The control of miscibility of PP/EPDM blends by adding lonomers and applying dynamic vulcanization

The control of miscibility for isotactic polypropylene (PP) and ethylene-propylene-diene terpolymer (EPDM) has been attempted by adding poly(ethylene-comethacrylic acid) (EMA) ionomers and by applying dynamic vulcanization. The rheological properties, crystallization behavior, and morphology of the dynamically vulcanized EPDM/PP/ionomer ternary blends were investigated with a Rheometrics dynamic spectrometer (RDS), a differential scanning calorimeter (DSC), and a scanning electron microscope (SEM). Two kinds of EMA ionomers neutralized with different metal ions (Na⁺ and ZN⁺⁺) were investigated. Blends were prepared on a laboratory internal mixer at 190°C. Blending and curing were performed simultaneously, i.e., EPDM was vulcanized with dicumyl peroxide (DCP) in the presence of PP/ionomer. The composition of PP and EPDM was fixed at 50/50 by wt% and the contents of EMA ionomer were vaired from 5 to 20 parts based on the total amount of PP and EPDM. It was found that the addition of ionomers and the application of the dynamic vulcanization were effective in enhancing the miscibility of PP and EPDM. The structure of the blends was controlled by the following three component phases, i.e., the phase of the dynamially valcanized EPDM, PP, and Zn-neutralized ionomer. The ternary blends showed more miscibility than the PP/EPDM binary blend. This is due to the thermoplastic interpenetrating polymer network (IPN) of the ternary blends. The structure and properties of the ternary blends differed, depending on the types and contents of ionomer, i.e., the ternary blend containing Na-neutralized ionomer did not show a thermoplastic IPN structure clearly, even though the blend was prepared by dynamic vulcanization. The ternary blend containing Zn-neutralized ionomer clearly showed the behavior of a thermoplastic IPN when the contents of ionomer and DCP were 15 parts and 1.0 part, respectively.     

动态硫化对三元乙丙橡胶/聚丙烯共混体系等温结晶行为和形态结构的影响

研究了三元乙丙橡胶/聚丙烯(EPDM/PP)共混物和动态硫化EPDM/PP热塑性弹性体(TPV)的等温结晶行为及形态结构,并用Avrami方程对其进行等温结晶动力学分析。结果表明,EPDM/PP共混物和EPDM/PP TPV的等温结晶行为符合Avrami方程,在相同的结晶温度下,TPV比共混物的Avrami指数小,半结晶时间短,结晶速率常数大;EPDM/PP共混物为双连续相结构,而EPDM/PP TPV是以硫化的细小橡胶颗粒为分散相、PP为连续相的"海-岛"结构,橡胶颗粒尺寸约为0.5μm。     

Optimized processing conditions for the preparation of dynamically vulcanized EPDM/PP thermoplastic elastomers containing PP resins of various melt indexes

We have investigated the mechanical and morphological properties of un‐vulcanized and dynamically vulcanized ethylene propylene diene terpolymer/polypropylene (EPDM/PP) thermoplastic elastomers prepared under various processing conditions and possessing various compositions. After melt‐blending EPDM and PP resins twice in a twin‐screw extruder, the values of tensile strength (σ_f) of the un‐vulcanized EPDM/PP samples were at most equal to that of the pure EPDM specimen, but were much lower than those of the pure PP specimens. The elongations at break (ε_f) of the un‐vulcanized EPDM/PP samples were, however, dramatically higher than those of their respective virgin PP resins, and they improved significantly upon increasing the shear viscosity (η_s) of the PP resins. The tensile properties of the dynamically vulcanized EPDM/PP samples were significantly better than those of the corresponding un‐vulcanized EPDM/PP specimens. Similar to the behavior of the un‐vulcanized EPDM/PP specimens, the tensile properties of the dynamically vulcanized EPDM/PP specimens were optimized when prepared at a screw rate of 115 rpm. Morphological analysis revealed that the un‐vulcanized and dynamically vulcanized EPDM/PP specimens both featured many EPDM domains finely dispersed in continuous PP matrices. Such domains were present on the surfaces of the dynamically vulcanized EPDM/PP specimens; the relative sizes of the vulcanized EPDM domains were minimized when the vulcanized EPDM/PP specimens were prepared at the optimal screw rate (115 rpm). In fact, under these conditions, the average sizes of the vulcanized EPDM domains decreased upon increasing the values of η_s of the PP resins used to prepare the vulcanized EPDM/PP specimens. To understand these interesting tensile and morphological properties of the un‐vulcanized and dynamically vulcanized EPDM/PP specimens, we measured the rheological properties of the base polymers and performed energy‐dispersive x‐ray (EDX) analyzes of the compositions of the un‐vulcanized and dynamically vulcanized EPDM/PP specimens. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Carbon black‐reinforced dynamically cured EPDM/PP thermoplastic elastomers. I. Morphology,rheology, and dynamic mechanical properties

