Maleated natural rubber prepared through mechanochemistry and its coupling effects on natural rubber/cotton fiber composites

Maleated natural rubber (MNR) was prepared by blending natural rubber (NR) and maleic anhydride (MA) in an internal mixer at 150 °C through mechanochemistry. The graft reaction of MA onto NR and the hydrogen bonding formed between fiber and MA were confirmed by Fourier transformation infrared spectrometer (FTIR). The quantity of grafted MA increased with increasing MA content. The composites showed better mechanical properties with MNR that contains higher MA content. The MNR with 20 phr MA was used as a coupling agent. Kraus equation showed the incorporation of MNR favored the reinforcement of fiber. The composites with MNR showed higher modulus and tensile strength than those without MNR. The coarse surfaces of the pullout fibers and the high storage modulus of composites with MNR implied the enhancement of interfacial adhesion.     

Properties of (Low‐density polyethylene)/(natural rubber)/(water hyacinth fiber) composites: The effect of polyaniline

The effects of polyaniline (PANI)‐modified water hyacinth fiber on the properties of (low‐density polyethylene)/(natural rubber)/(water hyacinth fiber) (LDPE/NR/WHF) composites were studied. The composites were prepared by using a Brabender Plasticorder at 160^oC and a rotor speed of 50 rpm for 6 minutes. LDPE/NR/WHF_PANI composites exhibited higher tensile strength, Young's modulus, elongation at break, melting temperature, and electrical conductivity but lower molar sorption, capacitance, percentage crystallinity, and interparticle spacing than LDPE/NR/WHF composites. Scanning electron microscopy morphology showed a better interfacial adhesion of PANI‐modified water hyacinth fiber (WHF_PANI) and the LDPE/NR phases than when unmodified WHF was used. J. VINYL ADDIT. TECHNOL., 20:122–130, 2014. © 2014 Society of Plastics Engineers     

Mechanical,thermal, morphological,and curing properties of geopolymer filled natural rubber composites

The main objective of this work was to investigate influence of natural rubber (NR) types on mechanical, thermal, morphological, and curing properties together with relaxation behavior of geopolymer filled NR composites with and without bis(triethoxysilylpropyl) tetrasulfide (TESPT) silane coupling agent. Three alternative types of NR: unmodified NR, and epoxidized NR with 25 (ENR-25) or 50 mol % epoxide (ENR-50) were exploited. Rubber compounds filled with GP particles were prepared in an internal mixer at 60 °C and 130–150 °C for the ones with and without TESPT, respectively. It was found that incorporation of GP significantly affected cure characteristics and mechanical properties of the rubber composites. That is, decreasing cure time was observed from 11.6, 3.2, and 7.0 min in gum NR, ENR-25, and ENR-50 to 6.9, 2.1, and 5.0 min in NR/GP, ENR-25/GP, and ENR-50/GP compounds, respectively. Furthermore, the ENR-25/GP and ENR-50/GP composites showed finely dispersed GP particles which indicate high filler–rubber interactions. The in situ silanization with TESPT in rubber composites enhanced the mechanical properties of NR/GP and ENR-25/GP composites but no such enhancement was found in the ENR-50/GP composite. This matched the observations of Payne effect, maximum tan δ, and stress relaxation properties of the composites. We found that the ENR-25/GP composites exhibited the best overall properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47346.     

Effect of Poly(methyl Methacrylate) Modified Water Hyacinth Fiber on Properties of Low Density Polyethylene/Natural Rubber/Water Hyacinth Fiber Composites

The effect of poly(methyl methacrylate) modified water hyacinth fiber on properties of low density polyethylene (LDPE)/natural rubber (NR)/water hyacinth fiber (WHF) composites were investigated. The composites were prepared with Z-blade mixer at 180°C and rotor speed of 50 rpm. The poly(methyl methacrylate) modified water hyacinth fibers in LDPE/NR composites (LDPE/NR/WHF-_PMMA) gave a greater value of tensile strength, Young's modulus, glass transition temperature (Tg), melting temperature (Tm), and % crystallinity compared to unmodified water hyacinth fibers in LDPE/NR composites (LDPE/NR/WHF). FTIR analysis shows the presence of ester carbonyl group and C-O ester group in poly (methyl methacrylate) modified water hyacinth fiber. The SEM micrograph also shows a better interfacial adhesion between the fibers and LDPE/NR matrixes for LDPE/NR/WHF-_PMMA composites than LDPE/NR/WHF composites. LDPE/NR/WHF-_PMMA composites had a lower value of interparticle spacing compared to LDPE/NR/WHF composites thatenhanced the interparticle interaction between fiber and LDPE/NR matrixes.     

