F. E. Okieimen

Utilisation of maleinized rubber seed oil and its alkyd resin as binders in water-borne coatings

Abstract Rubber seed oil—RSO (a renewable resource) was used in the production of alkyd emulsion. Samples of the oil were initially treated with different amounts of 2% (A), 5% (B), 10% (C), 15% (D) and 20% (E) of maleic anhydride. The resultant maleinized rubber seed oil (MRSO) samples (A–E) were used to formulate water-soluble alkyd samples (I–V), respectively. The MRSO samples and their corresponding alkyds were evaluated for their physico-chemical properties and compared to the pure RSO. Acid, saponification and iodine values were affected by maleinization. Samples of the MRSO and their alkyd derivatives were evaluated as binders in water-borne coatings. The MRSO samples were of relatively lower volatile organic compound (VOC) (between 1 and 1.5%) compared to their corresponding alkyd derivatives (about 10%). While the MRSO samples exhibited poor chemical resistance, the alkyds exhibited excellent resistance to acid, brine and water, and fair resistance to alkali.

Scavenging cadmium, copper, lead, nickel and zinc ions from aqueous solution by modified cellulosic sorbent

The adsorption of cadmium, copper, lead, nickel and zinc ions on maize Zea mays stalk meal was examined by equilibrium studies at 29°C. The amounts of the metal ions removed from solution depended on the metal ion type, the ionic size of the metals and were enhanced by EDTA (% N = 12.05) modification of the cellulosic sorbent. The sorption coefficient, Kd, of the metal ions between the adsorbent phase and the bulk aqueous phase was found. The sorption on the unmodified sorbent of lead ions from solutions containing zinc ions shows that lead ions are preferentially removed from solution.

Network Structures, Flexibility and Stability in Thermal and Chemical Environments of Polyurethane Prepared from Rubber Seed Oil.

Rubber seed oil monoglyceride was prepared by glycerolysis and characterized by chemical and spectroscopic methods. The monoglyceride was reacted with excess diisocyanates (hexamethylene -diisocyanate and toluene diisocyanate), and the network structures and molecular mass of the polyurethane were determined from swelling experiments in toluene and size exclusion chromatography respectively. The polyurethane films obtained were characterized in terms of their resistance to chemicals (water, brine, dilute acid and alkali) thermal stability and tensile and flexural strength and modulus. It was found that under the experimental conditions, conversion of the triglyceride content of the rubber seed oil to monoglyceride not quantitative less than 70%. The measured properties of the RSO-based polyurethanes were attributed to the degree of crosslinking and the observed superior properties of the polyurethane obtained with hexamethylene diisocyanate in comparison with polyurethane obtained with toluene diisocyanate were explained in terms of structure-property relationship. The measured properties of RSO-based polyurethanes compare favourably with the properties reported for polyurethanes derived from other vegetable oils.

Physico-Mechanical, Aging Properties, and Permeability of Ketones Through Vulcanizates Prepared by Different Mixing Schemes

This article reports on the physico-mechanical properties, chemical resistance, aging properties, sorption, diffusion, and permeability of ketones (cyclohexanone and acetone) through vulcanizates from blends of natural rubber (NR) and epoxidized low molecular weight natural rubber (ELMWNR) compounded by three different mixing schemes. The compounding ingredients were mixed with the two mentioned rubbers using three different mixing schemes by adopting a semi-efficient sulphur vulcanization compounding formulation. In Scheme 1, the natural rubber and ELMWNR were first mixed before adding the compounding ingredients. In Scheme 2, the compounding ingredients were first mixed with the NR before adding the ELWMNR and in Scheme 3, the compounding ingredients were first mixed with the ELMWNR before adding the NR. The physico-mechanical results of the vulcanizates showed that changes in the mixing schemes significantly influence the tensile properties of the vulcanizates. The tensile strength of the vulcanizates prepared with mixing Scheme 2 were 4.3 MPa lower than vulcanizates from Scheme 1, whereas Scheme 3 was lower than Scheme 1 with 8.5 MPa. The aging results of the vulcanizates from all the mixing schemes were found impressing. The activation energy and free energy change were highest for Scheme 1 whereas the extent of cyclohexanone and acetone penetrations were the lowest with Scheme 1, signifying well crosslinked and ketone resistant vulcanizates.