Mechanical properties,morphological structure,and thermal behavior of dynamically photocrosslinked PP/EPDM blends

A dynamically photocrosslinked polypropylene (PP)/ethylene–propylene–diene (EPDM) rubber thermoplastic elastomer was prepared by simultaneously exposing the elastomer to UV light while melt‐mixing in the presence of a photoinitiator as well as a crosslinking agent. The effects of dynamic photocrosslinking and blend composition on the mechanical properties, morphological structure, and thermal behavior of PP/EPDM blends were investigated. The results showed that after photocrosslinking, tensile strength, modulus of elasticity, and elongation at break were improved greatly. Moreover, the notched Izod impact strength was obviously enhanced compared with corresponding uncrosslinked blend. Scanning electron microscopy (SEM) morphological analysis showed that for uncrosslinked PP/EPDM blends, the cavitation of EPDM particles was the main toughening mechanism; whereas for dynamically photocrosslinked blends, shear yielding of matrix became the main energy absorption mechanism. The DSC curves showed that for each dynamically photocrosslinked PP/EPDM blend, there was a new smaller melting peak at about 152°C together with a main melting peak at about 166°C. Dynamic mechanical thermal analysis (DMTA) indicated that the compatibility between EPDM and PP was improved by dynamic photocrosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3371–3380, 2004     

PP／EPDM热塑性弹性体动态光交联制备法研究

采用动态光交联法制备了3种不同类型的PP/三元乙丙橡胶(EPDM)热塑性弹性体,探讨了PP的结构及化学组成、动态光交联时间对PP/EPDM热塑性弹性体性能的影响。力学性能、扫描电镜、动态力学热分析、熔体流动速率等测试结果表明,PP的结构及化学组成对体系性能的影响显著,H_2P/EPDM热塑性弹性体的综合性能最佳。而动态光交联能明显提高体系的相容性,进而大幅度提高体系的力学性能。H_2P_(70)V_0的拉伸强度为17．3 MPa,缺口冲击强度为34．9 kJ/m~2,而H_2p_(70)V_(60)的拉伸强度为21．2 MPa,缺口冲击强度为66．3 kJ/m~2,拉伸强度提高20％,缺口冲击强度提高近1倍。     

Mechanical properties and morphologies of polypropylene composites synergistically filled by styrene‐butadiene rubber and silica nanoparticles

The mechanical properties and morphologies of PP/SBR/SiO₂ nanocomposites have been studied using mechanical testing, wide‐angle X‐ray diffraction (WAXD), polarizing optical microscopy (POM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The mechanical properties of neat polypropylene can be considerably improved by synergistically filling with SiO₂ and SBR nanoparticles, especially for the notched Izod impact strength. The results from the WAXD, POM, SEM, DSC, and TGA measurements reveal that: (i) the β‐phase crystal structure of PP is formed when SiO₂ and SBR nanoparticles are synergistically filled with polypropylene and its formation plays a role for the enhancement of the impact strength for PP/SBR/SiO₂ nanocomposites; (ii) the dispersion of SiO₂ and SBR nanoparticles in PP/SBR/SiO₂ composites is homogeneous, indicating that synergistic incorporating method decreases the aggregation of nanoparticles and thus increases the sites for dissipation of shock for impact energy in PP/SBR/SiO₂ nanocomposites; (iii) the thermal analysis shows high thermal stability for the PP/SBR/SiO₂ nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

环氧树脂对PP/EPDM-g-MAH力学性能与形态结构的影响

将未固化的环氧树脂与不同比例的PP/EPDM-g-MAH共混挤出,得到复合材料。通过力学性能测试、动态力学性能分析(DMA)、差示扫描量热法(DSC)以及扫描电镜(SEM),研究了环氧树脂对共混物力学性能与形态结构的影响。结果表明:当PP/EPDM-g-MAH为80/20时,环氧树脂的加入能极大地提高共混物的缺口冲击强度,加入3%的环氧树脂,PP/EPDM-g-MAH(80/20)共混体系的缺口冲击强度从17.5 kJ/m2提高到62.47kJ/m2;在全体系中,环氧树脂的加入对拉伸性能影响较小,使EPDM-g-MAH分散相尺寸变小,在基体中分布更均匀。     

PP—g —HMA增容尼龙6／聚丙烯共混物结构与性能研究

采用固相力化学方法制备的聚丙烯接枝羟甲基丙烯酰胺作增容剂,制备了尼龙6／聚丙烯共混物,通过SEM、DSC、流变性能测试和力学性能测试研究了共混物的结构、流变性能和力学性能。 结果表明,当尼龙6体积分数为80％时,增容共混体系中冲击强度出现峰值,达到77J／m,分散相尺寸变小,增容共混体系熔融粘度增加。通过Molau实验和FT－IR分析对增容机理作了初步探讨。     