Enhancing interfacial adhesion performance by using poly(vinyl alcohol) in (low‐density polyethylene)/(natural rubber)/(water hyacinth fiber) composites

The effects of (a) the chemical modification of water hyacinth fiber by poly(vinyl alcohol) (WHF‐_PVA) and (b) loading on the properties of low‐density polyethylene (LDPE)/(natural rubber (NR))/(water hyacinth fiber (WHF)) composites were studied. Mechanical properties, water absorption behavior, morphology, and thermal properties were examined; X‐ray diffraction and infrared spectroscopic analysis were done. The results indicated that LDPE/NR/WHF‐_PVA composites had higher values of tensile strength, Young's modulus, melting temperature, and water absorption resistance but lower elongation at break than LDPE/NR/WHF composites. The LDPE/NR/WHF‐_PVA composites had better interfacial adhesion between the matrix and the fibers than LDPE/NR/WHF composites, as shown by SEM results. The LDPE/NR/WHF‐_PVA composites exhibited lower interparticle spacing than LDPE/NR/WHF composites, a feature which enhanced the interparticle interaction between the water hyacinth fibers and the LDPE/NR matrix. J. VINYL ADDIT. TECHNOL., 19:47–54, 2013. © 2012 Society of Plastics Engineers     

Influence of phenolic curative on crosslink density and other related properties of dynamically cured NR/HDPE blends

Dynamically cured 60/40 NR/HDPE blends with various amounts of phenolic curative were prepared in an internal mixer at 160°C. A simple blend (i.e., the blend without curative) was also prepared using the same materials and blend proportion for comparison purposes. Mechanical, dynamic, and morphological properties; swelling resistance and crosslink density of the blends were investigated. It was found that the thermoplastic vulcanizates (TPVs) gave superior mechanical and dynamic properties than the simple blend. Furthermore, the mechanical properties in terms of elongation at break, modulus and tensile strength and elastic response in dynamic test in terms of storage modulus increased with increased loading amount of the curative. The complex viscosity also increased but the tan δ and tension set decreased with increased loading level of the curative. The crosslink density of the TPVs was estimated based on the elastic shear modulus. It was found that the crosslink density of the blends increased with increased loading levels of the curative while the degree of swelling decreased. This correlated well with the trend of mechanical and dynamic properties. SEM micrographs were used to confirm the level of mechanical and dynamic properties. It was found that the simple blend at a given blend ratio exhibited co‐continuous phase morphology. However, the TPVs showed micron scale of vulcanized rubber domains dispersed in a continuous HDPE matrix. The size of vulcanized rubber domains decreased with increasing amounts of the curative. This led to greater interfacial adhesion between the phase and hence superior mechanical and dynamic properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology,interfacial interaction,and properties of a novel bioelastomer reinforced by silica and carbon black

A novel poly(diisoamyl itaconate‐co‐isoprene) (PDII) bioelastomer was prepared by redox emulsion polymerization based on itaconic acid, isoamyl alcohol, and isoprene. Carbon black (CB), silica, and silica with coupling agent (bis(3‐(triethoxysilyl)‐propyl)tetrasulfide [TESPT]‐silica) were used as fillers to reinforce the novel elastomer. The difference in morphology, interfacial interaction, thermal properties, and mechanical properties of PDII composites filled with different fillers was studied. The homogeneous dispersion of silica and CB in the PDII matrix was confirmed by scanning electron microscopy and transmission electron microscopy. Silica had homogenous dispersion possibly because of the formation of hydrogen bonds between the silica silanols and the PDII macromolecular chains. PDII/silica and PDII/TESTP‐silica have lower crosslink density and crosslinking rate than PDII/CB owing to the adsorption of accelerators by the silanols in the silica surfaces. PDII/silica had comparable tensile strength but higher elongation at break than PDII/CB. The tensile strength of PDII/TESPT‐silica was higher than PDII/CB and PDII/silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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     

