Effect of Ammonium Dihydrogen Phosphate (ADP) Addition as Catalyst on the Curing Maltodextrin Adhesives Properties

Ammonium dihydrogen phosphate (ADP) is expected to be an effective catalyst to increase the water-resistance and hasten the curing speed of maltodextrin as wood adhesives. This research investigated the effect of ADP addition on the curing maltodextrin properties. The ratio of maltodextrin/ADP was 100/0 and 90/10 wt%. The heat treatment was 180-220 °C for 10 min. The water-resistance improvement and the chemical changes were analyzed using insoluble matter rate against boiling water and Fourier Transform Infrared (FTIR) analysis, respectively. The thermal behavior of the dried mixture of adhesives was also analyzed through differential scanning calorimetry (DSC) analysis at room temperature until 400 °C. The results showed that the water-resistance properties of maltodextrin increased with the addition of 10 wt% ADP and increasing the heating temperature. FTIR analysis detected a high water-resistant substance of furan in the adhesives with maltodextrin/ADP ratio 90/10 wt% and heat treatment of 220 °C for 10 min. DSC analysis showed that ADP addition can hasten the reaction of maltodextrin as the endotherm peak temperature was shifted from 272 to 204 °C.

Thermochemical Properties of Nicotine Salts

The thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) results presented in this report clearly show that the thermal stability and the endothermic peak nicotine release temperatures are different for different nicotine salts and these temperatures appear to be linked to the general microstructural details of the salt itself. In addition, the peak nicotine release temperatures are highly dependent upon the sample size used. The heat of vaporization for neat (non-protonated) nicotine is also sample-size dependent. The TGA data showed that the least stable of the salts tested at elevated temperatures was the liquid salt nicotine triacetate followed by the crystalline materials (e.g., nicotine gallate) and finally, the amorphous salts (e.g., nicotine alginate). The DSC results revealed that the liquid and crystalline salts exhibit nicotine release endotherms that are strongly related to the sample weight being tested. The amorphous salts show nicotine endotherm peak temperatures that are nearly independent of the sample weight. The range of peak nicotine release temperatures varied depending upon the specific salts and the sample size from 83 oC to well over 200 oC. Based on these results, the evolution of nicotine from the nicotine salt should be expected to vary based on the composition of the salt, the details of its microstructure, and the amount of nicotine salt tested.