The structure development, rheological behavior, and viscoelastic properties of carbon black‐filled dynamically vulcanized thermoplastic elastomers based on the ethylene–propylene–diene terpolymer (EPDM) and polypropylene (PP) with the ratio range of 50/50 to 80/20 were studied and compared with similar but unfilled samples. Two‐phase morphology was observed at all ratios for the dynamically cured samples in which rubber particles are dispersed in the thermoplastic matrix. Carbon black distribution in each phase and damping behavior was found to be dependent upon the mixing condition and route of carbon black feeding. However, carbon black tends to stay mainly in the rubber phase, which leads to increase in the viscosity difference and, therefore, increase in the rubber particle size. Tensile strength and rupture energy increased with carbon black loading. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1127–1137, 2000     

Dynamic properties of rubber vibration isolators and antivibration performance of ethylene–propylene–diene monomer/nylon 6 blend systems

This article examines thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs) as two types of elastomers from melt-blended and dynamically vulcanized ethylene–propylene–diene monomer (EPDM) rubber materials and nylon 6 plastic materials. A series of investigations were conducted on the mechanical properties, morphology, dynamic mechanical properties, hysteresis behavior, and dynamic antivibration properties with different nylon 6 contents. The experimental results showed that the incompatibility between EPDM and nylon 6 led to the easy destruction of the TPV materials in two interfacial polymers upon the application of an external force. Thus, after a dynamic vulcanization process, the mechanical properties of the EPDM/nylon 6 blends were not as good as those of the TPE materials. In terms of morphology, nylon 6 plastics were uniformly distributed in the EPDM/nylon 6 blends during the EPDM rubber phase before vulcanization was performed. After the dynamic vulcanization, phase inversion was produced in which rubber microparticles were formed and dispersed in the nylon 6 plastic phase. The results of dynamic mechanical analysis, compression vibration hysteresis behavior, and dynamic property antivibration experiments showed that the blends provided better vibration isolation and antivibration performance after the amount of nylon 6 was increased and EPDM and nylon 6 were blended through dynamic vulcanization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

In‐situ ultrasonic compatibilization of unvulcanized and dynamically vulcanized PP/EPDM blends

Dynamically vulcanized PP/EPDM blends were treated by high‐intensity ultrasonic waves during extrusion. These blends were compared with unvulcanized PP/EPDM blends that were treated by ultrasound during extrusion and then dynamically vulcanized. Die pressure and power consumption were measured. The effects of different gap sizes, ratio of components, and number of ultrasonic horns were investigated. The rheological properties, morphology and mechanical properties of the blends with and without ultrasonic treatment were compared. The results obtained indicated that ultrasonic treatment induced thermo‐mechanical degradation, causing enhanced molecular transport and chemical reactions at the interfaces, thus leading to in‐situ compatibilization, which is evident by the morphological and mechanical property studies. Processing conditions were established for enhanced in‐situ compatibilization of the PP/EPDM blends that were either originally dynamically vulcanized and then ultrasonically treated or first treated and then dynamically vulcanized. Polym. Eng. Sci. 44:2019–2028, 2004. © 2004 Society of Plastics Engineers.     

Relationship between the rheology and morphology of dynamically vulcanized thermoplastic elastomers based on EPDM/PP

Relationship between the rheological properties and morphology of dynamically vulcanized thermoplastic elastomers (TPVs) based on Ethylene Propylene Diene Monomer (EPDM) and Polypropylene (PP) blends containing 20, 40 and 60% of EPDM were studied. The samples were prepared in a laboratory internal mixer at a rotor speed of 60 rpm. We performed morphological studies on the cryogenically fractured samples using scanning electron microscopy (SEM). The rheological behavior and melt viscoelastic properties of the samples were studied by rheometric mechanical spectrometry (RMS) at a temperature of 220°C. The TPV samples showed a significant viscosity upturn and a strong storage modulus that tended to plateau at low shear rates, with the highest extent for the sample containing 60% of EPDM. These results were attributed to a network structure resulting from agglomerates formed between the cured rubber particles, as evidenced by the morphological features of the samples. The multiple elastic response, expressed in terms of relaxation time distribution, H(λ), exhibited by the molten TPV sample containing 60% of EPDM suggests that apart from the contribution of flow‐induced molecular orientation of the PP matrix, there may also exist some elastic response induced by agglomerates formed between the cured rubber particles. The results predicted from the linear viscoelastic model proposed in the present work were found to be in good agreement with the experimental results. POLYM. ENG. SCI. 45:84–94, 2005. © 2004 Society of Plastics Engineers.     

Effect of dynamic cross‐linking on melt rheological properties of polypropylene/ethylene‐propylene‐diene rubber blends

Study of melts rheological properties of unvulcanized and dynamically vulcanized polypropylene (PP)/ethylene‐propylene‐diene rubber (EPDM) blends, at blending ratios 10–40 wt %, EPDM, are reported. Blends were prepared by melt mixing in an internal mixer at 190°C and rheological parameters have been evaluated at 220°C by single screw capillary rheometer. Vulcanization was performed with dimethylol phenolic resin. The effects of (i) blend composition; (ii) shear rate or shear stress on melt viscosity; (iii) shear sensitivity and flow characteristics at processing shear; (iv) melt elasticity of the extrudate; and (v) dynamic cross‐linking effect on the processing characteristics of the blends were studied. The melt viscosity increases with increasing EPDM concentration and decreased with increasing intensity of the shear mixing for all compositions. In comparison to the unvulcanized blends, dynamically vulcanized blends display highly pseudoplastic behavior provides unique processing characteristics that enable to perform well in both injection molding and extusion. The high viscosity at low shear rate provides the integrity of the extrudate during extrusion, and the low viscosity at high shear rate enables low injection pressure and less injection time. The low die‐swell characteristics of vulcanizate blends also give high precision for dimensional control during extrusion. The property differences for vulcanizate blends have also been explained in the light of differences in the morphology developed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1488–1505, 2000     

Effect of the compatibility on the morphology and properties of acrylonitrile–butadiene rubber/polypropylene thermoplastic vulcanizates

In this study, the morphologies of three types of acrylonitrile–butadiene rubber (NBR)/polypropylene (PP) thermoplastic vulcanizates (TPVs) (with an NBR/PP blend ratio of 70/30) were compared. The TPVs were (1) an ultrafine fully vulcanized acrylonitrile–butadiene rubber (UFNBR)/PP TPV made by the mechanical blending of UFNBR with PP, (2) a dynamically vulcanized NBR/PP TPV without the compatibilization of maleic anhydride grafted polypropylene (MP) and amine‐terminated butadiene–acrylonitrile copolymer (ATBN), and (3) a dynamically vulcanized NBR/PP TPVs with the compatibilization of MP and ATBN. The influence of the compatibility therein on the size of the dispersed vulcanized NBR particles and the crystallization behavior of the PP in the TPVs and the resultant properties are also discussed. As indicated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, polarizing microscopy, dynamic mechanical thermal analysis, and rheological and mechanical testing, the compatibility was significantly improved by the reactive compatibilization of MP and ATBN, which led to a uniform and fine morphology. The compatibilization increased the crystallization rate and reduced the size of the spherulites of PP. On the other hand, it was found that the dispersed vulcanized NBR particles lowered the degree of crystallinity. The better the compatibility of the blend was, the lower the degree of crystallinity and the storage modulus were, but the higher the loss factor and the processing viscosity were. All TPVs showed almost the same oil resistance, but the TPV prepared with reactive compatibilization had the best mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

动态硫化三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性弹性体的力学性能

研究了双螺杆挤出机制备EPDM/PP热塑性弹性体的工艺条件对其力学性能的影响,结果显示,当橡塑比为60/40.EPDM与PP预混合两次,双螺杆挤出机转速约9.5Hz,硫化剂的量为10份时,热塑性弹性体有较好的力学性能。     

Effect of dynamic crosslinking on impact strength and other mechanical properties of polypropylene/ethylene‐propylene‐diene rubber blends

The deformation and fracture behavior of several dynamic vulcanizate blends of isotactic polypropylene with ethylene‐propylene‐diene rubber (EPDM) was examined and compared with those of uncrosslinked blends of PP/EPDM. These blends were prepared by melt mixing in an internal mixer at 190°C in a composition range of 10–40 wt % EPDM rubber. The variation in yield stress, the strength of fibrils of the craze, and the number density of the EPDM rubber domains (morphology fixation) that are dominant factors for enhancing interfacial adhesion and toughness in dynamic vulcanizate blends were evaluated. The ductility and toughness of these materials were explained in light of the composition between crack formation and the degree of plastic deformation through crazing and shear yielding. The physicomechanical properties including the hardness, yield stress, Young's modulus, percentage elongation, impact strength, flexural strength, and flexural modulus of dynamic vulcanized blends were found to be consistent and displayed higher values compared with uncrosslinked blends. The nucleation effect of the crosslinked particles and the decrease of crystallinity of the EPDM rubber were also considered to contribute to the improvement in the impact strength. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2089–2103, 2000     

EPDM/PP有机过氧化物动态硫化研究

研究了EPDM／PP有机过氧化物动态硫化体系，结果表明，由该体系制得的EPDM／PP热塑性弹性体具备较好的力学性能和加工性能。     

The effects of dynamic vulcanization and compatibilizer on properties of paper sludge‐filled polypropylene/ethylene propylene diene terpolymer composites

The effects of dynamic vulcanization (DV) and dynamic vulcanization plus compatibilizer (DVC) of paper sludge (PS) filled polypropylene/ethylene propylene diene terpolymer (PP/EPDM) composites on torque development, mechanical properties, water absorption, morphology, and thermal properties were studied. Results show that DV and DVC composites exhibit higher stabilization torque than unvulcanized composites (UV). The dynamic vulcanized (DV) and dynamic vulcanized plus compatibilizer (DVC) composites exhibit higher tensile strength, elongation at break, and Young's modulus but lower water absorption than unvulcanized composites. The scanning electron microscopy (SEM) study of tensile fracture surface of DV and DVC composites shows the improved interfacial interaction between PS and PP/EPDM matrix. The DV and DVC composites also exhibit better thermal stability and higher crystallinity than unvulcanized PP/EPDM/PS composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

振动力场强化动态全硫化EPDM/PP热塑性硫化胶的研究

介绍了动态三螺杆反应挤出机的结构特征,采用动态三螺杆反应挤出机对EPDM/PP共混物进行动态全硫化挤出,并对其制品的物理力学性能进行了测试分析以及微观结构的电镜扫描分析,结果表明,由于在动态全硫化挤出的全过程中引入了振动力场,经动态三螺杆反应挤出机动态全硫化挤出的热塑性硫化胶(TPV)具有优化的微观结构,力学性能优异。     

动态硫化EPDM/PP共混物力学性能的研究

考察了硫黄用量和聚合物共混比对动态硫化ＥＰＤＭ／ＰＰ热塑性弹性体性能的影响。结果表明,随着硫黄用量增大,ＥＰＤＭ／Ｐ共混物的拉伸强度、１００％定伸应力和扯断伸长率先增大后减小、硬度有所增大,随着ＰＰ用量的增大,ＥＰＤＭ／ＰＰ共混物的拉伸强度、１００％定伸应力和硬度均有所增大,扯断伸长率也先大后减小。ＰＰ用量的变化对这些性能的影响更显。     

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热塑性弹性体动态硫化阻燃材料制备及性能研究

研究了聚丙烯/三元乙丙橡胶(PP/EPDM)体系在过氧化二异丙苯(DCP)、硫磺(S)和酚醛树脂(PF)三种不同硫化条件下的动态硫化过程。探讨了膨胀型阻燃剂三聚氰胺磷酸盐(MP)和双季戊四醇(DPER)对PP/EPDM动态硫化体系力学性能和阻燃性能的影响。结果表明:在加入阻燃剂的情况下,PP/EPDM体系的阻燃性能得到了改善,但体系的力学性能下降较多。     

动态三螺杆挤出机制备热塑性硫化胶的研究

对比分析了动态热塑性硫化胶(TPV)的加工设备,着重介绍了附加振动力场的三螺杆反应挤出机的结构特点以及利用该机进行三元乙丙橡胶/聚丙烯(EPDM/PP)的动态全硫化,对制品的物理力学性能和微观结构分别进行了测试分析和电镜扫描。结果表明,振动力场作用下EPDM/PP共混体系反应挤出动态硫化加工可有效地实现动态硫化反应、硫化橡胶的粉碎和分散以及相态反转,振动力场的作用明显提高了TPV性能。     

振动力场强化制备热塑性弹性体形态图像分析

基于Matlab图形图像处理技术,开发了聚合物共混材料微观结构形态图像处理与分析应用软件,对振动力场强化制备的动态硫化EPDM/PP热塑性弹性体SEM照片进行处理与分析,获得了EPDM在基体PP中的微观结构分布,进一步揭示振动参数对聚合物共混材料分散相细化与均布的强化作用。     

Evolution of rheological properties and morphology development during crosslinking of polyolefin elastomers and their TPV blends with polypropylene

This work investigates the evolution of the rheological properties of elastomeric dynamically vulcanized ethylene‐α‐olefin copolymers (ECs) and their blends with polypropylene (PP), during peroxide initiated crosslinking. Rheological techniques are used in conjunction with gel content measurements to determine the onset of gelation during static crosslinking. The complex viscosity and moduli follow power‐law dependence with respect to frequency at the gel point. The relaxation exponent and corresponding values of tan δ at the gel point are determined from the complex viscosity versus frequency curves and used as criteria for the determination of the instance of gelation. The evolution of morphology of thermoplastic vulcanizate (TPV) blends consisting of EC and PP during dynamic crosslinking is discussed in the context of the evolving rheological properties of the matrix and the dispersed phase that take place upon peroxide modification. TPVs having the crosslinked EC as the matrix present a very fine morphology, whereas the blends containing crosslinked EC particles, present a coarser morphology. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers