Surface treatment of cellulose fibers with methylmethacrylate for enhanced properties of in situ polymerized PMMA/cellulose composites

Cellulose micro/nanofibers (CNF), prepared from jute fibers were surface treated with methyl methacrylate (MMA) for better dispersion into poly methyl methacrylate (PMMA) matrix. PMMA/cellulose composites were prepared by in situ suspension polymerization technique. The surface treatment of CNF was confirmed by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance (NMR) analysis. MMA‐treated cellulose micro/nanofibers (MCNF) demonstrated improved affinity and dispersion in MMA monomer as well as in the PMMA/cellulose composites. Thermal properties of the cellulose composites were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass transition temperature (T_g) of PMMA increased by nearly 19°C in the in situ cellulose composites compared to that of unreinforced PMMA as indicated by DSC. TGA showed increased thermal stability of the cellulose composites. Enhanced tensile properties as well as significantly lower moisture uptake were observed in the in situ prepared PMMA/cellulose composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39808.     

An investigation of sound absorption coefficient on sisal fiber poly lactic acid bio‐composites

In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline‐treated sisal fiber‐reinforced poly‐lactic‐acid bio‐composites were analyzed. The bio‐composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat‐treated and alkaline‐treated sisal fibers. Composites with heat‐treated sisal fibers were found to exhibit the best mechanical properties. Thermo‐gravimetric analysis (TGA) was conducted to study the thermal degradation of the bio‐composite samples. It was discovered that the PLA‐sisal composites with optimal heat‐treated at 160°C and alkaline‐treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber‐matrix adhesion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42470.     

Wood flour-high density polyethylene composites: Influence of silanization and esterification on mechanical properties

Silanization and esterification are strategies used to treat wood flour (WF) to produce surface functionalized hydrophobic WF leading to an improvement in dispersion and compatibility between wood phase and polymer phase. Silanization involves functionalization of alkyl groups by coupling trimethoxy (propyl) silane (MPS), and esterification functionalizes WF with ester groups, using acetic anhydride (Ac). Modified WF was incorporated into recycled high-density polyethylene (HDPE) to form reHDPE/mod-WF composite system. Both modifications produced highly hydrophobic WF surfaces which improved the dispersion in the reHDPE matrix; resulting in a significant difference in impact strength, specifically at 20 wt% filler, from 74.5 Jm⁻¹ to 146.3 Jm⁻¹ and 113.5 Jm⁻¹, that is, up to 96% and 52% for MPS-WF and Ac-WF, respectively. However, filler agglomeration higher than 20 wt% reduces the composite impact strength. The results herein demonstrate that alkyl-functionalized WF show excellent dispersion in the reHDPE system and is the preferred technique to improve system mechanical resilience as compared to esterification.     

Thermal,mechanical, and dielectric properties of aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) layered composites

In this study, a novel aluminum phosphate (AlPO₄) heat‐resistant layer reinforced with aluminum silicate fiber (ASF) was successfully compounded on a poly(ether sulfone) (PES) matrix via the preparation process of high‐temperature heat treatment and vacuum hot‐pressing sintering technique. The influence of the ASF content on the morphology, thermal, mechanical, and dielectric properties of the as‐fabricated aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) (ASF/AlPO₄–PES) layered composite was investigated. The results reveal that the incorporation of aluminum silicate fiber/aluminum phosphate (ASF/AlPO₄) heat‐resistant layer can significantly improve the thermal stability and mechanical performances of the PES matrix composites. Compared with the pristine PES, the ASF/AlPO₄–PES layered composite containing 8.0 wt % ASF exhibited better high‐temperature resistance properties (300 °C) and a lower thermal conductivity (0.16 W m^?1 K^?1). Furthermore, the dielectric constant and dielectric loss tangent of this PES matrix composite decreased to 2.16 and 0.007, respectively. Meanwhile, the frequency stability of the dielectric properties for the ASF/AlPO₄–PES layered composites was remarkably enhanced with increasing ASF addition at frequencies ranging from 10² Hz to 5 MHz. This was attributed to the existence of microscopic pores within the ASF/AlPO₄ layer and the strong interfacial bonding between the ASF/AlPO₄ layer and the PES matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45542.     

