Preparation and performance of oleylamine modified silica-reinforced natural rubber composites

Oleylamine (OA) modified silica (SiO₂-g-OA) was prepared using γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560) and OA, silica/natural rubber (NR) and SiO₂-g-OA/NR composites were prepared by mechanical blending in an internal mixer, and SiO₂-g-OA was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analyzer, and contact angle analyzer. The mechanical properties, abrasion resistance, curing characteristics, Payne effect, and morphology of silica/NR and SiO₂-g-OA /NR composites were investigated using universal testing machine, Akron abrasion tester, rubber processing analyzer, and scanning electron microscope, respectively. The results showed that SiO₂-g-OA became more hydrophobic and had better compatibility with NR. Moreover, SiO₂-g-OA/NR had weaker Payne effect, better vulcanization performance, and more excellent mechanical properties. As the content of filler was more than 30 phr, SiO₂-g-OA/NR had lower rolling resistance and higher wet skid resistance. Compared with silica modified by other coupling agents, SiO₂-g-OA had the best reinforcement effect on NR.     

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.     

Cardanol grafted natural rubber: A green substitute to natural rubber for enhancing silica filler dispersion

Natural rubber (NR) usage is wide‐spread from pencil erasers to aero tyres. Carbon black and silica are the most common reinforcing fillers in the rubber industries. Carbon black enhances the mechanical properties, while silica reduces the rolling resistance and enhances the wet grip characteristics. However, the dispersion of polar silica fillers in the nonpolar hydrocarbon rubbers like natural rubber is a serious issue to be resolved. In recent years, cardanol, an agricultural by‐product of the cashew industry is already established as a multifunctional additive in the rubber. The present study focuses on dispersion of silica filler in natural rubber grafted with cardanol (CGNR) and determination of its technical properties. The optimum cure time reduces and the cure rate increases for the CGNR vulcanizates as compared to that of the NR vulcanizates at all loadings of silica varying from 30 to 60 phr. The interaction between the phenolic moiety of cardanol and the siloxane as well as silanol functional groups present on the silica surface enhances the rubber–filler interaction which leads to better reinforcement. The crosslink density and bound rubber content are found to be higher for the silica reinforced CGNR vulcanizates. The physico‐mechanical properties of the silica reinforced CGNR vulcanizates are superior to those of the NR vulcanizates. The CGNR vulcanizates show lower compression set and lower abrasion loss. The dynamic‐mechanical properties exhibit less Payne effect for silica reinforced CGNR vulcanizates as compared to the NR vulcanizates. The transmission electron photomicrographs show uniform dispersion of silica filler in the CGNR matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43057.     

The preparation of microcrystalline cellulose–nanoSiO2 hybrid materials and their application in tire tread compounds

Microcrystalline cellulose (MCC) was hybridized with nano‐SiO₂ to improve its interaction with a rubber matrix. The hybrids (MCC–SiO₂) were prepared with the “microreactor” and “sol–gel” technologies, using MCC as the carrier and tetraethoxysilane as the precursor. The structure and morphology of the hybrids were studied by infrared spectrometry, thermogravimetric analysis, and scanning electron microscopy. The results showed that the nano‐SiO₂ had been loaded successfully on the surface of the MCC with a loading ratio of approximately 30%. The nano‐SiO₂ can take on the morphologies of particles, tubes, or rods by controlling the size of the “microreactor”. The hybrids were then used in silica/SSBR compounds to replace part of the silica, and their effects on the physio‐mechanical and dynamic properties were discussed. The results showed that the vulcanizates with the hybrids had improved physio‐mechanical and dynamic properties. The vulcanizates of MCC–SiO₂ also had a higher wet‐skid resistance and a lower rolling resistance than did the silica vulcanizates when they were used in tire tread compounds. The SEM photos showed that the interfacial adhesion between the MCC and rubber was improved. The size of the MCC hybrids was also in situ decreased during the processing of the rubber compounds. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44796.     

Study on properties of natural rubber reinforced by poly(sodium‐4‐styrenesulfonate)‐decorated carbon black with a latex compounding technique

Natural rubber filled with poly(sodium‐4‐styrenesulfonate) (PSS)‐decorated carbon black (CB) by employing a latex compounding technique was prepared. The result of scanning electron microscope demonstrated that CB was uniformly dispersed in the matrix. Comparing to traditional dry compounding, an improvement in physical and mechanical properties was observed in the composites attributed to the homogeneous distribution of CB in matrix and an augment of bound rubber. Owing to the changes of the physical properties of CB surface, vulcanizate filled with oxidized CB via latex way exhibited higher mechanical properties. The resulting vulcanizates displayed a diminished interaction between fillers based on the consequence of strain dependence of storage modulus. Furthermore, a splendid wet‐skid resistance was obtained in vulcanizates fabricated by latex compounding technique in comparison with vulcanizates prepared by traditional dry compounding. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42346.     

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     

Utilization of silane functionalized carbon nanotubes‐silica hybrids as novel reinforcing fillers for solution styrene butadiene rubber

Carbon nanotubes‐silica (CNTs‐SiO₂) nanohybrid filler was fabricated by coating inorganic silica on multi‐wall CNTs through a sol–gel process. The CNTs‐SiO₂ nanohybrids were then functionalized by 3‐methacryloxypropyltrimethoxysilane (3‐MPTS) followed by compounding to solution styrene butadiene rubber (S‐SBR) through mechanical mixing. The Fourier‐transform infrared spectroscopy showed that the CNTs were coated by inorganic SiO₂, and grafted with 3‐MPTS successfully. The functionalized CNTs‐SiO₂ nanohybrids had a rough surface as revealed by transmission electron microscope images. After hybridization and grafting, the functionalized CNTs‐SiO₂ nanohybrids still maintained the crystal structure of CNTs, which was determined by X‐ray diffraction and Raman spectrum. The addition of nanohybrids accelerated the vulcanization process and improved the crosslinking degree of vulcanizates. With adding 10 phr (parts per hundred of rubber) functionalized CNTs‐SiO₂, the mechanical properties of S‐SBR vulcanizates were improved significantly. The tensile moduli at 100% elongation (M₁₀₀) and tensile strength had 54% and 28% increase, respectively. The incorporation of functionalized CNTs‐SiO₂ nanohybrids also largely enhanced the storage modulus, and slightly increased the thermal conductivity of vulcanizates. POLYM. COMPOS., 00:000–000, 2013. © 2013 Society of Plastics Engineers POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Improved mechanical properties of natural rubber composites reinforced by novel SiO2@HCNFs nanofillers at a low filler loading

In order to improve high reinforcement properties of natural rubber (NR), SiO₂@HCNFs as novel double-phase nanofillers at low content have been loaded in NR by using mechanical mixing method. The morphologies and structures of SiO₂@HCNFs and NR composites were characterized, and the performances of NR composites were measured. The results show that compared with pure N330/NR, the modulus at 300% strain, tensile strength, elongation at break of NR composites increase by 10.7, 17.9, and 9.0%, respectively, at only 2.5 phr SiO₂@HCNFs content. Meanwhile, the volume abrasion of NR composites is also dramatically reduced at 2.5 phr SiO₂@HCNFs content, about 53.4% less than that of N330/NR, though the shore hardness increases by only 3.7%. It is also found that NR composites reinforced by SiO₂@HCNFs at 2.5 phr content have much higher hardness and abrasion performance than HCNFs/NR. The DMA results show that high wet skid resistance and low rolling resistance of NR composites were also achieved by loading 6.5 phr SiO₂@HCNFs. The unique structure of SiO₂@HCNFs double-phase nanofillers plays a crucial role in properties of NR composites, in virtue of the significant synergetic reinforcing effect of both HCNFs and silica.     

炭黑在天然橡胶/溶聚丁苯橡胶硫化胶中的分散及其对性能的影响

考察了溶聚丁苯橡胶(SSBR)用量、炭黑的种类及用量对天然橡胶(NR)/SSBR硫化胶动态力学性能和力学性能的影响.结果表明,炭黑与SSBR的结合作用比与NR弱;随SSBR用量的增加,炭黑在NR/SSBR共混硫化胶中的分散性提高,Payne效应减弱,频率敏感性增强;随SSBR用量的增加,NR/SSBR共混硫化胶的拉伸强度和撕裂强度减小,扯断伸长率变化不大;而定伸应力则呈先减小后增大的趋势;随不同种类的炭黑在NR/SSBR硫化胶中分散性的提高,定伸应力呈上升趋势,损耗因子和压缩生热呈减小趋势.     

Silica nanoparticles reinforced natural rubber latex composites: The effects of silica dimension and polydispersity on performance

The nano-size autonomous monodisperse silica (AS) particles were prepared by hydrolysis and condensation of tetraethoxysilane using l -lysine as catalyst. The silica/natural rubber (NR) masterbatches were then produced via latex compounding, in which NR latex was mixed with the above AS dispersion. The commercial precipitated silica (PS) was introduced as a control. The effects of both AS and PS particles on the interfacial and mechanical properties of composites were systematically examined. It was found that the AS formed bead-like morphology wherein the clear particle edges can be distinguished in rubber matrix. Compared with PS/NR, the AS/NR composites were proved to possess more bound rubber and weaker filler–filler interaction resulting in higher tensile strength, abrasive resistance, and resilience. Meanwhile, the efficiency of premodified AS and PS surfaces using bis-(3-triethoxysilylpropyl) tetrasulfide on reinforcing the properties of silica/NR composites was studied. The results presented that the overall properties of modified silica/NR vulcanizates were improved significantly. In special, the values of heating building-up and compression set showed an evident decline which was of great significance for tire tread or other rubber products. For the dynamic properties, the magic angle spinning/NR composites had lower rolling resistance. In short, AS may be applied as an ideal substitution of PS in rubber. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47449.     

Grafting polyisoprene onto surfaces of nanosilica via RAFT polymerization and modification of natural rubber

In this contribution, we reported the investigation of natural rubber (NR) reinforced by silicon dioxide‐graft‐polyisoprene (SiO₂‐g‐PIP) core–shell nanoparticle. First, the hydroxyl on the surface of the SiO₂ nanoparticles was reacted with 2‐methyl‐2‐[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid to produce trithioester‐capped SiO₂ (denoted as SiO₂‐CTA). SiO₂‐CTA was used as a nanoparticle chain transfer agent, and SiO₂‐g‐PIP core–shell nanoparticles were synthesized via reversible addition‐fragmentation chain transfer polymerization (RAFT). The results of FTIR spectroscopy and TGA showed that the grafting weight of the PIP block in SiO₂‐g‐PIP was 2.1 wt%. SiO₂‐g‐PIP and SiO₂ were simultaneously incorporated into NR. The curing properties of the NR compounds showed that the vulcanization rates of the NR/SiO₂‐g‐PIP compounds were much higher than those of NR/silica compounds. The results of scanning electron microscopy showed that SiO₂ microdomains in the NR/SiO₂‐g‐PIP vulcanizate were much better disperse and distribute than SiO₂ microdomains in the NR/SiO₂ composite. The filler–rubber interaction of the NR/SiO₂‐g‐PIP composite endowed the composite with improved mechanical properties. POLYM. ENG. SCI., 59:1167–1174 2019. © 2019 Society of Plastics Engineers     

混炼方式对螺旋纳米碳纤维增强天然橡胶复合材料力学性能的影响

采用干法和湿法两种混炼工艺制备了螺旋纳米碳纤维(HCNFs)/炭黑(CB)/天然橡胶(NR)复合材料,通过扫描电镜、拉伸试验机和应变扫描仪分别对所制备复合材料的界面形貌、力学性能和Payne效应进行了测试分析,考察了混炼方式对复合材料宏观力学性能及Payne效应的影响。结果表明,与纯CB填料相比,在干湿两种混炼方式下,添加适量的HCNFs(1～6份)能提高HCNFs/CB/NR复合材料的300%定伸应力、扯断伸长率、拉伸强度和硬度。与干法混炼相比,湿法混炼能明显增强HCNFs/CB/NR复合材料的Payne效应,并提升在HCNFs高添加量(2～6份)条件下的拉伸强度和扯断伸长率,这主要源于湿法混炼能够有效改善HCNFs在橡胶基质中的分散性。     

Dispersion and properties of natural rubber‐montmorillonite nanocomposites fabricated by novel in situ organomodified and latex compounding method

Natural rubber (NR)‐montmorillonite (MMT) nanocomposites were prepared by a novel in situ organomodified and latex compounding method, followed by melt compounding technique. Effects of cationic surfactant on MMT dispersion, curing characteristic, mechanical, and dynamical properties were investigated. The number of layers in the layered MMT stack was determined by Small‐Angle X‐Ray Scattering (SAXS). The dispersion of MMT tends to form high ordered structure in NR‐MMT masterbatch when cationic surfactant of more than 4 phr was used. The morphology of Na‐MMT shows partly intercalated and exfoliated structure in the matrix after mixing and hot pressing process with reduced number of layers compared to the pristine MMT. The use of cationic surfactant over 4 phr introduces a plasticizing effect resulting in the reduction of crosslink density, hardness and modulus, but increase in tensile strength due to higher interfacial adhesion between NR and MMT as determined by Maeir‐Goritz model and Field Emission Scanning Electron Microscopy (FESEM). The optimum cationic surfactant loading is observed at 4 phr with the highest stable bonds, which result in the highest crosslink density, tear strength and storage modulus while the lowest Payne effect and tan delta at 60°C. POLYM. ENG. SCI., 59:1830–1839, 2019. © 2019 Society of Plastics Engineers     

Thermal aging properties and chemical resistance of blends of natural rubber and epoxidized low molecular weight natural rubber

Studies into solvent resistance and aging properties of blends of natural rubber and epoxidized low molecular weight natural rubber were carried out. Vulcanization of the blends using the semi‐efficient vulcanization (semi‐EV) system was found to have curing advantages over conventional vulcanization (CV) and efficient vulcanization (EV) systems. The rheological properties (cure time, t₉₀, and scorch time, t₂), solvent resistances, and aging properties of the vulcanizates were found to improve as the level of epoxidized low molecular weight natural rubber in the blends increases. The mechanical properties of the blends were also found to be within the accepted level for NR vulcanizates. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1733–1739, 2005     

New approach for preparation of dry natural rubber nanocomposites through acid‐free co‐coagulation: Effect of organoclay content

Natural rubber (NR) vulcanizates exhibit good mechanical properties compared to vulcanizates of synthetic rubbers. Incorporation of a conventional filler at higher loadings to NR enhances its modulus, while reduction in tensile strength and elongation. This paper presents a new strategy for development of a NR‐clay nanocomposite with enhanced mechanical properties by incorporation of lower loadings (2–8 phr) of cetyl trimethyl ammonium bromide modified montmorillonite clay (OMMT‐C) under acid‐free environment. The effect of OMMT‐C loading on cure characteristics, rubber‐filler interactions, crosslink density, dynamic mechanical thermal properties, and mechanical properties were evaluated. Incorporation of OMMT‐C accelerated the vulcanization process and enhanced mechanical properties. X‐ray diffraction analysis and scanning electron microscopy images revealed that the formation of intercalated clay structures at lower OMMT‐C loadings, and clay aggregates at higher loadings. A nanocomposite at OMMT‐C loading of 2 phr exhibited the best balanced mechanical properties, and was associated with highest crosslink density and rubber–filler interactions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46502.     

Modified wheat flour–natural rubber blends. II

Effect of cyanoethylation of starch on the properties of starch xanthide–NR vulcanizates has been studied. Significant improvements in compounding, tensile modulus, tensile strength, and retention of wet strength of the vulcanizates have been recorded. Equilibrium swelling of vulcanizates by water is also greatly suppressed. The role of cyanoethylation of starch in imparting such specific effects has been analyzed in the light of the polarity of the cyanoethyl group and its effect in lowering the critical yield stress of the modified starch for efficient dispersive mixing in NR matrix.     

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     

Promoting the dispersibility of silica and interfacial strength of rubber/silica composites prepared by latex compounding

The dispersibility of precipitated silica and its interfacial interaction with rubber matrix can affect the performances of tires which is a difficult problem to be solved. A well-dispersed silica dispersion was obtained through ball milling and modification process followed by heat treatment to enhance the properties of NR composites prepared by latex compounding. Benefiting from the modifier Si-747, the well-dispersed silica/NR composite (Silica-MSH-C) shows excellent tensile strength of 30.8 ± 0.5 MPa, which is 17.6 ± 3.8% higher than latex compounding pure silica/NR composite (Silica-C) and 21.7 ± 4.3% higher than traditional mechanical blending pure silica/NR composite (T-Silica-C). The tan delta values indicate that Silica-MSH-C has better dynamic properties and also has stronger interface strength according to swelling tests, heat capacity curves and Mooney-Rivlin equation. The molecular dynamics (MD) simulation further shows the binding energy between NR and Si-747 modified SiO₂ is 58.88 Kcal/mol larger than the value of NR and pure silica.     

Curing characteristics and mechanical properties of rattan‐powder‐filled natural rubber composites as a function of filler loading and silane coupling agent

Curing characteristics, tensile properties, morphological studies of tensile fractured surfaces using scanning electron microscopy (SEM), and the extent of rubber filler interactions of rattan‐powder‐filled natural rubber (NR) composites were investigated as a function of filler loading and silane coupling agent (CA). NR composites were prepared by the incorporation of rattan powder at filler loading range of 0–30 phr into a NR matrix with a laboratory size two roll mill. The results indicate that in the presence of silane CA, scorch time (t_s2), and cure time (t₉₀) of rattan‐powder‐filled NR composites were shorten, while, maximum torque (M_H) increased compared with NR composites without silane CA. Tensile strength and tensile modulus of composites were enhanced whereas elongation at break reduced in the presence of silane CA mainly due to increase in rubber‐filler interaction. It is proven by SEM studies that the bonding between the filler and rubber matrix has improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties,chemical and aging resistance of natural rubber filled with nano‐Al2O3

Al₂O₃ nanoparticles were introduced to natural rubber (NR) to investigate its reinforcement effect on filled NR vulcanizates. The results show that Nano‐Al₂O₃/NR nanocomposites exhibit significantly improved tensile strength, elongation at break, modulus, and tearing strength. Scanning electron microscopy analyses indicate that nanoparticles dispersed in NR matrix at nanoscale and show nano‐reinforcement effect on NR vulcanizates. The aging resistances of filled NR vulcanizates improve. After aging test, tensile strength, tearing strength, and modulus improved, and elongation at break decreased. These attribute to the crosslink maturation reactions, which result in the conversion of polysulfidic linkages into disulfidic and monosulfidic ones. The acid and alkaline resistances of nano‐Al₂O₃‐filled NR vulcanizates improve compared with that of unfilled NR systems. After acid and alkaline test, tensile strength and elongation at break improve, and modulus decrease. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers