Synthesis,characterization, and evaluation of natural rubber‐graft‐N‐(4‐aminodiphenyl methane) acrylamide as an antioxidant

The synthesis of N‐(4‐aminodiphenylmethane) acrylamide (ADPMA) was performed through the reaction of 4,4′‐diaminodiphenyl methane and acryloyl chloride in the presence of triethyl amine. The grafting of ADPMA onto natural rubber was executed with UV radiation. Benzoyl peroxide was used to initiate the free‐radical grafting copolymerization. Natural rubber‐graft‐N‐(4‐aminodiphenyl methane) acrylamide (NR‐g‐ADPMA) was characterized with an IR technique. 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‐ADPMA 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. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 843–849, 2006     

The structure change of dynamically fatigued unfilled natural rubber vulcanizates

The submicrostructure of dynamically fatigued unfilled natural rubber vulcanizates was investigated by using scanning electron microscope (SEM) and atomic force microscope (AFM). AFM photographs showed the sample surface roughness became worse after tensile fatigue and the largest surface undulation was as twice that of the unfatigued sample. SEM photographs showed that many micropores of 10¹–10² nm, a sort of defect, occurred on the cross section of samples after tensile fatigue. The surface roughness became weaker and the size of the micropore was reduced to a few to dozens of nanometers with the addition of antiaging agent N‐(1,3‐dimethyl butyl butyl)‐N′‐phenyl‐p‐phenylene diamine (4020); furthermore, the mechanical properties and dynamic viscoelastic properties in the later period of fatigue changed much. E′ decreased greatly and tan δ increased obviously with the extension of fatigue. It indicated that 4020 was only effective in the early period of tensile fatigue.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Amelioration of acrylonitrile–butadiene copolymer properties using natural rubber graft p‐aminophenol

A two‐roll mill machine was used for the grafting of p‐aminophenol (pAP) onto natural rubber (NR). The prepared NR graft p‐aminphenol (NR‐g‐pAP) was characterized by ¹H NMR and IR spectroscopy techniques. The goal of this article is to study the effect of commercial antioxidants, N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (6PPD) and N‐phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD), and the prepared NR‐g‐pAP, on the mechanical properties of acrylonitrile–butadiene (NBR) vulcanizates, the fluid compatibility of NBR vulcanizates, the hydraulic brake and clutch fluid dot, the diffusion out for NBR vulcanizate components, and the compression recovery of NBR vulcanizates. This study indicates that the NBR copolymer vulcanizate which contains the prepared NR‐g‐pAP has good protection against mechanical stress and the diffusion out of NBR vulcanizate components. The 6PPD and the prepared NR‐g‐pAP ameliorates the fluid compatibility of the oil seals, which is based on NBR as elastomer, and the hydraulic brake and clutch fluid dot. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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     

Influence of rubber composition on migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates composed of NR,SBR, and BR

Migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates with different rubber compositions of natural rubber (NR), styrene–butadiene rubber (SBR), and butadiene rubber (BR) were studied at constant temperatures of 40–100°C and outdoors. Three single rubber‐based vulcanizates, three biblends, and three triblends were used. N‐Phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD) and N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD) were employed as antiozonants. Migration rates of the antiozonants became faster with increasing the temperature. The order of the migration rates in the single rubber‐based vulcanizates was BR > NR > SBR. The migration rates in the vulcanizates containing SBR, on the whole, increased with decreasing the SBR content, while those in the vulcanizates containing BR decreased with decreasing the BR content. Difference in the migration behaviors of the antiozonants depending on the rubber composition was explained both by the intermolecular interactions of the antiozonants with the matrix and by interface formed between dissimilar rubbers in the blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 237–242, 2001     

Preparation of lignin-based filling antioxidant and its application in styrene-butadiene rubber