Effect of pulverized coal/carbon black hybrid fillers on mechanical properties and thermal stability of styrene butadiene rubber composites

Pulverized coal (coal) possesses a layered structure similar to graphite and is a potential reinforcing filler. In this paper, ball milling is used to reduce the particle diameter of coal. The coal is modified with KH-560 to obtain K-COAL and prepared K-COAL/styrene-butadiene rubber (SBR) composites. In addition, carbon black (CB) is modified to obtain CB-Si69, K-COAL and CB-Si69 are added to SBR in different ratios to prepare COAL/CB/SBR composites. The results show that the addition of K-COAL can improve the vulcanization performance, thermal stability, and mechanical properties of SBR composites, but the reinforcing effect is weak. In the COAL/CB/SBR composites, the vulcanization and mechanical properties of the composites gradually increase with the increase of CB, while those of the thermal stability decrease. The tensile strength of the 10 phr COAL/30 phr CB/SBR composite is 24.1 MPa, which is elevated by 1105% and 205% compared with the pure SBR and 40 phr K-COAL/SBR composites, respectively. The composites maintain high elasticity while the tensile strengths are greatly improved, and the mechanical properties are significantly enhanced. In conclusion, this paper provides a reference for the clean utilization of coal and shows new possibilities for finding new fillers to replace CB.     

The effect of silica addition on the microstructure and properties of polyethylene separators prepared by thermally induced phase separation

Novel composite polyethylene (PE) separators were prepared via thermally induced phase separation using SiO₂ as the inorganic dopant and dioctyl phthalate as solvent. Through the control of silica content, the microstructure, thermal and crystalline properties, electrolyte uptake, thermal stability, and mechanical properties of the as‐prepared separators were investigated. The results showed that the doped silica particles favored the formation of the large pore size. The crystalline degree of PE was enhanced when doping silica in the ternary system below 3 wt %. The liquid electrolyte uptake was increased from 30.2% to 63.2% with doping silica content at 5 wt % in the mixed system, which benefits from the large pore size structure and the hydrophilicity of silica. The thermal decomposition temperature of the composite PE separators is 40°C higher than the pure PE separator due to the steric stabilization and the more stable space structure induced by the doped silica. The tensile strength was increased from 12 MPa to 13.3 MPa when doping 1 wt % silica, but decreased with further silica addition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40724.     

Preparation,structural characterization,and properties of poly(methyl methacrylate)/montmorillonite nanocomposites by bulk polymerization

Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were synthesized by a simple technique of a monomer casting method, bulk polymerization. The products were purified by hot acetone extraction and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), examination of their mechanical properties, and light transmittance testing. Although XRD data did not show any apparent order of the MMT layers in the nanocomposites, TEM revealed parallel MMT layers with interlamellar spacings of an average of 9.8 nm and the presence of remnant multiplets of nonexfoliated layers. Therefore, PMMA chains were intercalated in the galleries of MMT. DSC and TGA traces also corroborated the confinement of the polymer in the inorganic layer by exhibiting the increase of glass‐transition temperatures and mass loss temperatures in the thermogram. Both the thermal stability and the mechanical properties of the products appeared to be substantially enhanced, although the light transmittances were not lost. Also, the materials had excellent mechanical properties. Measurement of the tensile properties of the PMMA/MMT nanocomposites indicated that the tensile modulus increased up to 1013 MPa with the addition of 0.6 wt % MMT, which was about 39% higher than that of the corresponding PMMA; the tensile strength and Charpy notched impact strength increased to 88 MPa and 12.9 kJ/m², respectively. As shown by the aforementioned results, PMMA/MMT nanocomposites may offer new technology and business opportunities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 348–357, 2005     

Preparation and properties of poly(lactic acid)/lignin-modified polyvinyl acetate composites

Poly(lactic acid)(PLA) has good application in the field of packaging because of its good biodegradability, tensile strength, and film-forming properties. However, the disadvantages of high brittleness and high cost limit the wider application of PLA. PLA/lignin-modified polyvinyl acetate (L-PVAc) composites with excellent toughness were prepared by melt blending PLA with modifier L-PVAc. The mechanical properties, thermal properties and morphology of the composites were characterized to evaluate the effect of L-PVAc content on the properties of the composites. The results showed that the introduction of L-PVAc could increase the impact strength, elongation at break, glass transition temperature, melting temperature and the degree of crystallinity of PLA/L-PVAc composites. When the L-PVAc content reached up to 20.0 wt%, the impact strength, elongation at break, glass transition temperature, melting temperature and the degree of crystallinity of the composites were increased by 298.2%, 167.5%, 3.8%, 1.8%, and 78.8%, respectively compared to pure PLA due to the good toughness of PVAc and heterogeneous nucleation of lignin. This research can promote the high-value utilization of lignin and the application of PLA in the fields of clothing, agriculture, medical and hygiene.     

Preparation and properties of modified aluminum diethylphosphinate flame retardant for low-density polyethylene

To improve the flame retardancy of low-density polyethylene (LDPE) and mechanical properties of LDPE composites, phenol-formaldehyde aluminum diethylphosphinate microcapsules (PF@ADP) was prepared by in-situ polymerization with phenol-formaldehyde (PF) resin as the wall material and halogen-free flame-retardant aluminum diethylphosphinate (ADP) as the core material. The effects of PF@ADP on flame retardancy and mechanical properties of LDPE were investigated by methods of combustion experiments, mechanical analysis, thermogravimetric analysis (TGA), and smoke density analysis. The results indicated that, compared with ADP/LDPE composites, the flame retardancy and mechanical properties of PF@ADP/LDPE were obviously improved. With the addition of 20 wt% PF@ADP (PF:ADP = 3:7), the limit oxygen index (LOI) of LDPE composites increased to 30.7% and UL-94 reached V-1 grade. The tensile strength and elongation at break reached 12.5 MPa and 431.2%, which was 20.2% and 23.1% higher than that of ADP/LDPE with the same addition. The addition of PF@ADP was beneficial to the smoke suppression of LDPE.     

Comparison of the effects of phenyl dichlorophosphate modified and unmodified β‐iron(III) oxide hydroxide on the thermal,combustion, and mechanical properties of ethylene–vinyl acetate/magnesium hydroxide composites

The objective of this study was to compare the impact of β‐iron(III) oxide hydroxide [β‐Fe(O)OH] and iron hydroxide modified with phenyl dichlorophosphate [β‐Fe(O)OPDCP] on the thermal, combustion, and mechanical properties of ethylene–vinyl acetate (EVA)/magnesium hydroxide (MH) composites. For the EVA/MH composites in combination with these iron‐containing co‐additives, β‐Fe(O)OH and β‐Fe(O)OPDCP both led to an increase in the thermal stability at higher temperatures. The results of microscale combustion calorimetry indicate that the peak heat‐release rate, total heat release, and heat‐release capacity, which are indicators of a material fire hazard, all decreased. Moreover, significant improvements were obtained in the limiting oxygen index (LOI) and Underwriters Laboratories 94 ratings. However, the EVA4 system reached a V‐0 rating, whereas the EVA3 system reached a V‐2 rating. The LOI values for the EVA3 and EVA4 systems were 35 and 39, respectively. A homogeneous and solid structure of char residue caused by β‐Fe(O)OPDCP was observed by scanning electron microscopy. Furthermore, because of the good interfacial compatibility between the fillers and the EVA matrix, the EVA4 system presented better mechanical properties than the EVA3 system. Thermogravimetric analysis/IR spectrometry showed that β‐Fe(O)OPDCP reduced the combustible volatilized products of EVA/MH. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40112.     

Influence of talc fillers on bimodal polyethylene composites for ground heat exchangers

In this study, a commercial grade of talc is used as filler in a bimodal high-density polyethylene (HDPE) used for the pressure pipe application. The composites are characterized by thermogravimetric analysis (TGA), differential scanning calorimetry, dynamic mechanical thermal analysis, and tensile testing. The results illustrate that the presence of talc has a considerable effect on the material properties and the pipe life-length. It is presented that the thermal stability measured by TGA is enhanced, while the oxidation induction time decreases in cooperation of the talc. The nucleation behavior of talc particles during crystallization has no obvious effect on melting temperature; however, an increase in crystallization temperature is evidenced. Storage modulus as recorded from the dynamic mechanical analysis is also increased in all composites, furthermore, the temperature of the α relaxation is shifted toward higher temperature and finally the strain hardening modulus for the HDPE/talc composites is assessed and compared to the neat HDPE as a measure of environmental stress crack resistance.     

