A comparative study on some properties of wood plastic composites using canola stalk,Paulownia, and nanoclay

In this research, the reinforcing effect of fillers including canola stalk, paulownia and nanoclay, in polypropylene (PP) has been investigated. In the sample preparation, 50 wt% of lignocellulosic materials and 0, 3, and 5 wt% of nanoclay particles were used. The results showed that while flexural and tensile properties were moderately enhanced by the addition of nanoclay in the matrix, notched Izod impact strengths decreased dramatically. However, with increase in the nanoclay content (5 wt%), the flexural and tensile properties decreased considerably. The mechanical properties of composites filled with paulownia are generally greater than canola stalk composites, due to the higher aspect ratio. The thickness swelling and water absorption of the composites significantly decreased with the increase in nanoclay loading. Except tensile modulus, the differences between the type of fibrous materials and nanoclay contents had significant influence on physicomechanical properties. Morphologies of the composites were analyzed using transmission electron microscopy (TEM) and X‐ray diffraction (XRD), and the results showed increased d‐spacing of clay layers indicating enhanced compatibility among PP, clay, and lignocellulosic material. TEM micrographs also confirmed that the composites containing 3 wt% nanoclay had uniform dispersion and distribution of clay layers in the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of layering pattern on the physical,mechanical, and thermal properties of jute/bagasse hybrid fiber‐reinforced epoxy novolac composites

In this study, randomly oriented short jute/bagasse hybrid fiber‐reinforced epoxy novolac composites were prepared by keeping the relative volume ratio of jute and bagasse of 1:3 and the total fiber loading 0.40 volume fractions. The effect of jute fiber hybridization and different layering pattern on the physical, mechanical, and thermal properties of jute/bagasse hybrid fiber‐reinforced epoxy novolac composites was investigated. The hybrid fiber‐reinforced composites exhibited fair water absorption and thickness swelling properties. To investigate the effect of layering pattern on thermomechanical behavior of hybrid composites, the storage modulus and loss factor were determined using dynamic mechanical analyzer from 30 to 200°C at a frequency of 1 Hz. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy. The morphological features of the composites were well corroborated with the mechanical properties. Thermogravimetric analysis indicated an increase in thermal stability of pure bagasse composites with the incorporation of jute fibers. The incorporation of hybrid fibers results better improvement in both thermal and dimensional stable compared with the pure bagasse fiber composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Enhanced properties of phthalonitrile‐terminated polyarylene ether nitriles embedded with hybrid MWCNT–boehmite nanocomposites

The main motivation of the present work was to fabricate novel multifunctional polymer‐based nanocomposites. The nanocomposites embedded with multi‐walled carbon nanotube‐boehmite (MWCNT‐boehmite) were prepared via hot pressure casting technique. The MWCNT coated with boehmite were synthesized by hydrothermal synthesis. Subsequently, as‐prepared MWCNT‐boehmite was added into the phthalonitrile‐terminated polyarylene ether nitriles (PEN‐t‐CN) matrix in order to benefit from the synergetic effect of MWCNT and boehmite. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) X‐ray diffraction (XRD), and Fourier transform infrared (FTIR) were employed to confirm the existence of MWCNT‐boehmite in our article. Furthermore, the structures, fracture morphologies, thermal, mechanical and dielectric properties of the nanocomposites were investigated, respectively. SEM images indicated that the MWCNT‐boehmite was homogeneously dispersed in the polymer, which acted as an essential factor to ensure good physical properties. The TGA analysis showed that the incorporation of MWCNT‐boehmite enhanced the thermal stability of the nanocomposites with initial degradation temperature (T_id) increasing from 458 to 492°C, while that of the pure PEN‐t‐CN was 439°C. The mechanical testing proved that significant enhancement of mechanical properties has been achieved. The tensile strength of PEN‐t‐CN/MWCNT‐boehmite composites with 3 wt% MWCNT‐boehmite reached the maximum (78.33 MPa), with a 41.7 % increase compared to the pure polymer. More importantly, the unique dielectric properties were systematically discussed and the results demonstrated that dielectric properties exhibited little dependency on frequency. For the incorporation of hybrid filler, the positive impact of MWCNT‐boehmite hybrid material resulted in polymer‐based nanocomposites with enhanced physical properties. POLYM. COMPOS., 36:2193–2202, 2015. © 2014 Society of Plastics Engineers     

Synthesizing multi‐walled carbon nanotube‐polymethyl methacrylate conductive composites and poly(lactic acid) based composites

Multi‐walled carbon nanotube was modified with polymethyl methacrylate (MWCNT‐PMMA) by in situ solution radical polymerization in the presence of 2,2′‐Azobis (isobutyronitrile) as an initiator. The products with different addition of methyl methacrylate (MMA) were pressed into slices to prepare specimens for electrical conductivity testing. It was found that the MWCNT‐PMMA nanocomposites demonstrate excellent electrical conductivity. To investigate the microsphere morphology and the colloidal surfactant of MWCNTs in MWCNT‐PMMA composites, samples were submitted to scanning electron microscopy and transmission electron microscopy. The thermogravimetric analysis of the prepared composites confirmed that MWCNTs as a thermal stabilizer for PMMA, which could have a wide range of potential applications, such as in catalysts, sensors, environmental remediation, and energy storage. Two series of poly(lactic acid) (PLA) based biocomposites with different MMA additions and MWCNT‐PMMA composites contents were prepared with twin‐screw extruding and injection molding. The results show the mechanical properties changed a little with the MMA and MWCNT‐PMMA composites contents increasing, which suggested the well compatibility between MWCNT‐PMMA composites and PLA. POLYM. COMPOS., 37:503–511, 2016. © 2014 Society of Plastics Engineers     

Hybrid composite using recycled polycarbonate/waste silk fibers and wood flour

In this work, hybrid composite materials were made from the combination of waste silk fibers (WSFs) and poplar wood flour (PWF) as reinforcement, recycled polycarbonate (RPC) as polymer matrix, and silane as coupling agent. RPC was obtained from waste compact discs. The effects of fiber type and loading on the mechanical and physical properties of the composites were studied. Experimentally, it was found that the weight content of PWF is a key parameter that would substantially influence the mechanical properties of the samples. The obtained results showed that tensile and flexural strengths and moduli of the composites were significantly enhanced with the addition of biofibers in both types (fiber and flour), as compared with neat RPC. However, the increase in WSFs and PWF contents substantially improved the notched Izod impact strength, but reduced the thermal stability. The significant improvements in mechanical properties of the composites with the incorporation of WSF and PWF were further supported by scanning electron microscopy micrographs. Composites containing more fraction of WSF exhibited higher water absorption (WA) compared with PWF‐filled composites. In addition, composite with higher WSF and PWF (30 wt%) loading showed maximum WA during the whole duration of immersion. POLYM. COMPOS., 37:1667–1673, 2016. © 2014 Society of Plastics Engineers     

Preparation and mechanical properties of waterborne polyurethane/carbon nanotube composites

Waterborne polyurethane (WBPU) and multiwalled carbon nanotubes (CNTs) composite films with 0–4.0 wt% CNTs were prepared by ultrasonic dispersion of carboxylic acid‐functionalized CNTs in WBPU followed by emulsion casting process. The elongations at break of the WBPU/CNTs composites increase with the incorporation of CNTs. The tensile strength and crystallinity of the nanocomposite films with lower CNTs contents (<2 wt%) increase obviously; while the tensile strengths of the composites with more CNTs (≥2 wt%) decrease, in contrast to the pure PU film. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that the CNTs are uniformly dispersed in the composites incorporated with lower CNTs contents (≤1.5 wt%). However, aggregation of CNTs increased with increasing CNTs content in the WBPU/CNTs composites, causing the macrophase separation. The dispersion state of the CNTs affects the crystallinity of the PU matrix and the phase separation of the composites, which are two key factors to influence the mechanical properties of the WBPU/CNTs composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation and properties of polyurethane/multiwalled carbon nanotube nanocomposites by a spray drying process

A spray drying approach has been used to prepare polyurethane/multiwalled carbon nanotube (PU/MWCNT) composites. By using this method, the MWCNTs can be dispersed homogeneously in the PU matrix in an attempt to improve the mechanical properties of the nanocomposites. The morphology of the resulting PU/MWCNT composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM observations illustrate that the MWCNTs are dispersed finely and uniformly in the PU matrix. X‐ray diffraction results indicate that the microphase separation structure of the PU is slightly affected by the presence of the MWCNTs. The mechanical properties such as tensile strength, tensile modulus, elongation at break, and hardness of the nanocomposites were studied. The electrical and the thermal conductivity of the nanocomposites were also evaluated. The results show that both the electrical and the thermal conductivity increase with the increase of MWCNT loading. In addition, the percolation threshold value of the PU composites is significantly reduced to about 5 wt % because of the high aspect ratio of carbon nanotubes and exclusive effect of latex particles of PU emulsion in dispersion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Amino functionalization of multiwalled carbon nanotubes by gamma ray irradiation and its epoxy composites

