Interface Modification and Mechanical Properties of Natural Fiber-Polyolefin Composite Products

Abstract

Natural fibers are potentially a high-performance and non-abrasive reinforcing fiber source. In this study, mechanical properties of polypropylene (PP) composites with various natural fibers such as old newsprint, kraft pulp and hemp were studied. The effect of a low-molecular weight, maleated type coupling agent, on the mechanical properties of these natural fiber-filled PP composites was also investigated and the results showed that this can be used as a good interface modifier for improving the strength properties of the PP-filled composites and the optimum level of the coupling agent was found to be around 3-4 percentage by weight of the composite. Kraft pulp and hemp fiber-filled composites showed better tensile, flexural and un-notched impact strength compared to the glass fiber-filled composites at the same fiber loading. Hybrid composite produced using 10 wt% of glass fiber and 30 wt% of hemp fiber showed only a marginal improvement in the mechanical properties.

Estimation of the interfacial shears strength, orientation factor and mean equivalent intrinsic tensile strength in old newspaper fiber/polypropylene composites

“…Actually, coupling agents, which react with the fiber's hydroxyl groups, but additionally are able to interlock with matrix chains are the best treatment to increase the mechanical properties of the composite. In this respect, the use of an interfacial coupling agent, such as Maleated polyolephines is the most commonly used method to improve the fiber-matrix interface, by means of -OH/maleic chemical interactions [16,20]. More specifically the use of maleated polypropylene (MAPP) has yielded good tensile properties of the composites [9,21].…”

“…This fact normally results in poor interfacial adhesion and in restricted ability of stress transfer from the matrix to the reinforcement. Therefore, the enhancement of 3 compatibility between the hydrophobic thermoplastic polymer and the hydrophilic natural fibers has attracted much attention of the researchers, and various techniques were evaluated in previous works [15][16][17][18]. Generally speaking, chemical modifications are used to decrease the polarity of the fibers surface in order increase its compatibility with the polymer surface.…”

Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers–polypropylene composites

“…The strength of natural fiber reinforced composites is highly influenced by the incompatibility between the hydrophilic fibers and the hydrophobic polymers. The most common way to improve the interface is the addition of coupling agents [10,17,[19][20][21][22]. However that treatment slightly affects the stiffness of the natural fiber reinforced composites.…”

Wood flour filled PP composites: Compatibilization and adhesion

“…Some sources claim that tensile and flexural strength as well as impact resistance pass through a maximum as a function of the amount of functionalized polymer [32], but most research groups do not study this question, but apply the coupling compound in a fixed amount related to the mass of the wood [21,29]. Similarly, the effect of the characteristics, i.e.…”