空气等离子体处理芳纶纤维及其与天然橡胶/乳聚丁苯橡胶的黏合性能

考察了空气等离子体处理对芳纶纤维表面结构形态的影响,研究了空气等离子体和间苯二酚-甲醛-胶乳(RFL)浸胶处理芳纶纤维与天然橡胶(NR)/乳聚丁苯橡胶(ESBR)的黏合性能,并对经处理的芳纶纤维与NR/ESBR体系的界面层作了动态力学分析。结果表明,芳纶纤维经空气等离子体处理后,表面粗糙度增大,表面积增加,结晶度减小,但处理功率过大、处理时间过长时,芳纶纤维的表面又变得比较光滑、结晶度又呈增大趋势。随着等离子体处理时间的延长,芳纶纤维与NR/ESBR的黏合性能增强,但处理时间过长时,芳纶纤维与NR/ESBR的黏合性能下降;等离子体处理芳纶纤维经RFL进一步浸胶处理后,芳纶纤维与NR/ESBR的黏合性能大幅度提高。芳纶纤维与NR/ESBR的界面存在介于高模量芳纶纤维和低模量橡胶之间的过渡层。     

低共熔溶剂与偶联剂协同改性白炭黑对胎面胶性能的影响

研究了硅烷偶联剂(TESPT)与低共熔溶剂(DES)协同改性白炭黑对作为胎面胶的天然橡胶复合材料性能的影响.用傅里叶变换红外光谱分析了 TESPT和DES与白炭黑之间的相互作用,用橡胶加工分析仪和扫描电镜分析了白炭黑之间的相互作用,并测试了复合材料的硫化特性、力学性能和耐磨性,通过动态力学分析仪考察了其滚动阻力和抗湿滑...     

Cotton fibers reinforcement of HNBR: Control of fiber alignment and its influence on properties of HNBR vulcanizates

This article focuses on the reinforcement of hydrogenated acrylonitrile butadiene rubber (HNBR) by cotton fiber as natural reinforcing filler. The effect of fiber alignment on the properties of HNBR compounds and vulcanizates is investigated. Properties of interest include rheological behavior, cure, tensile, abrasion, and dynamic mechanical properties which are correlated to the magnitudes of state‐of‐mix, bound rubber content, crosslink density and fiber alignment. Results obtained reveal that mechanical properties of rubber composites are improved dramatically by the addition of cotton fiber due to the enhanced hydrodynamic effect in association with crosslink density. Furthermore, the degree of fiber alignment is found to depend strongly on shear strain. The results demonstrate the importance of fiber alignment controlled efficiently by shear strain. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41090.     

An investigation for the effect of recycled matrix on the properties of textile waste cotton fiber reinforced (T‐FRP) composites

The main objective of this research is to study the effect of recycled low density polyethylene (r‐LDPE) matrix on the tensile, impact, and flexural properties of the novel textile waste cotton fiber reinforced (T‐FRP) composites. For this purpose, the T‐FRP composites were manufactured by using two different matrix types; namely, virgin LPDE (v‐LDPE) and r‐LDPE, with different waste cotton fiber content. All composites were compatibilized by maleic anhydride‐LDPE (MA‐LDPE) in order to increase the interfacial adhesion between fibers and matrices. Differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analyzer studies were performed in order to characterize the materials. The results have shown that best tensile and flexural properties have been obtained from the composites with the content of 30 wt% cotton fiber, 5 wt% maleic anhydride‐LDPE, and 65 wt% recycled LDPE matrix. However, the impact properties of the composites were decreased drastically compared to the pure LDPE matrix. POLYM. COMPOS., 38:1231–1240, 2017. © 2015 Society of Plastics Engineers     

The effect of dynamic vulcanization on mechanical properties and water absorption of silica and rubberwood filled polypropylene/natural rubber hybrid composites

Dynamic vulcanized silica and rubberwood filled polypropylene (PP)/natural rubber (NR) hybrid composites were prepared using a Brabender plasticorder at 150°C and a rotor speed of 50 rpm for 12 minutes. The effectiveness of the dynamic vulcanization was indicated by the Brabender plastograms. The mechanical and water absorption properties of hybrid composites with different concentration of sulfur were investigated. Significant enhancement in mechanical properties, viz. tensile strength, stress at peak, Young modulus and flexural modulus were observed for dynamically vulcanized hybrid composites compared to unvulcanized hybrid composites. This has been attributed to the increase in crosslink density, which was manifested by a reduction of water absorption and increase of stabilization torque at the end of mixing stage with increasing sulfur concentration.     