In this paper, γ‐ray radiation technique was utilized to simply functionalize multi‐walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs (MWCNTs‐Am) was proven and the physicochemical properties of MWCNTs before and after radiation grafting modifications were characterized using FT‐IR, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the γ‐ray radiation had the visible effects on the surface properties of MWCNTs. The effects of various functionalized MWCNTs on morphological, thermal, and mechanical properties of an epoxy‐based nanocomposite system were investigated. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy‐based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT‐Am showed 13.0% increase in tensile strength, 20.0% increase in tensile modulus, and 24.1% increase in thermal decomposition temperature. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Effects of novolac resin modification on mechanical properties of carbon fiber/epoxy composites

The epoxy resin matrix of carbon fiber (CF)‐reinforced epoxy composites was modified with novolac resin (NR) to improve the matrix‐dominated mechanical properties of composites. Flexural strength, interlaminar shear strength (ILSS), and impact strength were measured with unfilled, 7 wt% NR, 13 wt% NR, and 18 wt% NR filled to epoxy to identify the effect of adding NR on the mechanical properties of composites. The results showed that both interfacial and impact properties of composites were improved except for flexural property. The largest improvement in ILSS and impact strength were obtained with 13 wt% loading of NR. ILSS and impact strength were improved by 7.3% and 38.6%, respectively, compared with the composite without NR. The fracture and surface morphologies of the composite specimens were characterized by scanning electron microscopy. Intimate bonding of the fibers and the matrix was evident with the content of 7–13 wt% NR range. Decrease of crosslinking density and formation of NR transition layer were deduced with adding NR. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Sugarcane bagasse reinforced phenolic and lignophenolic composites

Lignin, extracted from sugarcane bagasse by the organosolv process, was used as a partial substitute of phenol (40 w/w) in resole phenolic matrices. Short sugarcane fibers were used as reinforcement in these polymeric matrices to obtain fiber‐reinforced composites. Thermoset polymers (phenolic and lignophenolic) and related composites were obtained by compression molding and characterized by mechanical tests such as impact, differential mechanical thermoanalysis (DMTA), and hardness tests. The impact test showed an improvement in the impact strength when sugarcane bagasse was used. The inner part of the fractured samples was analyzed by scanning electron microscopy (SEM), and the results indicated adhesion between fibers and matrix, because the fibers are not set free, suggesting they suffered a break during the impact test. The modification of fiber surface (mercerization and esterification) did not lead to an improvement in impact strength. The results as a whole showed that it is feasible to replace part of phenol by lignin in phenolic matrices without loss of properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 880–888, 2002     

A comparative studies on dispersion of multiwall carbon nanotubes in poly (ethylene oxide) matrix using dicarboxylic acid and amino acid based modifiers

A comparative study on the tensile properties of poly(ethylene oxide) (PEO)/multiwall carbon nanotubes (MWCNT) composites were conducted using sodium salt of 6‐aminohexanoic acid (SAHA) and half neutralized dicarboxylic acids having different number carbon atoms. Among all the modifiers, the sodium salt of 6‐aminohexanoic acid‐based composite showed the best tensile properties. The good dispersion of MWCNT and the resulting enhancement in thermomechanical properties can be attributed to the cation–π interaction between SAHA with MWCNT and H‐bonding interaction of SAHA with PEO. The proposed cation–π interaction and H‐bonding interaction was explained by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopic analysis. The dispersibility of MWCNT in the PEO matrix was assessed by using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The crystallization behavior of PEO/MWCNT composites was studied and discussed using differential scanning calorimetry (DSC). The present approach does not disturb the π electron clouds of MWCNT as opposed to chemical functionalization strategy. POLYM. COMPOS., 34:1003–1011, 2013. © 2013 Society of Plastics Engineers     

Effect of curauá fiber content on the properties of poly(hydroxybutyrate‐co‐valerate) composites

