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A maximum of 20% (w/w) lignin was used as a filler in low-density polyethylene (LDPE), together with 3–6% maleic anhydride-grafted LDPE as compatibilizer and 3–10% copper(II) sulphate pentahydrate (CuSO4·5H2O) as lignin’s dispersing agent. The resulting composites were investigated for both their mechanical properties and their melting point following the ASTM standards as well as their behaviour was compared with neat LDPE. The results reveal that addition of compatibilizer significantly improved the mechanical properties of lignin, yielding closer values to those of neat LDPE. In fact, the addition of 3% maleated polyethylene induced a 37% increase of the Young’s modulus, whilst 3% CuSO4·5H2O provides a good lignin dispersion. The above observations are further supported by the scanning electron micrographs of the blend specimens. Finally, the differential scanning calorimetry analysis revealed that the melting temperature and the crystallinity of LDPE slightly increase with the addition of 3% CuSO4·5H2O. [ABSTRACT FROM AUTHOR]

This study reports the effects of wood fibers and 3 wt% maleic anhydride-grafted polypropylene used as coupling agent on the tensile properties of polypropylene/wood composites. Compounding was done in a roller-based internal batch mixer followed by compression molding. Our findings show that both birch and aspen wood fibers improve the elastic modulus and the tensile strength of composites, and the chemical treatment improves the fiber–matrix interface. A comparison of experimental results’ elastic modulus with micromechanics theoretical models shows that the Lavengood–Goettler model is closer to experimental data. Also the results showed that the polypropylene/wood composites’ elastic modulus exceeds high-performance thermoplastics commonly used in gears manufacturing. Thus, the price of polypropylene/wood fibers makes it a viable alternative for similar application. [ABSTRACT FROM AUTHOR]

Central composite designed experiments are conducted to study the independent effects of maleated polyethylene, dicumyl peroxide and nanoclay in the forms of natural (Cloisite® Na+) and masterbatch (Nanoblend™ concentrates MB2001) on the mechanical properties of fiber reinforced PE composites with different fiber levels. The optimum values are predicted on the results of designed experiments and there are linear regressions between fiber content and their mechanical properties. The deposition and formation of nanoclay particles in PE composites are ascertained by scanning electron microscope and transmission electron microscope observations. Both natural nanoclay and MB2001 can be delaminated and even exfoliated in polarized PE matrix. As wood fiber is introduced, natural nanoclay particles (nanoclay-natural) are deposited on fiber surface even loaded in fiber lumens, but the nanoclay particles of MB2001 (nanoclay-concentrate) are mostly dispersed in the matrix. In addition, the different reinforcements between nanoclay-natural and nanoclay-concentrates are also investigated to find out the influence of particle formation on the quality of composite materials. [ABSTRACT FROM PUBLISHER]

Maleated polyethylene (MAPE) and dicumyl peroxide (DCP) are both popularly used in polyethylene-based composites combining with organic fillers such as natural fibers and inorganic fillers such as nanoclay. Systematic studies were undertaken to investigate the influences of MAPE and DCP on the mechanical properties and plasticity of PE composites with or without natural fibers. In addition, the effect of the fiber adding sequence was examined to obtain superior mechanical properties. POLYM. COMPOS., 36:287-293, 2015. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This work addressed questions regarding the fate of wood pulp fibers in the composite manufacturing process, for instance whether the processing induced fiber damages, and the improved interfacial adhesion accelerated this function. A number of wood fibers were blended with various maleic anhydride-grafted polymers fully and partially to study their morphological changes. The fractured fibers were separated from wood composites with aromatic hydrocarbons and analyzed using Fiber quality analyses, Scanning electron microscope, Fourier transform infrared analysis and X-ray photoelectron spectroscopy to validate the degree of fiber fractures and the esterification reaction. The fiber damages were related to the maleic anhydride grafting degree, molecular weight and molecular structures of maleated polymers. [ABSTRACT FROM AUTHOR]

Nanomer and Cloisite are the popular commercial nanoclays (NC) available in the market. The mechanical properties of wood—plastic composite (WPC) based on linear low density polyethylene with or without wood fiber are compared for different added nanoclays. In addition, the moisture uptakes at 23°C and 45% RH and water uptake/loss after immersion in water are evaluated. I.34TCN type nanoclay as well as Cloisite Na+ lead to composites with superior mechanical properties and better water resistance behaviors compared to the other kinds of nanoclays. It should be noted that the discoloration occurs in WPC reinforced with unmodified NC. [ABSTRACT FROM AUTHOR]

A systematic study of effects of concentrations of maleated polypropylene (MAPP), dicumyl peroxide (DCP), Nanoblend concentrate (MB1001) and birch fibers on the mechanical properties of birch-polypropylene (PP) composite was undertaken with the objective to protect or increase the impact strength without losing tensile strength. Using Stagraphic Plus, the Central Composite Design made it possible to determine the optimum concentrations of additives and to maximize both the impact as well as tensile properties to reach values well above that of virgin PP. [ABSTRACT FROM AUTHOR]

Systemic studies of the effects of the concentrations of maleated polyethylene (MAPE) loading, the content and addition sequence of dicumyl peroxide, the content and type of nanoclay (NC), and aspen fiber loading on the mechanical properties of PE-aspen composites were undertaken with the objective to increase the impact strength as well as the tensile properties. In this article, the formation of an optimal compatibilizing system for the hybrid composite PE-aspen-NC by combining basic principles for compatibilization was investigated. Statistical approach experimentation using Statgraphics Centurion® with the objective to maximize both the tensile strength as well as the impact properties of natural fiber and nanoclay filled PE was applied to reach values well above that of virgin PE. [ABSTRACT FROM AUTHOR]

Studies on the effect of blending method, the introduction method of initiator (dicumyl peroxide, DCP), and the blending time with antioxidant (Irganox) added on the mechanical properties of PP-Aspen composites with and without DCP, respectively are undertaken. An optimum blending time for the composite with Irganox is obtained. The optimum content of Irganox as well as pre-mixing and the final-step feeding-method of DCP are compared to that of conventional method of blending in order to achieve the optimum values of impact and tensile strength properties. [ABSTRACT FROM AUTHOR]

Study on the effect of concentration of maleated polypropylene (MAPP), dicumyl peroxide (DCP), nanoclay (NC), and aspen fiber loading on the mechanical properties of Aspen-PP composites has been undertaken with the objective to protect or increase the impact strength without losing or weakening the tensile strength. The central composite design of Statgraphic plus is used to determine the optimum concentration of additives and to maximize both the impact as well as tensile strength properties to be superior to that of pure PP. Finally, the material price of PP composites with an optimal composition of filler (aspen fiber and NC), coupling agent (MAPP), and initiator (DCP) is compared to that of pure PP and PP reinforced with glass fibers. [ABSTRACT FROM AUTHOR]

Composites were prepared by compounding linear low-density polyethylene (LLDPE) with cellulose fibers as reinforcing filler. Effect of a small addition of unsaturated or saturated long chain organic acid cellulose esters (cellulose undecylenate, undecanoate, oleate, stearate) with partial degrees of substitution and the presence of dicumyl peroxide (DCP) as a polymer crosslinking initiator was investigated on the rheological and tensile properties of hybrid composites. No grafting of polyethylene onto fibers surfaces occurred under processing conditions; however composites with DCP showed significant increase in tensile properties. The use of unsaturated cellulose esters in composites containing DCP was more effective in maintaining stress at yield and in progressive increase of energy to yield with higher cellulose esters content and degree of substitution in comparison with composites containing only cellulose fibers. The tensile properties decreased sharply in composites containing saturated cellulose esters. [ABSTRACT FROM PUBLISHER]

The xanthate method of grafting synthetic polymers on hardwood pulp has been successfully applied by Kokta et al. [1]. [ABSTRACT FROM PUBLISHER]