Interplay between chemical structure and ageing on mechanical and electric relaxations in poly(ether-block-amide)s

Todros, Silvia; Natali, Arturo N.; Piga, Matteo; Giffin, Guinevere A.; Pace, Giuseppe; Noto, Vito Di

doi:10.1016/j.polymdegradstab.2013.03.014

Cited by 22 publications

(46 citation statements)

References 31 publications

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“…After aging, the enthalpy of PA12 decreases for all the thicknesses, which means that the overall crystallinity decreases. This observation was found for Pebax with a high volume of soft segments, where the flexibility of PE polymer chains resulted in a reduction of PA crystals [32]. However, the same phenomenon probably also occurs for Pebax 7233.…”

Section: Effect Of Cavity Thicknesssupporting

confidence: 54%

Effects of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection mouldings

Zhang

Choi

et al. 2015

Materials & Design

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Miniaturized parts weighing single or tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding subject material to high shear rates and high cooling rates, and cause the same material to have different morphologies and final properties when used in conventional injection moulding. It also makes mold design challenging. This study investigates the effects of micro gate design (opening and thickness) and cavity thickness (100-500μm) on filling, morphology and the mechanical properties of miniaturized dumbbell parts. It is found that a reduction of gate size has two conflicting effects, namely, increased shear heating increases flow length, and increased cooling rate reduces flow length. Filling increases significantly with an increase of cavity thickness. In addition, the thickness of the skin layer reduces from ~70% to ~10% when part thickness increases from 100μm to 500μm. This oriented skin layer determines molecular orientation and broadly influences Young's modulus, elongation and yield stress. Natural aging at room temperature induces an increase of modulus and yield stress, and a decrease of strain at break. The mechanical properties of microinjection moldings is significantly different from those of conventional injection moldings and measurement at microscale is required for miniaturized product design. 1 Effect of Gate Design and AbstractMiniaturized parts weighing single or tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding subject material to high shear rates and high cooling rates, and cause the same material to have different morphologies and final properties when used in conventional injection moulding. It also makes mold design challenging. This study investigates the effects of micro gate design (opening and thickness) and cavity thickness (100-500μm) on filling, morphology and the mechanical properties of miniaturized dumbbell parts. It is found that a reduction of gate size has two conflicting effects, namely, increased shear heating increases flow length, and increased cooling rate reduces flow length.Filling increases significantly with an increase of cavity thickness. In addition, the thickness of the skin layer reduces from ~70% to ~10% when part thickness increases from 100μm to 500μm. This oriented skin layer determines molecular orientation and broadly influences Young's modulus, elongation and yield stress. Natural aging at room temperature induces an increase of modulus and yield stress, and a decrease of strain at break. The mechanical properties of microinjection moldings is significantly different from those of conventional injection moldings and measurement at microscale is required for miniaturized product design.

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Section: Effect Of Cavity Thicknesssupporting

confidence: 54%

Effects of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection mouldings

Zhang

Choi

et al. 2015

Materials & Design

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“…As expected, at lower temperature, material stiffness increases due to a restrained polymeric molecular motion below PA glass transition temperature. 18 From the comparison of the two different materials, it can be pointed out that PEBA 2 exhibits an higher stiffness than PEBA 1, due to an higher PA molecular weight in PEBA 2, while its elongation at break (PEBA 1, 220°C: 300%; PEBA 1, 10°C: 320%; PEBA 2, 220°C: 110%; PEBA 2, 10°C: 240%) is considerably lower than that of PEBA 1. These results are in accordance with previous studies on PEBAs with varying PA/PE block ratio, 20,23 where samples with relatively low PA block molecular weight exhibit lower stiffness in the elastic region and remarkably high elongation at break, while PEBAs with longer PA block are stiffer and with considerably lower elongation at break.…”

Section: Resultsmentioning

confidence: 97%

“…Further details on these polymers were provided in the previous article. 18 They are both based on Nylon 12 as the PA segment and polytetramethylene oxide (PTMO) as the PE segment. These polymers differ in the PA/PE ratio and thus are characterized by different mechanical properties.…”

