Comparative properties of silica- and carbon black-reinforced natural rubber in the presence of epoxidized low molecular weight polymer

This work investigates the effect of epoxidized low molecular weight natural rubber (ELMWNR) in silica- and carbon black-filled natural rubber (NR) compounds on processing and mechanical and dynamic mechanical properties. The ELMWNRs with different mol% epoxide content were prepared from depolymerization of epoxidized NR using periodic acid in latex state to have a molecular weight in a range of 50 000–60 000 g/mol. Their chemical structures and actual mol% of epoxide were analyzed by 1H NMR. The ELMWNRs were added to the filled NR compounds as compatibilizers at varying loadings from 0 to 15 phr. The addition of ELMWNR decreases compound viscosity and the Payne effect, that is, filler–filler interaction, of the silica-filled compound. In the silica–silane compound and the compound with 28 mol% epoxide (ELMWNR-28), the compound viscosities are comparable. The optimal mechanical properties of silica-filled vulcanizates are obtained at the ELMWNR-28 loading of 10 phr. In contrast, the addition of ELMWNR to a carbon black-filled compound shows only a plasticizing effect. The incorporation of ELMWNR into NR compounds introduces a second glass transition temperature and affects their dynamic mechanical properties. Higher epoxide contents lead to higher loss tangent values of the rubber vulcanizates in the range of the normal service temperature of a tir

Effect of silane coupling agents on basalt fiber-epoxidized vegetable oil matrix composite materials analyzed by the single fiber fragmentation technique

