Crude jatropha oil (JO) was modified to form jatropha oil-based polyol (JOL) via two steps in a chemical reaction known as epoxidation and hydroxylation. JOL was then reacted with isocyanates to produce JO-based polyurethane resin. In this study, two types of isocyanates, 2,4-toluene diisocyanate (2,4-TDI) and isophorone diisocyanate (IPDI) were introduced to produce JPUA-TDI and JPUA-IPDI respectively. 2,4-TDI is categorised as an aromatic isocyanate whilst IPDI is known as a cycloaliphatic isocyanate. Both JPUA-TDI and JPUA-IPDI were then end-capped by the acrylate functional group of 2-hydroxyethyl methacrylate (HEMA). The effects of that isocyanate structure were investigated for their physico, chemical and thermal properties. The changes of the functional groups during each synthesis step were monitored by FTIR analysis. The appearance of urethane peaks was observed at 1532 cm-1, 1718 cm-1 and 3369 cm-1 while acrylate peaks were detected at 815 cm-1 and 1663 cm-1 indicating that JPUA was successfully synthesised. It was found that the molar mass of JPUA-TDI was doubled compared to JPUA-IPDI. Each resin showed a similar degradation pattern analysed by thermal gravimetric analysis (TGA). For the mechanical properties, the JPUA-IPDI-based coating formulation exhibited a higher hardness value but poor adhesion compared to the JPUA-TDI-based coating formulation. Both types of jatropha-based polyurethane acrylate may potentially be used in an ultraviolet (UV) curing system specifically for clear coat surface applications to replace dependency on petroleum-based chemicals.
A study was carried out to produce polyurethane (PU) as a wood laminating adhesive from liquefied kenaf core (LKC) polyols by reacting it with toluene-2,4-diisocyanate (TDI) and 1,4-butanediol (BDO). The LKC polyurethane (LKCPU) adhesive has a molecular weight (MW) of 2666, viscosity of 5370 mPa s, and solids content of 86.9%. The average shear strength of the rubberwood (RW) bonded with LKCPU adhesive was 2.9 MPa. Most of the sheared specimens experienced a total adhesive failure. The formation of air bubbles through the liberation of carbon dioxide was observed to reduce the adhesive penetration and bonding strength which was obviously seen on the sheared specimens. The percentage of catalyst used can be varied based on the usage and working time needed. Nonetheless, the physical properties of LKCPU produced in this work had shown good potential as edge-bonding adhesive.
In this work, we reported the synthesis, characterization and adsorption study of two β-cyclodextrin (βCD) cross-linked polymers using aromatic linker 2,4-toluene diisocyanate (2,4-TDI) and aliphatic linker 1,6-hexamethylene diisocyanate (1,6-HDI) to form insoluble βCD-TDI and βCD-HDI. The adsorption of 2,4-dinitrophenol (DNP) on both polymers as an adsorbent was studied in batch adsorption experiments. Both polymers were well characterized using various tools that include Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis and scanning electron microscopy, and the results obtained were compared with the native βCD. The adsorption isotherm of 2,4-DNP onto polymers was studied. It showed that the Freundlich isotherm is a better fit for βCD-TDI, while the Langmuir isotherm is a better fit for βCD-HMDI. The pseudo-second-order kinetic model represented the adsorption process for both of the polymers. The thermodynamic study showed that βCD-TDI polymer was more favourable towards 2,4-DNP when compared with βCD-HDI polymer. Under optimized conditions, both βCD polymers were successfully applied on various environmental water samples for the removal of 2,4-DNP. βCD-TDI polymer showed enhanced sorption capacity and higher removal efficiency (greater than 80%) than βCD-HDI (greater than 70%) towards 2,4-DNP. The mechanism involved was discussed, and the effects of cross-linkers on βCD open up new perspectives for the removal of toxic contaminants from a body of water.
Toluene diisocyanate (TDI) is a major cause of chemical-induced occupational asthma, which contributes about 15% of global asthma burden. Resistance and compounded side effects associated with the use of corticosteroid in asthma necessitate the search for alternative drugs. Andrographolide (AGP), a naturally occurring diterpene lactone is known to exhibit various bioactivities. Its ability to ameliorate cardinal features of allergic asthma was previously suggested in an eosinophilic asthma endotype. However, its potential antiasthma activity and mechanism of action in a neutrophilic occupational asthma model, as well as its effect on epithelial dysfunction remain unknown. BALB/c mice were dermally sensitised with 0.3% TDI or acetone olive oil (AOO) vehicle on day 1 and 8, followed by 0.1% TDI intranasal challenge on days 15, 18 and 21. Endpoints were evaluated via bronchoalveolar lavage fluid (BALF) cell analysis, 2',7'-dichlorofluorescein diacetate (DCFDA) assays, immunoblotting, immunohistochemistry and methacholine challenge test. Decreases in total and differential leukocyte counts of BALF were recorded in AGP-treated animals. The compound dose-dependently reduced intracellular de-esterification of DCFDA, thus suggesting AGP's potential to inhibit intracellular reactive oxygen species (ROS). Mechanistically, the treatment prevented TDI-induced aberrant E-cadherin distribution and restored airway epithelial β-catenin at cell to cell contact site. Furthermore, AGP ameliorated TDI induced pulmonary collagen deposition. In addition, the treatment significantly upregulated pulmonary HO-1, Nrf2 and phospho-p38 levels. Airway hyperresponsiveness was markedly suppressed among AGP-treated animals. Collectively, these findings suggest AGP's protective function against TDI-induced airway epithelial barrier dysfunction and oxidative lung damage possibly through the upregulation of adherence junction proteins and the activation of p38/Nrf2 signalling. This study elucidates the therapeutic potential of AGP in the control and management of chemical-induced allergic asthma. To the best of our knowledge, the potential anti-asthma activity of AGP in TDI-induced occupational asthma has not been reported previously.