Poly(hydroxybutyrate‐co‐valerate) (PHBV), a biodegradable polymer produced from a renewable microbiological source, was reinforced with varying amounts of curauá fibers (CFs). The composites were produced using a twin‐screw extrusion and injection process. Scanning electron microscopy showed poor adhesion between the matrix and fiber; however, mechanical testing showed that the addition of the fiber improved the mechanical properties. Composites with 20 and 30 wt% CF displayed the best properties; however, because of the difficulties in processing composites with a CF content of 30 wt%, it was concluded that the ideal content of CF was 20 wt%. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Polystyrene composites containing crosslinked polystyrene‐multiwalled carbon nanotube balls

Crosslinked polystyrene‐multiwalled carbon nanotube (PS‐MWCNT) balls, which act as conductive microfillers, were prepared by the in situ suspension polymerization of styrene with MWCNTs and divinyl benzene (DVB) as a crosslinking agent. The diameters of the synthesized crosslinked PS‐MWCNT balls ranged from 10 to 100 μm and their electrical conductivity was about 7.7 × 10^?3 S/cm. The morphology of the crosslinked PS‐MWCNT balls was observed by scanning electron microscopy and transmission electron microscopy. The change in the chemical structure of the MWCNTs was confirmed by Raman spectroscopy and Fourier transform infrared spectroscopy. The mechanical and electrical properties of the PS/crosslinked PS‐MWCNT ball composites were investigated. It was found that the tensile strength, ultimate strain, Young's modulus, and impact strength of the PS matrix were enhanced by the incorporation of the crosslinked PS‐MWCNT balls. In addition, the mechanical properties of the PS/crosslinked PS‐MWCNT ball composites were better than those of the PS/pristine MWCNT composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

Enzyme‐Catalyzed Synthesis of Conducting Polyaniline Nanocomposites with Pure and Functionalized Carbon Nanotubes

The in situ enzymatic polymerization of aniline onto multi‐walled carbon nanotubes (MWCNT) and carboxylated MWCNT (COOH‐MWCNT) is reported. Nanostructured composites were prepared by this method. Polymerization was catalyzed with the enzyme horseradish peroxidase at room temperature in aqueous medium of pH 4. Hydrogen peroxide was used in low concentration as the oxidant. The nanocomposites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM studies showed tubular morphology with uniformly distributed MWCNT in the nanocomposites. The SEM and TEM investigations revealed wrapping of the MWCNT with polyaniline (PANI) chains. TGA demonstrated that the PANI component is thermally more stable in PANI/COOH‐MWCNT compared to the PANI/MWCNT composites. The synthesized nanocomposites showed higher conductivity than pure PANI, which may be due to the strong interaction between the PANI chains and the MWCNT.     

Morphological effect of fillers on graphite reinforced polydicyclopentadiene based composites

Graphite reinforced polydicyclopentadiene (polyDCPD) composites were synthesized via the in situ ring‐opening metathesis polymerization (ROMP) of DCPD with vapor‐grown carbon fiber (VGCF), acidified multiwall carbon nanotube (a‐MWCNT), and mildly oxidized graphene oxide (MOGO) as distinctive reinforcing fillers, respectively. We studied the morphological effect of the fillers on the mechanical and thermal properties of graphite/polyDCPD composites. Mechanical property tests showed that the addition of VGCF greatly strengthened the tensile strength, the introduction of a‐MWCNT dramatically extended the elongation at break, whereas the incorporation of MOGO enhanced both performances of the resulting composites. Impact tests showed that the maximum mechanical performances of a‐MWCNT/polyDCPD and MOGO/polyDCPD composites both were got with 0.4 wt% of fillers (a‐MWCNT and MOGO) loading. Meanwhile, all of the reinforced composites exhibited increased thermal stabilities compared with the unfilled polyDCPD, confirmed by increased T_gs and thermal decomposition temperatures at 5 wt% weight loss. POLYM. COMPOS., 35:1918–1925, 2014. © 2014 Society of Plastics Engineers     

Indentation and scratch behavior of functionalized MWCNT–PMMA composites at the micro/nanoscale

Polymethylmethacrylate (PMMA) and functionalized multiwalled carbon nanotube (F‐MWCNT) based composite films were prepared using solution casting method. Nanoindentation and scratch measurements were carried out to study the influence of F‐MWCNT as the reinforcement on the mechanical properties of the composite at the sub‐micron scale. The composites were prepared with varying weight percentages of F‐MWCNT in the PMMA matrix. The composites containing an adequate amount (0.25 wt%) of F‐MWCNT was found to demonstrate the maximum nanomechanical properties, viz. hardness, elastic modulus, recovery index. Scratch resistance measured in terms of coefficient of friction, also showed maximum value for the PMMA composite reinforced with 0.25 wt% of F‐MWCNT. POLYM. COMPOS., 35:948–955, 2014. © 2013 Society of Plastics Engineers     

