Effect of modification conditions of coal gangue on properties of natural rubber composites

The purpose of this work is to study the reinforcement effect of modified coal gangue (CG) on natural rubber (NR); carbon black (CB) was taken as reference filler. The addition of CG and CB to NR with the total filler loading fixed at 35 phr. The orthogonal experiment was employed to reveal the modification conditions on reinforcing properties. The results show that modification conditions such as weight ratio of coupling agent (CA), calcining temperature (CT), and calcining time (CM) affect the strengthening properties of CG, and CA is the most important factor influencing the tensile strength of NR, the order of influence can be expressed as CA > CT > CM. The optimum modification conditions are CT 800°C, CM 1 hr, and CA 2%. 300% modulus of NR composites filled with modified CG (17.5 phr)/CB (17.5phr) hybrid filler is similar to NR filled with CB alone at same filler loading, while elongation at break increases significantly for existent of CG. The effect of heat treatment and modification conditions of CG were tested by particle size distribution, scanning electron microscopy, Fourier transform infrared spectra, and X‐ray diffraction. The results show that the specific surface area of CG increased and hydroxyl group in crystal structure of CG removed under heat treatment. Dynamic mechanical analysis results show that the storage modulus and tan δ of CG filled NR composites are higher while T_g is less than that of CB, indicating the existence of a strong and stiff interface between filler and NR matrix. POLYM. COMPOS., 35:1911–1917, 2014. © 2014 Society of Plastics Engineers     

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     

Mechanical and dynamical mechanical properties of chloroprene rubber and cellulose II composites

Vulcanized composites of chloroprene rubber (CR) with cellulose II (Cel II) as a filler were investigated. Cel II, obtained by the coagulation of cellulose xanthate, was incorporated in the rubber by the traditional method. The filler content varied from 0 to 30 phr. For comparison purposes, carbon black (CB)–CR composites were also studied. The CB amount varied from 0 to 45 phr. The mechanical and dynamic mechanical properties were determined, and the CR composite containing 20 phr of Cel II showed the best set of properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2425–2430, 2004     

Studies of nanocomposites based on carbon nanomaterials and RTV silicone rubber

The mechanical and electrical properties were investigated for nanocomposites based on carbon nanotubes (CNTs) and conductive carbon black (CB). Solution room‐temperature‐vulcanized silicone rubber was used as a matrix. Vulcanizates based on CNTs and CB was prepared by solution mixing. With the addition of 2 phr of CNTs to the rubber matrix, the Young's modulus increased by 272% and reached as high as ～706% at 8 phr, whereas the modulus increased only 125% for CB specimens at 10 phr. Similarly, the electrical properties at 5 phr content of CNT were ～0.7 kΩ against ～0.9 kΩ at 20 phr CB. The Kraus plot from equilibrium swelling tests shows that the high properties for CNT specimens are due to high polymer–filler interfacial interactions, the small particle size that improves the distribution of the filler in a highly exfoliated state, and high electrical connective networks among the filler particles. These improvements can especially influence medical products such as feeding tubes, seals and gaskets, catheters, respiratory masks and artificial muscles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44407.     

Effect of coal gangue/carbon black/multiwall carbon nanotubes hybrid fillers on the properties of natural rubber composites

The objective of this study was to investigate three kinds of filler with completely different morphology on mechanical properties of natural rubber (NR). Coal gangue (CG) are derived from natural deposits are composed principally by illite and quartz. CG, carbon black (CB), and multiwalled carbon nanotube (CNT) were used as hybrid fillers in NR. CNTs were dispersed into NR latex by ultrasonic irradiation and then the mixed latex were coagulated to obtain the CNTs/NR masterbatch, then mechanical mixing method was employed to prepare the CG/CB/CNTs/NR composites. The addition of CG, CB, and CNTs to NR was varied with the total filler loading fixed at 35 phr. The mechanical properties of NR composites were studied in terms of tensile and dynamic mechanical analysis (DMA). The results showed that the tensile strength and modulus 300% (M300) of all hybrid samples were higher than the composites only loaded CG; and the highest tensile strength of NR loaded with hybrid fillers achieved at sample of loading amount of CG 17.5, CB 15.5, and CNTs 2 phr, whose M300 and elongation at break was obviously higher than that of only CB loaded NR composites; The inclusion CG improves the tensile strength of NR without the sacrifice of its extensibility, while CB and CNTs brings together the enhancement in the ultimate strength and the reduction in the extensibility. DMA results revealed that the existence of CG can improve the dispersion of CB and CNTs in NR matrix. POLYM. COMPOS., 37:3083–3092, 2016. © 2015 Society of Plastics Engineers     