Mechanical properties of surface‐modified ultra‐high molecular weight polyethylene fiber reinforced natural rubber composites

The mechanical properties of ultra‐high molecular weight polyethylene (UHMWPE) fibers reinforced natural rubber (NR) composites were determined, and the effects of fiber surface treatment and fiber mass fraction on the mechanical properties of the composites were investigated. Chromic acid was used to modify the UHMWPE fibers, and the results showed that the surface roughness and the oxygen‐containing groups on the surface of the fibers could be effectively increased. The NR matrix composites were prepared with as‐received and chromic acid treated UHMWPE fibers added 0–6 wt%. The treated UHMWPE fibers increased the elongation at break, tear strength, and hardness of the NR composites, especially the tensile stress at a given elongation, but reduced the tensile strength. The elongation at break increased markedly with increasing fiber mass fraction, attained maximum values at 3.0 wt%, and then decreased. The tear strength and hardness exhibited continuous increase with increasing the fiber content. Several microfibrillations between the fiber and NR matrix were observed from SEM images of the fractured surfaces of the treated UHMWPE fibers/NR composites, which meant that the interfacial adhesion strength was improved. POLYM. COMPOS., 38:1215–1220, 2017. © 2015 Society of Plastics Engineers     

Influence of complexing treatment and epoxy resin coating on the properties of aramid fiber reinforced natural rubber

In this work, natural rubber/aramid fiber (NR/AF) composites were prepared with master batch method. AF was modified by using epoxy resin (EP) and accelerator 2‐ethyl‐4‐methylimidazole (2E4MZ) through surface coating on the basis of the complexing treatment with CaCl₂ solution. Hydroxyl‐terminated liquid isoprene rubber (LIR) was regarded as a compatibilizer between EP and NR. It is found that the crystallinity on AF surface is decreased by complexing reaction with CaCl₂ solution. Swelling and mechanical properties of the vulcanized composites, such as swelling degree, tensile and tear strength, tensile modulus at 300% elongation, are measured, and the tensile fracture morphology and dynamic mechanical analysis of the composites are investigated. The results show that the mechanical properties of composites with modified fibers are improved obviously and interfacial adhesion between matrix and the fiber is enhanced, especially for the AF coated with EP and imidazole. The best comprehensive mechanical properties of the composites are obtained with using CaCl₂‐EP/2E4MZ system when the ratio of m(EP)/m(AF) is 3%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42122.     

Comparing effects of silanized silica nanofiller on the crosslinking and mechanical properties of natural rubber and synthetic polyisoprene

The effect of the same amount of precipitated silica nanofiller on the curing and mechanical properties of natural rubber and synthetic polyisoprene was investigated. The silica surfaces were pretreated with bis(3-triethoxysilylpropyl) tetrasulfide (TESPT) to chemically bond silica to rubber. The rubbers were primarily cured by using sulfur in TESPT, and the cure was optimized by the addition of accelerator and activator, which helped to form sulfur chemical bonds between the rubber and filler. Different amounts of accelerator and activator were needed to fully crosslink the filled rubbers. The hardness, tensile strength, elongation at break, stored energy density at break, tearing energy, and modulus of the vulcanizates improved substantially by the incorporation of the filler in the rubber. This was due to high level of rubber-filler adhesion and formation of chemical bonds between the rubber and TESPT. Interestingly, natural rubber benefited more from the filler than did synthetic polyisoprene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dynamic mechanical properties of oil palm microfibril‐reinforced natural rubber composites

