Anuwat Saetung

Synthesis of Novel Cationic Waterborne Polyurethane from Natural Rubber and its Properties Testing

The novel natural rubber based cationic waterborne polyurethanes (cWPUs) with having quaternary amine as an emulsifier were successfully synthesized by additional polymerization. These polyurethanes were synthesized by the reaction of hydroxyl the method of telechelic natural rubber. Molecular weight approximately of hydroxyl telechelic natural rubber (HTNR) for 3000 g.mole-1, toluene-2,4-diisocyanate (TDI), and N-methyl diethanol amine (NMDEA) (used as an emulsifier) were prepared for cWPU. The concentrations of NMDEA were examined in range of 0 – 2.0 moles. From the results under the isocyanate index of 100, the study revealed that cWPU with well-distributing had to consist of emulsion concentration more than 1.50 moles. Zetasizer nanorange was used to identify the prepared cWPU particle size distribution. The results showed that the particle size of cWPU was decreased from 86.6 to 78 nm with increasing of NMDEA concentration. The smallest particle size was 2 moles with non-acetic acid odor, and very soft film. In addition, cWPU would be well-dispersed more than 4 months. The 1H NMR spectroscopy and FT-IR confirmed that the cWPU has been successfully synthesized from natural rubber.

Influence of accelerator/sulphur and co-agent/peroxide ratios in mixed vulcanisation systems on cure characteristics, mechanical properties and heat aging resistance of vulcanised SBR

The influence of accelerator/sulphur and co-agent/peroxide ratios on cure characteristic and vulcanisate properties in mixed vulcanisation of styrene butadiene rubber (SBR) was investigated in this work. Accelerator/sulphur ratio was investigated with three alternative sulphur curing systems, namely conventional, semi-efficient and efficient vulcanisation (EV) systems. Zinc dimethacrylate (ZDMA) was used as a co-agent to enhance the performance of peroxide and to provide ionic linkages. Ionic linkages contributed by ZDMA create bridges between two polymer chains. The ZDMA/peroxide ratio was varied from 2 to 10. The concentration of dicumyl peroxide was held fixed while the ZDMA content was varied. Cure characteristics, mechanical properties, dynamic mechanical properties and heat aging resistance were investigated in relation to the crosslink structure. Increasing the ZDMA/peroxide ratio significantly increased density of ionic linkages, especially in combination with the EV system. The combination of EV system with high ZDMA/peroxide ratio provided the highest ionic crosslink density and the lowest polysulphidic crosslink density: this enhanced the mechanical properties, the dynamic mechanical properties and the thermal stability of SBR vulcanisates.

Modification of Used Palm Oil: Preliminary Study of its Potentiality as Polyurethane Foam Precursors

Polyol was successfully synthesized from used palm oil (UPO) via epoxidation and ring opening reaction. The mole ratio of UPO: formic acid: hydrogen peroxide was 0.3: 8: 1.5. The reaction had been continuously stirred at 400 rpm at 65°C with varied reaction time for 0.5, 1.0, 1.5, 2.0, and 4.0 h. The chemical structure of modified used palm oil (MUPO) or polyol was confirmed by 1H-NMR. OH number of polyols increased with an increase reaction time. Moreover, the preliminary study for the preparation of MUPO-based polyurethane (PU) foam was performed. A new MUPO-based PU foam was successfully prepared and theirs foam behaviors were investigated.

Preparation and Properties of Sponge Rubber Based on Natural Rubber and Cassava Starch

In this work, the sponge rubbers based on cassava starch masterbatch in latex phase with the difference technique (non-gelatinized and gelatinized cassava starch) were preformed. The cassava starch contents from 0 to 70 phr were also studied. The cure characteristic, mechanical and morphological properties were investigated. It was found that the scorch time and cure time were increased with an increasing of cassava starch contents in both techniques. The mechanical properties i.e., tensile strength, elongation at break and tear strength were decreased with an increasing of cassava starch contents, except 500% modulus. However, the sponge based on gelatinized technique gave the better mechanical properties than that of non-gelatinized cassava starch. The SEM micrographs of sponge NR from gelatinized technique were also able to confirm a good interfacial interaction between hydrophilic cassava starch and hydrophobic NR.

Preparation and Properties of Polyurethane Adhesive Derived from Modified Rubber Seed Oil and Toluene Diisocyanates

In this research, the polyurethane adhesive based on modified rubber seed oil with toluene diisocyanates was successfully synthesized in presence of DBTL catalyst. The chemical structure of modified rubber seed oil was characterized by 1H-NMR. The suitable reaction time of the polyurethane adhesive synthesis was 4h by providing with FT-IR technique. The effects of NCO index and chain extender (1,4-butane diols) content in adhesive formulation as well as cure temperature were also studied by leather to leather on adhesion peel strength. It was found that the higher NCO index or chain extender content gave the higher adhesion of substrate. The cure temperature of adhesive at 70 °C gave the better peel strength than that at 30 °C during 24 h.

The Influence of Zinc Dimethacrylate on Crosslink Density, Physical Properties and Heat Aging Resistance of Sulfur Vulcanized Styrene Butadiene Rubber

In this work, to study the utilization of zinc dimethacrylate (ZDMA) in sulfur vulcanized styrene butadiene rubber (SBR). The compounds were prepared by two roll mill mixer. Crosslink density and crosslink types were determined with an equilibrium swelling method. Physical properties and heat aging resistance were studied. The results shows that increase of ZDMA will decrease cure rate index and crosslink density which lead to decreased in 300% modulus and hardness. However, the addition of ZDMA can improve tensile strength, tear strength, elongation at break and heat aging resistance.