Synthesis and analysis of the glycolide, dl-lactide copolymers, propylene carbonate and Е-caprolactone copolymers

Glycolic acid biopolymers with addition of plasticisers are used to obtain flexible, durable, bio-degradable stitch materials, microcirculatory vessels, implants, etc. Trimethylene carbonate and e-caprolactone are the most spread plasticizing agents regularly used for glycolic acid copolymers obtaining. It is suggested to investigate the possibility of propylene carbonate synthesis instead of trimethylene carbonate one. £-caprolactone is used as a plasticizing agent. Synthesis of glycolide, dl-lactidecopolymers, propylene carbonate copolymers was carried out at the permanent supplying of nitrogen in a two-neck flask (50 ml) equipped with a thermometer, a back flow condenser, and a mixing machine. The amount of the added propylene carbonate and e-caprolactone in the mixture, the time of adding propylene carbonate to the polymerizing mixture, and polymerizing temperatures were diversified. The amount of stannous octoate (II) catalyst was 0.05 wt%. A molecular weight regulator - lauryl alcohol - was added to the polymerizing mixture in a number of samples. We used two types of mixtures: 1) glycolide, dl-lactide, propylene carbonate; and 2) glycolide, dl-lactide, e-caprolactone, propylene carbonate. The temperature was selected upon the results of differential scanning calorimetry. The DSC graphs show that mixture 1 melts at temperatures of 40-91°С. During polymerization the maximal exo-effect is reached at 186.4 °С. But if e-caprolactone is added the maximal exo-effect is registered at 188.5°С. For further researches polymerization temperature is chosen to be 170-175°С. Polymers of type 1 and 2 were produced in the result of varied introduction of propylene-carbonate (in the beginning of synthesis or after the mixture of monomers melts), with the presence of lauryl alcohol as the initiating catalyst. The effect of lauryl alcohol was not found. It was proved that to produce a homogeneous polymer propylene carbonate has to be introduced in the beginning of the synthesis. The fiber-forming properties originate only if propylene-carbonate is introduced together with e-caprolactone. There were produced different samples of copolymers. One sample with glycolide 65.8 wt%, dl-lactide 3.3 wt%, e-caprolactone 14.2 wt%, propylene carbonate 16.7 wt% can be used for production of polymer fiber. The polymer was used to produce a string that was dimensionally stretched till further production of mono-filamentous fiber.

Keywords

Authors

References