Method for making a poly-lactic acid/silica composite
Disclosed is a method for making a poly-lactic acid/silica composite. At first, silica particles are aminated, thus providing aminated silica particles. Secondly, the aminated silica particles are mixed with poly-lactic acid. Then, the mixture is blended and extruded by two micro-screws, thus providing a poly-lactic acid/silica composite. Thus, the mechanical properties of the poly-lactic acid are improved without affecting the biodegradability of the poly-lactic acid.
1. A method for making a poly-lactic acid/silica composite, the method including the steps of:
aminating silica particles, thus providing aminated silica particles; and
mixing the aminated silica particles with poly-lactic acid and extruding the mixture with two micro-screws, thus providing the poly-lactic acid/silica composite,
wherein the step of aminating the silica particles includes the steps of:
mixing the silica particles with methyl containing silane and amino containing silane;
adding a surfactant to the mixture;
executing a sol-gel process via acid or alkali catalysis to provide the aminated silica particles; and
washing and drying the aminated silica particles,
wherein the ratio of the methyl containing silane over the amino containing silane is 2:1 to 40:1.
2. The method according to claim 1 , wherein the diameter of the silica particles is 2 μm to 100 nm.
3. The method according to claim 1 , wherein the surfactant is selected from the group consisting of non-ionic surfactants and anion surfactants.
4. The method according to claim 1 , wherein the acid catalysis is executed by using acetic acid or hydrochloric acid to reduce the pH of the mixture to a value lower than 7 to facilitate the sol-gel process.
5. The method according to claim 1 , wherein the alkali catalysis is executed by using ammonia or sodium carbonate solution to increase the pH of the mixture to a value higher than 7 to facilitate the sol-gel process.
6. The method according to claim 1 , wherein the weight of the aminated silica particles is 1% to 7% of the weight of the poly-lactic acid.
7. The method according to claim 1 , wherein aminated silica particles are evenly distributed in the poly-lactic acid in the poly-lactic acid/silica composite.