Tensile elongation of high‐fluid polypropylene/ethylene–propylene rubber blends: Dependence on molecular weight of the components and propylene content of the rubber

Abstract

ABSTRACT:We studied tensile behavior of low-molecular-weight (MW) polypropylene (PP)/ethylene-propylene rubber (EPR; 70/30) blends from the viewpoint of the MWs of PP and EPR and the compatibility between PP and EPR. The value of the melt flow rate of PP varied from 30 to 700 g/10 min at 230°C. We studied the compatibility between PP and EPR by varying the propylene content in EPR (27 and 68 wt %). At the initial elongation stage, crazes were observed in all blends. When blends included EPR with 27 wt % propylene, the elongation at break of the low-MW PP improved little. The blends with EPR and 68 wt % propylene content were elongated further beyond their yielding points. The elongation to rupture was increased with increasing MW of EPR. Molecular orientation of the low-MW PP was manifested by IR dichroism measurements and X-ray diffraction patterns. The blends of low-MW PP and EPR could be elongated by the partial dissolution of EPR of high-MW in the PP amorphous phase.

Partial replacement of EPR by GTR in highly flowable PP/EPR blends: Effects on morphology and mechanical properties

“…The effect of the viscosity ratio between the materials, which is the ratio between the viscosities of the minor and major phases, may also be contributing to this type of morphology. Generally, the domains sizes reach a minimum when the viscosity of the minor phase is similar or lower than the viscosity of the major phase . In this particular case, the similarity between the EPR and PP viscosities can be contributing to the resulting morphology.…”

“…Generally, the domains sizes reach a minimum when the viscosity of the minor phase is ARTICLE WILEYONLINELIBRARY.COM/APP similar or lower than the viscosity of the major phase. 18,19,[25][26][27] In this particular case, the similarity between the EPR and PP viscosities can be contributing to the resulting morphology. The morphology of the P 30 V 70 binary blends [ Figure 2(e,f)] indicates the existence of a single phase, due to the EPR high content and compatibility between the materials.…”

“…The present work continues studying sustainable experimental design strategies for the recycling of GTR without the use of thermochemical techniques and reports the effect of a different fresh rubber material, an EPR with a high melt flow index (MFI), on the morphology and mechanical behavior of these blends. EPR copolymers may significantly enhance the mechanical toughness of the TPE GTR blends, especially those with higher propylene contents and also improve their processability. Scanning electronic microscopy (SEM) was used to analyze the morphology and also to study the encapsulation effect of GTR by EPR.…”

Preparation and characterization of high MFR polypropylene and polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys

“…What is more important, HF-PP synthesized by adding hydrogen is more transparent and involves no volatile organic compounds. 10 Just as common isotactic PP, the application of HF-PP is still limited by its high notch sensitivity and poor impact resistance, especially at low temperature and high strain rate, [21][22][23][24][25] and the limitation is even stronger for its lower molecular weight. To solve these problems, great efforts have been made to work out better modification methods.…”

Melting behavior and isothermal crystallization kinetics of polypropylene/metallocene‐catalyzed polyethylene elastomer blends

“…However, its application in some fields is limited by its low fracture toughness at low temperatures and high notch sensitivity at room temperature. To improve the impact properties of PP, blending PP with a dispersed elastomeric phase (e.g., polypropylene random, ethylene‐propylene rubber, styrene‐ethylene‐butadiene‐styrene, ethylene propylene diene monomer) is widely practiced1–7 because the elastomer can increase the overall toughness of the PP matrix 8. However, the addition of an elastomer often has negative effects on some properties of PP, such as stiffness and hardness 9…”