Polyolefin blends
Somayeh Rafiei; Davood Soudbar; Minoo Sadri; Fatemeh Shafiei
Abstract
Thermoplastic vulcanizates (TPVs) were prepared based on polypropylene (PP) and polybutadiene rubber (PBR) at different PP/PBR compositions (70/30 and 60/40). PP-grafted-maleic anhydride (PP-g-MA) was introduced into the TPVs at different concentrations (10 and 20%). The compatibilizing effect of PP-g-MA ...
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Thermoplastic vulcanizates (TPVs) were prepared based on polypropylene (PP) and polybutadiene rubber (PBR) at different PP/PBR compositions (70/30 and 60/40). PP-grafted-maleic anhydride (PP-g-MA) was introduced into the TPVs at different concentrations (10 and 20%). The compatibilizing effect of PP-g-MA was demonstrated through cross-sectional morphology. PP-g-MA exhibited a suppressing impact on the coalescence of the rubber domains, leading to a finer and more uniform distribution of the PBR phase. Due to the higher rubber content, the compatibilizing effect was more pronounced for the 60/40 composition, which was on the averge of forming a co-continuous morphology. However, it was found that a higher PP-g-MA content is needed to effectively compatibilize the TPVs. Rheological results revealed opposing effects on the viscoelastic response of the system. However, the elastic response was intensified once higher content of PP-g-MA was used, suggesting its compatibilizing role. Dynamic mechanical analysis results proved the existence of opposing effects and revealed the profound compatibilizing effects of PP-g-MA, especially at higher content (20%). Izod impact strength exhibited moderate and notable enhancements in both TPV compositions by adding 10% and 20% of PP-g-MA, respectively, attributed to the highly increased compatibility of the PP/PBR TPVs, especially at higher levels of PP-g-MA content.
Structure and property relationship
Zhijie Zhao; Ping Hai; Minjuan Zhang; Yongbiao Zheng; Yuerong Chen; Cunling Long; Hongtao Zhang; Xinyi Zhang
Abstract
The presence of ultrahigh molecular weight species in polymer melt facilitates the formation of highly-oriented crystalline structures and favors the improvement of mechanical properties. However, due to the random copolymer chain architecture, it is difficult to obtain high orientation of crystals for ...
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The presence of ultrahigh molecular weight species in polymer melt facilitates the formation of highly-oriented crystalline structures and favors the improvement of mechanical properties. However, due to the random copolymer chain architecture, it is difficult to obtain high orientation of crystals for polypropylene random copolymers (PPR). In this work, two binary blends including polypropylene (PP)/ultrahigh molecular weight polyethylene (UHMWPE) and polypropylene random copolymer (PPR)/UHMWPE were fabricated via solution blending and subsequent melt shear through mini-injection molding. It was found that a highly-oriented crystalline structure forms under shear flow in both blend series. The tensile strength of PP blends increased from 38.3MPa to 43.8MPa while the PPR blends showed a more significant property enhancement and increased from 32.5MPa to 38.1MPa. Importantly, PPR showed an increased miscibility with UHMWPE in comparison with PP due to the existence of ethylene segments. The tensile toughness of PPR samples was greatly maintained especially for blends with small addition of UHMWPE, which may be ascribed to the crack-suppression effect originated from well[1]dispersed UHMWPE domains (particle size < 0.50 μm) locked by the cocrystal structures between PPR segments and molecularly mixed PE chains.
Polyolefin blends
Aravind Raj; Pachipala Rithik; Prathipati Sai Sudheer; Kedarisetty Sampath Vachan; Murugasamy Kannan
Abstract
In this study, polypropylene (PP) was blended with polylactic acid (PLA) to enhance PP's mechanical properties, such as tensile strength and modulus, and to encourage the adoption of eco-friendly, renewable resource based material in polymer production. Even though PLA's biodegradability cannot be fully ...
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In this study, polypropylene (PP) was blended with polylactic acid (PLA) to enhance PP's mechanical properties, such as tensile strength and modulus, and to encourage the adoption of eco-friendly, renewable resource based material in polymer production. Even though PLA's biodegradability cannot be fully utilized in PP/PLA blends, but PLA can still improve PP's mechanical properties and provide an alternative resource for biobased raw materials. To meet the requirement, PP and PLA were blended in a 70:30 ratios with a compatibilizer and nanosilica at different loading levels by melt-blending. Blends of PP and PLA materials were processed without any problems, since both materials have melting points in the range of 170°C. Despite this, the properties of polymer blends are limited by the immiscibility between these neat polymers. To solve this problem, compatibilizers like polypropylene-grafted-maleic anhydride (PP-g-MA) were added to blends to improve their compatibility. Nanosilica was also added to this compatibilizer to study the system's compatibility and modify the hydrophobicity of PLA. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), tensile strength, and field emission scanning electron microscopy (FESEM) were used to analyze the polymer blend. Results indicate that compatibilizers play a significant role in improving tensile properties, thermal stability, and blend dispersion in the system, mainly in 5 parts compatibilizer-based systems. Composition with 5 parts compatibilizer increases tensile strength of 70/30 blend from 19.7 to 27 MPa, while elongation increases from 2.2 to 3.6 %. Additionally, a composition with 0.7 parts of nanosilica increases the modulus from 1488 to 1732 MPa when compared to the 70/30 blend.
Polyolefin blends
Mahsa Mobini-Dehkordi; Gholam-Reza Nejabat; Mohammad-Mahdi Mortazavi
Abstract
Varying amounts of a high molecular weight poly(1-hexene) (PH, Mv=1.7×106 Da) are substituted for EPDM in an iPP/iPP-g-MA/EPDM blend (weight ratio: 76:4:20) and mechanical properties as well as phase morphology of the blends are studied and compared. The results show that by substituting the entire ...
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Varying amounts of a high molecular weight poly(1-hexene) (PH, Mv=1.7×106 Da) are substituted for EPDM in an iPP/iPP-g-MA/EPDM blend (weight ratio: 76:4:20) and mechanical properties as well as phase morphology of the blends are studied and compared. The results show that by substituting the entire EPDM with PH, the tensile strength-at-break increases from 18.7 to 21.1 MPa, elongation-at-break increases from 15.5% to 370.8%, and impact strength increases from 6.4 to 50.1 kJ.m-2. Dynamic mechanical thermal analysis (DMTA) of the blends proved their immiscibility and SEM analysis confirmed these findings by showing droplet-matrix morphologies. Studying the creep behavior of the samples shows that the blends containing PH have more creep so that by substituting all EPDM in the blends with PH, the permanent deformation increases from 0.425% to 0.505%. According to the results, PH is introduced as a candidate for improving the impact properties of iPP/iPP-g-MA/EPDM blend.
