PP／HDPE／SBS三元共混物的研究：基体韧性和弹性体分散相对PP三…

研究了固定ＰＰ／ＨＤＰＥ／ＳＢＳ三地共混物配比，采用不同共混工艺条件下的脆－韧转变规律。研究表明：ＰＰ三元共混物的冲击强度与ＳＢＳ分散相粒径有密度关系，当ＳＢＳ分散相粒间距Ｔ等于临界值ＴＣ时、ＰＰ三元共混物将发生脆－韧转变研究还表明基体韧性与ＴＣ有密切关系，当基体韧性增高时，ＴＣ值将增大。     

降解PP/EPDM共混物的力学性能

用过氧化二异丙苯(DCP)将聚丙烯(PP)降解,制备降解PP与三元乙丙橡胶(EPDM)共混物,测试降解PP/EPDM共混物的冲击和拉伸性能,研究共混物的脆—韧转变,结果发现温度和EPDM含量对PP/EPDM共混物的韧性影响规律是相同的,增加温度和增加EPDM含量都能使PP/EPDM共混物的韧性增加。     

PP／HDPE／SBS三元共混物的研究——形态结构与性能

研究了PP/HDPE/SBS三元共混物的性能及形态结构特征。研究结果表明,PP三元共混物的冲击韧性除与SBS的含量密切相关外,还与HDPE的含量有关,HDPE起到了与SBS相似的增韧作用。由于HDPE的掺入,减少了SBS的含量,制成了一种力学性能均衡的超高韧性PP三元共混材料。形态结构的研究表明,共混物中,SBS呈颗粒状分布,另外SBS还与HDPE组成了具有包藏结构的复合粒子。     

纳米莫来石填充PP/EPDM共混物的脆韧转变

制备了含纳米莫来石的三元乙丙橡胶(EPDM)和马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH)母料,研究了纳米莫来石对聚丙烯(PP)/EPDM和PP/EPDM-g-MAH共混物脆韧转变的影响。结果表明:纳米莫来石的加入使PP/EPDM和PP/EPDM-g-MAH共混物的脆韧转变提前,尤其在纳米莫来石用KH-550改性后,PP/EPDM共混物发生脆韧转变时EPDM的含量由15%降至10%;在橡胶相含量相同时,加入纳米莫来石后共混物的弹性模量和拉伸强度略有下降,而断裂伸长率显著下降。     

PP/EPDM/纳米弹性体粒子三元共混体系的脆韧转变

研究了PP／EPDM／纳米弹性体粒子(ENP)三元共混体系的脆韧转变行为。结果表明，与PP／EPDM二元共混物相比，三元共混物的脆韧转变可以在EPDM质量分数较低的情况下发生；在橡胶总质量分数相同的情况下，三元共混物有更高的冲击强度，拉伸强度有一定提高。从脆断样条的扫描电镜照片观察到，在相同EPDM质量分数下，PP／EPDM／ENP三元共混物中的EPDM粒子明显细化，分布均一，粒子间距减小，这是脆韧转变提前的原因。     

PP/LLDPE交联共混物的力学性能研究

采用两步交联加工法制备出具有优良力学性能的PP／LLDPE共混物。实验表明：当m(PP)／m(LLDPE)／m(SBS)／m(交联剂)为80／20／10／3时，交联共混物的冲击强度、拉伸强度和断裂伸长率分别达到466．3J／m、27．1MPa和715．1％，比未交联的共混物分别提高262％、8．28％和115％；交联作用的存在使共混物的脆韧转变点明显提前；随交联剂用量的增加，共混物的力学性能不断提高，但增大趋势逐渐变小。     

PP/HDPE/弹性体三元共混改性的研究

用双螺杆挤出机制备了聚丙烯(PP)/高密度聚乙烯(HDPE)/弹性体三元共混物,分别探讨了3种弹性体乙烯-辛烯嵌段共聚物(OBC)、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)、苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物(SEBS)的含量对PP三元共混物力学性能的影响,并通过扫描电子显微镜观察其脆断表面形态。结果表明,OBC、SBS、SEBS和HDPE都对PP起到了一定的协同增韧作用,SEBS对PP的增韧效果最佳;SEM表明三元共混力学性能与相形态密切相关;所制备的PP/HDPE/OBC三元共混物的加工性能较好。     

PP/PS/SBS共混物的性能研究

通过添加聚苯乙烯(PS)、热塑性弹性体苯乙烯-丁二烯-苯乙烯共聚物(SBS),以改善聚丙烯(PP)的性能。先采用熔融法制备PP/PS共混物,在确定PP,PS最佳配比的基础上,再添加SBS制备PP/PS/SBS共混物,确定了PP,PS及SBS的最佳配比。研究了PP/PS,PP/PS/SBS共混物的力学性能、热性能及熔体流动行为。结果表明,当PP与PS的质量比为70∶30时,PP/PS共混物的性能最好,其拉伸强度为28.5 MPa,拉伸弹性模量为1 214 MPa,弯曲弹性模量为1 752 MPa,冲击强度为14.0 kJ/m2,断裂应变为130%,维卡软化温度为143.9℃。当PP,PS及SBS的质量比为70∶30∶10时,PP/PS/SBS共混物的性能最好,其拉伸强度为23.2 MPa,拉伸弹性模量1 040 MPa,断裂应变为260%,冲击强度为18.0 kJ/m2,弯曲强度为36.5 MPa,弯曲弹性模量为1 297 MPa,定挠度弯曲应力为36.1 MPa,弯曲破坏应力为36.5 MPa,熔体流动速率为8.94 g/(10 min),维卡软化温度为139.0℃。     

螺杆转速对PP/POE共混物形态及冲击性能的影响

通过双螺杆挤出机熔融共混制备了聚丙烯/(乙烯/辛烯)共聚物(PP/POE)共混物,研究了螺杆转速对PP/POE共混物形态及力学性能的影响。结果表明,随着螺杆转速的提高,共混物中POE粒子的尺寸先减小后增大,这可以通过Tokita公式来解释。缺口冲击实验表明,PP/POE共混物的缺口冲击强度随着螺杆转速的增加呈先升高后降低的趋势,当螺杆转速为110r/min时,共混物的缺口冲击强度最高,其相形态与冲击性能有很好的相关性;共混物的缺口冲击强度随POE粒径的增大而降低,达到一定程度时出现脆韧转变特征,这点与S.Wu理论相符合。     

乙烯共聚物弹性体在PP/LLDPE共混物中的增韧作用

研究了乙烯共聚物弹性体对聚丙烯/线型低密度聚乙烯(PP/LLDPE)共混物的增韧作用。结果说明,乙烯共聚物弹性体对LLDPE分散相起到了很好的分散作用,PP基体的韧性显著增大。     

The effect of matrix toughness and dispersed elastomer phase on the brittle-ductile transition in PP/HDPE/SBS blends

In this paper the sbrittle-ductile transition of polypropylene, high density polyethylene, and a styrene-butadiene-styrene triblock copolymer (PP/HDPE/SBS) ternary blends is investigated for fixed compositions and prepared under various conditions. The morphology of the SBS dispersed phase particles and impact strength of the PP ternary blends is closely related to the processing conditions. There is a sharp Brittle-Ductile transition for the ternary blends when interparticle distance T becomes less than the critical interparticle distance T_c. Both the impact strength in general and more specifically, T_c depend upon the toughness of the PP/HDPE composite matrix.     

Structure and properties of PP/POE/HDPE blends

This work was aimed to counteract the effect of ethylene‐α‐olefin copolymers (POE) by reinforcing the polypropylene (PP)/POE blends with high density polyethylene (HDPE) particles and, thus, achieved a balance between toughness and strength for the PP/POE/HDPE blends. The results showed that addition of HDPE resulted in an increasing wide stress plateau and more ductile fracture behavior. With the increase of HDPE content, the elongation at break of the blends increased rapidly without obvious decrease of yield strength and Young's modulus, and the notched izod impact strength of the blends can reach as high as 63 kJ/m² at 20 wt % HDPE loading. The storage modulus of PP blends increased and the glass transition temperature of each component of the blends shifted close to each other when HDPE was added. The crystallization of HDPE phase led to an increase of the total crystallinity of the blend. With increasing HDPE content, the dispersed POE particle size was obviously decreased, and the interparticle distance was effectively reduced and the blend rearranged into much more and obvious core‐shell structure. The fracture surface also changed from irregular striation to the regularly distant striations, displaying much obvious character of tough fracture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical properties and morphologies of PP/mPE/filler composites

Because of the poor impact behavior of polypropylene (PP) at low temperatures, the blending of PP with metallocene‐polymerized polyethylene (mPE) elastomers was investigated in this study. However, a reduced modulus of the overall blend was inevitable because of the addition to elastomers. To obtain a balance of the properties, we introduced rigid inorganic fillers to PP/mPE blends. The performance of the composites was characterized with tensile and Charpy notched impact tests, and the fracture morphology was examined with scanning electron microscopy. The results showed that the effects of fillers in a brittle matrix and in a ductile matrix were quantitatively different. For PP/mPE/filler ternary composites, the dependence of Young's modulus and yield strength on CaCO₃ content was not significant compared with that of PP/filler binary composites, whereas the elongation at break and tensile toughness at room temperature for PP/mPE/filler systems were more improved. The impact strength of the PP/mPE blends filled with untreated glass beads and CaCO₃ at a low temperature was lowered because of the weak interfacial bond. However, the values of the impact strength of the PP/mPE/filler composites at a low temperature remained at a high level compared with that of pure PP. In particular, a PP/mPE blend filled with surface‐treated kaolin had a higher low‐temperature impact toughness than the unfilled blend. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3029–3035, 2002; DOI 10.1002/app.2333     