聚丙烯/三元乙丙橡胶共混体系的研究

研究了三元乙丙橡胶（ＥＰＤＭ）对聚丙烯（ＰＰ）结晶行为的影响以及ＰＰ／ＥＰＤＭ共混物的形态与性能的关系。ＥＰＤＭ对ＰＰ的熔点、结晶温度无明显影响,ＰＰ／ＥＰＤＭ共混物的结晶度随ＥＰＤＭ组份含量的增加而降低,适量的ＥＰＤＭ可使ＰＰ的晶体尺寸减小,晶胞参数与组份比无关。当ＥＰＤＭ用量为３０％～４０％时,共混物的冲击强度迅速提高。     

Effect of ultrasound on extrusion of PP/EPDM blends: Structure and mechanical properties

The effects of ultrasonic irradiation on the mechanical properties, morphology, and crystal structure of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends were examined. Results show that appropriate irradiation intensity can noticeably increase the toughness of the PP/EPDM blends without reducing rigidity. Scanning electron microscopic (SEM) observation shows that with ultrasonic irradiation, the morphology of a well‐dispersed EPDM phase is formed in the PP/EPDM blend. The glass transition temperatures of PP and EPDM phase approach each other as a result of ultrasonic irradiation. Differential Scanning Calorimetric (DSC) analysis indicates that the crystallinities of the PP and EPDM phases increase with ultrasonic irradiation, and β crystals of PP form in the PP/EPDM blend with ultrasonic irradiation, which is proven by wide angle X‐ray diffraction (WAXD) analysis. Polym. Eng. Sci. 44:1509–1513, 2004. © 2004 Society of Plastics Engineers.     

Properties of copolymer-type polyacetal/ethylene–propylene–diene terpolymer blends

Two kinds of polymer blends, polyacetals (POMs) and ethylene–propylene–diene terpolymer (EPDM), have been prepared by mechanical blending. The rubbery EPDM was added to the rigid POM matrix to increase toughness. The mechanical, physical, thermal, dynamic mechanical, and morphological properties of these samples have been measured. The notched Izod impact strength and the elongation of the blends reaches a maximum at 7.5 wt % EPDM content. Scanning electron micrographs (SEM) showed that the domain sizes of EPDM vary from 0.25 to 1.0 μm and were independent of the composition. The POM/EPDM blends were determined to be immiscible by SEM, but showed single T_g behavior as determined by differential scanning calorimetry (DSC) and dynamic mechanical analyses up to 7.5 wt % EPDM. Because of that, the T_g's of POM and EPDM were very similar in value. © 1993 John Wiley & Sons, Inc.     

PP/EPDM热塑性弹性体结晶与熔融行为研究

采用动态光交联法制备了PP／EPDM[聚丙烯／（乙烯／丙烯／二烯）共聚物]热塑性弹性体。运用广角X射线衍射（WAXD），偏光显微镜（POM）与差示扫描量热仪（DSC）对PP的结晶形态及结晶与熔融行为进行表征。结果表明，EPDM的加入妨碍PP形成完善的球晶，而动态光交联体系中PP的球晶更不完善；动态光交联对PP的结晶温度及熔点影响不大，结晶度低于未交联体系的。     

悬浮法EPDM-g-MAN对SAN的增韧及其共混物的热稳定性分析

用悬浮法在乙烯-丙烯-乙叉降冰片烯三元乙丙橡胶(EPDM)上接枝甲基丙烯酸甲酯-丙烯腈(MMA-AN),将接枝共聚物EPDM-g-MAN与苯乙烯-丙烯腈共聚物(SAN)树脂共混,得到高抗冲、耐老化性能优异的工程塑料。FTIR分析表明,EPDM确已接枝上了MMA-AN支链。研究了AN含量和EPDM含量对EPDM-g-MAN/SAN共混物力学性能的影响。随着EPDM含量的增加,共混物缺口冲击强度先升后降,在AN质量分数为5%,EPDM质量分数为25%时达到最大值76.8kJ/m2,拉伸和弯曲强度逐步下降。扫描电镜(SEM)和差示扫描热(DSC)分析表明,在EPDM质量分数为15%时,共混物室温条件下受外界冲击发生脆韧转变,EPDM-g-MAN与SAN具有较好的相容性。TG分析表明,随着EPDM含量增加,EPDM-g-MAN/SAN共混物的热失重起始温度有所上升,热稳定性得到提高。     

Simultaneously improving the toughness,flexural modulus and thermal performance of isotactic polypropylene by α‐β crystalline transition and inorganic whisker reinforcement

Magnesium salt (M‐HOS) whisker and β‐nucleating agent were introduced into polypropylene and their effects on the crystalline structures, morphologies, mechanical properties, and thermal resistance of polypropylene (PP) were investigated. The results of wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and polar optical microscopy (POM) examinations suggested that the presence of the whisker did not cause any negative effect on the occurrence of β‐modification, and β‐phase became absolutely dominant form in β‐nucleated samples. The mechanical and thermal properties tests demonstrated that there is an excellent synergy between the β‐nucleating agent and the whisker. For PP composite containing 0.1 wt% of the β‐nucleating agent and 10 wt% of the whiskers, the Izod notched impact strength, elongation at break, flexural modulus, and heat deflection temperature were increased by 108, 194, 31, and 40%, respectively, compared with those of neat PP. By combining the toughening effect of α–β transition with the reinforcing effect of the whisker, simultaneous improvement in toughness, flexural modulus, and thermal performance of PP was successfully achieved. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Melting and crystallization behaviors,morphology, and mechanical properties of β‐polypropylene/polypropylene‐graft‐maleic anhydride/calcium sulfate whisker composites

The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface‐treated calcium sulfate (CaSO₄) whisker (T‐CSW), β‐PP/T‐CSW, and β‐PP/polypropylene‐graft‐maleic anhydride (PP‐g‐MAH)/T‐CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T‐CSW was an α‐nucleating agent and increased the crystallization temperatures of PP, but PP‐g‐MAH and high loadings of T‐CSW had weakly negative effects on the crystallization rates of PP. The T‐CSW restrained the formation of β‐spherulites, and the spherulitic size decreased in the composites. PP‐g‐MAH improved the compatibility and adhesion between T‐CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T‐CSW, while the flexural modulus was weakened for β‐PP/T‐CSW and β‐PP/PP‐g‐MAH/T‐CSW composites versus PP/T‐CSW composites. POLYM. COMPOS., 37:2121–2132, 2016. © 2015 Society of Plastics Engineers     

新型热塑性弹性体增韧聚丙烯的研究

以聚烯烃弹性体(POE,乙烯-辛烯共聚物)为PP的增韧性剂,利用转矩流变仪、差示量热扫描(DSC)及力学性能测试方法,比较研究了PP/POE及PP/EPDM共混物的加工性能、结晶性能及力学性能;结果表明,POE在加工性、改性效果等方面比EPDM更具优势。还探讨了POE用量对PP/CaCO     

Effect of spatial confinement on the development of β phase of polypropylene

The focus of this study was the effect of spatial confinement on the development of nucleating agent-induced β phase polypropylene (PP) in the dynamically vulcanized thermoplastic elastomers (TPVs) based on dynamically vulcanized PP/ethylene-propylene-diene rubber (EPDM) blend. The melting behaviors, crystalline structures and the morphologies of the blends were studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). The results indicate that the EPDM phase undergoes a series of changes from the dispersed phase to a continuous one, and again to the dispersed phase with increased content of curing agent, and the PP component always shows itself in a continuous phase. In this process, with the content of the nucleating agent unchanged, the content of β phase PP in the blends initially increases a little and then decreases with increasing PF (Phenolic resin) content. We believe spatial confinement provides a good explanation for the development of β phase PP.     

Special effect of epoxy resin E-44 on compatibility and mechanical properties of poly(butylene terephthalate)/polyamide-6 blends

An attempt was made to modify the properties of poly(butylene terephthalate) (PBT) by blending it with polyamide-6 (PA-6). Since PBT and PA-6 are incompatible, epoxy resin was used as a compatibilizer to form an alloy. Alloys of PBT and PA-6 with varying amounts (0–12%) of epoxy resin E-44 were prepared by melt blending. The notched Izod impact strength and flexural strength as a function of epoxy resin E-44 content were studied. Ultimate mechanical properties showed significant improvement on addition of epoxy resin E-44. The maximum increase of the notched Izod impact strength (≈600%) of PBT/PA-6 blends is obtained at 3% (weight) epoxy resin E-44 content. The impact fracture surfaces were studied using scanning electron microscopy (SEM): The SEM micrographs showed a noticeable change in the type of surface structure on adding epoxy resin E-44. DMTA also showed improved compatibility between PBT and PA-6 on adding epoxy resin E-44. DSC studies showed that the presence of epoxy resin E-44 hindered the crystallization of both PBT and PA-6 in the alloys. Wide-angle X-ray diffraction (WAXD) showed no obvious difference on crystallinity of PBT and PA-6 in the alloys with the presence of a small amount of epoxy resin E-44. © 1996 John Wiley & Sons, Inc.     