Effects of fiber‐surface treatment on the properties of hybrid composites prepared from oil palm empty fruit bunch fibers,glass fibers,and recycled polypropylene

In this article, we report the effects of hybridization and fiber‐surface modification on the properties of hybrid composites prepared from recycled polypropylene (RPP), coupling agents, oil palm empty fruit bunch (EFB), and glass fibers through a twin‐screw extruder and an injection‐molding machine. The surface of the EFB fibers was modified with different concentrations (10–15 wt %) and temperatures (60–90°C) of alkali solutions. The structure and morphology of the fibers were observed with the help of Fourier transform infrared spectroscopy and scanning electron microscopy. Different types of composites were fabricated with untreated, alkali‐treated, and heat‐alkali‐treated fibers. Comparative analysis of the mechanical, structural, morphological, and thermal properties of the composites was carried out to reveal the effects of treatment and hybridization. The analysis results reveal that composites prepared from the alkali‐treated (in the presence of heat) fibers show improved mechanical, thermal, and morphological properties with a remarkably reduced water absorption. Additionally, the crystallinity of RPP also increased with the development of biaxial crystals. The improvement of various properties in relation to the structures and morphologies of the composites is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43049.     

Reinforcement of graphene nanoplatelets on plasticized poly(lactic acid) nanocomposites: Mechanical,thermal, morphology,and antibacterial properties

Plasticized poly(lactic acid) (PLA)‐based nanocomposites filled with graphene nanoplatelets (xGnP) and containing poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) with ratio 2 : 1 (2P : 1E) as hybrid plasticizer were prepared by melt blending method. The key objective is to take advantage of plasticization to increase the material ductility while preserving valuable stiffness, strength, and toughness via addition of xGnP. The tensile modulus of PLA/2P : 1E/0.1 wt % xGnP was substantially improved (30%) with strength and elasticity maintained, as compared to plasticized PLA. TGA analysis revealed that the xGnP was capable of acting as barrier to reduce thermal diffusion across the plasticized PLA matrix, and thus enhanced thermal stability of the plasticized PLA. Incorporation of xGnP also enhanced antimicrobial activity of nanocomposites toward Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41652.     

Effect of the talc filler content on the mechanical properties of polypropylene composites

This research examines the effect of a microsize/nanosize talc filler on the physicochemical and mechanical properties of filled polypropylene (108MF10 and 33MBTU from Saudi Basic Industries Corp. and HE125MO grade from Borealis) composite matrices. A range of mechanical properties were measured [tensile properties, bending properties, fracture toughness, notched impact strength (at the ambient temperature and ?20°C), strain at break, and impact strength] along with microhardness testing and thermal stability testing from 40 to 600°C as measured by differential thermal analysis and thermogravimetric analysis. Increasing filler content lead to an increase in the mechanical strength of the composite material with a simultaneous decrease in the fracture toughness. The observed increase in tensile strength ranged from 15 to 25% (the maximum tensile strength at break was found to be 22 MPa). The increase in mechanical strength simultaneously led to a higher brittleness, which was reflected in a decrease in the mean impact strength from the initial 18 kJ/m² (for the virgin polypropylene sample) to 14 kJ/m², that is, a 23% decrease. A similar dependency was also obtained for the samples conditioned at ?20°C (a decrease of 12.5%). With increasing degree of filling of the talc–polypropylene composite matrix, the thermooxidative stability increased; the highest magnitude was obtained for the 20 wt % sample (decomposition temperature = 482°C, cf. 392°C for the virgin polymer). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fabrication and properties of carbon nanotube/styrene–ethylene–butylene–styrene composites via a sequential process of (electrostatic adsorption aided dispersion)‐plus‐(melt mixing)

Carbon nanotube (CNT)/styrene–ethylene–butylene–styrene (SEBS) composites were prepared via a sequential process of (electrostatic adsorption assisted dispersion)‐plus‐(melt mixing). It was found that CNTs were uniformly embedded in SEBS matrix and a low percolation threshold was achieved at the CNT concentration of 0.186 vol %. According to thermal gravimetric analysis, the temperatures of 20% and 50% weight loss were improved from 316°C and 352°C of pure SEBS to 439°C and 463°C of the 3 wt % CNT/SEBS composites, respectively. Meanwhile, the tensile strength and elastic modulus were improved by about 75% and 181.2% from 24 and 1.6 MPa of pure SEBS to 42 and 4.5 MPa of the 3 wt % CNT/SEBS composite based on the tensile tests, respectively. Importantly, this simple and low‐cost method shows the potential for the preparation of CNT/polymer composite materials with enhanced electrical, mechanical properties, and thermal stability for industrial applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40227.     

