动态硫化EPDM／PP共混体系中PP相的结晶度及晶体结构的研究

研究了动态硫化ＥＰＤＭ／ＰＰ共混物中ＰＰ相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中ＰＰ相的结晶度和晶体结构的影响。结果表明：在动态硫化ＥＰＤＭ／ＰＰ共混物中,硫化的ＥＰＤＭ的分子键没有穿入ＰＰ的晶区,ＰＰ的结晶度随ＥＰＤＭ含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中ＰＰ的结晶度降低,共混时间１５ｍｉｎ时,共混物中ＰＰ相的结晶度最低,但ＰＰ的晶格不受制备工艺条件的影响。     

EVA增容PP/HDPE共混体系的形态结构与性能

采用乙烯－醋酸乙烯酯共聚物（ＥＶＡ）作为聚丙烯（ＰＰ）／高密度聚乙烯（ＨＤＰＥ）共混体系的增容剂,通过冲击实验、拉伸实验、示差量热扫描仪（ＤＳＣ）和扫描电镜（ＳＥＭ）,系统地研究了共混体系的性能与其形态结构之间的。结果表明,ＥＶＡ是ＰＰ／ＨＤＰＥ共混物较好物增容剂,ＥＶＡ可以使ＰＰ、ＨＤＰＥ的晶相结构受到一定程度的破坏,增加ＰＰ和ＨＤＰＥ的相容性,同时共混物的冲击韧性明显提高。     

PP/LDPE共混体系的辐射效应

研究了在多官能团单体—三烯丙基异氰脲酸酯存在下ＰＰ／ＬＤＰＥ共混体系接受γ－辐射的效果。用溶解度参数和ＴＥＭ技术评估了共混体系的相容性与多官能团单体在共混体系中的分布，并用ＳＥＭ、ＤＳＣ、动态力学等方法对共混体系相容性进行了表征。结果表明，ＰＰ／ＬＤＰＥ是不相容的共混体系，三烯丙基异氰脲酸酯主要分布在共混体系的相界面区域，辐照强化了共混体系的相间结合，增加了界面厚度，改善了共混体系的相容性。     

纳米刚性微粒与橡胶弹性微粒同时增强增韧聚丙烯的研究

通过力学性能测试、动态力学试验、ＤＳＣ 分析以及材料断面形貌与结构分析等手段,对以纳米二氧化硅（ＳｉＯ２） 为刚性微粒、以三元乙丙橡胶（ＥＰＤＭ） 为弹性微粒组成的聚丙烯（ＰＰ）／ 纳米ＳｉＯ２／ＥＰＤＭ 的同时增强增韧效果进行了研究．结果显示,上述两种微粒可同时大幅度提高ＰＰ 的韧性、强度和模量,当ＰＰ／ 纳米ＳｉＯ２／ＥＰＤＭ 为８０／３／２０ 时,两种微粒体现较明显的协同增韧效应．纳米ＳｉＯ２ 可提高ＰＰ 的结晶温度和结晶速度,并使球晶细化．纳米ＳｉＯ２ 刚性微粒在ＰＰ连续相中以微粒团聚体形态分布,构成团聚体的平均微粒数约为６ ～７ ,其与ＰＰ基体表现出较强的结合牢度．ＰＰ／ 纳米ＳｉＯ２／ＥＰＤＭ 的综合性能已接近或达到工程塑料的性能．     

PP／LDPE共混体系的辐射效

研究了在多官能团单体－三烯丙基异氰脲酸酯存在下ＰＰ／ＬＤＰＥ共混体系接受γ－辐射的效果。用溶解度参数和ＴＥＭ技术评估了共 体系的相容性与多官能团单体在共混体系中的分布，并用ＳＥＭ、ＤＣＳ、动态力学等方法对共混体系相容性进行了表征。     

离散物Surlyn对PBT／PP共混体系的力学性能及形态结构的影响

用力学性能测试，ＤＭＡ、ＳＥＭ等方法研究了离聚物Ｓｕｒｌｙｎ对ＰＢＴ／ＰＰ共混体系的力学性能及形态结构的影响。结果表明，在ＰＢＴ／ＰＰ共混体系中引入少量Ｓｕｒｌｙｎ可以改善界面的粘接性，从而改善其力学性能。     

聚二甲基硅氧烷／聚氨酯共混体系的增容作用（I）

采用二甲基硅氧烷－ｂ－乙二醇嵌段共聚物（ＤＭＳ－ｂ－ＯＥ）对聚二甲基硅氧烷／聚氨酯（ＰＤＭＳ／ＰＵ）共混体系的增容，重点研究了增容共混体系的微观形态结构和软科学性能之间的关系。扫描电子显微镜、动态力学分析和力学性能测试结果表明：ＤＭＳ－ｂ－ＯＥ对ＰＤＭＳ／ＰＵ具有优良的增容作用，改善了ＰＤＭＳ／ＰＵ共混体系的相容性，提高了该共混物的力学性能。其抗张强度由３．４ＭＰａ提高到７．６ＭＰａ。     

含有机硅三元多嵌段共聚物的研究5.含有机硅三元多嵌段共聚物的形态结构

利用ＤＭＡ，ＴＥＭ和ＳＡＸＳ对ＰＳＦ－ＰＤＭＳ－ＰＨＳｎ，ＰＳＦ－ＰＤＭＳ－ＰＨＥｎ，ＰＰＯ－ＰＤＭＳ－ＰＨＳｎ和ＰＨＳ－ＰＤＭＳ－ＰＢＥｎ四种三元多嵌段共聚物的形态结构进行了研究，结果表明，不同三元多嵌段共聚物中三种链段的相互作用情况不同，其动态力学性能和形态结构有很大差异，并与嵌段共聚物微相分离的几种基本形态不同，特别是通过ＴＥＭ在ＰＳＦ－ＰＤＭＳ－ＰＨＳｎ和ＰＰＯ－ＰＤＭＳ－ＰＨＳｎ中观察到清晰的互容界面相。     

离聚物Surlyn对PBT/PP共混体系的力学性能及形态结构的影响

用力学性能测试、ＤＭＡ、ＳＥＭ等方法研究了离聚物Ｓｕｒｌｙｎ对ＰＢＴ／ＰＰ共混体系的力学性能及形态结构的影响。结果表明，在ＰＢＴ／ＰＰ共混体系中引入少量Ｓｕｒｌｙｎ可以改善界面的粘接性，从而改善其力学性能。当共混体系中ＰＢＴ／ＰＰ的组份比不变（９０／１０）且Ｓｕｒｌｙｎ的含量为６ｐｈｒ左右时，共混物的冲击强度出现极大值；而弯曲强度在Ｓｕｒｌｙｎ含量为１－２ｐｈｒ左右时有最大值。当共混体系中Ｓｕｒｌｙｎ的含量不变（６ｐｈｒ）时，其力学性能随ＰＰ含量的增加而下降。用玻璃纤维增强共混体系，可显著提高力学性能。     

经γ射线辐照的LLDPE与氢氧化铝体系冲击性能的研究

研究了γ射线剂量率对线性低密度聚乙烯（ＬＬＤＰＥ）氧化与降解的影响和ＬＬＤＰＥ／γ－ＬＬＤＰＥ／ＡＴＨ（氢氧化铝）体系的冲击性能。结果表明，剂量率越低，ＬＬＤＰＥ氧化和降解的程度越高。γ－ＬＬＤＰＥ的加入可明显改善ＬＬＤＰＥ和ＡＴＨ的相容性，提高ＬＬＤＰＥ／ＡＴＨ体系的冲击强度，改善ＡＴＨ在ＬＬＤＰＥ树脂相中的分散性。     

Shear-induced crystallization in phase-separated blends of isotactic polypropylene with ethylene-propylene-diene terpolymer

The compatibility between isotactic polypropylene(i PP) and ethylene-propylene-diene terpolymer(EPDM) in the blends was studied. SAXS analysis indicates that i PP and EPDM phases in the binary blend are incompatible. Isothermal crystallization behaviors of i PP in phase-separated i PP/EPDM were studied by in situ POM equipped with a Linkam shear hot stage. It was found that typical spherulites of i PP were formed both in neat i PP and in i PP/EPDM blends. The radial growth rate(d R/dt) of spherulites of i PP in the blend was not influenced by EPDM phases. Further investigations on isothermal crystallization of i PP in i PP/EPDM after shear with a fixed shear time showed that the crystallization rate of i PP in the blends increased with increasing shear rates, whereas, the crystallization rate was much lower than that of neat i PP. WAXD results showed that ?-crystal i PP was formed in neat i PP as well as in i PP/EPDM blends after shearing and the percentage of ?-crystal bore a relationship to the applied shear rate. The presence of EPDM resulted in lower percentage of ?-crystal in the blends than that in neat i PP under the same constant shear conditions. SAXS experiments revealed that shear flow could induce formation of oriented lamellae in i PP and i PP in the blends, and the presence of EPDM led to a reduced fraction of oriented lamellae.     

Prediction models for the key mechanical properties of EPDM/PP blends as affected by processing parameters and their correlation with stress relaxation and phase morphologies

The optimum condition of processing parameters (mixing temperature, rotor speed, fill factor, and blend ratio) and prediction models for the best key mechanical properties of ethylene propylene diene terpolymer/polypropylene thermoplastic vulcanizates (EPDM/PP TPVs) was investigated by using the Taguchi's optimization technique and data analysis. The results reveal that all of the processing parameters affected significantly the mechanical properties of the EPDM/PP TPVs, but specifically the blend ratio contributed more than 90% in effect size on tensile strength and tension set. There were three main factors, the mixing temperature, the fill factor, and the blend ratio, influencing the elongation at break. Furthermore, the mathematic models were effective and reliable in predicting the properties of TPVs. The correlation of mechanical properties, stress relaxation, and phase morphologies of the TPVs prepared from the predicted models was also investigated. It can be summarized that the morphological structure and stress relaxation of the TPVs were strongly governed by the EPDM content in the blend ratio. That is, the higher the EPDM content, the better phase morphology having smaller size of the vulcanized EPDM particles distributed in the PP matrix and the higher rate of stress relaxation. Moreover, these two properties were then principally pushing the mechanical characteristics of the EPDM/PP TPVs. Copyright © 2015 John Wiley & Sons, Ltd.     

Interaction of two phases in PP/EPDM polymer blend probed by positron annihilation: CONTIN analysis

Positron annihilation lifetime measurements were performed on pure polypropylene (PP), ethylene-propylene-diene monomer (EPDM) rubber, and their blends PP/EPDM with a series of EPDM volume fraction ϕ (= 10–40%). A numerical Laplace inversion technique (i.e., CONTIN algorithm), was employed to obtain the probability distribution functions (PDF) of free-volume radius. We observed that, first, the average free-volume radius in PP/EPDM blends is generally same as that in PP and is much smaller than that in EPDM. Second, the standard deviation σ_R or the width of the free-volume radius PDF in the blend decreases with ϕ in the region of ϕ = 10ndash;30%, and it increases when ϕ increases from 30% to 40%. The difference in the σ_R of the blend and the calculated value σ^c _R according to the simple-mixing rule of PP and EPDM is interpreted by the existence of the two-phase interaction (i.e., the residual thermal pressure and shear stress between PP and EPDM phases in the PP/EPDM blends). The correlation between σ_R, which indicates the interaction of two phases, and the impact strength of PP/EPDM blends was found and discussed. © 1996 John Wiley & Sons, Inc.     

Mechanical and Rheological Behavior of Unvulcanized and Dynamically Vulcanized i-PP/EPDM Blends

The mechanical and rheological behavior of dynamically vulcanized PP/EPDM blends is examined and compared with those of unvulcanized blends. The effect of blend ratio and dynamic vulcanization of EPDM rubber on tensile properties and flow are investigated. The mechanical properties of the blends are strongly influenced by the blend ratio. With the increasing of EPDM content the value of yield stress in a solid state decreases with the elastomer volume fractions less than 0.45 for the unvulcanized blends. For the dynamically vulcanized blends the interval of EPDM content, at which the yield peak is seen, is rather limited below 0.25 elastomer volume fractions. It is shown that dynamic vulcanization changes the deformational behavior of PP/EPDM blends. The rheological properties of dynamically vulcanized blends depending on the ratio of the components may be similar to the properties of polymer composites containing the highly disperse structuring filler. The distinction between the rheological behavior of unvulcanized and dynamically vulcanized blends is related to differences of their structures and viscoelastic characteristics of unvulcanized and vulcanized EPDM phase.     

STUDY ON THE MISCIBILITY OF DYNAMICALLY VULCANIZED EPDM/PP BLEND BY POSITRON ANNIHILATION SPECTROSCOPY*

Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume holeproperties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region ofPP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent ofEPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with variouscompositions.     

Polypropylene Crystallization in an Ethylene-propylene-diene Rubber Matrix

The effect of the incorporation of an amorphous immiscible polymer (ethylene-propylene-diene- terpolymer) on the PP crystallization kinetics and thermodynamics is investigated by thermal analysis. The results of the investigation have shown that EPDM acts as a nucleant agent. A marked decrease of the half time of PP crystallization, τ_1/2 , as well as a sensible increase of the overall crystallization rate, K _n , has been observed in the presence of EPDM. Moreover, at any crystallization temperature, a minimum of τ_1/2 , is obtained at 25% EPDM content in the blend. The Avrami model has been successfully applied to describe the crystallization kinetics of the blend. The kinetic curves obtained under non-isothermal conditions confirm the results obtained under isothermal conditions and demonstrate the nucleant action of the EPDM phase on the PP crystallization. This revised version was published online in July 2006 with corrections to the Cover Date.     

共混过程中EPDM/PP共混热塑弹性体的结构、形态和性能的变化

用SEM,TEM,DSC,WAXD和有效网链密度(v_e)测定,研究了共混时间长短和返炼对EPDM/PP共混物结构和性能的影响。两相分散随共混时间和返炼而更趋均匀。随共混时间,PP结晶度(x_c)先行降低然后升高,抗张强度正相反,v_e则降低x_e和v_e返炼后总是较一次共混降低。影响强度的因素主要是两相分散均匀和两相界面的相互渗透。     

Erosion‐dependant continuity development in high viscosity ratio blends of very low interfacial tension

This work studies continuity development and cocontinuity in high viscosity ratio EPDM/PP blends. A very low interfacial tension (0.3 mN/m) between the blend components together with high viscosity ratios (11 and 17) result in a variety of unusual morphological features, including isolated nanometer diameter fibers, very large particles, partially coalesced particles, and numerous particles interconnected by fibers. This unique combination of morphologies leads the blend to a novel and stable cocontinuous structure of partially coalesced particles and particles interconnected by fibers. Compared with low to medium viscosity ratio EPDM/PP blends, these cocontinuous networks demonstrate early percolation thresholds, rapid continuity development, and attain cocontinuity at lower compositions of minor phase. The slow surface erosion of the high viscosity EPDM phase during melt blending is shown to be responsible for the generation of these unusual morphological structures. Typically the timescale for erosion phenomena are so small that they have defied study in the mixing environment itself and typical blend morphology studies almost always examine the final steady‐state morphology obtained after several minutes of mixing. The combination of very low interfacial tension and very high viscosity ratios of these EPDM/PP systems provide a unique opportunity to examine erosion phenomena persisting over longer time scales during melt mixing. We propose a new concentration‐dependant erosion mechanism that is based on particle collision–coalescence–separation dynamics. The proposed conceptual mechanism is shown to dramatically accelerate the erosion process and maintain cocontinuity over prolonged periods of mixing. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1919–1929, 2006     

Morphology development and phase inversion during dynamic vulcanisation of EPDM/PP blends

Morphology development and phase inversion were investigated during dynamic vulcanisation of ethylene–propylene–diene terpolymer (EPDM)/polypropylene (PP) blends. The effects of viscosity ratio and cross-linking reactions were also addressed. EPDM/PP blends were dynamically vulcanised in a Haake batch mixer using resole and SnCl₂ as cross-linking agents. The morphology development and cross-linking degree with reaction time were followed by morphology analysis (SEM and TEM) and measurement of EPDM gel content, respectively. For the same reaction time, it was found that the EPDM gel content decreased when the low-molecular-weight EPDM was used. As a result, the morphological development was delayed and the phase-inversion point was shifted to higher reaction times, allowing us to monitor morphological development during a thermoplastic vulcanisate (TPV) preparation. Using the low-molecular-weight EPDM and increasing the PP viscosity accelerated the morphological development, shifting phase-inversion to lower reaction times. While blend composition influenced final TPV morphology, it had a minor effect on the mechanism of morphological development. A correlation between cross-linking degree and morphology development was established. The results obtained allowed to propose a mechanism of morphology development during dynamic vulcanisation of the EPDM/PP blends, including phase inversion.     

iPP/HDPE/EPDM三元共混体系的组分分布、相容性和结晶行为

用DSC、~(13)C-NMR、SEM和WAXD等方法研究了IPP/HDPE/EPDM三元共混体系的组分分布、相容性和结晶行为。实验结果表明,EPDM与PE组分的相容性优于与PP组分的相容性,多数EPDM分子链段能够分布在PE组分中;EPDM含量为15％时,共混物相容性最好,SEM照片呈现晶体微区的互连或网络状结构;随EPDM含量增加,总结晶度X_c减小,其中PE组分结晶度X_(cE)有较大幅度地降低,PP组分结晶度X_(cp)基本没有变化,这可以根据EPDM和PE、PP之间相容性的差异以及PE、PP两组分在冷却过程中不同的结晶行为来解释。