Crosslinking kinetics of SBR composites containing vulcanized ground scraps as filler

The aim of this study was to characterize the cure reaction of styrene–butadiene rubber (SBR) composites containing industrial rubber scraps. Different proportions of SBR ground scraps (SBR-r), varying from 10 to 80 parts per hundred of rubber, were incorporated into a base formulation of identical composition. Crosslink formation and the kinetics of the cure reaction were evaluated through oscillatory disk rheometry, differential scanning calorimetry, and crosslink density. Cure characteristics, such as scorch time and cure time, decreased with increasing SBR-r content. Minimum torque indicated only a small variation in the viscosity with the incorporation of SBR-r. The maximum torque decreased with the addition of scrap rubber, as a consequence of the reduction in virgin rubber content where crosslinks had been formed. Crosslink density values corroborated these findings, presenting a slight decrease with the increase in the SBR-r content. The kinetic study indicated lower enthalpy values for SBR-r composites compared to those of the control sample. The kinetic parameters, such as activation energy and reaction order, indicated a change in the mechanism of reaction, related to the increased complexity of the systems.     

Development and characterization of graphitic carbon nitride as nonblack filler in natural rubber composites

A new type of elastomeric composite containing natural rubber (NR) and graphitic carbon nitride (g-C₃N₄) has been successfully prepared with the reinforced property. The reinforcing effect of g-C₃N₄ in NR composites was examined by cure, mechanical, morphological, and swelling studies. Besides, epoxidized NR with 50-mol % epoxy level (ENR-50) was used as a compatibilizer to enhance the hydrophilic g-C₃N₄ filler capacity for hydrophobic NR composites. At the same filler load level, the mechanical properties of NR/g-C₃N₄ composites, such as tensile strength and tensile modulus, were consistently increased with increased ENR-50 content. To note, the ENR compatibilized composites have shown better-reinforced performance, which has been attributed to the hydrogen bonding interactions between the uncondensed amine groups in g-C₃N₄ and the polar groups in ENR. We believe that these newly prepared NR composites based on g-C₃N₄ as nonblack filler and ENR-50 as compatibilizer can find potential applications in modern day rubber research. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48136.     

石墨烯/室温硫化硅橡胶复合材料的制备及性能

采用水合肼对氧化石墨进行还原获得石墨烯,通过高速剪切分散法将石墨烯分散到α,ω-羟基聚二甲基硅氧烷中,固化后得到石墨烯/室温硫化(RTV)硅橡胶复合材料。对石墨烯和复合材料的微观形貌进行了表征,并考察了复合材料的性能。结果表明,所制备石墨烯的厚度为1～3 nm,为具有较少层数的石墨烯片层结构;复合材料断面呈微相分离结构,但其差示扫描量热曲线只有1个玻璃化转变温度(Tg)。随着石墨烯用量的增加,复合材料的Tg升高,结晶熔点降低。石墨烯对RTV硅橡胶有增强作用,当石墨烯的质量分数为0.5%时,复合材料的拉伸强度达到0.35 MPa,较纯RTV硅橡胶的拉伸强度提高了67%。     

Property optimization in nitrile rubber composites via hybrid filler systems

Nitrile rubber–PVC composites having carbon black and mica fillers in different compositions as hybrid reinforcements were studied. The effect of the silane treatment of mica, the degree of replacement, and the molecular architecture of nitrile rubbers on static‐dynamic mechanical, swelling, and curing behavior of the resultant composites are discussed. The results showed that an increase in unsilanized and silanized mica total filler resulted in increased toughness values and decreased swelling in organic solvents together with increased vibrational damping capacity for all types of nitrile rubber composites, depending on the polyacrylonitrile content. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 366–374, 2001     

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     

Influence of nanocrystalline cellulose on structure and properties of natural rubber/silica composites

A complex of resorcinol and hexamethylenetetramine (RH) was utilized to modify nanocrystalline cellulose (NCC). The modified NCC (MNCC) was then mixed with natural rubber (NR) filled silica. The structure, processing properties, mechanical properties, and dynamic compression fatigue properties of the NR/MNCC/Silica nanocomposites were characterized by scanning electron microscopy (SEM), rubber processing analyzer, electronic tensile machine, and dynamic compression fatigue performance tester. The results showed that the processing properties, mechanical properties, and dynamic compression fatigue properties of NR/MNCC/Silica nanocomposites were substantially improved over NR/Silica composites. Their better performances in terms of processing, mechanical properties, heat build‐up, and permanent set were correlated to the better dispersion of MNCC and stronger interface interaction between NR and MNCC than NR/Silica composites. POLYM. COMPOS., 36:861–868, 2015. © 2014 Society of Plastics Engineers     