Interface engineering for the improvement of mechanical and thermal properties of covalent functionalized graphene/epoxy composites

Functionalized reduced graphene oxide (GO)/epoxy composites are fabricated through solution mixing. GO is functionalized using 3‐amino‐1,2,4‐triazole (TZ) in presence of potassium hydroxide (KOH). KOH is expected to serve dual role as catalyst for nucleophilic addition reaction between GO and TZ, and also as reducing agent. The grafting of TZ moiety on GO is confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The prepared composites show remarkable improvement in mechanical and thermal stability. The fracture toughness of the composites (critical stress intensity factor, K_IC) achieved from single edge notched bending testing is improved by ～111% against pure epoxy at 0.1 wt % loading of TZ functionalized GO. Further, the tensile strength and Young's modulus are improved by ～30.5% and 35%, respectively. Thermal stability of the composites as investigated by thermogravimetric analysis showed 29 °C rise in onset degradation temperature for 0.1 wt % TZ functionalized GO incorporated composite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46124.     

Flame retardant and mechanical properties of epoxy composites with ammonium polyphosphate and hyperbranched silicon-containing polymers

The epoxy resin was mixed with ammonium polyphosphate (APP) and hyperbranched silicon-containing polymers (HBP-B2). The cured composites were investigated by thermogravimetric analysis, Underwriters Laboratory standard for the flammability properties under vertical burning (UL-94V), and limited oxygen index (LOI) test methods. The LOI of 43.5 and could be obtained at the weight ratio of 70:25:5 for the epoxy resin:APP:HBP-B2, Sample A25B5, and the LOI was higher than that of the composite with 30 wt % APP only, Sample A30B0, of which the LOI was 34.5. It suggested that the HBP-B2 could cooperate with the epoxy/APP composite to form a more effective protection layer during combustion, which resulted in a higher second-stage thermal degradation temperature. During the UL-94V test, the flame was extinguished immediately once the burner was removed. Furthermore, the tensile and impact strength of the epoxy/APP composite could also be improved by using HBP-B2 compound as the toughening agent. The composite containing 20% of APP and 10% of HBP-B2, Sample A20B10, still had excellent flame retardant properties with a V-0 rating. Moreover, the tensile strength and impact strength of that composite got 19 and 25% increases compared with the Sample A30B0, which contained 30% of APP only. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48857.     

Characteristics of murta bast fiber reinforced epoxy composites

The growing global concern over environment protection has led to the application of natural fiber reinforced polymer composites as alternative materials in manufacturing sectors. Various natural fibers are therefore being explored for reinforcement of polymer matrices. In the present work, murta bast fibers of varying length and weight percent are mixed randomly with the epoxy matrix and the composites are prepared from these mixtures by using the hand lay‐up method. The composites are characterized on the basis of density, thermal gravimetric analysis, infrared spectroscopy, scanning electron microscopy, tensile strength, flexural strength, compressive strength, impact strength, and Rockwell hardness studies. Tensile, flexural, and compressive moduli of the composites are also determined. The tensile strength of the composite was analyzed in the light of the different analytical models. Composites containing 30 weight % fibers of length 25 or 35 mm have the optimum mechanical properties. Murta bast fiber has the characteristics to become a good natural material for reinforcement. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44142.     

Enhancement in electrical and thermal performance of high-temperature vulcanized silicone rubber composites for outdoor insulating applications

High-temperature vulcanized silicone rubber composites are highly desirable as outdoor insulating materials due to their immense thermal and electrical performance. The aim of this work is to study the role of co-combined fillers (modified fumed silica [MFS], titanium dioxide [TiO₂], with graphene [G]) on electrical and thermal properties of silicone rubber (S) composites. The dielectric response of S/MFS_10 phr and S/TiO₂_20 composites tailored with 2 phr G was characterized by broadband dielectric spectroscopy. The hybrid filler/composites were found to show higher thermal stability when 2 phr G was added. In addition, a low quantity of G filler was found to slightly increase the AC dielectric breakdown strength of the S/MFS_10 and S/TiO₂_20, where an improvement of 3 and 5% was found, respectively. Several steps were observed in the thermal decomposition of the S rubber composites by thermogravimetric analysis-Fourier-transform infrared spectroscopy. Our findings revealed great potentials for fabricating hybrid-filler/silicone rubber composites with enhanced electrical and thermal properties for outdoor insulating applications.