and HNR phases in vulcanizates were not affected by rubber blend ratio. This suggests that the decomposition pattern of HNR has no influence on another constituent. The increase in HNR content in the blends could retard the ozonolysis resulting in the surface cracking attacked by ozone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Cure characteristics and mechanical properties of hydrogenated natural rubber/natural rubber blends

The cure characteristics and mechanical properties of blends consisting of hydrogenated natural rubber (HNR) and natural rubber (NR) blends were investigated. The HNR/NR blends at 50/50 wt ratio were vulcanized using various cure systems: peroxide vulcanization, conventional vulcanization with peroxide, and efficient vulcanization with peroxide. The HNR/NR vulcanizates cured by the combination of peroxide and sulfur donor (tetramethylthiuram disulfide, TMTD) in the efficient vulcanization with peroxide exhibited the best mechanical properties. It was also found that the hydrogenation level of HNR did not affect the tensile strength of the vulcanizates. The tensile strength of the blends decreased with increasing HNR content because of the higher incompatibility to cause the noncoherency behavior between NR and HNR. However, the HNR/NR vulcanizate at 50/50 wt ratio showed the maximum ultimate elongation corresponding to a co‐continuous morphology as attested to by scanning electron micrographs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties of deproteinized natural rubber in comparison with synthetic cis‐1, 4 polyisoprene vulcanizates: Gum and black‐filled vulcanizates

Gum and black‐filled vulcanizates having various crosslink densities were prepared from 2 types of rubber, namely, deproteinized natural rubber (DPNR) and synthetic cis‐1, 4 polyisoprene vulcanizates (IR). Their mechanical properties, such as tensile strength, tear strength, abrasion loss, and heat buildup resistance, at various crosslink densities as well as at similar optimum crosslink density were compared. For both gum and black‐filled systems, IR possessed a higher crosslink density than that of DPNR at a fixed curative content. Tensile and tear strength of all vulcanizates passed through a maximum with increasing crosslink density. For gum vulcanizates, tensile and tear strengths of DPNR and IR below the maximum were not much different. However, IR had a narrower tear strength peak relative to DPNR. At a comparable optimum crosslink density, DPNR exhibited higher tensile strength and crack growth resistance than IR. For black‐filled vulcanizates, tensile and tear strengths, and heat buildup resistance of DPNR and IR at a given crosslink density were similar. The results revealed that the properties of gum samples were more dependent upon crosslink density than the black‐filled ones because the reinforcement by carbon black overshadowed the intrinsic properties of the rubbers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1139–1144, 2005     

The behavior of dithiocarbimate derivative as safety accelerator of natural rubber compounds

A conventional vulcanization system containing tetrabutylammonium bis(4‐methylphenyldithiocarbimato)zincate(II) (ZNIBU) was used for curing of natural rubber (NR) compounds. Rheometric (t_s1, t₉₀, and CRI) and mechanical properties, such as tensile and tear strengths and modulus at 300%, were measured to evaluate the acceleration potential of ZNIBU. Commercial accelerators (TMTD, MBTS, and CBS) and a binary system CBS/ZNIBU were also tested for comparison purposes. It was observed that ZNIBU alone does not give either safe scorch time or cure rates appropriate for industrial applications. Nevertheless, mechanical properties are comparable to those given by the other accelerators used. As for the binary system, positive synergistic effects can be found in tear strength and modulus of NR vulcanizates. Besides, ZNIBU does not contribute for the formation of nitrosamines in the vulcanization process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Utility of Zinc (Lignin/Silica/Fatty Acids) Complex Driven From Rice Straw as Antioxidant and Activator in Rubber Composites

This article presents a method to precipitate zinc (lignin/silica/fatty acids) complex (Zn LSF complex) from the black liquor of pulped rice straw and studying the efficiency of it as green activator and antioxidant in natural rubber composites. The results obtained revealed that the investigated zinc complex has dual function as activator and antioxidant in natural rubber composites. This evaluation was supported by physico‐mechanical properties of the vulcanizates which showed a considerable improvement of rheometric characteristics, tensile strength, strain at break, hardness, Young's modulus, thermal oxidative aging, and thermal stability of NR composites. The composite loaded with 7 phr of Zn LSF complex as activator exhibited the best mechanical properties in comparison with the same concentrations of control activator zinc stearate. Also, results revealed that Zn LSF complex is efficient as antioxidant in NR vulcanizates compared conventional antioxidants, namely polymerized 2,2,4‐trimethyl‐1,2‐dihydroquinoline. POLYM. ENG. SCI., 59:E196–E205, 2019. © 2018 Society of Plastics Engineers     