Preparation,structure, and properties of montmorillonite/cellulose II/natural rubber nanocomposites

In this work, sodium montmorillonite clay was added, as filler, to nanocomposites of natural rubber (NR) and cellulose II (regenerated cellulose) in amounts varying from 0 to 5 phr (per hundred resin). Natural rubber (NR)/cellulose II/montmorillonite nanocomposites were prepared by co‐coagulating NR latex, montmorillonite aqueous suspension and cellulose xanthate. The clay was previously exfoliated in water, and the resulting suspension was then added to the mixture of NR latex with cellulose xanthate. Morphological, rheometric, mechanical, and dynamic mechanical properties were evaluated, and an increase in these properties was observed upon the addition of cellulose and clay nanomaterials to the rubber matrix. The results show the advantage in using cellulose as a nanopolymer as well as MMT as nanofiller. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

An innovative material based on natural rubber and leather tannery waste to be applied as antistatic flooring

In recent decades, the production chain of beef and bovine leather has grown significantly because of an increase in the world's population and improved access to consumption. However, the generation of waste derived from this sector has grown simultaneously, and consequently, improved ways of adding value, reusing, and disposing these waste materials are being sought. In this article, we present a new and innovative composite material based on vulcanized natural rubber (NR), carbon black (CB), and leather waste (NR/CB/leather). The NR/CB/leather composites were prepared by thermal compression with 60 phr of CB and 60 or 80 phr of leather waste. In accordance with Brazilian sanitary laws, we exposed these composites for 24 h to bleach (B) and a disinfectant with the aim of simulating a true everyday cleaning use. The deconvolution of the impedance semicircles was carried out, and two relaxation phenomena around linear relaxation frequencies of about 10⁵ and 10⁶ Hz were found and associated mainly with charge carriers from CB and leather waste. With the addition of leather, the electrical conductivity of the composites increased two orders of magnitude from 5.70 × 10^?6 for the NR/CB to 7.97 × 10^?4 S/cm for NR/CB/leather‐60 phr B. These results point to the possibility of using these composites as an antistatic flooring once they exhibit acceptable values of electrical conductivity and once they withstand, from the structural, morphological, and electrical point of view, exposure to sanitizing agents. Furthermore, the production of these composites will add value to and enable an environmentally acceptable disposal of leather waste. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41297.     

炭黑/煤矸石/碳纳米管复合填料体系对天然橡胶性能的影响研究*

利用硝酸氧化法对碳纳米管(CNTs)进行纯化,并用环氧天然橡胶(ENR)进行改性处理。结合胶质量分数测定结果表明, ENR用量15%(质量)时效果最佳。采用胶乳凝聚法制备CNTs/天然橡胶(NR)母料。煤矸石粉(CG)经高温煅烧和表面改性处理。 将CNTs/天然橡胶(NR)母料、CG和炭黑(CB)通过机械混炼法与天然橡胶及配合剂混合,制备CB/CG/CNTs/NR复合材料,并对复合材料进行硫化特性及物理机械性能。结果表明： CNTs延迟硫化效应明显;相比炭黑,CG对硫化具有促进作用。硫化特性和甲苯溶胀法测定结果表明,在填料份数相同的条件下,单独由CB填充的NR有最大的交联密度,CNTs对交联密度影响不明显。物理机械性能测试结果表明,当CG：CB：CNTs=17.5:16.5:1(Phr)时,NR硫化胶的300%定伸应力和扯断伸长率明显高于单独由CB填充NR,而拉伸强度与之接近,复合填料样填充NR具有较好的综合性能。扫描电镜测试结果表明,复合填料在NR基体中分布均匀。     

Surface modification of nanocrystalline cellulose and its application in natural rubber composites

