The past few decades have seen extraordinary gain in interest for bio-based products, driven by the intensifying call of the society for petrochemical material replacement and developing materials with next-to-no environmental impact. Cellulose, which is an abundantly available "green" material, can be derived from plant fibers and tailored for a plethora of possible uses where it can be used as a substrate or as a filler material. However, emerging technologies and product advancements necessitate the search for materials that are small, biodegradable, lightweight, and strong. Nanocellulose, which can be obtained through as mechanical and chemical production methods with tensile strength and Young's modulus of up to 0.5 and 130 GPa, respectively, proves to be the answer that they were looking for. However, the inherent hydrophilic nature of nanocellulose limited its potential widespread application. Surface modifications of nanocellulose to alter and diminish its hydrophilicity were done to address the aforementioned issues. In this article, we had reviewed on different types of surface modifications and their resulting impact on the properties of nanocellulose and their effect on polymer composites. The importance of nanocellulose in emerging applications such as biosensor, nanoremediation, papermaking, and automotive as well as the current state of the industry and the commercialization progress of nanocellulose were also discussed.

This work reports the mechanical, morphological, and thermal properties of the polypropylene (PP) nanocomposites containing nanosilica (nano‐SiO2) which were treated by different functional group silane coupling agents. Four types of silane coupling agents namely aminopropyltriethoxy silane (APTES), glycidyloxypropyltrimethoxy silane (GPTMS), trimethoxysilylpropyl methacrylate (TMPM), and dichlorodimethyl silane (DCMS) were used to modify the surface‐activated nanosilica. To enhance the effectiveness of the coupling, nanosilica was chemically activated and analyzed through FTIR and X‐ray photo electron spectroscopy (XPS). The highest tensile strength was recorded by the activated nanocomposites treated with APTES followed by nanocomposite treated with GPTMS, TMPM, and DCMS, respectively. The addition of silane coupling agents into nano‐SiO2/PP system further improved the tensile modulus of the PP nanocomposites. From the transmission electron microscopy (TEM) analysis, activated nanosilica treated with APTES showed better nanosilica dispersion in the PP matrix and lesser agglomeration occurred when compared with the other silane coupling agents which were used in this study. Surface activation process does not effectively increase the degree of crystallinity and thermal stability on the PP nanocomposites. However, with the assistance of the surface treatment, it was found that the thermal behavior of the PP nanocomposites had been enhanced. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

In this work, nanosilica/polypropylene composites containing 1 wt% of silica nanoparticles were prepared by melt mixing in a Thermo Haake internal mixer. Prior compounding, nanosilica was subjected to surface activation using sodium hydroxide (NaOH) solution. The effectiveness of the activation process was evaluated by measuring the amount of hydroxyl groups (À ÀOH) on the surface of nanosilica via titration method and supported by FTIR analysis. Two coupling agents namely 3-aminopropyl triethoxysilane (APTES) and neopentyl (diallyl)oxy,tri(dioctyl) phosphate titanate (Lica 12) were used for surface treatment after activation process. The mechanical properties of polypropylene matrix reinforced with silica nanoparticles were determined by tensile and impact test. Hydroxyl groups on the nanosilica surface played an important role in enhancing the treatment with silane coupling agents. To increase the amount of hydroxyl groups on the nanosilica surface, the optimum concentration of NaOH is 1 mol%. Tensile strength, tensile modulus, and impact strength of nanosilica/PP composites improved with activation process. As the coupling agent is concerned, APTES coupling agent is more pronounced in enhancing the mechanical properties of the composites when compared with Lica 12 coupling agent.FIG. 6. Tensile properties of nanosilica filled polypropylene as a function of coupling agents at 1 wt% filler content: (a) tensile strength, (b) Young's modulus, (c) elongation at break, and (d) un-notched Izod impact strength.

The effect of coupling agents on the properties of alumina-filled polypropylene (PP) has been studied. Several types of coupling agents such as silane Z-6020 ((Aminoethylaminopropyl) trimethoxysilane), 3-GPS (3-(Glycidyloxypropyl) trimethoxysilane), and titanium dioxide powder (TiO2) were employed either during compounding or before compounding i.e., at pre-treatment stage. The silane coupling agent was first diluted into ethanol in appropriate ratio and subsequently dried before compounding. In the case of titanate, the powder was directly mixed with alumina-PP compound during mixing using Brabender internal mixer. Series of mechanical tests such as tensile and flexural testing were carried out using Instron model 3366 machine in accordance to ASTM D368 and D790-92 respectively. It has been found that the tensile strength of alumina-filled PP composite has increased considerably when both types of coupling agents are added. PP filled alumina composite with titanium as coupling agent showed a greater value of tensile strength as compared to silane-treated and untreated alumina-filled PP composites. Similarly, the flexural strength recorded was higher as compared to the untreated system with silane-treated alumina-filled composites showing the most positive results of all the systems. Consequently, study on the impact properties showed that titanium has notably improved the impact resistance of alumina-filled PP composite as compared to silane-treated composite. Study on the scanning electron micrograph revealed that improved texture on the treated composite has allowed greater plastic deformation to occur with improved adhesion and interaction between filler and matrix.