Improvement of the impact strength of ethylene‐propylene random copolymers by nucleation

Horváth, Z.; Menyhárd, Alfréd; Doshev, Petar; Gahleitner, Markus; Friel, D.; Varga, J.; Pukánszky, Béla

doi:10.1002/app.43823

Cited by 16 publications

(11 citation statements)

References 47 publications

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“…Crystallization that does not take place in a quiescent melt, for example, in solution or under shear, is also affected by other phenomena. Wang et al showed that isothermal crystallization under shear flow may suppress the formation of γ phase, but more recent work by Horváth et al proves otherwise. De Rosa et al described the deformation behavior of iPPs with various content of stereodefects, showing that the γ form of an unstretched sample transforms to α form, and finally to mesomorphic phase at large strain …”

Section: Introductionmentioning

confidence: 99%

Influence of 2,1‐erythro regiodefects on the crystallization behavior of isotactic polypropylene

Tranchida

Resconi

2018

Polymer Crystallization

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We produced isotactic polypropylene (iPP) samples with metallocene catalysts, containing 2,1‐erythro regiodefects between ∼0% and 3.4% and only trace amounts of stereodefects, and studied their thermal properties in order to quantify the influence of regiodefects on the crystallization behavior of iPP. Isothermal and nonisothermal experiments performed on these samples show that increasing the regiodefects content proportionally slows down crystallization rate, apparently without phase transitions or additional phenomena. The analysis of the rigid amorphous fraction and the mobile amorphous fraction however reveals a different behavior of samples containing more than ∼1.5% regiodefects, related to the inclusion of these defects in the lamellae. Additionally, the wide range of regiodefects and a novel calculation approach allowed us to estimate the equilibrium melting temperature of a fully iPP free of defects to be 206°C .

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Section: Introductionmentioning

confidence: 99%

Influence of 2,1‐erythro regiodefects on the crystallization behavior of isotactic polypropylene

Tranchida

Resconi

2018

Polymer Crystallization

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“…Generally, the AFM results agree with deductions from PLOM analysis, which showed that the use of NA‐71 promoted the formation of a greater amount of crystalline phase that is smaller in size than the ones observed in samples nucleated with NX8000 and DMDBS. Moreover, it was possible to observe that neat i‐PP has larger‐sized spherulites compared to the crystalline structures (fibrillar and transcrystalline structures, similar to shish kebabs 8,10,21,22 ) formed in the samples containing the different nucleating agents.…”

Section: Resultsmentioning

confidence: 98%

Influence of nucleating agents on morphology and properties of injection‐molded polypropylene

Abreu

Talabi

Lucas

2021

Polymers for Advanced Techs

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Isotactic polypropylene (i‐PP) samples containing three nucleating agents: 1,3:2,4‐bis(3,4‐dimethylobenzylideno)sorbitol (DMDBS), bis(4‐propylbenzylidene)propilsorbitol (NX8000), and lithium2,2‐methylene‐bis(4,6‐di‐tert‐butylphenyl)phosphate (NA‐71) were prepared via a twin‐screw extruder. The role of these additives on i‐PP properties was studied using polarized light microscopy (PLOM) with hot stage, atomic force microscopy (AFM), differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and Haze‐Gard Plus equipment. All the investigated nucleating agents were effective regarding the onset of crystallization, although the influence of the sorbitol derivatives depends on concentration. WAXD measurement indicated that these additives do not affect the typical pattern of α‐crystalline i‐PP. The nucleated PP samples have a fibrillar transcrystalline structure (compared to spherulites structure of the neat i‐PP), which reduces the crystalline phase interaction with visible light and consequently improved its optical feature. The most refined fibrils were formed by i‐PP containing lithium organophosphate additive. Compared to DMDBS, NA‐71 and NX8000 were more effective at lower concentration (2000 ppm). For example, the addition of 2000 ppm NA‐71 increases the crystallization temperature (Tc) of i‐PP from 113 to 132°C and its crystallinity index (Xc) from 45% to 51%. Whereas the Tc and Xc of i‐PP containing the same amount of DMDBS were 125°C and 49%, respectively. The highest crystallinity index (58%) was recorded when 4000 ppm NX8000 was added to the i‐PP before processing. The developed samples can be used as film products or injection‐molded parts in automotive interiors.

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“…It is well known that sorbitol derivatives, such as Millad, exhibit considerable potential as nucleating agents and additionally act as excellent clarifiers when incorporated (usually in small amounts) into a polyolefin matrix; thus, they are known to increase the nuclei density, leading to very small spherulites, so that the transparency is considerably improved [ 50 ]. Moreover, they enhance the γ modification in PPR copolymers [ 51 ].…”

Section: Resultsmentioning

confidence: 99%

Composites of a Polypropylene Random Copolymer and Date Stone Flour: Crystalline Details and Mechanical Response

et al. 2021

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Several composites were prepared based on a polypropylene random copolymer (PPR) and different amounts of date stone flour (DSF). This cellulosic fiber was silanized beforehand in order to reduce its hydrophilicity and improve the interfacial adhesion with the polymer. Other composites were also obtained, including a sorbitol derivative as an effective nucleant. Films made from these composites were prepared using two different thermal treatments, involving slow crystallization and rapid cooling from the melt. Scanning electron microscopy was used to evaluate the morphological features and the DSF particle dispersion within the PPR matrix. X-ray diffraction experiments and differential scanning calorimetry tests were employed to assess the crystalline characteristics and for the phase transitions, paying especial attention to the effects of the DSF and nucleating agent on PPR crystallization. An important nucleation ability was found for DSF, and evidently for the sorbitol derivative. The peak crystallization temperature upon cooling was considerably increased by the incorporation of either the nucleant or DSF. Additionally, a much higher proportion of orthorhombic crystals developed in relation to the monoclinic ones. Moreover, the mechanical responses were estimated from the microhardness experiments and significant improvements were found with increasing DSF contents. All of these findings indicate that the use of silanized DSF is a fairly good approach for the preparation of polymeric eco-composites, taking advantage of the widespread availability of this lignocellulosic material, which is otherwise wasted.

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Improvement of the impact strength of ethylene‐propylene random copolymers by nucleation

Abstract: Five ethylene-propylene random copolymers were nucleated with two soluble nucleating agents. Ethylene content changed between 1.7 and 5.3 wt%, while nucleating agent content was adjusted according to the solubility of the additive. It changed from 0 to 5000

Cited by 16 publications

References 47 publications

Influence of 2,1‐erythro regiodefects on the crystallization behavior of isotactic polypropylene

Influence of 2,1‐erythro regiodefects on the crystallization behavior of isotactic polypropylene

Influence of nucleating agents on morphology and properties of injection‐molded polypropylene

Composites of a Polypropylene Random Copolymer and Date Stone Flour: Crystalline Details and Mechanical Response

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