The effect of coupling agent and chemical treatment on rice husk ash‐ filled natural rubber composites

Rice husk ash was incorporated into natural rubber (NR) using a laboratory size two‐roll mill. Curing using a conventional vulcanization system (CV) was chosen, and cure studies were carried out on a Monsanto rheometer. Physical testing of the NR vulcanizates involved the determination of tensile, tear, and abrasion resistances, and hardness. Fourier transform infrared spectroscopy (FTIR) analysis was done to verify the presence of the characteristic functional groups of precipitated silica in MHA (milled husk ash) and THA (treated husk ash). The effect of the coupling agent, bis(3‐triethoxysilylpropyl)‐tetrasulfane (Si‐69), on the curing and physical properties of the vulcanizates was investigated. A chemical treatment on a rice husk ash was done, and the effects of this procedure are also reported. For comparison, two commercial fillers, precipitated silica (Zeosil‐175) and carbon black (N774), were also used. Although the presence of the silane coupling agent had not brought the expected increase in properties, treated husk ash showed exceptional performance in terms of tensile strength and abrasion resistance of the filled vulcanizates. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1019–1027, 2000     

Assessment degradation of natural rubber by moving die processability test and FTIR spectroscopy

Thermal and mechanical degradation of natural rubber (NR) mixed with N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐p‐phenylenediamine (6PPD), polymerized 1,2‐dihydro‐2,2,4‐trimethyl‐quinoline (TMQ), and 50/50 weight basis mixture under high temperature and shearing conditions were investigated using a moving die processability test and FTIR spectroscopy. Relationship between dynamic properties in terms of tan δ value and chemical changes of NR molecules during degradation were correlated. The results indicated that the NR mixed with antioxidants caused decreased level of chain scission and oxidative degradation. The 6PPD provided better protection of NR against degradation at elevated temperature than TMQ. Furthermore, it was found that a prolonged mixing time caused more pronounced oxidative degradation on NR molecules than increased mixing temperature. The antioxidative capability of those antioxidants on NR was ordered based on their effectiveness as follows: 6PPD > 6PPD mixed with TMQ > TMQ. It was also found that the moving die processability test and FTIR spectroscopy are efficient routes to estimate the oxidative degradation of NR molecules. Therefore, the techniques could be applied to assess or compare antioxidative capability of various types and amounts of antioxidants used in the rubber formulation within a reasonable testing time. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Physico-Mechanical,Aging Properties,and Permeability of Ketones Through Vulcanizates Prepared by Different Mixing Schemes

This article reports on the physico-mechanical properties, chemical resistance, aging properties, sorption, diffusion, and permeability of ketones (cyclohexanone and acetone) through vulcanizates from blends of natural rubber (NR) and epoxidized low molecular weight natural rubber (ELMWNR) compounded by three different mixing schemes. The compounding ingredients were mixed with the two mentioned rubbers using three different mixing schemes by adopting a semi-efficient sulphur vulcanization compounding formulation. In Scheme 1, the natural rubber and ELMWNR were first mixed before adding the compounding ingredients. In Scheme 2, the compounding ingredients were first mixed with the NR before adding the ELWMNR and in Scheme 3, the compounding ingredients were first mixed with the ELMWNR before adding the NR. The physico-mechanical results of the vulcanizates showed that changes in the mixing schemes significantly influence the tensile properties of the vulcanizates. The tensile strength of the vulcanizates prepared with mixing Scheme 2 were 4.3 MPa lower than vulcanizates from Scheme 1, whereas Scheme 3 was lower than Scheme 1 with 8.5 MPa. The aging results of the vulcanizates from all the mixing schemes were found impressing. The activation energy and free energy change were highest for Scheme 1 whereas the extent of cyclohexanone and acetone penetrations were the lowest with Scheme 1, signifying well crosslinked and ketone resistant vulcanizates.     

Upgrading of acrylonitrile–butadiene copolymer properties using natural rubber–graft–N‐(4‐aminodiphenylether) acrylamide

The grafting of ADPEA onto natural rubber was executed with UV radiation. Benzoyl peroxide was used to initiate the free‐radical grafting copolymerization. Natural rubber‐graft‐N‐(4‐aminodiphenylether) acrylamide (NR‐g‐ADPEA) was characterized with an IR technique. The ultrasonic velocities of both longitudinal and shear waves were measured in thermoplastic discs of NBR vulcanizates as a function of aging time. Ultrasonic velocity measurements were taken at 2 MHz ultrasonic frequency using the pulse echo method. We studied the effect of aging on the mechanical properties and the swelling and extraction phenomena for acrylonitrile–butadiene copolymer (NBR) vulcanizates, which contained the prepared NR‐g‐ADPEA and a commercial antioxidant, N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine. The prepared antioxidant enhanced both the mechanical properties of the NBR vulcanizates and the permanence of the ingredients in these vulcanizates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of chemically modified waste rubber powder as a filler in natural rubber vulcanizates

Waste rubber powder (RP) was subjected to chemical modification by using different concentrations of oxidizing agents such as nitric acid and 30% hydrogen peroxide solution. This treatment leads to introducing some functional groups onto the surface of RP. The chemically modified RP was incorporated in natural rubber mixes either alone or in combination with carbon black (HAF). The physicomechanical properties of NR vulcanizates obtained were studied and compared to NR vulcanizates filled with untreated RP. It was found that the chemically modified RP improves tensile strength and aging resistance of NR vulcanizates compared with untreated RP. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 30–36, 2004     

维生素C镧配合物对天然橡胶的防护作用

将自制的维生素C镧配合物（VCLa）作为新型防老剂用于天然橡胶（NR）中,考察VCLa对胶料性能的影响。结果表明：VCLa对NR具有一定的硫化促进作用,显著缩短胶料的t90,略微提高硫化胶拉伸性能;VCLa对NR具有优良的防护作用,其防臭氧老化效果显著优于常用防老剂4010NA,RD和MB,防热氧老化效果与防老剂4010NA和RD相当,优于防老剂MB,防紫外光老化效果接近于防老剂4010NA和RD,但优于防老剂MB;VCLa减缓NR应力老化,提高硫化胶的耐磨性和耐屈挠疲劳性能。     

Effect of crosslink structures on dynamic mechanical properties of natural rubber vulcanizates under different aging conditions

The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated before and after aerobic and anaerobic aging at 100°C. The three unfilled NR vulcanizates cured with the CV, SEV, and EV systems had about the same mechanical loss factor (tan δ) values at about 0°C but showed some apparent differences in the tan δ values in the order EV > SEV > CV at relatively high temperatures of 40–80°C before aging. However, N330‐filled NR vulcanizates gave higher tan δ values than the unfilled vulcanizates and showed little effect of the crosslink types on the tan δ at different temperatures over the glass‐transition temperature (T_g) before aging. Aerobic heat aging increased the T_g and tan δ values of the vulcanizates over a wide range of temperatures from ?80 to 90°C that was mainly due to the changes in the total density and types of crosslinks. The unfilled vulcanizates cured with the CV system showed the greatest change in DMP because of their poor resistance to heat aging. Aerobic heat aging of NR vulcanizates caused a more significant change in the DMP than anaerobic heat aging because of the dominant effect of the oxidative degradation during aerobic heat aging on the main‐chain structure, crosslink structures, and DMPs of the vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 710–718, 2001     

白炭黑用量对氯丁橡胶/天然橡胶共混物性能的影响

研究了不同用量的沉淀法白炭黑填充质量比75/25的氯丁橡胶/天然橡胶共混物的物理机械性能、耐热老化性能和耐油性能,并用扫描电镜研究了共混物的结构。结果显示,白炭黑的加入改善了共混硫化物的拉伸强度、100%定伸应力和邵尔A硬度。压缩永久变形减小,黏度增大,从而导致在形变的过程中天然橡胶分散相占有率相对减少。相关性能也证明随着白炭黑用量的增加,硫化胶的耐热和耐油性能显著提高。