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1.
Hybrid composites of epoxy novolac reinforced with short bagasse fibres and short coir fibres were prepared. The mechanical and dynamic mechanical properties of these bagasse-coir hybrid fibres reinforced epoxy novolac composites were investigated with reference to different layering patterns of the composites. The tensile properties of the tri-layer composites are recorded higher than those of the bi-layer composites, whereas the flexural properties of the tri-layer composites are lower than bi-layer composites. The tensile strength of the intimate mix composite is comparable with trilayer composite having bagasse as skin material. The effect of layering pattern on storage modulus (E′), damping behavior (tan δ), and loss modulus (E″) was studied as a function of temperature and frequency. The E′ values of the bi-layer composites are recorded lower than those of tri-layer (bagasse/coir/bagasse) and intimately mixed hybrid composites. The minimum E′ value is obtained for the composites made with coir as skin layer. Bi-layer composite shows maximum damping property. The theoretical modeling showed good correlation with experimental results at above glass transition temperature (T g ), while theoretical model deviates experimental data at lower T g . The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites.  相似文献   

2.
Based on the situ preparation of silica nanoparticles (SiO2) on the surface of Graphene nanoplatelets (GNPs) in the previous work, these unique three dimensional (3D) materials were introduced into epoxy resin to study the reinforcing and toughening synergy effect on the composites. Firstly, the tensile tests showed that Graphene/SiO2 hybrid materials attached with different size of SiO2 particles exhibited different reinforcing and toughening effect on the composites. With the increasing of the diameter of SiO2 particles, the toughness and strength properties of the composites firstly improved and then decreased, and when the average diameter was 0.14 μm, the elongation reached the max.. Meanwhile, the fractured surfaces presented on SEM images were consistent with the results of the tensile tests, which further explained the hybrid materials increased the interfacial adhesion between the fillers and matrix, leading to significant improvement in mechanical properties. Moreover, the DSC curves demonstrated that Graphene/SiO2 hybrid materials accelerated the curing process of epoxy resin due to the cross-link structure between fillers and matrix. Lastly, the crack propagation modes were built to clarify the synergy effect mechanism of reinforcing and toughening on nanoparticles/epoxy resin composites.  相似文献   

3.
The present paper is concerned with the effect of cork and rice husk ash micro particles fillers on the mechanical properties (flexural resistance, fracture toughness, impact absorbed energy, elastic and viscous moduli) of polyester based composite. Composite sheets were hand molded using weight filler fractions of 1, 2.5, and 5 %. Flexural strength of filled materials was much lower than the polyester matrix, with more pronounced effect for cork powder, decreasing significantly with filler content increases. Fracture toughness decreases also on the filled composites. Using cork powder fracture toughness decreases significantly when filler content increases, while for rice husk ash filler a slight increase was observed. Both fillers improve absorbed impact energy, peaking at about 2.5 % of filler content. Best improvements were obtained using rice husk ash powder, reaching about 30 %. Both fillers increase glass transition temperature and the maximum use temperature and also the elastic modulus compared with polyester. It can be concluded from this study that the used agro-waste materials are attractive reinforcements from the standpoint of their mechanical properties.  相似文献   

4.
The basalt chopped fiber reinforced epoxy composites using different curing systems were prepared in order to investigate the thermal characteristics of the composites. 2 different curing systems for bisphenol F type epoxy resin — an epoxy-amine curing system and an epoxy-anhydride curing system — were selected and used to investigate the interaction between matrix resin and basalt fiber in the means of thermal properties and physical properties. Through the evaluation of T g and thermal degradation behavior of both systems, it was deduced that the type of curing system as well as basalt fiber reinforcement have a great role in determining thermal properties of the composites. Also, the tensile and flexural properties of the composites were systematically evaluated in order to further understand the effect of curing agents on the interaction with basalt fiber.  相似文献   

5.
Glycerol-plasticized wheat gliadin bioplastics were prepared through thermo-molding method. The effect of glycerol content on the morphology and the mechanical properties of wheat gliadin bioplastics was studied. Morphology, tensile properties (tensile strength and elongation at break), dynamic mechanical properties and rheological properties were evaluated in relation to glycerol content. Experimental results reveal that the morphology, the glass transition temperatures (Tg) of both the gliadin-rich and the glycerol-rich domains and the tensile properties are closely linked to the glycerol content. The time–temperature superposition (TTS) fails to be applied to the dynamic loss modulus G″ (all temperatures) and the dynamic storage modulus G′ (above 80 °C) of wheat gliadin bioplastics.  相似文献   

6.
Unsaturated polyester (UP) resin has been blended with phenolic resin (PF) resole type at various ratios to obtain a homogeneous blend with improved flame resistance compared to its parent polymers. The polymer blend was reinforced with 20 wt% kenaf using hand lay out technique. Fourier transform infrared spectroscopy (FT-IR) was used to characterize changes in the chemical structure of the synthesized composites. The thermal properties of the composites were investigated using thermogravimetric analysis (TGA). The thermal stability of UP/PF kenaf composites co-varies with the PF content, as shown by the degradation temperature at 50 % weight loss. The char yield of the composites increases linearly with PF content as shown by the TGA results. The flammability properties of the composites were determined using the limiting oxygen index (LOI) and UL-94 fire tests. The LOI increased with the PF content while the composites exhibit improved flame retardancy as demonstrated by UL-94 test. The mechanical and morphological properties of the composites were determined by tensile test and scanning electron microscopy (SEM), respectively. The tensile strength and the Young’s modulus of the blend/composites slightly decreased with increasing PF content albeit higher than PF/kenaf fiber composites.  相似文献   

7.
The thermal behavior, morphology, ester-interchange reaction of Poly(trimethylene terephthalate) (PTT)/Poly(ethylene terephthalate) (PET) melt blends were investigated over the whole composition range(xPTT/(1-x)PET) using a twinscrew Brabender. The melt blends were analyzed by differential scanning calorimetry (DSC), nuclear magnetic resonance spectroscopy (13C-NMR), and scanning electron microscopy (SEM). Single glass transition temperature (T g ) and cold crystallization temperature (T cc ) were observed in all melt blends. Melt blends were found to be due to the ester-interchange reaction in PTT/PET blend. Also the randomness of copolymer increases because transesterification between PTT and PET increases with increasing blending time. This reaction increases homogeneity of the blends and decreases the degree of crystallinity of the melt blends. In PTT-rich blends, mechanical properties decrease with increase of PET content compared with that of pure PTT. And, in PET-rich blends, tensile modulus decreases with increase of PTT content, but tensile strength and elongation is similar to that of pure PET.  相似文献   

8.
This study presents the mechanical and thermal properties of environment-friendly composites made from recycled newspaper fibers reinforced recycled poly(ethylene terephthalate) (rPET) resin with the addition of styrene-ethylene-butylene-styrene grafted maleic anhydride (SEBS-g-MA) as compatibilizer. The effect of SEBS-g-MA addition (i.e., 10 phr) by using a twin-screw extruder to the rPET resin, followed by different fiber content (5, 10 and 15 wt.%) on the tensile, flexural and impact properties of the composites were determined. Stiffness of composites increased significantly compared to those of rPET/SEBS-g-MA blend. Fiber addition resulted in moderate increases in both tensile and flexural strength of the composites. Scanning electron microscope (SEM) photomicrographs of the impact fracture surfaces demonstrate good adhesion at 5 and 10 % fiber content. Differential scanning calorimetry (DSC) showed that the presence of newspaper fibers enhanced the nonisothermal crystallization kinetics and crystallinity. Thermal stability of the composites was improved as indicated by thermogravimetric analysis (TGA).  相似文献   

9.
Composites were prepared with 13, 23 30 and 40 % fiber and evaluated the mechanical performance in tensile, flexural and impact. The mechanical properties of these composites were also evaluated function of time at 110 °C thermal exposure. Caroa fibers were characterized by techniques such as thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the best mechanical properties were achieved for composites containing 23 to 30 % fiber. The incorporation of 23 % fiber caroa increased both the modulus of elasticity in the tensile test as the flexural strength and impact, the composite with 30 % fiber caroa showed higher tensile strength. The results show that the tensile and flexural strength of the composite decreased with time of thermal exposure. The thermal aging at 110 °C caused a decrease in tensile properties of the composites.  相似文献   

10.
The surface topography, tensile properties, and thermal properties of ramie fibers were investigated as reinforcement for fully biodegradable and environmental-friendly ‘green’ composites. SEM micrographs of a longitudinal and cross-sectional view of a single ramie fiber showed a fibrillar structure and rough surface with irregular cross-section, which is considered to provide good interfacial adhesion with polymer resin in composites. An average tensile strength, Young’s modulus, and fracture strain of ramie fibers were measured to be 627 MPa, 31.8 GPa, and 2.7 %, respectively. The specific tensile properties of the ramie fiber calculated per unit density were found to be comparable to those of E-glass fibers. Ramie fibers exhibited good thermal stability after aging up to 160°C with no decrease in tensile strength or Young’s modulus. However, at temperatures higher than 160°C the tensile strength decreased significantly and its fracture behavior was also affected. The moisture content of the ramie fiber was 9.9%. These properties make ramie fibers suitable as reinforcement for ‘green’ composites. Also, the green composites can be fabricated at temperatures up to 160°C without reducing the fiber properties.  相似文献   

11.
Since natural fiber/polymer composites are increasingly used, the development of safe and environmental friendly flame retarding bio-based composites is of great importance. But this issue must maintain the mechanical performance of these composites. To study these objectives, four levels of magnesium hydroxide Mg(OH)2 of (0, 10, 20, 30 phc) and two levels of nanoclay (0, 3 phc) were considered and incorporated into HDPE/wheat straw composites. Maleic anhydride grafted polyethylene (PE-g-MA) was also used as a compatibilizer at constant content. The samples were prepared by melt compounding and injection molding processes, respectively. The some properties of samples including burning rate and mechanical properties (tensile and impact strengths) were tested based on the ASTM standard. The results showed that the burning rate of samples decreased with increasing the nanoclay and Mg(OH)2 content. The tensile and impact strengths showed a marginal reduction by adding Mg(OH)2 from 10 phc to 30 phc and the tensile modulus and impact strength revealed an increase by increasing the amount of nanoclay up to 3 phc. Generally, these results confirmed that the fire retarding and mechanical properties of HDPE/wheat straw composites could be significantly improved with an appropriate combination of the nanoclay and Mg(OH)2 in the composites.  相似文献   

12.
Fully biodegradable and environment-friendly green composite specimens were made using ramie fibers and soy protein concentrate (SPC) resin. SPC was used as continuous phase resin in green composites. The SPC resin was plasticized with glycerin. Precuring and curing processes for the resin were optimized to obtain required mechanical properties. Unidirectional green composites were prepared by combining 65 % (on weight basis) ramie fibers and SPC resin. The tensile strength and Young’s modulus of these composites were significantly higher compared to those of pure SPC resin. Tensile and flexural properties of the composite in the longitudinal direction were moderate and found to be significantly higher than those of three common wood varieties. In the transverse direction, however, their properties were comparable with those of wood specimens. Scanning electron microscope (SEM) micrographs of the tensile fracture surfaces of the green composite indicated good interfacial bonding between ramie fibers and SPC resin. Theoretical values for tensile strength and Young’s modulus, calculated using simple rule of mixture were higher than the experimentally obtained values. The main reasons for this discrepancy are loss of fiber alignment, voids and fiber compression due to resin shrinking during curing.  相似文献   

13.
The dynamic mechanical properties such as storage modulus, loss modulus, and tan δ of banana fiber reinforced PF composites fabricated by RTM and CM techniques were investigated as a function of fiber content, fiber treatment, temperature and frequency. Storage modulus (E′) increases with increase in fiber content and records maximum for the composites having a fiber loading of 40 wt % at all temperature ranges. The loss modulus and damping increases to great extent by the addition of filler, a maximum was observed for filler with 10–20 wt % fiber content followed by a slight decrease in loss modulus and damping with increasing filler content. Alkali treatment of the fiber shows a great enhancement in E′ and T g of the composites. Comparison is made between the composites fabricated by RTM and CM. RTM composites exhibited higher storage modulus and lower damping compared to CM composites.  相似文献   

14.
Delamination is the most common failure mode in laminated composites due to the reduced strength in the through-the-thickness direction. Air-jet texturing was used to provide more surface contact between the fibres and the resin by producing bulk and loops in the yarn. The development and characterization of core-and-effect textured glass yarns and the effect of texturing on the mechanical properties of laminated composites were presented in the previous papers. This paper describes the effect of texturing on the inter-laminar fracture toughness (Mode I) of glass laminated composites. The composites of twill weave fabrics were developed from both the textured and non-textured yarn and fracture toughness is tested in warp and weft directions. Significant improvement was observed in the Mode I fracture toughness of the composites after texturing. The bulkier, loopy structure of the textured yarn provided more surface contact between the fibre and the resin and significantly improved the bonding strength.  相似文献   

15.
In this study, PLA/PC blends were prepared in order to investigate the effects of the addition of PC loading level into PLA matrix on the mechanical properties of these blends. After that, PLA/PC (70/30), which has the lowest tensile strength value, was selected as a control sample for the compatibilization study. Commercial styrene-acrylic multi-functional-epoxide oligomeric agent (SAmfE), styrene maleic anhydride copolymer (SMA), tetrasilanol phenyl polyhedral oligomeric silsesquioxane (T-POSS) and glycidyl isooctyl-polyhedral oligomeric silsesquioxane (G-POSS) were used as compatibilizers for PLA/PC blends. The variation of mechanical, thermal, structural and morphological properties were examined by conducting tensile tests, dynamic mechanical analyses, differential scanning calorimetry, Fourier Transform IR and scanning electron microscope analyses. Tensile test results showed that the tensile strength and elongation at break values of the PLA/PC blend compatibilized with SAmfE were higher than those of the other blends. DSC analyses revealed that Tg and Tm values of the blends were not significantly affected by compatibilizer but, degree of crystallinity was found to be sensitive to compatibilizer type. DMA results showed that the best mechanical properties were obtained for the PLA/PC/SAmfE blend. When all of the results evaluated, it was found that the SAmfE is the most effective compatibilizer among the using compatibilizer types for PLA/PC blends.  相似文献   

16.
Polymer matrix composites (PMCs) owing to their outstanding properties such as high strength, low weight, high thermal stability and chemical resistance are broadly utilized in various industries. In the present work, the influence of silanized CaCO3 (S-CaCO3) with 3-aminopropyltrimethoxysilane (3-APTMS) coupling agent at different values (0, 1, 3 and 5 wt.% with respect to the matrix) on the mechanical behavior of basalt fibers (BF)/epoxy composites was examined. BF-reinforced composites were fabricated via hand lay-up technique. Experimental results from three-point bending and tensile tests showed that with the dispersion of 3 wt.% S-CaCO3, flexural strength, flexural modulus, tensile strength and tensile modulus enhanced by 28 %, 35 %, 20 % and 30 %, respectively. Microscopic examinations revealed that the development of the mechanical properties of fibrous composites with the incorporation of modified CaCO3 was related to enhancement in the load transfer between the nanocomposite matrix and BF as well as enhanced mechanical properties of the matrix part.  相似文献   

17.
Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism.  相似文献   

18.
In this study, the maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MA) is used as the compatilizer for polylactic acid (PLA)/carbon fiber (CF) composites. The effects of SEBS-g-MA on the mechanical properties, thermal behavior, interfacial compatibility, and electrical characteristics of composites are then evaluated. The mechanical property tests indicate that when the amount of compatilizer increases, the tensile properties and flexural property of the composites decrease while their impact strength increases. The SEM results show that the compatilizer can decrease the interstices between PLA and CF, and thereby augments their interfacial compatibility. The differential scanning calorimetry (DSC) results confirm that the compatilizer results in a greater crystallization temperature and a greater crystallinity of the composites. The electrical characteristic results indicate that neither PLA nor SEBS-g-MA is not interfered with the conductive network that is constructed by CF, which is exemplified by an average electromagnetic shielding effect of above ?30 dB. This study confirms that SEBS-g-MA can improve interfacial compatibility and toughness, as well as attain good electrical characteristics of PLA/CF composites.  相似文献   

19.
Acrylonitrile-Butadiene-Styrene copolymers (ABS) reinforced with wood flour were investigated for rheological, mechanical and thermal properties. Three grades of commercial ABS resin (high flow (HF-ABS), medium impact (MI-ABS) and super high impact (SI-ABS) grades) were characterized using H-NMR and elemental analysis for the determination of co-monomer content. Wood flour from Para rubber trees treated with N-2 (aminoethyl)-3-(aminopropyl) trimethoxy silane was blended with ABS in the melt blending process using a twin-screw extruder. Wood flour contents used in this work were 0.0 %, 9.1 %, and 33.3 % wt. The composites with higher acrylonitrile contents showed higher melt viscosity especially at the low shear rate. Carreau’s model was used for curve-fitting. The extrudate swell ratio of the composites tended to increase at the shear rate of 10–500 s−1 and then decreased dramatically once the shear rate were further applied. Neat ABS and wood/ABS composites with higher butadiene content illustrated a higher swelling ratio. The neat MI-ABS and composites showed the highest ultimate tensile strength and modulus due to the butadiene content effect. As the wood flour loading was increased, the tensile modulus of all ABS composites increased with the sacrifice of the tensile strength of composites. The elongation at break and impact strength were noticeably the highest for wood/SI-ABS composites among all because of the effect of rubbery butadiene content. Thermal stability of plastic in 9.1 % wood in HF-ABS composites was improved compared with the neat HF-ABS due to the low acrylonitrile content.  相似文献   

20.
This paper presents the results of a current study on polypropylene matrix composites processed by injection, with two different glass fiber lengths and five different volume fractions. Physical and mechanical properties were obtained, namely flexural strength, stiffness modulus and fracture toughness. The mechanical properties of the composites increased significantly with the increase of the fibers volume fraction in agreement with the Counto model. The effect of water immersion time was also analysed. Immersion in water promotes a marked decrease in mechanical properties in the early seven-ten days, and afterwards tends to stabilize. Water causes a decrease of the relative strength which increases with fiber volume fraction and reaches about 29 % and 32 % for 20 % of 4.5 mm fiber length and for 25 % of 12 mm fiber length respectively, after 28 days immersion in water. Fracture toughness increases with fiber volume fraction and is always higher for 12 mm fiber length composites than for 4.5 mm fiber length composites.  相似文献   

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