Effect of rubber interparticle distance distribution on toughening behavior of thermoplastic polyolefin elastomer toughened polypropylene

In this study, a blend of polypropylene (PP) and two types of thermoplastic polyolefin elastomers (TPO) were prepared by melt mixing. The TPOs were either ethylene‐ or propylene‐based copolymer. The mechanical response and morphology of the blends were investigated using tensile and impact tests and scanning electron microscopy technique. There was significant increase in the impact strength of the TPO‐modified PP, which was an outcome of fine dispersion of TPO inclusions. In particular, the blends containing PP‐based TPO exhibited dramatic enhancement in toughness energy as featured by a plastic deformation in tensile test. The brittle‐tough transition had several deviations from theoretical models, in which generally the interparticle distance criterion was realized as a single parameter, only controlled the transition of brittle to tough behavior. Moreover, the brittle‐tough transition in tensile and impact mode tests was not coincident in the blend with a broad distribution of interparticle distance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44068.     

Brittle‐Ductile Transition and Toughening Mechanism in POM/TPU/CaCO3 Ternary Composites

Summary: Polyoxymethylene (POM)/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane(TPU) and an inorganic filler, CaCO₃, were used to achieve balanced mechanical properties of POM. A two‐step processing method, in which the elastomer and the filler were mixed to a masterbatch first and then the masterbatch was melt‐blended with pure POM, was used to obtain a core‐shell microstructure with CaCO₃ covered by TPU. A brittle‐ductile transition phenomenon was observed with increasing TPU content for this ternary system. To better understand the toughening mechanism, we investigated the fractured surface, interparticle distance, and the spherulite size of POM as function of the TPU and CaCO₃ content. The critical TPU content depended on not only the content of CaCO₃, but also the size of CaCO₃ particles. The observed brittle‐ductile transition was discussed based on the crystallinity and spherulite size of POM as well as Wu's critical interparticle distance theory. The results showed that the impact strength of POM/TPU/CaCO₃ ternary system depends on a critical, interparticle distance, which varies from one system to another. The dependence of the impact strength on the spherulite size was considered for the first time, and a single curve was constructed. A critical spherulite size of 40 micron was found, at which brittle‐ductile transition occurs, regardless of the TPU and CaCO₃ content or the size of CaCO₃ particles. Our results indicate that the spherulite size of POM indeed plays a role in determining the toughness, and must be considered when discussing the toughening mechanism.

Izod impact strength vs. the crystal size for POM/TPU blends and POM/TPU/CaCO₃ ternary composites.     

SIS/SBS/PP共混改性的研究

研究了新型聚丙烯(PP)合金材料的配方、制备、工艺及性能。分别讨论了不同用量的三元乙丙橡胶 (EPDM)、苯乙烯与异戊二烯嵌段共聚物(SIS)及苯乙烯与丁二烯嵌段共聚物(SBS)与PP组成的二元和三元共混体系对材料力学性能的影响。结果表明:SIS为PP较好的增韧剂,PP／SIS/SBS三元共混体系具有较好的协同效应,在某种程度上可以代替EPDM改性PP,共混改性后拉伸强度、扯断伸长率等性能优良。     

SBS／EVA改制PP力学性能的研究

研究了PP／EVA、PP／SBS和PP／EVA／SBS共混体系,对其不同配比的共混体系进行了物理机械性能测试与讨论。结果表明,SBS和EVA并用增韧PP时,当质量份大于17份时有着显著的协同效应,PP／EVA／SBS三元共混物具有优良的抗冲击性能。     

Probing toughness of polycarbonate (PC: ductile and brittle)/polypropylene (PP) blends and talc-triggered PC/PP brittle composites with diverse impact fracture parameters

Polycarbonates (PCs) are commonly used as a blend and a composite to achieve pecuniary advantages and dimensional stability. While the toughness of a homogeneous PC matrix has been extensively investigated, examination for the toughness of heterogeneous blend systems such as PC/polypropylene (PP) blends has been limited. Furthermore, recent interest in highly flowable PCs (low-molecular-weight PCs with low ductility) has surfaced due to the large and geometrically complex plastic parts. Herein, the toughness for PC/PP blends and PC/PP/talc composites in a ductile and a brittle PC matrix was explored by using various toughness measurements such as notched Izod impact strength, falling dart impact, boss quasi-static energy/impact energy, and tensile toughness tests. In a ductile PC matrix [melt flow index (MFI) = 8], the incorporation of PP gradually reduced the toughness. On the other hand, the toughness was improved by 450% at 2 wt % PP in a brittle PC matrix (MFI = 19). Similarly, in the talc-induced brittle PC matrix, the toughness was enhanced at the PP loading from 2 to 10 wt %. The density of PC/PP blends was gradually reduced from 1.19 to 1.10 g cm⁻³ with increasing PP concentration from 0 to 20 wt %. Degradation, density, thermal behaviors, and morphology were also investigated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47110.