Rheological properties of corona modified cellulose/polyethylene composites

The rheological behavior of wood fiber/polyethylene composites made of corona treated constituents was investigated. Corona treatment of one or both of the constituents resulted in decreased melt viscosities relative to compounds containing untreated materials. The reduction of melt viscosity may originate from low molecular weight moieties formed on the surfaces of both polyethylene and cellulose during corona treatment. These may act as lubricants at interfaces. Also it was found that the corona treatment of fibers leads to higher packing volumes; this may result from a reduction in fiber length when treated fibers are processed under high shear conditions. As a result these fibers perturb the normal flow pattern in the melt to a lesser degree than the longer fibers of untreated cellulose.     

Mechanical properties of NR/BR/cellulose II composites

Summary Blends of natural rubber (NR) and butadiene rubber (BR) with cellulose filler have been investigated. The coprecipitation of the rubber latex-cellulose xanthate mixtures by acidulation lead to elastomer-cellulose II composites in granular form. In these blends, the NR/BR ratio has been varied from 75/25 to 25/75, and the cellulose content has been increased from 0 to 25 phr. Mechanical tests have been applied to the composite samples, and the results showed that cellulose II may be considered as a reinforcing agent. Those results gave also an insight into the role of NR and BR on the properties of the composite samples.     

Mechanical properties of natural rubber/grafted cellulose fibre composites

Mechanical properties of natural rubber/allyl acrylate and allyl methacrylate grafted cellulose fibre composites are presented. Stress/strain measurements and dynamic mechanical measurements indicate that the adhesion between grafted fibres and matrix is better than that in samples containing untreated cellulose fibres. This makes it possible to vary the composite properties by varying the fibre type and/or fibre amount.     

Structure and properties of composites of polyethylene or maleated polyethylene and cellulose or cellulose esters

Composites of linear low‐density poly(ethylene‐co‐butene) (PE) or maleated linear low‐density poly (ethylene‐co‐butene) (M‐PE) and cellulose (CEL), cellulose acetate (CA), cellulose acetate propionate (CAP), or cellulose acetate butyrate (CAB) were prepared in an internal laboratory mixer with 20 wt % polysaccharide. The structure and properties of the composites were studied with tensile testing, dynamic mechanical thermal analysis, differential scanning calorimetry, extraction with a selective solvent, Raman spectroscopy, and X‐ray diffraction. Composites prepared with M‐PE presented yield stress and elongation values higher than those of composites prepared with PE, showing the compatibilizer effect of maleic anhydride. Dynamic mechanical thermal analysis performed for M‐PE–CEL, M‐PE–CA, M‐PE–CAP, and M‐PE–CAB composites showed one glass‐transition temperature (T_g) close to that observed for pure M‐PE, and for M‐PE–CAP, another T_g lower than that measured for the polysaccharide was observed, indicating partial mutual solubility. These findings were confirmed by the extraction of one phase with a selective solvent, gravimetry, and Raman spectroscopy. X‐ray diffraction showed that the addition of CEL, CA, CAP, or CAB had no influence on the lattice constants of PE or M‐PE, but the introduction of the reinforcing material increased the amorphous region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:402–411, 2007     

Interfacial phenomena in cellulose/polyethylene composites

A systematic study of the mechanical properties of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) filled with cellulose was conducted. When benzoyl peroxide (BPO) was used and when the components were mixed at 160°, the yield strength of the LLDPE/cellulose composite increased by 70% whereas that of HDPE increased by only 15%. If BPO is replaced by dicumyl peroxide (DCP) the yield strength attains a plateau value at a lower concetration. Yield strength for the cellulose/LLDPE system, where the cellulose had been pretreated with silane, showed a relatively small improvement as compared to the effect of the peroxides addition. The presence of gel in the compound is also discussed.     