Recycled milk pouch and virgin LDPE‐LLDPE‐based jute fiber composites

The present investigation deals with the thermo‐mechanical recycling of post consumer milk pouches (LDPE‐LLDPE blend) and its use as jute fiber composite materials for engineering applications. The mechanical, thermal, morphological, and dynamic‐mechanical properties of recycled milk pouch‐based jute fiber composites with different fiber contents were evaluated and compared with those of the virgin LDPE‐LLDPE/jute fiber composites. Effect of artificial weathering on mechanical properties of different formulated composites was determined. The recycled polymer‐based jute fiber composites showed inferior mechanical properties as well as poor thermal stability compared to those observed for virgin polymer/jute fiber composites. However, the jute‐composites made with (50:50) recycled milk pouch‐virgin LDPE‐LLDPE blend as polymer matrix indicated significantly superior properties in comparison to the recycled milk pouch/jute composites. Overall mechanical performances of the recycled and virgin polymeric composites were correlated by scanning electron microscopy (SEM). The dynamic mechanical analysis showed that storage modulus values were lower for recycled LDPE‐LLDPE/jute composites compared to virgin LDPE‐LLDPE/jute composites throughout the entire temperature range, but an increase in the storage modulus was observed for recycled‐virgin LDPE‐LLDPE/jute composites. POLYM. COMPOS. 28:78–88, 2007. © 2007 Society of Plastics Engineers     

Synthesis and characterization of multiwalled carbon nanotube/polyurethane composites via surface modification multiwalled carbon nanotubes using silane coupling agent

Well‐dispersed multiwalled carbon nanotubes/polyurethane (MWCNTs/PU) composites were synthesized in situ polymerization based on treating MWCNTs with nitric acid and silane coupling agent. The morphology and degree of dispersion of the MWCNTs were studied using a high resolution transmission electron microscopy (HR‐TEM) and X‐ray powder diffraction (XRD). The result showed that MWCNTs could be dispersed still in the PU matrix well with the addition of 2 wt% MWCNTs. The thermal and mechanical properties of the composites were characterized by dynamic mechanical thermal analysis, thermogravimetric analysis, tensile, and impact testing. The result suggested that the glass transition temperature (T_g) of composites increased greatly with increasing MWCNTs content slightly, and the MWCNTs is also helpful to improve mechanical properties of composites. Furthermore, the composites have an excellent mechanical property with the addition of 0.5 wt% MWCNTs. The electrical property testing indicates that the MWCNTs can improve evidently the electrical properties of composites when adding 1 wt% MWCNTs to the PU matrix. The volume resistivity of composites reaches to an equilibrium value. POLYM. COMPOS., 33:1866–1873, 2012. © 2012 Society of Plastics Engineers     

Properties of kenaf fiber/polylactic acid biocomposites plasticized with polyethylene glycol

Biocomposites of kenaf fiber (KF) and polylactic acid (PLA) were prepared by an internal mixer and compression molding. PLA was plasticized with polyethylene glycol (PEG) (10 wt%) and evaluated as the polymer matrix (p‐PLA). Fiber loadings were varied between 0 and 40 wt%. The tensile, dynamic mechanical, and morphological properties and water absorption behavior of these composites were studied. Reinforcing effect of KF was observed when fiber loading exceeded 10 wt% despite of the inferior fiber‐matrix adhesion observed via scanning electron microscopy (SEM). Un‐plasticized PLA/KF composite exhibited higher tensile properties than its plasticized counterpart. Fiber breakage and heavily coated short pulled‐out of fibers were observed from the SEM micrographs of the composite. The presence of PEG might have disturbed the fiber‐matrix interaction between KF and PLA in the plasticized composites. Addition of PEG slightly improved the un‐notched impact strength of the composites. Dynamic mechanical analysis showed that the storage and loss moduli of p‐PLA/KF composites increased with the increase in fiber loading due to increasing restrictions to mobility of the polymer molecules. The tan delta of the composites in contrast showed an opposite trend. p‐PLA and p‐PLA/KF composites exhibited non‐Fickian behavior of water absorption. SEM examination revealed microcracks on p‐PLA and p‐PLA/KF surfaces. POLYM. COMPOS., 31:1213–1222, 2010. © 2009 Society of Plastics Engineers