As a biopolymer with high mechanical strength, nanocellulose was generally considered as a green filler for reinforcing polymer. In this study, nanocrystalline cellulose (NCC) isolated from softwood pulp was successfully modified by cetyltrimethyl ammonium bromide (CTMAB), a cationic surfactant, and the modified nanocrystalline cellulose (m-NCC) was used to reinforce natural rubber (NR). In this composite architecture, it was found that when the filler content was 5 or 10 phr, the surface modification of NCC improved the dispersion state of NCC in NR matrix and the interfacial interaction between NR and NCC. Therefore, the NR/m-NCC composites exhibited outstanding mechanical properties, and its tensile strength, elongation at break and tear strength was increased by 132.8, 20, and 66.1%, respectively, compared to pristine NR composites. Besides, the modified NCC could accelerate the vulcanization and improve wet-skid resistance and aging resistance of NR composites. It is envisioned that the modified NCC has the potential to be generalized to manufacturing other polymer matrix composites strengthened with nanocellulose.     

Effect of Multifunctional Additive on Filler Dispersion in Carbon-Black- and Silica-Filled Natural Rubber Compounds

The effect of multifunctional additive (MFA) on filler dispersion in carbon-black- (CB) and silica-filled natural rubber (NR) compounds has been studied. Silica dispersion, measured by computer-aided image analysis and scanning electron microscopy (SEM), showed a substantial improvement when MFA concentration is increased from 1 to 3 phr. After this level, there is a further but small improvement. However, for CB-filled NR compounds, CB dispersion showed a substantial improvement when the MFA used between 0 and 1 phr. As in silica-Filled NR compounds, there is only a small improvement in dispersion after 1 phr.     

Synergistic effects of hybrid carbon nanomaterials in room‐temperature‐vulcanized silicone rubber

This work examines nanocomposites based on nanofillers and room‐temperature‐vulcanized silicone rubber. The carbon nanofillers used were conductive carbon black (CB), carbon nanotubes (CNTs) and graphene (GE). Vulcanizates for CB, GE, CNTs as the only filler and hybrid fillers using CNTs, CB and GE were prepared by solution mixing. The elastic modulus for CNT hybrid with CB at 15 phr (4.65 MPa) was higher than for CB hybrid with GE (3.13 MPa) and CNTs/CB/GE as the only filler. Similarly, the resistance for CNT hybrid with CB at 10 phr (0.41 kΩ) was lower than for CB (0.84 kΩ) at 20 phr and CNTs as the only filler. These improvements result from efficient filler networking, a synergistic effect among the carbon nanomaterials, the high aspect ratio of CNTs and the improved filler dispersion in the rubber matrix. © 2016 Society of Chemical Industry     

纳米微晶纤维素对炭黑补强天然橡胶硫化特性和耐老化性能的影响（二）

（续上期） 2．5复合材料的老化性能 在热氧条件下,橡胶大分子链断裂致使分子链变短,材料密度增大,宏观上表现为橡胶硬度提高、物理性能下降,即橡胶材料发生了老化。NR的分子链中含有大量不饱和双键,易受到氧及臭氧的侵蚀而破坏,其热氧老化性能有待提高。     

Viscoelastic properties of natural rubber composites reinforced by defatted soy flour and carbon black co‐filler

Filler mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce natural rubber (NR) composites and their viscoelastic properties were investigated. DSF is an abundant and renewable commodity and has a lower material cost than CB. Aqueous dispersions of DSF and CB were first mixed and then blended with NR latex to form rubber composites using freeze‐drying and compression molding methods. A 40% co‐filler reinforced composite with a 1 : 1 DSF : CB ratio exhibited a 90‐fold increase in the rubber plateau modulus compared with unfilled NR, showing a significant reinforcement effect by the co‐filler. The effect, however, is lower than that observed in the carboxylated styrene–butadiene rubber composites reported earlier, indicating a significant effect from the rubber matrix. The co‐filler composites have elastic moduli between those of DSF and CB reinforced composites. Stress softening and recovery experiments indicated that the co‐filler composites with a higher CB content tend to have a better recovery behavior; however, this can not be simply explained from the recovery behaviors of the single filler (DFS and CB) composites. CB composites prepared by freeze‐drying show a strain‐induced reorganization of fillers. Strain sweep experiment data fit with the Kraus model indicates the co‐filler composites with a higher CB content are more elastic, which is consistent with the recovery experiments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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。     

