Gogolewski S, Mainil-Varlet P, Dillon J G
AO/ASIF Research Institute, Davos, Switzerland.
J Biomed Mater Res. 1996 Oct;32(2):227-35. doi: 10.1002/(SICI)1097-4636(199610)32:2<227::AID-JBM12>3.0.CO;2-G.
The effect of low-temperature plasma on sterility, molecular, mechanical, and crystalline properties of poly (L-lactide), poly (L/D-lactide) and poly (L/DL-lactide) was investigated. Polymers were treated for 15 and 30 min at 100 W with nitrogen, argon, oxygen, and carbon dioxide plasma. All polymers treated with oxygen or carbon dioxide plasma were rendered sterile after 15 min of treatment. Only 70% of the samples treated under similar conditions with nitrogen or argon plasma were sterile. Extension of the exposure time to 30 min and increasing power to 200 W did not improve sterilization efficiency. Plasma sterilization, under the conditions used, caused no significant decrease or increase in overall molecular weight or polydispersity of the polylactides used. In most instances the effect of plasma sterilization was to slightly increase the overall molecular weight of the polymers studied. Treatment with argon plasma led to a more consistent increase in molecular weight than did treatment with nitrogen, oxygen, or carbon dioxide. Analysis of the surface (skin) of a poly(L-lactide) injection-molded rod following plasma sterilization indicated an increase in molecular weight as related to the interior (core) of the rod. Comparison of Mark-Houwink plots for the surface and interior of poly(L-lactide) injection-molded rods following plasma sterilization indicated an increase in chain branching for the surface relative to the interior of the rod. Generally the highly crystalline poly(L-lactide) was less susceptible to change upon plasma treatment than was the less crystalline poly(L/D-lactide) and poly(L/DL-lactide). The mechanical properties (shear strength, bending strength, and moduli) of the polylactides were not affected by plasma treatment. The overall melting temperature and the heat of melting of polylactides studied were not affected by plasma treatment. The melting temperature of the skin of the samples was about 1 degree C higher than the melting temperature of the core due to the chain orientation upon injection-molding. Plasma treatment of the polylactides reduced the melting temperature of the skin by 3 degrees C to 5 degrees C due to the crosslinking or branching at the surface layer.
研究了低温等离子体对聚（L-丙交酯）、聚（L/D-丙交酯）和聚（L/DL-丙交酯）的无菌性、分子、机械和结晶性能的影响。聚合物分别用氮气、氩气、氧气和二氧化碳等离子体在100W功率下处理15分钟和30分钟。所有用氧气或二氧化碳等离子体处理的聚合物在处理15分钟后都达到了无菌状态。在类似条件下用氮气或氩气等离子体处理的样品只有70%是无菌的。将暴露时间延长至30分钟并将功率提高到200W并没有提高灭菌效率。在所使用的条件下，等离子体灭菌并未导致所用聚丙交酯的总分子量或多分散性显著降低或增加。在大多数情况下，等离子体灭菌的效果是使所研究的聚合物的总分子量略有增加。与用氮气、氧气或二氧化碳处理相比，用氩气等离子体处理导致分子量增加更一致。对等离子体灭菌后的聚（L-丙交酯）注塑棒的表面（皮层）分析表明，与棒的内部（芯层）相比，分子量有所增加。等离子体灭菌后聚（L-丙交酯）注塑棒表面和内部的Mark-Houwink图比较表明，相对于棒的内部，表面的链支化增加。一般来说，高度结晶的聚（L-丙交酯）比结晶度较低的聚（L/D-丙交酯）和聚（L/DL-丙交酯）在等离子体处理后更不易发生变化。聚丙交酯的机械性能（剪切强度、弯曲强度和模量）不受等离子体处理的影响。所研究的聚丙交酯的总熔点和熔化热不受等离子体处理的影响。由于注塑成型时的链取向，样品皮层的熔点比芯层的熔点高约1℃。由于表层的交联或支化，聚丙交酯的等离子体处理使皮层的熔点降低了3℃至5℃。
