In the present work, poly(lactic acid) (PLA) was modified with two peroxide initiators: biphenyl peroxide (BPO) and dicumyl peroxide (DCP). The samples were all prepared with melt compounding method. Changes in the structure of PLA after the modification were analyzed with Fourier transformed infrared spectroscopy, gel penetration chromatography, and field emission scanning electron microscopy. Thermomechanical properties of the samples were determined with tensile test, dynamic mechanical analysis, and thermal gravimetric analysis/differential scanning calorimetry simultaneous thermal analyzer. Both BPO and DCP initiated free‐radical reactions at PLA polymer chains, which led to the formation of crosslinking structure. By this way, the tensile strength of PLA was elevated to about 50 MPa, which was much higher than the tensile strength of unmodified PLA (35.5 MPa). The glass‐transition temperature and melting temperature of the samples slightly decreased after modification. The different influences of BPO and DCP on PLA were mainly derived from their different chemical structures and activities.

中文翻译：

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两种过氧化物引发剂对聚乳酸结构和性能的不同影响

在目前的工作中，聚乳酸（PLA）用两种过氧化物引发剂改性：过氧化联苯（BPO）和过氧化二枯基（DCP）。样品均采用熔融复合法制备。改性后的PLA结构变化通过傅里叶变换红外光谱，凝胶渗透色谱和场发射扫描电子显微镜进行了分析。通过拉伸试验，动态力学分析和热重分析/差示扫描量热法同时热分析仪测定样品的热机械性能。BPO和DCP均会在PLA聚合物链上引发自由基反应，从而导致交联结构的形成。通过这种方式，PLA的拉伸强度提高到约50 MPa，它比未改性的PLA的抗张强度（35.5 MPa）高得多。改性后样品的玻璃化转变温度和熔融温度略有降低。BPO和DCP对PLA的不同影响主要是由于它们的化学结构和活性不同。