Synergistic improvement of toughness of isotactic polypropylene: The introduction of high density polyethylene and annealing treatment

Zhou, Xiang; Feng, Jiachun; Yi, Jianjun; Wang, Li

doi:10.1016/j.matdes.2013.01.069

Cited by 45 publications

(41 citation statements)

References 36 publications

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“…During annealing, molecular chains rearrange themselves to change the relative crystallinity, crystal form, lamellae thickness, rigid and mobility fraction, and obtain an optimized macro performance (mechanical, thermal and surface properties). [11][12][13] A toughness mechanism for microvoid formation [12,14] and molecular relaxation during the annealing process of polyolefin has been proposed previously, [15] which is helpful to understand the effect of annealing/crystallization on the physical properties of neat PLA and its composites.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the thermal and mechanical properties of injection‐molded poly (lactic acid) parts through annealing

Yang

Han

et al. 2020

J of Applied Polymer Sci

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The effect of cold‐crystallization on poly (lactic acid) (PLA) injection‐molded parts was systemically investigated at different annealing temperatures (80/100/120°C) and annealing times (0.5/1/1.5/2 hr). The relative crystallinity (Xc) and crystal form (α' and α) of samples was investigated by differential scanning calorimetry (DSC) and wide X‐ray angle diffraction (WAXD). The dependence of the thermal and mechanical performance on relative crystallinity and crystal form/morphology was discussed in detail. A linear relationship between the increment of heat distortion temperature (HDT) and that of Xc was found. The tensile strength, tensile modulus and storage modulus all increased with annealing time and annealing temperature, while the tensile toughness presented a different behavior. The elongation at break for specimens reached a maximum value of 16.9% after annealing at 80°C for 2 hr, which is a threefold improvement compared to PLA samples prepared without annealing. This work suggests that annealing is an effective method for tailoring the physical properties of PLA products.

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Section: Introductionmentioning

confidence: 99%

Tailoring the thermal and mechanical properties of injection‐molded poly (lactic acid) parts through annealing

Yang

Han

et al. 2020

J of Applied Polymer Sci

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“…38,39 With the increase in HDPE content and the decrease in IPC simultaneously, most characteristic peaks of HPP, such as at (110), (300), (130) and (131) & (041) lattice planes, rst increase and then decrease, while the diffraction intensity of both the lattice planes of PE strengthens. J. C. Feng et al 23 once reported the decreased spherulite size of PP and the increased concentration of PP intercrystalline due to blending HDPE with PP. The only exception is that, PP crystals along the (040) lattice plane exhibit a slow increase with the increase of PE.…”

Section: Crystallization and Interaction Of Componentsmentioning

confidence: 99%

“…Some of the nanoscale particles even play the role of nucleation agent and inuence toughness through reducing spherulite size. 10,[22][23][24][25] It was reported that the introduction of polyethylene into PP brought dramatic improvement in toughness 23,24 and J. C. Feng et al 23 believed that it should be mainly ascribed to the reduced spherulite size of PP by the introduction of HDPE. 20,21 In addition, incorporation of another crystalline polymer in the modied polymer can also improve toughness without serious sacrice of stiffness and various toughening mechanisms have been presented.…”

Section: Introductionmentioning

confidence: 99%

Simultaneously enhancing strength and toughness for impact polypropylene copolymers by regulating the dispersed phase with high density polyethylene

et al. 2014

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By introducing high density polyethylene (HDPE) into the dispersed phase of impact polypropylene copolymers (IPCs), the morphologies of IPC/HDPE blends were regularly tailored and consequently the tensile and impact properties were simultaneously improved. Morphological observations showed a series of multilayered core-shell dispersed particles when the content of HDPE was less than 40%, while the continuous network structure was observed beyond 40%. With an increase in the content of HDPE, the size of the core increased and the number of dispersed particles with incomplete encapsulated polyethylene (PE) cores rose. More valid 'bridges' made up of segmented ethylene-propylene copolymer (sEbP) appeared and connected the PE core and polypropylene (PP) matrix. Meanwhile, co-crystallization occurred in the core phase, between long ethylene chain segments of the joined HDPE and sEbP in multi-component IPCs. The increased HDPE in blends reduced defective co-crystals, and in turn led to a thicker average lamellar thickness and thinner amorphous thickness of PE. Partial inserted ethylenepropylene random sequences are constrained by narrowed PE amorphous layers. Hence, the connection between the PP matrix and the dispersed phase was strengthened by co-crystals, 'bridges' and restriction effects. The tensile strength of the blends was slightly enhanced with an increase in HDPE, while the greatly improved toughness was achieved at a HDPE content of 30 wt% and kept constant with more HDPE. Thus, the interactions rather than core-shell phase morphology are regarded as the predominate factor for the excellent properties.

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“…However, i ‐PP, which is the most widely used type of PP homopolymer in these applications, exhibits some technical drawbacks, including a low impact strength under ambient conditions, low elasticity, and low melt strength. Different methods have been developed to expand the applications of i ‐PP under challenging thermal and mechanical conditions, including blending with other high‐impact polymers, compounding with various types of organic and/or inorganic fillers, and copolymerization with some comonomers . Blending with other thermoplastics or compounding with fillers generally requires a third component called a compatibilizer , an interfacial agent, and/or additional processing steps because of immiscibility issues arising from the nonpolar nature of the polyolefins .…”

Section: Introductionmentioning

confidence: 99%

Effect of the comonomer content on the solid‐state mechanical and viscoelastic properties of poly(propylene‐co‐1‐butene) films

Kaşgöz

Tamer

Koçyiğit

et al. 2018

J of Applied Polymer Sci

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In this study, we quantified the thermal and solid-state mechanical and viscoelastic properties of isotactic polypropylene (i-PP) homopolymer and poly(propylene-1-butene) copolymer films having a 1-butene ratio of 8, 12, and 14 wt %, depending on the comonomer content. The uniaxial tensile creep and stress-relaxation behaviors of the samples were studied in a dynamic mechanical analyzer at different temperatures. The creep behaviors of the samples were modeled with the four-element Burger equation, and the longterm creep strains were predicted with the time-temperature superposition method. The short-term mechanical properties of the samples were also determined with tensile and impact testing at room temperature. We found that the Young's modulus and ultimate strength values of the samples decreased with increasing amount of 1-butene in the copolymer structure. On the other hand, the strain at break and impact strength values of the samples improved with increasing amount of 1-butene. Creep analysis showed that i-PP exhibited a relatively lower creep strain than the poly(propylene-co-1-butene)s at 30 8C. However, interestingly, we discovered that the temperature increase resulted in different effects on the creep behaviors. We also found that short-chain branching improved the creep resistance of polypropylene at relatively high temperatures.

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Synergistic improvement of toughness of isotactic polypropylene: The introduction of high density polyethylene and annealing treatment

Cited by 45 publications

References 36 publications

Tailoring the thermal and mechanical properties of injection‐molded poly (lactic acid) parts through annealing

Tailoring the thermal and mechanical properties of injection‐molded poly (lactic acid) parts through annealing

Simultaneously enhancing strength and toughness for impact polypropylene copolymers by regulating the dispersed phase with high density polyethylene

Effect of the comonomer content on the solid‐state mechanical and viscoelastic properties of poly(propylene‐co‐1‐butene) films

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