The effects of radiation cross‐linking and process parameters on the behavior of polyamide 12 in vacuum thermoforming

Seefried, Andreas; Drummer, Dietmar

doi:10.1002/pen.22155

Cited by 10 publications

(8 citation statements)

References 11 publications

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“…The mode of deformation found in these experiments was between uniaxial and planar elongation. Results on the influences of temperature, strain rate and mode of deformation can be found in [9,10,21,23]; the results of these investigations affirm the assumption that uniaxial elongational tests at 1 s -1 can give relevant information about material properties important for thermoforming. The following strainstress-curves show mean values of three reproducible single values.…”

Section: Rheological Measurementssupporting

confidence: 52%

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Mechanical properties of radiation cross linked polyamide 12 after vacuum thermoforming

Seefried

Heinle

Drummer

2016

Prod. Eng. Res. Devel.

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Generally semi-crystalline thermoplastics have an inferior thermoformability compared to amorphous thermoplastics. This is because of their sharp drop in stiffness and viscosity with crystalline melting. Radiation cross-linking of semi-crystalline thermoplastics offers a solution for this limitation. The thermoformability is essential for processing, but the parts properties like the mechanical ones are important for the application of thermoformed parts. In this article the effects of mold geometry and temperature, forming temperature and film thickness on the mechanical properties of thermoformed cross-linked polyamide 12 (PA12) are investigated. The results show the improvement of the thermoformability of semi-crystalline thermoplastics by cross-linking. Concerning the mechanical properties of the parts, a significant enhancement in stiffness and tensile strength can be obtained, while the ultimate strain at break decreases compared to the smooth film's properties. Thermal processing conditions, deformations during forming and the degree of cross-linking of the film material have an influence on these effects.

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Section: Rheological Measurementssupporting

confidence: 52%

“…This novel approach to improve thermoformability of semi-crystalline thermoplastics has been described in [9,10]. Now it seems to be important to investigate the influences on mechanical properties during thermoforming of cross-linked polyamide to get knowledge for technical applications.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of radiation cross linked polyamide 12 after vacuum thermoforming

Seefried

Heinle

Drummer

2016

Prod. Eng. Res. Devel.

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“…In general, the penetration depth depends on the density and the atomic number of the irradiated material, and the geometry could also have some interests affected, as reported in [21,22,23,24,25]. Most previous studies [28,29,30,31,32] that examined the effect of irradiation on the resulting properties of materials primarily focused on describing the structural changes, mechanical properties, and chemical- and temperature-resistance dependence on radiation doses. Gheysari et al [23] referred the positive effect of high-energy β − radiation on the mechanical and thermal properties of low-density and high-density polyethylene (LDPE and HDPE, respectively), which were modified by using radiation doses ranging from 50 to 250 kGy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Beta Radiation on the Quality of the Bonded Joint for Difficult to Bond Polyolefins

et al. 2019

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Bonding is increasingly being used, and it is an ever-evolving method for creating unbreakable bonds. The strength of adhesive bonds determines, to a significant extent, the possible applications of this technology and is influenced by many factors. In addition to the type of adhesive used, the characteristics of the surface layers play a significant role; therefore, significant attention is paid to their adjustment and modification. Radiation crosslinking is one of the most important methods for modifying polymer properties. Currently, the most frequently used type of radiation for polymer crosslinking is beta minus (β−) radiation, which affects not only mechanical but also surface properties, chemical and temperature resistance, and surface layer characteristics of polymers. This study investigated the effect of β− radiation on the surface layer properties of low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) and the effects of surface-layer modification on the ultimate tensile strength of bonded joints. Based on the results, we concluded that β− radiation significantly changes the properties of the tested surface layers, increases the surface energy, and improves the adhesiveness of bonds. Consequently, the final strength of the LDPE, HDPE, and PP bonds increases significantly.

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“…Whereas DIC is widely used for other applications where full field strain measurements are required, the use of DIC in thermoforming applications is rare. Only two DIC studies for a thermoforming process are known to the authors [5,6]. In the following section, a brief overview on how DIC is implemented in the thermoforming process and the specific measures that have to be taken into consideration when using DIC for thermoforming applications are itemized.…”

Section: Introductionmentioning

confidence: 99%

Improvements in thermoforming simulation by use of 3D digital image correlation

Mieghem¹,

Desplentere²,

Bael³

et al. 2015

Express Polym. Lett.

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Abstract. Numerical simulation tools for the thermoforming of unfilled thermoplastic polymers already exist for a while, but are seldom used to full extent in industry. When it is used, it is mostly only for comparative studies and prediction of relative wall thickness. One of the major reasons is the difficulty to correctly calibrate and integrate all necessary material and process parameters into the simulation software. This paper introduces and validates a methodology, in which digital image correlation (DIC) is used as the key enabling technology that improves the knowledge of the process parameters and optimizes simulation accuracy by taking away a number of uncertainties and assumptions. DIC in combination with infrared thermal measurements and pressure monitoring is used to track sheet sagging and bubble inflation of a HIPS sheet, the two main process steps in the thermoforming of positive (male) products or the only two steps in the case of free forming. The results of these in-situ measurements are used as a guideline for selecting the correct input parameters in the commercial thermoforming simulation software T-SIM ® . A similar methodology can be further implemented for subsequent process steps such as forming and cooling or even to validate the material data used in the simulation software.

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The effects of radiation cross‐linking and process parameters on the behavior of polyamide 12 in vacuum thermoforming

Cited by 10 publications

References 11 publications

Mechanical properties of radiation cross linked polyamide 12 after vacuum thermoforming

Mechanical properties of radiation cross linked polyamide 12 after vacuum thermoforming

Effect of Beta Radiation on the Quality of the Bonded Joint for Difficult to Bond Polyolefins

Improvements in thermoforming simulation by use of 3D digital image correlation

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