Organomodified kaolin as a reinforcing filler for natural rubber

China clay (kaolin) has been modified with sodium salt of rubber seed oil (SRSO). SRSO was characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), and differential thermal analysis (DTA). XRD of the unmodified and SRSO‐modified kaolins showed an increase in the d‐(001) spacing of kaolin platelets from 7.15 to 14 Å. FTIR spectroscopy indicated possible grafting of the organic moiety of rubber seed oil (RSO) onto the clay surface. DTA of the SRSO‐modified kaolin indicated that the SRSO is more strongly bound in a constraint environment within the lamellae of kaolin. Natural rubber (NR) mix containing 10 phr of SRSO‐modified kaolin was found to cure faster than that of a similar mix containing unmodified kaolin. NR vulcanizates containing SRSO‐modified kaolin showed considerable increase in tensile modulus, tensile strength, and elongation at break indicating its potential as an organomodified nanofiller. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

马来酸酐接枝天然橡胶对纤维素纤维增强天然橡胶复合材料的增容作用

在无引发剂的熔融状态下,利用剪切力将马来酸酐接枝于天然橡胶分子链上,并将马来酸酐接枝天然橡胶(MNR)作为增容剂添加到纤维素纤维增强天然橡胶复合材料中,研究其对复合材料性能的影响.结果表明,在熔融状态下利用剪切力能够发生自由基反应或Diels-Alder反应,将马来酸酐接枝于天然橡胶分子链上而制得MNR.添加了MNR的纤维增强天然橡胶硫化胶的物理机械性能,尤其是定伸强度比未添加MNR的硫化胶有明显提高,应力弛豫程度减小;扫描电镜分析也说明添加MNR使填料与橡胶基质之间有了更强的界面黏合力.     

偶联剂改性填充剂在橡胶中的应用

比较不同种类偶联剂改性白炭黑和碳酸钙对胶料性能的影响及偶联剂用量对胶料物性的影响。结果表明：偶联剂Si-69对白炭黑的改性效果比钛酸酯偶联剂改性效果优越；偶联剂改性碳酸钙填充硫化胶的性能与未填充碳酸钙胶料的性能接近，并提高产品性价比，偶联剂Si-69在胶料中的用量以无机填料用量的4%-6%左右效果较好。     

Kinetics of filler wetting and dispersion in carbon nanotube/rubber composites

The effects of the surface modification of multi-walled carbon nanotubes (MWCNTs) by an ionic liquid, 1-butyl 3-methyl imidazolium bis(trifluoromethyl-sulphonyl)imide (BMI) on the kinetics of filler wetting and dispersion as well as resulting electrical conductivity of polychloroprene (CR) composites were studied. Two different MWCNTs were used, Baytubes and Nanocyl, which differ in their structure, purity and compatibility to CR and BMI. The results showed that BMI can significantly improve the macrodispersion of Baytubes, and increases the electrical conductivity of the uncured BMI–Baytube/CR composites up to five orders of magnitude. In contrast, the use of BMI slows the dispersion process and the development of conductivity of BMI–Nanocyl/CR composites. Our wetting concept was further developed for the quantification of the bound polymer on the CNT surface. We found that the bonded BMI on the CNT surface is replaced by the CR molecules during mixing as a result of the concentration compensation effect. The de- and re-agglomeration processes of CNTs taking place during the subsequent curing process can increase or decrease the electrical conductivity significantly. The extent of the conductivity changes is strongly determined by the composition of the bound polymer and the curing technique used.     

Characterization and transport properties of ceramic filler incorporated natural rubber composites