Mechanical properties and foaming behavior of cellulose fiber reinforced high‐density polyethylene composites

This article investigates the effects of fiber length and maleated polymers on the mechanical properties and foaming behavior of cellulose fiber reinforced high‐density polyethylene composites. The results from the mechanical tests suggested that long fibers provided higher flexural and impact properties than short fibers. In addition, the maleated high‐density polyethylene increased flexural strength significantly, while the maleated thermoplastic elastormers increased notched Izod impact strength dramatically. On the other hand, the results from the extrusion foaming indicated that the composites with long and short fibers demonstrated similar cell morphology, i.e., a similar average cell size and cell size distribution. However, the addition of maleated high‐density polyethylene caused an increase of the average cell size and cell size distribution in the composites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Mechanical properties of ultrahigh-molecular-weight polyethylene fiber-reinforced PE composites

Three types of high-strength polyethylene (PE) fiber-reinforced composite sheets were made by compression molding at the vicinity of melting point of the fiber. Sheet I was molded from only PE fibers. Sheets II and III were prepared by the compression molding of PE fiber with conventional high- and low-density polyethylene films, respectively. The mechanical properties, thermal behavior, and morphologies of the sheets have been investigated and compared with each other. The tensile strength and elastic modulus of sheet III are 660 MPa and 14 GPa, respectively, which were 60 and 30 times higher than those of typical low-density PE film. Although the elastic modulus of sheet III is 6 GPa less than that of sheet II, the tensile strength of 660 MPa is highest in the three types of sheets prepared in this study. The mechanical properties of sheets II and III were about half of predicted theoretical ones. It was concluded that the interfacial adhesion between PE fiber and PE matrix was an important factor to improve the mechanical properties of this PE sheet. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1431–1439, 1998     

Mechanical and thermal properties of polypropylene/recycled polyethylene terephthalate/chopped rice husk composites

The various ratios of recycled polyethylene terephthalate (rPET) into polypropylene (PP) filled with 40 parts chopped rice husk per hundred part of polymer have been studied. Composites were prepared using a corotating twin screw extruder at temperature zones of 165–215, well below 250°C (rPET mp temperature) and characterized by mechanical and thermal properties. To improve the compatibility between different components, PP grafted with maleic anhydride was added as a coupling agent in all the compositions studied. The results showed that the addition of rPET improved the tensile and flexural modulus and impact strength of the composite while reducing its tensile and flexural strength. The scanning electron microscopy micrographs of samples in the injection direction showed that some particle shaped rPET inside the composites appear as drawn fibrils and some appear as plates. Differential scanning calorimetric studies showed that the addition of rPET particles to the composites decrease the PP crystallization temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical and thermal properties of exfoliated graphite nanoplatelets reinforced polyethylene terephthalate/polypropylene composites

Exfoliated graphite nanoplatelets (GNP) reinforced composites materials based on blend of poly(ethylene terephthalate) (PET) and polypropylene (PP) were prepared by melt extrusion followed by injection molding. 10 parts per hundred resin (phr) styrene‐ethylene‐butylene‐styrene‐g‐maleic anhydride was added to the base formulation PET/PP (70/30) as a compatibilizer. PET/PP/GNP composites 0–5 phr were prepared and characterized using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared (FTIR) spectroscopy analysis. The morphological studies revealed a homogenous dispersion of GNPs in PET/PP blends up to 3 phr loading after which agglomeration occurred. Flexural strength was enhanced by 80% at 3 phr GNPs loading which was the highest value obtained. Interestingly, the highest value for the impact strength was also recorded at 3 phr loading. The thermal stability of the composites were generally improved at all filler loading with the highest at 3 phr. From the overall results, it is clear that the optimum concentration of GNPs in the PET/PP/GNP system in terms of both mechanical and thermal properties was 3 phr loading. Although, the mechanical and thermal properties of the composites were improved, the FTIR analysis did not reveal any chemical interaction between GNP and the polymer matrix. POLYM. COMPOS., 35:2029–2035, 2014. © 2014 Society of Plastics Engineers     

Mechanical properties and water absorption of low‐density polyethylene/sawdust composites

The mechanical properties and water absorption of low‐density polyethylene/sawdust composites were investigated. The relationship between the filler content and the composite properties was also studied. Different degrees of esterification of the sawdust with maleic anhydride were obtained with different reaction times. The experimental results demonstrated that the treatment of sawdust by maleic anhydride enhanced the tensile and flexural strengths. The water absorption for maleic anhydride treated sawdust indicated that it was more hydrophobic than untreated sawdust. The effects of the addition of benzoyl peroxide during the preparation of composite samples on the water absorption and mechanical properties were also evaluated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical and thermal properties of waterborne epoxy composites containing cellulose nanocrystals

