Study On Polyamide-Polyurea Macrocapsule Prepared By Interfacial Polymerization

Capsule technology is widely used in such industry production fields as pharmacy, makeup, food, etc... Because material has a lot of special performance after kystis, capsule technology was widely researched by various countries' scientific technical staffs. The research of the capsule concentrates mainly on the field of microcapsule (those are smaller than 50 microns) at present. And studying relatively less to capsule of the large size (one is greater than 0.5 mm). Macrocapsule has the properties of high encapsulate ratio, low specific surface, low cost and prolonged-release speed. So the research to the macrocapsule is very important. This research selects 1, 6-hexanediamine (HDA) and tetraethylene pentamine (TPA) as the reactants in water phase, hexanedioic chloride (HDC) and toluene-2, 4-diisocyanate (TDI) as the reactants in oil phase to prepare polyamide-polyurea macrocapsules with 0.5-2mm in diameters by interfacial polymerization. By changing the ratio of the reactants different capsules were prepared. The experiment adopts IR spectrum to study the composition of the capsule wall. The ratio of the reactants and stirring speed on the average diameter of capsule were studied in the experiment. The mechanic strength of capsules was studied by laboratory method. The release process of the low volatile medicine in liquid phase and that of high volatile medicine in gas phase were studied by ultraviolet spectrophotometers. This research has made the following results: 1. Analysis different samples by IR spectrum. The results shows that the composition of the capsule walls correspond to the anticipation. This proved the feasibility of the method. 2. By changing the ratio of the reactants, capsules with different size were got. Capsules get larger then get smaller with the increasing of TDI content. When use TDI as the only oil phase reactant, no macrocapules were got. When the ratio between TDI and HDC was 1 to 5, the mean diameters of the capsules have a maximum value. Capsules get smaller with the increasing of TPA content in water phase. When use HDA as the only water phase reactant, there were no capsules formed, only polymer agglomeration were formed. 3. The study to the effect of stirring speed on the diameter of capsules was corresponding to other research works in interfacial polymerization. That is that the capsule diameter decrease and size distribution become narrow with the increasing of stirring speed. 4. The mechanical strength of the capsules increase with the increase of TDI consumption. When the consumption of TDI reaches a certain value, the capsule will not have an obvious breaking point. Increasing of TPA consumption will make the capsule fragile; Increasing that of HDA consumption will make the capsule tough. 5. The release study shows that the macrocpsules release core materials more slowly than microcapsules in the same condition. Study shows thatmacrocapsules also have a good release profile in gas phase. Changing the ratio of the reactant, capsules with different release profiles were prepared.