The fiber-matrix interfacial shear strength (IFSS) of biobased epoxy composites reinforced with basalt fiber was investigated by the fragmentation method. Basalt fibers were modified with four different silanes, (3-aminopropyl)trimethoxysilane, [3-(2-aminoethylamino)propyl]-trimethoxysilane, trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane and (3-glycidyloxypropyl)trimethoxysilane to improve the adhesion between the basalt fiber and the resin. The analysis of the fiber tensile strength results was performed in terms of statistical parameters. The tensile strength of silane-treated basalt fiber is higher than the tensile strength of the untreated basalt fiber; this behavior may be due to flaw healing effect on the defected fiber surfaces. The IFSS results on the composites confirm that the interaction between the fiber modified with coupling agents and the bio-based epoxy resin was much stronger than that with the untreated basalt fiber. POLYM. COMPOS., 36:1205-1212, 2015. (c) 2014 Society of Plastics EngineersContract grant sponsor: Programme Support Research and Development (Polytechnic University of Valencia); contract grant number: PAID-00-12.Samper Madrigal, MD.; Petrucci, R.; Sánchez Nacher, L.; Balart Gimeno, RA.; Kenny, JM. (2015). Effect of silane coupling agents on basalt fiber-epoxidized vegetable oil matrix composite materials analyzed by the single fiber fragmentation technique. Polymer Composites. 36(7):1205-1212. https://doi.org/10.1002/pc.23023S12051212367Lopattananon, N., Kettle, A. P., Tripathi, D., Beck, A. J., Duval, E., France, R. M., … Jones, F. R. (1999). Interface molecular engineering of carbon-fiber composites. Composites Part A: Applied Science and Manufacturing, 30(1), 49-57. doi:10.1016/s1359-835x(98)00109-2Nishikawa, M., Okabe, T., & Takeda, N. (2008). Determination of interface properties from experiments on the fragmentation process in single-fiber composites. Materials Science and Engineering: A, 480(1-2), 549-557. doi:10.1016/j.msea.2007.07.067Rao, V., Herrera-franco, P., Ozzello, A. D., & Drzal, L. T. (1991). A Direct Comparison of the Fragmentation Test and the Microbond Pull-out Test for Determining the Interfacial Shear Strength. The Journal of Adhesion, 34(1-4), 65-77. doi:10.1080/00218469108026506Doan, T.-T.-L., Brodowsky, H., & Mäder, E. (2012). Jute fibre/epoxy composites: Surface properties and interfacial adhesion. Composites Science and Technology, 72(10), 1160-1166. doi:10.1016/j.compscitech.2012.03.025Koyanagi, J., Nakatani, H., & Ogihara, S. (2012). Comparison of glass–epoxy interface strengths examined by cruciform specimen and single-fiber pull-out tests under combined stress state. Composites Part A: Applied Science and Manufacturing, 43(11), 1819-1827. doi:10.1016/j.compositesa.2012.06.018Johnson, A. C., Hayes, S. A., & Jones, F. R. (2012). The role of matrix cracks and fibre/matrix debonding on the stress transfer between fibre and matrix in a single fibre fragmentation test. Composites Part A: Applied Science and Manufacturing, 43(1), 65-72. doi:10.1016/j.compositesa.2011.09.005Pupurs, A., Goutianos, S., Brondsted, P., & Varna, J. (2013). Interface debond crack growth in tension–tension cyclic loading of single fiber polymer composites. Composites Part A: Applied Science and Manufacturing, 44, 86-94. doi:10.1016/j.compositesa.2012.08.019TRIPATHI, D., & JONES, F. R. (1998). Journal of Materials Science, 33(1), 1-16. doi:10.1023/a:1004351606897Awal, A., Cescutti, G., Ghosh, S. B., & Müssig, J. (2011). Interfacial studies of natural fibre/polypropylene composites using single fibre fragmentation test (SFFT). Composites Part A: Applied Science and Manufacturing, 42(1), 50-56. doi:10.1016/j.compositesa.2010.10.007Kelly, A., & Tyson, W. R. (1965). Tensile properties of fibre-reinforced metals: Copper/tungsten and copper/molybdenum. Journal of the Mechanics and Physics of Solids, 13(6), 329-350. doi:10.1016/0022-5096(65)90035-9Altuna, F. I., Espósito, L. H., Ruseckaite, R. A., & Stefani, P. M. (2010). Thermal and mechanical properties of anhydride-cured epoxy resins with different contents of biobased epoxidized soybean oil. Journal of Applied Polymer Science, 120(2), 789-798. doi:10.1002/app.33097Harry-O’kuru, R. E., Mohamed, A., Gordon, S. H., & Xu, J. (2012). Syntheses of Novel Protein Products (Milkglyde, Saliglyde, and Soyglyde) from Vegetable Epoxy Oils and Gliadin. Journal of Agricultural and Food Chemistry, 60(7), 1688-1694. doi:10.1021/jf204701tPan, X., Sengupta, P., & Webster, D. C. (2011). High Biobased Content Epoxy–Anhydride Thermosets from Epoxidized Sucrose Esters of Fatty Acids. Biomacromolecules, 12(6), 2416-2428. doi:10.1021/bm200549cStemmelen, M., Pessel, F., Lapinte, V., Caillol, S., Habas, J.-P., & Robin, J.-J. (2011). A fully biobased epoxy resin from vegetable oils: From the synthesis of the precursors by thiol-ene reaction to the study of the final material. Journal of Polymer Science Part A: Polymer Chemistry, 49(11), 2434-2444. doi:10.1002/pola.24674Kim, H. (2012). Thermal characteristics of basalt fiber reinforced epoxy-benzoxazine composites. Fibers and Polymers, 13(6), 762-768. doi:10.1007/s12221-012-0762-zWang, H., Wang, G., Zhang, L., Jiang, Z., Guan, S., & Zhang, S. (2012). Influence of the addition of lubricant on the properties of poly(ether ether ketone)/basalt fiber composites. High Performance Polymers, 24(6), 503-506. doi:10.1177/0954008312443845Tehrani Dehkordi, M., Nosraty, H., Shokrieh, M. M., Minak, G., & Ghelli, D. (2013). The influence of hybridization on impact damage behavior and residual compression strength of intraply basalt/nylon hybrid composites. Materials & Design, 43, 283-290. doi:10.1016/j.matdes.2012.07.005Guillebaud-Bonnafous, C., Vasconcellos, D., Touchard, F., & Chocinski-Arnault, L. (2012). Experimental and numerical investigation of the interface between epoxy matrix and hemp yarn. Composites Part A: Applied Science and Manufacturing, 43(11), 2046-2058. doi:10.1016/j.compositesa.2012.07.015Pickering, K. L., Sawpan, M. A., Jayaraman, J., & Fernyhough, A. (2011). Influence of loading rate, alkali fibre treatment and crystallinity on fracture toughness of random short hemp fibre reinforced polylactide bio-composites. Composites Part A: Applied Science and Manufacturing, 42(9), 1148-1156. doi:10.1016/j.compositesa.2011.04.020Charlet, K., Jernot, J.-P., Gomina, M., Bizet, L., & Bréard, J. (2010). Mechanical Properties of Flax Fibers and of the Derived Unidirectional Composites. Journal of Composite Materials, 44(24), 2887-2896. doi:10.1177/0021998310369579Barreto, A. C. H., Esmeraldo, M. A., Rosa, D. S., Fechine, P. B. A., & Mazzetto, S. E. (2010). Cardanol biocomposites reinforced with jute fiber: Microstructure, biodegradability, and mechanical properties. Polymer Composites, 31(11), 1928-1937. doi:10.1002/pc.20990Bledzki, A. K., & Jaszkiewicz, A. (2010). Mechanical performance of biocomposites based on PLA and PHBV reinforced with natural fibres – A comparative study to PP. Composites Science and Technology, 70(12), 1687-1696. doi:10.1016/j.compscitech.2010.06.005Terenzi, A., Kenny, J. M., & Barbosa, S. E. (2006). Natural fiber suspensions in thermoplastic polymers. I. Analysis of fiber damage during processing. Journal of Applied Polymer Science, 103(4), 2501-2506. doi:10.1002/app.24704Herrera-Franco, P. J., & Drzal, L. T. (1992). Comparison of methods for the measurement of fibre/matrix adhesion in composites. 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Poly(lactic acid) composites reinforced with leaf fibers from ornamental variety of hybrid pineapple (Potyra).