Cellulose nanocrystals (CNCs) are reinforcing fillers of emerging interest for polymers due to their high modulus and potential for sustainable production. In this study, CNC-based composites with a waterborne epoxy resin matrix were prepared and characterized to determine morphology, water content, and thermal and mechanical properties. While some CNC aggregation was observed, the glass transition temperature (T_g) and modulus for the composites increased with increasing CNC content. Relative to neat epoxy, at 15 wt.% CNC the storage modulus increased by 100%, the T_g increased from 66.5 °C to 75.5 °C, and tensile strength increased from 40 MPa to 60 MPa, suggesting good adhesion between epoxy and CNC surfaces exposed to the matrix. Additionally, no additional water content resulting from CNC addition were observed. These results provide evidence that CNCs can improve thermomechanical performance of waterborne epoxy polymers and that they are promising as reinforcing fillers in structural materials and coatings.     

Synthesis and properties of magnets/polyethylene composites

Polyethylene‐based magnetic composites have been prepared by ethylene polymerization on the surface of NdFeB magnets, which is previously activated by ball milling with catalyst components. The level of magnets has been controlled by catalyst preparation and polymerization parameters such as Al/Ti ratio and polymerization temperature. The coertivity and the residual magnetizability were investigated. It was found that the magnetic properties of magnet powders are largely retained. In addition, in contrast to composites prepared by melt mixing, the adhesion force between magnets and polymer matrix is improved significantly and better mechanical properties are expected. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3412–3416, 1999     

Mechanical and flow properties of high-density polyethylene/low-density polyethylene blends

The recycling of plastic waste is of particular interest in large urban areas where municipal waste represents a large ecological problem. To achieve their objective (consumer products from plastic waste), formulators of a recycling program have to understand the implications of working with mixtures of different resins. Furthermore, in a multiphase system, the thermomechanical history experienced by the resins during processing represents an important link between operating conditions, resin properties, and final product performance. High-density polyethylene/low-density polyethylene (HDPE/LDPE) blends (10, 20, 35, 50, 65, 80, and 90 percent by weight HDPE) were melt blended in an internal mixer. A complete rheological characterization was performed on each blend. The resulting blends were extruded under different processing conditions. The extruded sheets were further characterized to determine their mechanical properties, The experimental results show important differences in the mechanical properties (transverse and longitudinal) of the sheets obtained from the blends. These differences are explained on the basis of the processing conditions (thermomechanical history) and the rheological properties of the molten blends.     

PPR/甘蔗渣复合材料的力学性能

利用硅烷处理的甘蔗渣纤维填充无规共聚聚丙烯制备了复合材料,研究其力学性能与相态结构。结果表明:在甘蔗渣用量为10～15份时,用硅烷KH570处理的甘蔗渣制备的复合材料较直接填充物的拉伸强度与冲击强度各提高30％以上;试样结晶更完善,纤维在树脂中分布更均匀。     

Mechanical and dielectric properties and crystalline behavior of multilayer graphite-filled polyethylene composites

As one of the duplicated cases of ultrathin polymer films, multilayer graphite/polymer composites are of great interests in various applications. Graphite/polyethylene (PE) composites with various layer numbers and graphite particle sizes were prepared by lamination. The mechanical and dielectric properties and crystalline behavior of the composites were investigated by scanning electron microscopy, differential scanning calorimetry, tensile test, and dielectric strength test. With the same amount of graphite addition, the tensile strength of the composites increases with decreasing layer thickness, but decreases with increasing graphite particle size. The longitudinal tensile strength is greater than the transverse one. The tensile strength of the 3⁶-layer composites with a particle size of 15 μm has enhancements of 34.76 and 68.39% in the longitudinal and transverse directions compared with that of the single-layer pure PE film. The dielectric constant of the composites nonlinearly increases with decreasing layer thickness, while the dielectric loss is independent of this factor. The dielectric constant of the 3⁶-layer composites with a particle size of 15 μm is about two times as large as that of the single-layer pure PE film. The crystalline peak temperature and the crystallinity of the composites increase with the decrease in layer thickness. Coarse-grained molecular dynamics simulations were also carried out to understand the experimental observations by getting an insight into the microstructure of the multilayer composites. This work would be helpful for the production of optimized of multilayer graphite/polymer composites by lamination for electric energy storage. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48131.     