Compatibilization of PP/EPDM blends by grafting acrylic acid to polypropylene and epoxidizing the diene in EPDM

In this article, ethylene–propylene–diene‐rubber (EPDM) was epoxidized with an in situ formed performic acid to prepare epoxided EPDM (eEPDM). The eEPDM together with the introduction of PP‐g‐AA was used to compatibilize PP/EPDM blends in a Haake mixer. FTIR results showed that the EPDM had been epoxidized. The reaction between epoxy groups in the eEPDM and carboxylic acid groups in PP‐g‐AA had taken place, and PP‐g‐EPDM copolymers were formed in situ. Torque test results showed that the actual temperature and torque values for the compatibilized blends were higher than that of the uncompatibilized blends. Scanning electron microscopy (SEM) observation showed that the dispersed phase domain size of compatibilized blends and the uncompatibilized blends were 0.5 and 1.5 μm, respectively. The eEPDM together with the introduction of PP‐g‐AA could compatibilize PP/EPDM blends effectively. Notched Izod impact tests showed that the formation of PP‐g‐EPDM copolymer improved the impact strength and yielded a tougher PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3949–3954, 2006     

pCBT/ABS共混合金的制备与表征

采用原位聚合法制备了原位聚合聚对苯二甲酸丁二酯(pCBT)/丙烯腈-丁二烯-苯乙烯塑料(ABS)共混合金,并对共混合金进行了差示扫描量热、动态热机械、扫描电子显微镜、广角X射线衍射和力学性能研究.结果表明,加入ABS可有效降低pCBT的结晶度,共混合金在保持较好刚性的同时,韧性有所提高.当ABS用量为1份时,共混合金的...     

空心玻璃微珠增韧高密度聚乙烯

采用悬臂梁缺口冲击、DSC、SEM 等方法研究了空心玻璃微珠(HGB)用量、粒径大小、偶联剂处理和基体韧性等因素对高密度聚乙烯(PE-HD)/HGB 复合材料冲击强度和热性能的影响。结果表明:复合材料的冲击强度首先随 HGB 含量的增加而增大,当 HGB 用量超过一定值后,冲击强度又随 HGB 含量的增加而减小。HGB 的粒径越小,增韧效果越好,当粒径较大时,增韧作用不明显。偶联剂可以明显改善 HGB 在基体中的分散,进而达到较好的增韧效果。对于 PE-HD/HGB 复合材料,要求基体的最低冲击强度为5.2 kJ/m~2。     

Mechanical property and morphology comparison between the two blends poly(propylene)/ethylene‐propylene‐diene monomer elastomer and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer

The comparison of the mechanical properties between poly(propylene)/ethylene‐propylene‐diene monomer elastomer (PP/EPDM) and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer [PP/MEPDM (MAH‐g‐EPDM)] showed that the latter blend has noticeably higher Izod impact strength but lower Young's modulus than the former one. Phase morphology of the two blends was examined by dynamic mechanical thermal analysis, indicating that the miscibility of PP/MEPDM was inferior to PP/EPDM. The poor miscibility of PP/MEPDM degrades the nucleation effectiveness of the elastomer on PP. The observations of the impact fracture mode of the two blends and the dispersion state of the elastomers, determined by scanning electron microscopy, showed that PP/EPDM fractured in a brittle mode, whereas PP/MEPDM in a ductile one, and that a finer dispersion of MEPDM was found in the blend PP/MEPDM. These observations indicate that the difference in the dispersion state of elastomer between PP/EPDM and PP/MEPDM results in different fracture modes, and thereby affects the toughness of the two blends. The finer dispersion of MEPDM in the blend of PP/MEPDM was attributed to the part cross‐linking of MEPDM resulting from the grafting reaction of EPDM with maleic anhydride (MAH) in the presence of dicumyl peroxide (DCP). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2486–2491, 2002     

Investigation of multiphase polymeric systems of poly(vinyl chloride)/ethylene-propylene-diene-gp-(styrene-CO-acrylonitrile) blends

The graft copolymer, ethylene-propylene-diene rubber (EPDM)-gp-(styrene-co-acrylonitrile) has been synthesized by solution precipitation polymerization using benzoyl perixide as initiator. The graft copolymer has been characterized after separation through soxhlet extraction by IR, NMR, and elemental analysis techniques. The graft copolymer of EPDM is melt blended with PVC. The nature of compatibility of the graft copolymers with PVC has been studied by means of morphological analysis and by thermal analysis. The mechanical properties, Izod impact strength, tensile strength, and flexural modulus of the blends are extensively studied over the wide range of concentrations. The results of both compatibility and mechanical properties are compared with those of PVC/EPDM blends. The nature of compatibility obtained shows that PVC/EPDM blends are incompatible and the PVC/EPDM-gp-SAN system is semicompatible. Also, these results indicate that the PVC/EPDM-gp-SAN system has its highest impact strength at 14 wt% of EPDM/gp-SAN graft copolymer. The fractured surface analysis of the impact fractured samples is also undertaken by an SEM technique. The results of the mechanical properties are discussed in view of existing theories of impact modification, along with the morphological feature of fractographs.