Crystalline glass–ceramic fillers were prepared from calcium carbonate, silica, alumina, and calcium fluoride by heating and subsequent quenching in cold water. The fillers were incorporated into natural rubber (1,4-cis-polyisoprene) and the filled rubber composites were crosslinked with sulfur in the presence of different rubber additives. The unfilled and filled rubber composites were characterized. The transport properties of benzene, toluene, and p-xylene (BTX) through the rubber composites were studied in terms of sorption, diffusion, permeation, and mass transfer coefficients. The effect of the ceramic fillers on the mechanical, thermal and transport properties were studied. The sorption data at different temperatures were used for calculating activation energy of diffusion, permeation, free energy, and enthalpy of sorption. The BTX remained in the liquid state within the composite matrix as evident from negative ΔS. The diffusion coefficient (D) and mass transfer coefficient (k_mtc) of BTX decreased with the increase in filler loading. Accordingly, for the transport of BTX the unfilled rubber showed a D (D × 10⁷ cm²/s) and mass transfer coefficient (k_mtc × 10⁴ cm/s) of 5.67/3.97/2.96 and 7.71/7.08/7.04, respectively which decreased to 5.06/2.95/2.57 and 7.53/6.95/6.90, respectively for the composite containing 50 wt.% ceramic filler.     

Utilization of bowstring hemp fiber as a filler in natural rubber compounds

The cure characteristics and physicomechanical properties of natural rubber (standard Nigerian rubber) vulcanizates filled with the fiber of bowstring hemp (Sansevieria liberica) and carbon black were investigated. The results showed that the scorch and cure times decreased, whereas the maximum torques increased, with increasing filler loadings for both bowstring hemp fiber and carbon black filled vulcanizates. The tensile strength of both bowstring hemp fiber and carbon black filled vulcanizates increased to a maximum at a 40 phr filler concentration before decreasing. The elongation at break and rebound resilience decreased, whereas the modulus, specific gravity, abrasion resistance, and hardness increased, with increasing filler contents. The carbon black/natural rubber vulcanizates had higher tensile strength, which was about 1.5 times that of bowstring hemp fiber/natural rubber vulcanizates. This superiority in the tensile strength was probably due to the higher moisture content and larger particle size of the bowstring hemp fiber. However, the bowstring hemp fiber/natural rubber vulcanizates showed superior hardness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Utilization of peanut shell powder as a novel filler in natural rubber

This work focuses on the use of peanut shell powder (PSP) as filler in natural rubber (NR). Peanut, one of the food crops in the world, generates large amounts of waste namely peanut shell. Modified and unmodified PSP-NR composites with varying particle size and dosages were prepared by an open mill mixing technique. The processing characteristics and the curing behavior of the composites were determined by Monsanto Rheometer. The technological performance was done by analyzing the tensile strength, tear strength, and hardness of the vulcanizates. The swelling studies were carried out to observe the crosslink density, rubber-filler interaction, and the reinforcing nature of the filler on NR. The observed variation in mechanical properties has been supported by the fractography of the composites obtained by Scanning Electron Microscopy. The result of the study shows that the PSP is most effective filler in NR at 10 parts per hundred (phr) loading. Filler reinforcement ability of modified PSP is more when compared with unmodified PSP; therefore, modified PSP-NR composites shows better physicomechanical properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties of natural rubber/grafted cellulose fibre composites

Mechanical properties of natural rubber/allyl acrylate and allyl methacrylate grafted cellulose fibre composites are presented. Stress/strain measurements and dynamic mechanical measurements indicate that the adhesion between grafted fibres and matrix is better than that in samples containing untreated cellulose fibres. This makes it possible to vary the composite properties by varying the fibre type and/or fibre amount.     

Organomodified montmorillonite as filler in natural and synthetic rubber

The filler action of dodecylamine (12C) intercalated montmorillonite (MNT) referred to as organomodified montmorillonite (12C‐MNT) up to 4 wt % on natural rubber (NR) and styrene butadiene rubber (SBR) was studied and findings were compared with respect to the unmodified Na‐MNT. X‐ray analysis was used to calculate the interchain separation (R and R′), degree of crystallinity (X_c), and distortion factor (k). It is noted that R and R′ showed the opposite trend, whereas X_c as well as k showed overall increasing trend with an increasing amount of 12C‐MNT on both NR and SBR. For Na‐MNT (1 wt %) filled NR and SBR, the corresponding magnitude of R and R ′ and X_c showed nearly no change, whereas k_c increased significantly. The crosslinking density (v_c) does not show any significant changes in NR, whereas for SBR, it increases with increasing 12C‐MNT as filler. Interestingly, in the case of 1 wt % pure Na‐MNT used as filler for both NR and SBR, v_c was lower compared to the virgin rubbers. Both swelling index (s_i) and sol fraction (Q) do not show any significant variation for NR composites, whereas these decrease for SBR composites with increasing concentration of 12C‐MNT filler. On the contrary, NR and SBR with 1 wt % of Na‐MNT filler show greater magnitude of s_i and Q corresponding to the pure ones. Measurements of mechanical properties showed a significant increase in tensile strength and elongation at break for NR‐12C‐MNT (4 wt %) when compared with either virgin NR. In addition, modulus at the elongation at 100 and 200% in general increases with increasing loading of 12C‐MNT filler in NR. Similar observations were also noted in the case of SBR. Interestingly, when only pure Na‐MNT is used as filler, the strength of NR and SBR decreases drastically. Scanning electron microscopic studies were also to used support the mechanical behavior of NR‐12MNT and SBR‐12CMNT composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3583–3592, 2004     