While there have been many studies of fibers extracted from pineapple leaves as reinforcement in polymer composites, to date, only commercial varieties have been examined. This work aims to investigate the fibers from the leaves of a hybrid pineapple called Potyra as a mechanical reinforcement in a poly(lactic acid) (PLA) matrix. The fibers were pre-treated in a NaOH solution (1 wt%) and were incorporated into the PLA by a torque rheometer mixer followed by twin-screw extrusion. Samples of each composition were injected. The molded composites showed increases of tensile strength from 58.8 to 69.6 MPa, of Young?s modulus from 1.9 to 3.5 GPa, and of impact resistance from 28 to 44 J/m, and showed an increase of 58C in the heat deflection temperature (Abstract Figure). The measured tensile strength and Young?s modulus values are lower than the theoretical values obtained by micromechanics theory due to the pull-out of the matrix fiber and due to the orientation of the fibers in the composites. It was concluded that the pineapple hybrid fibers have potential for use as mechanical reinforcement in green composites. POLYM. COMPOS., 00:000?000, 2017. VC 2017 Society of Plastics Engineer

Adhesion of pineapple-leaf fiber to epoxy matrix: The role of surface treatments

Natural fibers are considered to have potential use as reinforcing agents in polymer composite materials because of their principle benefits: moderate strength and stiffness, low cost, and be an environmental friendly, degradable, and renewablematerial. Due to their inherently hydrophilic nature, they are prone to absorb moisture, which can plasticise or weaken theadhesion of fibers to the surrounding matrix and by this affect the performance of composites used in atmospheric humidity,particularly at elevated temperatures. The surface treatments are often applied to the fiber to improve the bond strengthbetween the fibers and matrix. This work discussed the effect of sodium hydroxide (NaOH) treatment and epoxy resin as acompatibilizing agent on interface properties of pineapple leaf fiber (PALF)-epoxy composites. A single-fiber fragmentationtest coupled with data reduction technique was employed to assess interface quality in terms of apparent interfacial shearstrength (IFSS or a) of untreated, NaOH, and epoxy resin treated PALFs-epoxy composites. Tensile properties of untreatedand treated PALFs were also examined. It was found that both treatments substantially increase a, corresponding to animproved level of adhesion. The improvement in the level of adhesion for the alkali and epoxy treated fiber composites wasdue to an increase in the physical bonding between the alkali treated fibers and the matrix, and due to a promoted compatibilitybetween the epoxy treated fibers and matrix, respectively

Compatibilization of natural rubber (NR) and chlorosulfonated polyethylene (CSM) blends with zinc salts of sulfonated natural rubber

