A series of new waterborne polyurethanes (WPUs) was successfully prepared by prepolymer process from renewable source, hydroxytelechelic natural rubber (HTNR), with different amounts of DMPA (1.6-8.4 wt %), different molecular weights (1000-4000 g mol À1 ), and different levels of epoxide (0%-20%) of HTNR. It was found that the urethane conversions of prepolymer were over 80% as calculated by FTIR technique. The resulting HTNR2000-based WPUs exhibit a uniform particle size, which decreases from 420-to 83-nm diameters with an increase in the amount of DMPA from 2.9 to 6.6 wt %. The particle size also decreases with an increase of soft segment or with an increase of epoxide content. They are well stable more over 6 months and without a significant difference in particle size compared with starting of them. Chemical structure of WPU films was confirmed by FTIR, 1 H-NMR, and 13 C-NMR. Molecular weight and polydispersity were determined by SEC. In addition, thermal and water uptake properties were investigated. The experimental results reveal that the DMPA content, molecular weight of HTNR, and epoxide content play an important key role in water uptake and thermal properties.

The cashew tree (Anacardium occidentale L.) is a tropical plant found widely in many Southeast Asian countries, including Thailand, and contains bioactive phenolic compounds with antioxidant activity. The natural antioxidants such as collagenase and tyrosinase inhibitors found in medicinal plants are promising agents in cosmetic products. This study evaluated the inhibitory activities of the collagenase and tyrosinase from cashew leaf extracts by developing and evaluating the stability of facial cream formulations. The ethanol (DEN), ethyl acetate (DEA) and distilled water (DDW) crude extracts of cashew leaves were investigated for their bioactive compound efficacy. The DDW extract had the highest yield (24.97%). All the extracts were investigated for their antioxidant activities. The DEN extract showed the highest DPPH radical-scavenging ability, ferric-reducing power and flavonoid compounds, which were 152.04 ± 2.40 mg gallic acid/g extract, 37.90 ± 1.07 mg gallic acid/g dry weight and 7.63 ± 0.07 mg quercetin/g dry weight, respectively. The DDW extract exhibited the highest potent activity, which was 111.00 ± 0.78 mg gallic acid/g dry weight in terms of phenolic content, while the DEN extract showed the highest tyrosinase inhibition at 0.100 mg/mL (46.97 ± 3.34%) and collagenase activity at 40 µg/mL. The results suggested that the ethanolic extracts from cashew leaves showed promise for use in skincare product development. Cosmeceutical formulations for skincare were prepared. The formula mixed with DEN extract and added to whitening and anti-aging skincare cream demonstrated good stability and physical properties.

Waterborne polyurethane (WPU) has its main applications in coatings and adhesives. Compared with the competing PU products from solvent-based processes, it has a more environmentally friendly manufacturing process. Its economic competitiveness could also be improved by the use of aromatic isocyanates that are widely available and cheaper than the currently used aliphatic isocyanates. We report on the synthesis and properties of WPU, based on natural rubber (NR) whose molecular structure has been altered, in combination with an aromatic isocyanate. The NR modification is by hydroxyl termination, with experiments using two chain lengths (HT600 and HT1000, named after molecular weight). The aromatic isocyanates used are 4,4’-Methylene bis (phenyl isocyanate) (MDI) and polymethylene polyphenyl polyisocyanate (p-MDI). The synthesized chemical structure is characterized using ATR-FTIR, while the key material properties reported here are the pH value, mean particle size and size distribution, and glass transition temperature. The WPU achieved suitable material properties, with small particles sizes and good dispersion, for applications in coatings.