胶粉的生产方法

介绍了国内外胶粉的生产方法,即常温粉碎法,低温粉碎法和湿法或溶液粉碎法,并着重介绍了常温粉碎法胶粉生产技术。     

Torrefied agro-industrial residue as filler in natural rubber compounds

This study explored the feasibility of using torrefied biomass as a reinforcing filler in natural rubber compounds. Carbon black was then replaced with the torrefied biomass in elastomer formulations for concentrations varying from 0% to 100% (60 parts per hundred rubber or phr total). Their influence on the curing process, dynamic properties, and mechanical properties was investigated. Results were compared with the properties of vulcanizates containing solely carbon black fillers. Time to cure (t₉₀) for compounds with torrefied biomass fillers increased, while filler-filler interactions (ΔG') decreased, compared to carbon black controls. At low strains, the tan δ values of the torrefied fillers vulcanizates were similar to the controls. Incorporation of torrefied biomass into natural rubber decreased compound tensile strength and modulus but increased elongation. Replacement with torrefied fillers resulted in a weaker filler network in the matrix. Still, results showed that moderate substitution concentrations (~20 phr) could be feasible for some natural rubber applications.     

氯醚硫化橡胶化学再生

采用对比试验法,主要研究了再生温度、再生时间、活化剂种类、活化剂用量对共聚氯醚橡胶(ECO)硫化胶的化学动态脱硫法制得的再生氯醚橡胶性能的影响。研究结果表明:在一定时间和温度范围内,随着再生温度的提高,ECO再生胶的拉伸强度、扯断伸长率、永久变形、撕裂强度、硬度下降。在不同温度下,再生时间对再生胶性能影响有一些差别,总体存在温度与时间等效关系,较好的再生条件为:温度110℃×(2～3)h、190℃×1 h、230℃×(0.25～0.5)h。活化剂以活化剂510综合性能较好,最佳用量为0.5质量份。     

Surface modification of synthetic vulcanized rubber

Surface modifications produced by treatments (mainly halogenation) of synthetic vulcanized styrene-butadiene rubber (SBR) leading to increased adhesion properties with polyurethane adhesives have been studied. T-peel tests, scanning electron microscopy (SEM), advancing contact angle measurements, infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) were used to analyze the nature of surface modifications produced in the rubber. Although some surface heterogeneities were created, physical treatments (ultrasonic cleaning, solvent wiping, abrasion) did not noticeably increase the adhesion strength because certain abhesive substances (e.g. zinc stearate, paraffin wax) cannot be removed from the rubber surface by such treatments. Chemical treatment (chlorination) was carried out using ethyl acetate solutions of trichloroisocyanuric acid (TCI) (1,3,5-trichloro-1,3,5-triazine-2,4,6-trione). Chlorination of SBR with trichloroisocyanuric acid produced a significant improvement in T-peel strength, due to the contribution of mechanical (surface roughness, microcracks), thermodynamical (increase of polar contribution to the surface energy) and chemical (removal of abhesive substances, creation of polar groups) rubber surface modifications. The strong adhesion between the chlorinated SBR surface and the polyurethane adhesive was due to the presence of oxidized species of >C=O, -C-OH and -COR type. Chlorination of SBR is a fast reaction which needs only a small concentration of chlorination agent (< 1 wt% TCI/ethyl acetate) to produce high adhesion levels. An increased amount of TCI facilitated the chlorination reaction progressing from the exterior to the internal rubber bulk; however, although a thicker layer of chlorinated rubber created no further increase in adhesion strength was obtained.     

氯丁橡胶硫化胶粉的应用

研究了汽车V带，同步带后加工中生成的胶粉在天然橡胶、丁苯橡胶及氯丁橡胶中的应用。胶粉粒径60目以上，用量60份时对胶料物理机械性能基本无影响，对耐油性有所改善。