SOURCE:

Faculty: Engineering
Department: Chemical Engineering

CONTRIBUTORS:

Ejikeme, P. C. N.
onukwuli, D. O.

ABSTRACT:

This study examined the effect of chemical treatments of natural fibers on the physico-mechanical and surface properties of natural fibers reinforced High Density Polyethylene (HDPE) composites. Ampelocissus cavicaulis, Adenia lobata, Morinda morindoidies and Ampelocissus leonensis fibers were used as reinforcements in the polymer material. To improve the fiber –matrix adhesion properties, each of the fibers was separately treated with Sodium Hydroxide, Acetic Anhydride, Nitric Acid and Zinc Chloride. The chemical treatments were optimized using central composite design (CCD). Quadratic models were developed and validated for the treatment processes with error of 2.0%. The result showed that the chemical treatments were capable of increasing the tensile strengths by 35% of the original strength. Scanning electron microscopy (SEM) and Fourier transform infra red spectroscopy (FTIR) showed that the chemical treatments successfully reduced the hemicelluloses and surface contaminants on the surface of the fibers. From the results it was found that for Ampelocissus cavicaulis, Adenia lobata, Morinda morindoidies, and Ampelocissus leonensis fibers treated with sodium hydroxide, the tensile strengths (Mpa) were 365.02, 676.2, 1623.07, 123.34. All the other fibers treated with the other chemicals (acetic anhydride, nitric acid and zinc chloride) had similar trends. The fibers were compounded with high density polyethylene (HDPE) in a two roll mill. The compounding process was optimized using Box Behnken Design (BBD), quadratic models were developed for all the fibers and were validated. SEM analysis of the compounded blend showed that there was a proper and intimate mixing of the fibers with the polymer, while that of the uncompounded revealed presence of white spots indicating that the polymer was separated from the fibers. The natural fibers reinforced HDPE composite was produced using compression molding process. Quadratic models were developed and validated for the compression molding process for all the fibers. Effect of fiber length (mm) (0.5, 1, 2, 3, 4, 5, 6), fiber loading (wt%) (5, 10, 20, 30, 40, 50), molding temperature (oC) (140, 150, 160, 170, 180, 190), molding time(minutes) of ( 5, 10, 13, 16, 20), molding pressure (bar) (10, 20, 30, 40, 50) on the tensile strengths of the fiber- reinforced composites were studied. Results showed that the tensile strengths of all the fiber reinforced composites increased as these process conditions were increased to a point that further increase led to the decrease of the tensile strengths. The results on the physico-mechanical properties of the fiber reinforced composites showed that composites from sodium hydroxide treated Ampelocissus cavicaulis, Adenia lobata, Morinda morindoidies, Ampelocissus leonensis fibers reinforced HDPE composites, the tensile strengths (Mpa) were 40, 40.6, 78.36, 30.52, the flexural strengths (Mpa) were 44.8, 54.1, 82.5, 34.9, the impact strengths (J/m) were 54.0, 55.1, 67.1, 47.3, for elongation at break (%) were 6.8, 5.8, 4.0, 8.1, the hardness number were 4.0, 4.5, 5.5, 3.5, the bending at break (mm) were 14.2, 13.8, 13.5, 15.4, the water absorption (%) were 0.23, 1.4, 2.0, 0.15, and the swelling thickness (%) were 0.78, 0.91, 2.47, 0.71, respectively. The chemical resistance tests (%) for sodium hydroxide treated Ampelocissus cavicaulis, Adenia lobata, morinda Morindoidies and Ampelocissus leonensis fibers reinforced HDPE composites were, for water, 0.31, 1.45, 1.97, 0.17, for 0.5N NaOH, 0.15, 1.00, 1.42, 0.18, for acetic acid, 0.36, 1.42, 1.38, 0.81,and for 1N HCl, 0.38, 1.36, 1.20, 0.58, respectively. SEM and FTIR analysis clearly indicated that there was very strong interfacial bonding between the fiber and the matrix interface. The above results showed that the chemical treatments were capable of enhancing the interfacial bonding of the fiber,matrix interface for the production of composites that can be used as storage, furniture and transport facility.