A novel filling antioxidant (Lig-g-RT) to improve the mechanical properties and antiaging performance of styrene-butadiene rubber (SBR) composites was prepared by grafting antioxidant intermediate p-aminodiphenylamine (RT) on the surface of lignin via the linkage of silane coupling agent. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) measurements confirmed that RT was successfully grafted on the surface of lignin to produce the functionalized Lig-g-RT which shows a better thermal stability than lignin. Compared with SBR/lignin composite, the SBR/Lig-g-RT composite using latex co-precipitation method exhibits a much better filler dispersion, which contributes to the maintain of the physical mechanical properties of SBR vulcanizates. Moreover, the SBR/Lig-g-RT vulcanizate exhibits less chemical crosslink concentration and higher entanglement density than SBR/lignin vulcanizate according to the Mooney–Rivlin model analysis. In addition, the stabilizing effect of lignin/Lig-g-RT on the carbon-black filled SBR vulcanizates is comparable with that of commercial antioxidant N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (4020), especially the SBR vulcanizate filled with 10 phr Lig-g-RT obtains the optimum thermo-oxidative aging properties. This functionalized Lig-g-RT not only provides an intramolecular synergistic antiaging effect for SBR vulcanizates and an improvement of filler dispersion, but greatly extends the comprehensive utilization of industrial lignin.     

Comparative study on natural antioxidant as an aging retardant for natural rubber vulcanizates

The research aim is mainly to investigate the effectiveness of natural antioxidant (NA) obtained from oil palm leaves (Elaeis guineensis) as an aging retardant in natural rubber (NR) vulcanizates. Comparison of NA with other commercial antioxidants, trimethyl quinoline (TMQ) and butylated hydroxy toluene (BHT), is investigated. The effect of natural and commercial antioxidants on NR vulcanizates was explored before and after aging. Aging test was carried out at 70°C for three different periods, 4, 7, and 14 days to determine aging property by performing the tensile and tear tests. NA shows lower tensile properties, crosslink density, tack strength but high tear strength compared to the commercial antioxidants, BHT and TMQ. However, upon aging NR vulcanizates with NA retains its properties equivalent to that of commercial antioxidants, BHT and TMQ. Thus, NA can be used as an aging retardant for short‐term protection in application requiring moderate tensile properties and can be used as alternative source for commercial antioxidant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of blends containing natural and some synthetic rubbers with synthesized aromatic polyester

This work deals with the synthesis of aromatic polyester (AP) from polyarylate [Bisphenol A (BPA)/dimethyl terephalate (DMT)/ethylene glycol (EG)] and maleic anhydride (MA) in presence of dibutyl tin oxide (DBTO) as a catalyst. Blends were prepared from candidated AP (10–30 phr) with different types of rubber [natural rubber (NR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR) and ethylene‐propylene‐diene monomer (EPDM)]. The obtained blends were subjected to physicomechanical measurements to evaluate their properties as efficient blends for economic industrial applications. In case of AP blended with rubber, better properties were obtained than that of rubber vulcanizates. The fatigue life values decreases by increasing the AP contents for all types of the tested blends. The equilibrium swelling (%) for the prepared blends exhibits different behavior in solvents like toluene and motor oil. The addition of N‐isopropyl‐N′‐phenyl‐p‐phenylene diamine (IPPD), as antioxidant, affects the properties of all the prepared products. These properties were in consequent with the data of the initial shear modulus, which is calculated from the Mooney‐Rivlin equation and the percentage of the equilibrium swelling. Scanning electron microscope (SEM) was used to study the morphological structure; the SEM results show the changes in surface of the rubber before and after being blended with AP. The investigated blends are considered a new trend in giving products with variable physicomechanical characteristics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Migration behaviors of antiozonants to the surface in NR vulcanizates,depending on the season: The effect of wax

Influence of wax film on the surface of a rubber vulcanizate on migration of antiozonants was studied using NR vulcanizates containing various types of waxes. The waxes have different molecular weight distributions. N‐phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD), N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD), N,N′‐di(sec‐butyl)‐p‐phenylenediamine (SBPPD), and N,N′‐di(1,4‐dimethylpentyl)‐p‐phenylenediamine (DMPPD) were used as antiozonants. Migration experiments were performed outdoors for two months in the summer, fall, and winter. The migration rates of the antiozonants in the vulcanizate without wax are faster than those in the vulcanizates with waxes. The antiozonants migrate slower in the vulcanizate containing wax with a high‐molecular‐weight distribution than in the vulcanizate with a low one. In the summer, the migration rates of SBPPD and DMPPD are faster than those of IPPD and HPPD, respectively. But, in the fall, the migration rates of SBPPD and DMPPD are slower than those of IPPD and HPPD, respectively. The differences of migration behaviors of the antiozonants, depending on season and wax type, was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1987–1993, 1999     

几种防老剂对环氧化天然橡胶性能的影响

研究几种常用的防老剂（RD、4010NA、4020、MB）对环氧化程度为25的环氧化天然橡胶（ENR25）的硫化特性、硫化胶的交联网络结构、耐热空气老化性能以及热稳定性的影响。研究结果表明,防老剂的加入有助于促进ENR25的硫化：防老剂4020具有较好的力学性能、最佳的耐热空气老化性能和较好的热热稳定性,是ENR25的最佳的防老剂。     

Ozonolysis of model olefins—Efficiency of antiozonants

In this study, the efficiency of several potential long lasting antiozonants was studied by ozonolysis of model olefins. 2‐Methyl‐2‐pentene was selected as a model for natural rubber (NR) and 5‐phenyl‐2‐hexene as a model for styrene butadiene rubber (SBR). A comparison was made between the efficiency of conventional antiozonants like N‐(1,3 dimethylbutyl)‐N′‐phenyl‐p‐phenylene diamine (6PPD), N‐isopropyl‐N′‐phenyl‐p‐phenylene diamine (IPPD), and a mixture of diaryl p‐phenylene diamines (Wingstay 100) and some newly synthesized antiozonants. The stearic acid salt of 6PPD (PPD‐C18), 2,4,6‐tris(4‐(phenylamino)phenyl)‐1,3–5‐triazinane (ADPAT), and 4‐pyrole diphenylamine (PDPA) showed a higher efficiency than the conventional antiozonants in both NR as well as SBR model system. Special attention was paid to the carboxylic acid salts of 6PPD such as PPD‐C18, which has shown good long‐term protection of passenger tire sidewall compounds. It was demonstrated that by varying the chain length, C7, C18, and C22, of the carboxylic acid part of the 6PPD salts, the ozone protection was not influenced under the selected test conditions. The 6PPD salts made from strong acids like succinic acid (SA) and methyl sulfonic acid (MSA) appeared to be less efficient than PPD‐C18. It was also investigated whether the reactions between ozone and the double bonds of the model rubber could be measured online by a spectroscopic technique. It was demonstrated that near infrared spectroscopy is a suitable technique to study these reactions. FT Raman looked also a promising technique because of the high response factor of double bonds. However, the addition of p‐phenylene diamines (PPDAs) to the sample solution resulted in a strong discoloration (dark brown) and therefore in a high fluorescence background signal. This technique can therefore not be used for the evaluation of staining antiozonants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 100: 853–866, 2006     

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     

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     

防老剂350和PS-988与其它防老剂的性能对比试验

在NR中进行了新型防老剂３５０和ＰＳ－９８８与传统防老剂Ａ，D，RD和4010NA的热氧老化、抗屈挠龟裂与抗裂口增长及大气老化对比试验，并研究了对NR胶料硫化速度的影响。结果表明，不同防老剂对NR胶料的硫化速度基本无影响；对NR胶料热氧老化性能影响的优劣顺序为：RD和4010NA，A和D，0．5份PS－988，0．3份PS－988；防老剂4010NA的抗屈挠性能量优，而防老剂350与A相当，且优于防老剂PS－988和350；防老剂4010NA和0．5份PS－988的大气老化抗龟裂扩展性能好于防老剂A，350和0．3份PS－988。     

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。     

Studies on natural rubber bound para-phenylenediamine antioxidants in NBR

Para-phenylenediamine (PD) was chemically attached to depolymerized natural rubber by a photochemical reaction. The rubber bound PD was characterized by TLC, ¹H-NMR, IR, and TGA. The efficiency and permanence of the bound PD were compared with conventional antioxidants in NBR vulcanizates. The rubber bound PD was found to be less volatile and more resistant to water and oil extraction. The vulcanizates showed improved aging resistance in comparison to vulcanizates containing conventional antioxidants. The liquid rubber bound antioxidant reduces the amount of plasticizer required for compounding. © 1995 John Wiley & Sons, Inc.     

Preparation and evaluation of some novel organo‐phosphorus compounds as antioxidants and antifatigue agents in rubber

Six organo‐phosphorus compounds were synthesized and incorporated in NR and SBR mixes. The rheometric characteristics of the green rubber mixes were determined using the oscillating disc rheometer. The prepared compounds were evaluated as antioxidants and antifatigue agents in NR and SBR vulcanizates. It was found that the prepared compounds are good antioxidant and antifatigue agents and their efficiency was better than that obtained by 4‐methyl‐2,6‐di‐tert‐butyl phenol, which is used in the rubber industry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2984–2992, 2002; DOI 10.1002/app.2327     

Evaluation of New Thermal Stabilizers and Antifatigue Agents for Rubber Vulcanizates

Seven organo-phosphorus compounds were synthesized and incorporated in natural rubber (NR) and styrene-butadiene rubber (SBR) mixes. The rheometric characteristics of the green rubber mixes were determined using the oscillating disc rheometer. The prepared compounds were evaluated as thermal stabilizers and antifatigue agents in NR and SBR vulcanizates. The results revealed that the prepared compounds were good antioxidants and antifatigue agents for rubber vulcanizates exceeding the commercial antioxidant 4-methyl-2,6-di-tert-butyl phenol, which is used in the rubber industry. In addition, the efficiency of such compounds depends on their chemical structure.     

不同防护体系对胎面胶耐臭氧老化性能的影响

进行了不同防护体系对载重轮胎胎面胶耐臭氧老化性能的影响研究,采用不同配比的防老剂如常用的防老剂4010NA、防老剂4020和防老剂RD、防护蜡并用的防护体系进行研究与应用。结果表明：①载重轮胎采用该3种防老剂并用时最佳总用量范围应控制在5.5份左右,其中防老剂4010NA 3.0份、防老剂4020 1.0份、防老剂RD1.5份所取得的防护臭氧效果最好;②在选择防护体系时要同时选择化学防护及物理防护,在动态情况下选择微晶蜡做物理防护效果特好,份数控制在1.5份左右。     

Dual Activity of Some Modified Thiocarbamyl Sulfenamides in the Vulcanization of NR Accelerated by Dibenzothiazyl Disulfide

The retarding and the accelerating activities of some modified thiocarbamyl sulfenamides—namely, N-cyclopentamethylene thiocarbamyl-N′-(cyclohexyl, thiocyclohexyl) sulfenamide (CPCTS), N-cyclopenta-methylenethiocarbamyl-N′-(cyclohexyl, N-cyclopentamethylene thio) sulfenamide (CPCCS), and N-cyclopentamethylenethiocarbamyl-N′-(cyclohexyl, N-oxydiethylene thio) sulfenamide (CPCOS)—have been studied in dibenzothiazyl disulfide (MBTS)-accelerated vulcanization of natural rubber (NR). It is found that CPCTS, CPCOS, and CPCCS delay the onset of cure and generate active accelerators during vulcanization. In addition to this, the accelerator systems are quite capable of producing age-resistant vulcanizates. The results indicate that thiocarbamyl sulfenamides modified chemically at the >NH functionality retain their accelerating property. Thus CPCTS, CPCOS, and CPCCS play the dual role of an accelerator and a retarder in the vulcanization of NR accelerated by MBTS.