The dynamic mechanical properties of macro and microfibers of oil palm‐reinforced natural rubber (NR) composites were investigated as a function of fiber content, temperature, treatment, and frequency. By the incorporation of macrofiber to NR, the storage modulus (E') value increases while the damping factor (tan δ) shifts toward higher temperature region. As the fiber content increases the damping nature of the composite decreases because of the increased stiffness imparted by the natural fibers. By using the steam explosion method, the microfibrils were separated from the oil palm fibers. These fibers were subjected to treatments such as mercerization, benzoylation, and silane treatment. Resorcinol‐hexamethylenetetramine‐hydrated silica was also used as bonding agent to increase the fiber/matrix adhesion. The storage modulus value of untreated and treated microfibril‐reinforced composites was higher than that of macrofiber‐reinforced composites. The T_g value obtained for this microfibril‐reinforced composites were slightly higher than that of macrofiber‐reinforced composites. The activation energy for the relaxation processes in different composites was also calculated. The morphological studies using scanning electron microscopy of tensile fracture surfaces of treated and untreated composites indicated better fiber/matrix adhesion in the case of treated microfibril‐reinforced composites. Finally, attempts were made to correlate the experimental dynamic properties with the theoretical predictions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation,characterization, and mechanical properties of poly(ε‐caprolactone)/polylactic acid blend composites

Mechanical properties of poly(ε‐caprolactone) (PCL) and polylactic acid (PLA) blend reinforced with Dura and Tenera palm press fibers were studied. Dicumyl peroxide (DCP) was used as compatibilizer in the blend composites. Fourier transforms infrared spectrophotometer (FTIR) and field emission scanning electron microscope (FESEM) was used to study the effect of treatment on the fibers and fiber/matrix adhesion respectively. The uncompatibilized blend composites exhibited higher Young's modulus than the compatibilized blend composites. Impact strength of compatibilized blend composites of Tenera fibers (FM) increased by 161% at 10 wt% fiber load more than the uncompatibilized blend composites at same fiber load. The Dura fibers (FN) enhanced impact strength by 133% at 10 wt% fiber load. Tensile strength increased by 40% for compatibilized FM blend composites. In conclusion, it was observed that DCP incorporation resulted in good interfacial adhesion as revealed by the FESEM micrographs and evidenced in the improved mechanical properties. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Possible use of ultra‐fine acrylonitrile butadiene rubber powder as filler in natural rubber vulcanizates

Possible use of ultra‐fine acrylonitrile butadiene rubber powder (UFNBRP) as a filler for natural rubber (NR) was investigated. The UFNBRP was added into NR at various concentrations, and the compound properties were determined. It is found that, with increasing UFNBRP loading, the compound viscosity is increased, whereas both scorch time and optimum curing time are significantly reduced. The results also reveal that UFNBRP has negative effect not only on crosslink density but also on most mechanical properties of the vulcanizate, such as tensile strength, tear strength, compression set, and abrasion resistance. The deterioration of these mechanical properties is thought to arise mainly from the combined effect of large phase size of the dispersed UFNBRP and low interfacial adhesion taking place from the polarity difference between UFNBRP and NR. Interestingly, it is found that, after aging, UFNBRP could promote postcuring phenomenon leading to increases of both relative 100% modulus and relative tensile strength. Oil resistance is also found to improve considerably with increasing UFNBRP loading. This improvement is mainly attributed to the dilution effect, i.e., the higher the UFNBRP loading, the lower the NR portion and, thus, the greater the oil resistance of the vulcanizate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of chemical modification of epoxy‐(ethylene diamine) on water hyacinth fibers (Eichhornia crassiper)‐filled (low‐density polyethylene)/(natural rubber) blends

The effects of modification by epoxy‐(ethylene diamine) (EED) on (water hyacinth fiber)‐filled (low‐density polyethylene)/(natural rubber) (LDPE/NR/WHF_‐EED) composites were studied. The LDPE/NR/WHF and LDPE/NR/WHF_‐EED composites were prepared by using a Brabender Plasticorder. LDPE/NR/WHF_‐EED showed higher tensile strength, Young's modulus, and elongation at break but lower molar sorption of toluene compared with LDPE/NR/WHF composites. The Fourier‐transform infrared radiation analysis indicated that the absorption peak at 1,648 cm^?1 exhibited the C? N band. This C? N band was formed from the bond of the epoxy group and the amine group in the WHF‐g‐epoxy‐(ethylene diamine) (WHF_‐EED). The scanning electron microscopic morphology of LDPE/NR/WHF_‐EED composites displayed rougher surfaces and less fiber pull, which improved the interfacial adhesion among the fiber/matrix. J. VINYL ADDIT. TECHNOL., 20:201–209, 2014. © 2014 Society of Plastics Engineers