A rubbery ionomer of zinc salt of sulfonated natural rubbers (Zn-SNR) was synthesized and used as a new compatibilizerfor the blends of natural rubber (NR) and chlorosulfonated polyethylene (CSM). Epoxidized natural rubber (ENR)was also used for the preparation of NR/CSM blends. The effect of ionomer concentration on melt viscosity of the 50/50(%wt/wt) NR/CSM blends at different constant shear rates was characterized. It was found that the incorporation of ionomerincreased shear viscosity of the blends, indicating an increase in interfacial interaction between the NR and CSM. Themaximum shear viscosity was observed when the ionomer of 10% by weight of NR was added into the blends. The tensile,tear, oil resistant properties and morphology of the various 20/80 NR/CSM blends with and without the Zn-SNR and ENR atthe 10% wt of NR were examined. The 100% modulus, tensile strength, tear strength and oil resistance of the compatibilizedblends improved over those of the uncompatibilized blends. The blends compatibilized with the Zn-SNR showed higher levelsof improvement in modulus, tensile and tear strength than those of ENR. The tensile strength of 20/80 blends with the Zn-SNRand ENR compatibilizers increased by 38 and 30% over the corresponding neat blends. Furthermore, the addition of ionomerand ENR resulted in decreased domain of dispersed NR phase size and improved interfacial adhesion between the NR andCSM, indicating enhanced blend compatibility. These results suggest that the Zn-SNR is a new effective compatibilizer forNR and CSM blends

Property enhancement of silica-filled natural rubber compatibilized with epoxidized low molecular weight rubber by extra sulfur

The properties of both compounds and vulcanizates of silica-filled natural rubber (NR) compatibilized with epoxidized low molecular weight natural rubbers (ELMWNRs) consisting of 12 and 28 mol% epoxide are investigated. The ELMWNRs with a molecular weight range of 50,000 to 60,000 g/mol are produced by depolymerization of epoxidized natural rubber (ENR) latex using periodic acid, and then used as compatibilizer in a range of 0 to 15 phr in virgin NR. The compounds with LMWNR without epoxide groups, and with bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent are also prepared for comparison purpose. Incorporation of ELMWNRs lowers Mooney viscosity and Payne effect to the level closed to that of silica/TESPT compound, and clearly enhances the modulus and tensile strength of vulcanizates compared to the compounds with no compatibilizer and LMWNR. The higher epoxide groups content results in the better tensile properties but somewhat less than the compound with TESPT. Addition of extra sulfur into the compounds with LMWNR and ELMWNRs to compensate for the sulfur released from silane molecule in the silica/TESPT system shows small influence on Mooney viscosity, but remarkably enhances 300% modulus, tensile strength and loss tangent at 60°C as a result of the better network formation

Compatibilization of Silica-filled Natural Rubber Compounds by Combined Effects of Functionalized Low Molecular Weight Rubber and Silane

Epoxidized low molecular weight natural rubber (ELMWNR) with 28 mol% epoxide groups and weight average molecular weight of 49,000 g mol−1 was prepared by oxidative degradation of epoxidized natural rubber (NR) using periodic acid in the latex state. ELMWNR-28 was used at 10 parts per hundred parts of rubber (phr) loading in combination with bis-(triethoxysilylpropyl) tetrasulfide (TESPT) as the silane coupling agent in the range of 0–4.5 phr in silica-reinforced NR compounds. The use of TESPT in combination with ELMWNR-28 gives lower mixing torques and compound viscosities compared with the use of TESPT alone and the system without any compatibilizer. The bound rubber content, modulus, and tensile strength of the compounds with only TESPT strongly depend on the TESPT loading. The use of ELMWNR-28 as a compatibilizer clearly improves such properties compared with the non-compatibilized systems. By adding TESPT into the compound with ELMWNR-28, the properties further improve with increasing TESPT loading. The combined effect of ELMWNR-28 at 10 phr with a small amount of TESPT at 1.5 phr results in compounds with superior processability (i.e. low Mooney viscosity and Payne effect), and only slightly lower modulus and reinforcement index (M300/M100) compared with the use of the optimum content of TESPT. This compatibilizer/TESPT combination has the environmental benefits that the ELMWNR is a naturally based product, and that the reduced amount of TESPT silane coupling agent emits a greatly reduced amount of ethanol during processin