TPE Magazine international

Issue 04 | 2017

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Editorial
215
Dear readers!

Thank you for your interest in our magazines. We look forward to your continued support in the next year.

The team of Dr. Gupta Verlag wishes you a peaceful holiday season and a healthy, happy and successful New Year 2018.


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Article
232
TPS for extrusion-based 3D printing – A new material class for the most widely used additive manufacturing process

The use of extrusion-based 3D printing in both industrial and private areas has grown significantly and the range of processible materials was considerably broadened. However, TPS have still not been available for this additive manufacturing process. Within the scope of a research project, TPS grades with hardness down to 60 Shore A were developed, opening up new application areas for extrusion-based additive manufacturing from soft and elastic printed parts to two-component objects with hard/soft combination.


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236
Fatigue characterization of a thermoplastic elastomer

The capacity to resist crack development in an olefinic thermoplastic elastomer (TPE) has been measured via a set of experiments that quantify: 1) the fracture mechanical strength of the material under quasi-static loads, 2) the rate of growth of a crack under dynamic solicitations as a function of the energy release rate, and 3) the size of crack precursors in new material. Because the subject TPE exhibited strong inelasticity in the stress-strain response, it also was necessary to characterize the development of inelastic set under cyclic loading as a function of the applied strain. Combined with the multiplicative kinematic split, this additional measurement yields the elastic part of the strain. It also enables engineering calculations to be made of fatigue life. 


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243
Exploring electron beam irradiated EVA/TPU blends for cable applications

The effects of electron beam radiation (EBR) on the blends of ethylene vinyl acetate/thermoplastic polyurethane (EVA/TPU) at two different blend ratios prepared via melt blending technique were investigated. All the samples were irradiated by using a 2.5 MeV electron beam accelerating energy over a dose range from 25 to 200 kGy. The blends exhibit drastic improvement in the mechanical properties with increasing radiation dose up to an optimum dosage, beyond which the properties began to deteriorate. Modification of the blends via EBR enhances the elastic recovery of the blends resulting in an significantly improved tension set behaviour. Dynamic mechanical analysis (DMA) was conducted to investigate the change of loss tangent and storage modulus with varying radiation dose. Thermogravimetric analysis (TGA) suggests that irradiation induced crosslinks also help to improve the thermal stability of the blends to some extent. Scanning electron microscopy (SEM) study was performed to explore the changes in morphology before and after irradiation. All the irradiated blends have higher electrical resistivity than the blends without irradiation and the volume resistivity increases up to 150 kGy. The samples were found to exhibit remarkable improvement in oil resistance after irradiation which is more prominent in EVA/TPU 70/30 blends.


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254
Why hot melts do not stick to cold surfaces

Many industrial polymer processing operations (e.g., extrusion, injection molding, etc.) include solid-to-liquid or liquid-to-solid phase changes at non-isothermal interfaces. Stickiness (tack) can occur depending on the process conditions. However, prediction of tack formation is not trivial. This work presents a hypothesis for tack formation between molten polymers and solids under non‑isothermal conditions. Our hypothesis states that strong adhesion requires wetting (and thus surface creation) at the interface upon contact and, consequently, contact temperatures above the polymer’s solidification point. Lower contact temperatures result in a solid-solid interface with negligible adhesion. It was suggested that the contact temperature determines the existence or non‑existence of surface sticking. The hypothesis was supported by non‑isothermal tack experiments, which show that the change from stickiness to non-stickiness is surprisingly pronounced with changing surface temperature of the solid material. From a practical perspective, the work may be useful both for professionals (e.g., designing new processing equipment and performing process troubleshooting) and home users (e.g., working with hot melt glue or 3d printers).


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262
Tuning properties and morphology in high vinyl content styrene-­butadiene-styrene (SBS) block copolymer via thiol-ene modification

This investigation reports the thiol-ene modification of high vinyl content styrene-butadiene-styrene (SBS) block copolymer (BCP) in toluene at 70 °C using different ­thiolating agents. 1H NMR analysis confirmed the participation of vinyl double bond in thiol-ene modification reaction of SBS. Surface morphology of the block copolymers evaluated by AFM analysis showed higher roughness after thiol-ene reaction. The thiol-­modified SBS block copolymer showed better adhesion strength and oil resistance properties than the pristine SBS.


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Report
250
Safe material inspection and sorting for medium and high-voltage cable production

Plastics that are used for the insulation of medium, high- and extra-high voltage cables (MV, HV, EHV) have to comply with highest purity standards. Most commonly XLPE (crosslinkable polyethylene) is used for the insulation of cables. For crosslinking of the XLPE the cable passes through a CV tube (continuous vulcanization tube) where it is exposed to high temperatures. Typically the CV tube is filled with nitrogen and operated at a pressure of approximately 10 bars. Before the cable can be processed further, a degassing is necessary, which may take up to several weeks. Commonly, the line is built as a CCV or VCV line (Catenary Continuous Vulcanization or Vertical Continuous Vulcanization). This technology is well proven and used for decades, but involves high costs for the building and the production line. Another method is currently advancing where a high performance thermoplastic elastomer (HPTE) based on polypropylene is used as insulation material. This new technology has been further developed by Prysmian under the brand name “P-Laser” technology [1]. The material exhibits good electrical and thermomechanical properties, comparable and in some aspects even superior to those of XLPE. The elastomer does not require a crosslinking section and no degassing treatments. That means that the complete cable - the insulation, the shielding and the outer sheath - can be manufactured in an inline production process.


No matter which approach is applied, the demands for dielectric strength of XLPE and HPTE remains on the same high level and needs to be assured. Important in this regards is the cleanliness of the insulating material. This is the point where the advanced purity inspection and sorting system comes into focus. This paper will introduce an online inspection and sorting system that detects contamination inside and on the pellets such as metallic or organic contamination, color variations, agglomerates, cross-contamination and also detects wrong pellets. The system presented includes the unique combination of X-ray technology and an optical camera technology for highest detection probability for all sort of contamination. Thus, the quality of XLPE or HPTE material and accordingly the production process are optimized and costs reduced. Furthermore, the paper will briefly refer to an innovative offline system, which inspects and analyzes small batches of pellets. This system is useful for sampling inspections or to check pellets that have been sorted out by the above described online inspection and sorting system.


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268
New venue and new theme zones – Chinaplas 2018 moves to new fairground and introduces dedicated TPE and rubber zone

Chinaplas 2018 will be held for the first time at the National Exhibition and Convention Center (NECC) in Hongqiao, Shanghai, from 24 – 27 April. The organiser Adsale expects the exhibition area to exceed 320,000 m2. This would be 30 % more exhibition space than that of the 2016 edition of the show in Shanghai in 2016. 4,000 exhibitors from around the world are expected to register for the event. They will be allocated over a series of theme zones, among them a dedicated TPE and rubber zone. 


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271
From SPE Antec 2017 in Anaheim

Antec 2017, the Annual Technical Conference, organised by the Society of Plastic ­Engineers (SPE) took place 8-10 May 2017 in Anaheim, CA, USA with the total attendance of more than 1,500. In addition to the technical program and other scheduled events, there was an exhibition with a total of 65 exhibitors. 


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