The effects of processing conditions were studied on the phase morphology and mechanical properties of the polypropylene/polybutylene terephthalate (PP/PBT) blends toughened by styrene-butadiene triblock copolymer thermoplastic elastomers. Highly toughened PP-based blends that exhibited increased impact strength (seven- to ninefold) and little loss of stiffness (< 15%) in comparison with neat PP resin were successfully developed through manipulation of the dispersion state and interfacial interactions in the blend systems. A combination of core–shell and separately dispersed morphologies was predicted theoretically and identified by scanning electron microscopy (SEM) observations. It was found that the mixing order and intensity (screw speed) significantly affected the dispersion state of the modifier domains in the blends, which in turn, profoundly influenced the mechanical performance of the resulting blends. The phase interactions and crystalline structure of the blends were examined by DMTA and DSC analyses. The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. The toughened blends revealed enhanced crystallization behavior in the form of higher cold-crystallization temperature of the PP matrix and larger crystallinity degree over the neat PP resin. Fractography analysis showed numerous voids in the matrix and around the dispersed PBT domains which affected the energy absorbing mechanism during impact loading.

Graphic abstract

中文翻译：

---

加工条件对高韧聚丙烯/聚对苯二甲酸丁二醇酯（PP/PBT）共混物相形态和机械性能的影响

研究了加工条件对苯乙烯-丁二烯三嵌段共聚物热塑性弹性体增韧的聚丙烯/聚对苯二甲酸丁二醇酯 (PP/PBT) 共混物的相形态和机械性能的影响。与纯 PP 树脂相比，高度增韧的 PP 基共混物具有更高的冲击强度（7 到 9 倍）且刚度损失很小（< 15%），通过控制共混体系中的分散状态和界面相互作用成功开发。核壳和单独分散的形态的组合在理论上进行了预测，并通过扫描电子显微镜 (SEM) 观察进行了鉴定。发现混合顺序和强度（螺旋速度）显着影响共混物中改性剂域的分散状态，反过来，对所得共混物的机械性能产生了深远的影响。通过 DMTA 和 DSC 分析检查共混物的相相互作用和晶体结构。The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. 与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，在基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。通过 DMTA 和 DSC 分析检查共混物的相相互作用和晶体结构。The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. 与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，在基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。通过 DMTA 和 DSC 分析检查共混物的相相互作用和晶体结构。The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. 与纯 PP 树脂相比，增韧的共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. 与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。The results indicated that the two-step melt blending approach with properly selected mixing parameters was more effective in producing toughened PP/PBT blends with superior impact resistance than the one-step melt mixing procedure. 与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，在基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。与纯 PP 树脂相比，增韧共混物表现出增强的结晶行为，表现为 PP 基体的冷结晶温度更高，结晶度更高。断口分析表明，在基体中和分散的 PBT 域周围存在大量空隙，这些空隙影响了冲击载荷期间的能量吸收机制。

图形摘要