Section: Materials Sample Preparation and Treatmentsmentioning

confidence: 99%

“…In particular, the effect of water on the structure and properties of PEBAs with different PA/PE ratios was recently studied. 18 Freezing and melting thermal cycles in association with water adsorption were found to modify the crystalline structure, varying the physicochemical and mechanical properties. This effect is closely related to the molecular weight of the PA segment: PAs are actually known to be particularly affected by water uptake due to the hydrophilic character of the amide moiety, with relevant influences on the mechanical properties of the polymer.…”

Section: Introductionmentioning

confidence: 99%

“…30,31 In this study, the weathering effect of both UV-visible radiation and water on PEBAs is investigated, simulating the exposure to environmental conditions. The results of tensile tests and DMA, integrated with physicochemical characterization data, 18 are important for the comprehension of the elastic and visco-elastic behaviour of PEBAs, in a wide temperature and frequency range. These data prove to be important for an accurate design and manufacturing of ski boots, especially when different polymeric materials are coupled in the same structure and interfaces are present in critical regions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of the mechanical behaviour of Telemark ski boots: Part I – materials characterization in use conditions

Natali

Todros

Venturato

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part P:

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This study reports the first part of the analysis for the evaluation of the mechanical behaviour of ski boots by means of an integrated approach that considers polymeric materials characterization, in Part I, and numerical structural analysis, in Part II. In the present Part I, different techniques are adopted to characterize the mechanical behaviour of the polymeric materials used for ski boots, to define the elastic, visco-elastic, temperature and weathering-dependent characteristics. Experimental data provide fundamental information on mechanical response, in particular taking into account the effect of the environmental conditions, due to temperature variation, ultraviolet radiation and water absorption, which are correlated to the definition of reliability and durability of the materials. In more detail, experimental results from tensile tests and dynamic mechanical analysis are reported, evaluating mechanical response and chemical conformation of the polymers. Materials properties are correlated with the specific use conditions and boot structure, to be able to evaluate and preserve overall performances and general safety requirements of ski boots. This activity represents a reference procedure for the evaluation of the material mechanical behaviour that must be considered within the structural analysis.

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Synthesis and characterization of a high performance polyamide‐6 elastomer based on poly(ether‐block‐amide) multiblock copolymer by reactive processing in torque rheometer

Yuan

et al. 2017

Adv Polym Technol

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The polyamide-6 based poly(ether-block-amide) (PEBA) multiblock copolymers were reactively prepared in typical processing equipment, torque rheometer. The reactive processing conditions of PEBA were discussed in details on the base of the tensile strength as the main quantization parameter and the torque rheological curves.The optimized reaction temperature, reaction time, and rotational speed were 150°C, 10 min, and 40 rpm respectively. The chemical structure, tensile properties, thermal transition, thermal stability, water absorption, and solubility in organic solvents of PEBA prepared in optimized reaction conditions were characterized by Fourier transform infrared spectroscopy, tensile testing, differential scanning calorimetry, thermogravimetric analysis, and soaking testing in water and organic solvents. The tensile strength and elongation at break of PEBA are 35.9 MPa and 580% respectively. The glass transition temperature and melting temperature of soft segment of PEBA are −50 and 15°C, respectively; the glass transition temperature and melting temperature of hard segment of PEBA are 50 and 140°C respectively. Meanwhile, the PEBA has low water absorption, robust organic solvent resistance, and good thermal stability. The optimization process of PEBA will give the deep understanding of reactive processing of polymer materials. K E Y W O R D Scondition optimization, environmentally friendness, multiblock copolymer, reactive preparation, torque rheometer

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Interplay between chemical structure and ageing on mechanical and electric relaxations in poly(ether-block-amide)s

Cited by 22 publications

References 31 publications

Effects of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection mouldings

Effects of gate design and cavity thickness on filling, morphology and mechanical properties of microinjection mouldings

Evaluation of the mechanical behaviour of Telemark ski boots: Part I – materials characterization in use conditions

Synthesis and characterization of a high performance polyamide‐6 elastomer based on poly(ether‐block‐amide) multiblock copolymer by reactive processing in torque rheometer

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