Mechanical properties of oriented polyethylene/polystyrene blends

Incompatible blends comprised of polystyrene and various high density polyethylenes were processed into tapes, in which both the phase and molecular orientations were parallel to the machine direction, by a combination of extrusion and mechanical stretching of the melt prior to quenching. Machine direction tensile yield strengths and ultimate elongations were found to be considerably higher than those obtained for comparable compression molded samples throughout the range of blend compositions and processing conditions investigated. Transverse tape properties were consistently poor due to poor interfacial adhesion. An optimum in machine direction properties was observed as the stretch ratio was increased at various melt temperatures. This optimum is likely due to a competition between morphological and molecular orientation rates during the stretching process and is a complex function of stretching rate and melt temperature as well as blend composition, relative phase viscosities, polyethylene crystallinity, and interfacial adhesion. Tapes stretched at high melt temperatures tended to show decreasing ductility and increasing tensile strength as room temperature storage time increased. This is believed to be due to secondary crystallization of the polyethylene phase. Oriented tapes were found to be easily fibrillated by mechanical heating to form a pulp. This material may prove suitable as a high grade replacement for cellulose pulp in paper making and could be formed at low cost from waste plastic feed stock.     

Mechanical and interfacial properties of phenolic composites reinforced with treated cellulose fibers

Cellulose fiber‐reinforced phenolic composites were prepared and characterized by mechanical tests and morphological analysis in this study. First, preparation of the phenolic matrix was optimized using an experimental design. The variables studied were curing temperature and time. The responses measured were strength, elongation, modulus, and strain energy density, in tensile and flexural tests. After fixing the optimal curing conditions of the matrix at 75°C and 2.75 h, the effect of a latest drying stage was studied. Strengths in tensile and flexural tests of the matrix after the incorporation of the drying stage were 156 and 189% of the strengths of the undried matrix, and elastic moduli were three‐fold. Finally, cellulose fibers were incorporated as reinforcement. Alkali treatment of the fibers (1 and 5% NaOH), employment of silanes as coupling agents [(3‐aminopropyl) trimethoxysilane (APS) and 3‐(2‐aminoethylamino) propyltrimethoxysilane (AAPS)], and combined treatments alkali‐silane were tested. The AAPS silane treated cellulose fiber‐reinforced phenolic composite was the material with the best mechanical performance and adhesion fiber–matrix. The most significant improvements obtained with the AAPS silane treatment of the fibers were 25, 52, and 110% for tensile strength, elongation, and SED, respectively, in relation to the unreinforced material properties. POLYM. ENG. SCI., 54:2228–2238, 2014. © 2013 Society of Plastics Engineers     

Mechanical and dynamical mechanical properties of chloroprene rubber and cellulose II composites

Vulcanized composites of chloroprene rubber (CR) with cellulose II (Cel II) as a filler were investigated. Cel II, obtained by the coagulation of cellulose xanthate, was incorporated in the rubber by the traditional method. The filler content varied from 0 to 30 phr. For comparison purposes, carbon black (CB)–CR composites were also studied. The CB amount varied from 0 to 45 phr. The mechanical and dynamic mechanical properties were determined, and the CR composite containing 20 phr of Cel II showed the best set of properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2425–2430, 2004     

Preparation and properties of cellulose/silica hybrid composites

Cellulose/silica hybrid (CSH) composites were prepared from bleached Eucalyptus globulus kraft pulp or primary treatment sludge cellulose fibers by a sol–gel method, using solely tetraethoxysilane or with the addition of trimethoxyoctylsilane as the silica precursors and heteropoly acid (H₃PW₁₂O₄₀) as the catalyst. Silica aging was accomplished during the hot pressing of preformed CSHs plates, and the properties of the resulting materials have been evaluated. The incorporation of a silica network in cellulosic materials increased their dimensional stability significantly during soaking in water, hydrophobicity, thermal stability, and bending strength. The thermal conductivity of these hybrid materials is comparable to commercially available insulation foams. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers