Investigation of the effect of spherulite size on the strength and deformation characteristics of isotactic polypropylene films

Pavlov, V. I.

doi:10.1007/bf00721450

Cited by 10 publications

(11 citation statements)

References 3 publications

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“…The obtained T g suggests the presence of a syndiotactic PMMA fraction for which the crystallization process is slow, leading to very low degrees of crystallinity. However, it is accompanied by a spherulitic structure, with the semicrystalline regions [ 63 ], characterized by self-generated fields of lamellas or fibrils in the different regions of polymers [ 64 ], affecting the mechanical properties of polymers [ 65 ].…”

Section: Resultsmentioning

confidence: 99%

The Role of Electrical Polarity in Electrospinning and on the Mechanical and Structural Properties of As-Spun Fibers

et al. 2020

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Electric field strength and polarity in electrospinning processes and their effect on process dynamics and the physical properties of as-spun fibers is studied. Using a solution of the neutral polymer such as poly(methyl methacrylate) (PMMA) we explored the electrospun jet motion issued from a Taylor cone. We focused on the straight jet section up to the incipient stage of the bending instability and on the radius of the disk of the fibers deposited on the collecting electrode. A new correlation formula using dimensionless parameters was found, characterizing the effect of the electric field on the length of the straight jet, L˜E~E˜0.55. This correlation was found to be valid when the spinneret was either negatively or positively charged and the electrode grounded. The fiber deposition radius was found to be independent of the electric field strength and polarity. When the spinneret was negatively charged, L˜E was longer, the as-spun fibers were wider. The positively charged setup resulted in fibers with enhanced mechanical properties and higher crystallinity. This work demonstrates that often-overlooked electrical polarity and field strength parameters influence the dynamics of fiber electrospinning, which is crucial for designing polymer fiber properties and optimizing their collection.

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Section: Resultsmentioning

confidence: 99%

The Role of Electrical Polarity in Electrospinning and on the Mechanical and Structural Properties of As-Spun Fibers

et al. 2020

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“…A lower crystallization temperature is assumed to result in smaller spherulites. As reported in literature [37][38][39], the spherulite size is known to impact on the mechanical properties of polymer. Small spherulites thus lead to a more ductile material and reduce its tensile strength, which is in accordance with our results.…”

Section: Thermomechanical Propertiesmentioning

confidence: 99%

Influence of the chain extension on the crystallization behavior of polylactide

et al. 2013

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International audienceA semicrystalline poly(lactic acid) (PLA) was modified with the help of an epoxy-based chain extender (CE) during reactive extrusion. Different amounts of CE were used resulting in samples with increased and broadened molar mass distributions as revealed by size exclusion chromatography. Thermal properties were then investigated using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). On one hand, the thermal ramps performed with DSC revealed that the glass transition was not modified by the chain extension process. On the other hand, thecrystallization behavior was found to be highly impacted by this molecular modification. Decreases in the cold crystallization temperatures Tcc and in the melting temperatures Tm occurred when the CE content was raised. Isothermal crystallizations from the melt were performed using both DSC and POM. It revealed that the overall crystallization process was significantly faster for the chain-extended PLAs while crystalline ratios were lowered. An improvement of the nucleation process coupled with a reduced crystal growth was assumed to be responsible for this change

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“…For instance, semicrystalline polymers with a spherulitic structure can be brittle and easily crack under load due to break up at the spherulite boundary. 63 Alternatively, the percolated fiber morphology of PDMS−peptide PUs facilitates stress transfer via fiber−fiber interactions. 16 Thus it is anticipated that variations in morphological development between the network PUs will result in tunable mechanics.…”

Section: Resultsmentioning

confidence: 99%

Secondary-Structure-Mediated Hierarchy and Mechanics in Polyurea–Peptide Hybrids

Matolyak

Thompson

et al. 2018

Biomacromolecules

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Peptide-polymer hybrids combine the hierarchy of biological species with synthetic concepts to achieve control over molecular design and material properties. By further incorporating covalent cross-links, the enhancement of molecular complexity is achieved, allowing for both a physical and covalent network. In this work, the structure and function of poly(ethylene glycol) (PEG)-network hybrids are tuned by varying peptide block length and overall peptide content. Here the impact of poly(ε-carbobenzyloxy-l-lysine) (PZLY) units on block interactions and mechanics is explored by probing secondary structure, PEG crystallinity, and hierarchical organization. The incorporation of PZLY reveals a mixture of α-helices and β-sheets at smaller repeat lengths ( n = 5) and selective α-helix formation at a higher peptide molecular weight ( n = 20). Secondary structure variations tailored the solid-state film hierarchy, whereby nanoscale fibers and microscale spherulites varied in size depending on the amount of α-helices and β-sheets. This long-range ordering influenced mechanical properties, resulting in a decrease in elongation-at-break (from 400 to 20%) with increasing spherulite diameter. Furthermore, the reduction in soft segment crystallinity with the addition of PZLY resulted in a decrease in moduli. It was determined that, by controlling PZLY content, a balance of physical associations and self-assembly is obtained, leading to tunable PEG crystallinity, spherulite formation, and mechanics.

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Investigation of the effect of spherulite size on the strength and deformation characteristics of isotactic polypropylene films

Cited by 10 publications

References 3 publications

The Role of Electrical Polarity in Electrospinning and on the Mechanical and Structural Properties of As-Spun Fibers

The Role of Electrical Polarity in Electrospinning and on the Mechanical and Structural Properties of As-Spun Fibers

Influence of the chain extension on the crystallization behavior of polylactide

Secondary-Structure-Mediated Hierarchy and Mechanics in Polyurea–Peptide Hybrids

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