KH-550对纤维素纳米晶替代炭黑补强天然橡胶的影响

本文采用酸水解工业微晶纤维素(MCC)制备纤维素纳米晶(NCC),将其与天然胶乳共凝沉,混炼时加入炭黑(CB),制备了天然橡胶(NR)/NCC/CB复合材料,研究了偶联剂KH-550对NR/NCC/CB(100/10/35)性能的影响,结果表明,KH-550用量为1-2phr时,NR/NCC/CB的硫化性能、混炼胶的加工性能、硫化胶的交联密度、抗屈挠龟裂性能、动态压缩疲劳生热、永久变形和耐磨耗性能明显改善。     

炭黑在沥青基短切碳纤维补强天然橡胶中的作用

研究炭黑及沥青基短切碳纤维表面臭氧改性对碳纤维填充天然橡胶(NR)硫化胶物理性能的影响。结果表明:臭氧改性后,碳纤维的涂覆层基本去除且表面粗糙度明显增加;碳纤维/NR复合材料拉伸断面中碳纤维表面光滑且与NR发生明显脱粘,复合材料物理性能较低;填充30份炭黑N330后,碳纤维/NR复合材料物理性能显著提高,炭黑/短纤维/NR复合材料和炭黑/臭氧改性碳纤维/NR复合材料的拉伸强度分别达到18.6和26.9 MPa,较碳纤维单独填充时分别提高了431%和627%;碳纤维与炭黑具有类似的微观结构,炭黑在碳纤维补强NR时起到桥梁作用,从而大大增强了两者间的界面强度。     

Preparation of nano‐reinforced thermal conductive natural rubber composites

Natural rubber (NR) composites highly filled with nano‐α‐alumina (nano‐α‐Al₂O₃) modified in situ by the silane coupling agent bis‐(3‐triethoxysilylpropyl)‐tetrasulfide (Si69) were prepared. The effects of various modification conditions and filler loading on the properties of the nano‐α‐Al₂O₃/NR composites were investigated. The results indicated that the preparation conditions for optimum mechanical (both static and dynamic) properties and thermal conductivity were as follows: 100 phr of nano‐α‐Al₂O₃, 6 phr of Si69, heat‐treatment time of 5 min at 150°C. Furthermore, two other types of fillers were also investigated as thermally conductive reinforcing fillers for the NR systems: (1) hybrid fillers composed of 100 phr of nano‐α‐Al₂O₃ and various amounts of the carbon black (CB) N330 and (2) nano‐γ‐Al₂O₃, the particles of which are smaller than those of nano‐α‐Al₂O₃. The hybrid fillers had better mechanical properties and dynamic performance with higher thermal conductivity, which means that it can be expected to endow the rubber products serving under dynamic conditions with much longer service life. The smaller sized nano‐γ‐Al₂O₃ particles performed better than the larger‐sized nano‐α‐Al₂O₃ particles in reinforcing NR. However, the composites filled with nano‐γ‐Al₂O₃ had lower thermal conductivity than those filled with nano‐α‐Al₂O₃ and badly deteriorated dynamic properties at loadings higher than 50 phr, both indicating that nano‐γ‐Al₂O₃ is not a good candidate for novel thermally conductive reinforcing filler. POLYM. COMPOS., 37:771–781, 2016. © 2014 Society of Plastics Engineers     

白炭黑/炭黑复合填充对NR性能的影响

在白炭黑和炭黑填料总量一定的情况下,研究了不同白炭黑/炭黑配比对NR性能的影响。结果表明,白炭黑用量增加,NR硫化速率下降,体系中炭黑填料网络被破坏且白炭黑-橡胶间较弱的相互作用也会对NR硫化胶力学性能产生一系列影响。DMA结果表明,加入20~25份白炭黑对提高硫化胶的抗湿滑性和降低滚动阻力最为有效。     

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     

Influence of cellulose as a filler in vulcanized rubber composites

Composites of elastomers and cellulose have been investigated. Copolymers of styrene-butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) as well as natural rubber (NR) were compounded with regenerated cellulose (Cellulose II). The technique for the incorporation of filler was based on the coprecipitation of the rubber latex-cellulose xanthate mixture. Cellulose filler was used in the range of 0 to 30 phr. The best results were shown by the natural rubber-regenerated cellulose systems. The different behavior of the systems is explained by experimental evidence. The reinforcement mechanism for NR compositions, which involves an induced crystallizing rubber (NR), seems to be different from the mechanism for SBR and NBR.