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Investigations on Tightness of Polymer-Metal Hybrids in Environments with Thermal, Media, and Mechanical Loads
(2017-07-31)
With polymer-metal hybrids becoming more commonly used as structural components it was investigated how they perform in complex environments with combined thermal, media, and mechanical loads. Special attention was put on media tightness under said loads. This paper sums up the activities of the polymer technology research group of the University of Kassel on hybrids produced by overmolding metal inserts. Investigations concerning joint strength and influence of (cyclic) temperature loads and chemical corrosion on ...
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Mechanical Properties of Polydimethylsiloxane as a Function of the Amount and Type of Crosslinking Agent
(2017-06-13)
In this investigation, a high-consistency rubber (HCR) was mixed with five different, typically used crosslinking agents that are based on organic peroxide. Furthermore, the amount of crosslinking agent was varied in order to quantify the effect on the mechanical properties. All materials were processed in a hot pressing process, and, subsequently, post-cured. The properties were characterized by the measurement of the swelling ratio, shore A-hardness, rebound resilience and tensile test. We successfully proved that ...
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Pathways towards grain boundary engineering for improved structural performance in polycrystalline Co-Ni-Ga shape memory alloys
(2018)
Co-Ni-Ga high-temperature shape memory alloys attracted a lot of scientific attention due to their superior functional material properties in recent years. In the single crystalline state Co-Ni-Ga HT-SMAs feature a good pseudoelastic response up to 500°C. However, in the polycrystalline condition Co-Ni-Ga suffers significant grain constraints and premature fracture at grain boundaries. In this regard, crystallographic orientation of the grain being involved as well as morphology and geometrical orientation of the ...
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Influence Of The Fiber-Matrix-Interaction On The Fracture Behavior Of Regenerated Cellulose Fiber Reinforced Polypropylene
(Society of Plastics Engineers, 2017)
This investigation focuses on the fiber-matrix-interaction of man-made cellulose fibers (RCF) in a PP matrix with an additional MAPP content using an energetic evaluation of the single fiber pull-out test (SFPT). Furthermore glass fibers were characterized for reference purposes. With the SFPT the interfacial shear strength (IFFS) and the critical fiber length (lc) as well as the consumed energy of a fiber pull-out and a fiber rupture were determined. In a following step the resulting values of lc were related to the ...
Konferenzveröffentlichung
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Blending CA with PBS to increase the bonding strength in two-component injection molding
(Society of Plastics Engineers, 2019)
Since CA shows no adhesive properties in the two-component injection molding process with bio based TPU, blends of CA and PBS were produced to decrease the interfacial tension between the materials. While the interfacial tension was calculated from the results of a drop shape analysis, the adhesion strength was measured in peel tests according to the guideline VDI 2019. The comparison of the results gave information about whether the drop shape analysis is a valid method to analyze the adhesive characteristics of ...
Konferenzveröffentlichung
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Natural fiber reinforced technical (bio-) composites modified with halogen-free flame retardants
(Society of Plastics Engineers, 2019)
Under the aspect of sustainability and the use of alternative materials, engineering thermoplastics such as polybutylene terephthalate (PBT) will be reinforced with renewable raw materials such as regenerated cellulose fibers.
The University of Kassel is developing cellulose regenerated fiber reinforced technical thermoplastics in a state-funded project with further companies. Since pure natural fibers cannot withstand the high operating temperature of engineering thermoplastics (Ts>230°C), regenerated cellulose ...
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Effect of nanometric γ´-particles on the stress-induced martensitic transformation in ⟨001⟩-oriented Co49Ni21Ga30 shape memory alloy single crystals
(2019)
The effect of finely dispersed particles on the functional properties and morphology of thermally induced martensite in Co-Ni-Ga shape memory alloys has been already reported in literature, however, still important aspects are not fully understood. The current study focuses on the stress-induced martensitic transformation of solution-annealed, i.e. precipitate-free, and aged 〈001〉-oriented single crystals. In situ optical microscopy and neutron diffraction experiments show a significant influence of γ′-particles on ...
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Wood-Polypropylene Composites: Influence of Processing on the Particle Shape and Size in Correlation with the Mechanical Properties Using Dynamic Image Analysis
(2018-11-16)
The particle size and shape are of momentous significance for the mechanical properties of plastic composites. However, natural fillers, like wood, are not consistent in these attributes. In order to investigate the shared traits between these characteristics, WPCs were produced using polypropylene, hardwood and softwood fillers with different particle sizes and a coupling agent. Afterwards, specimens were processed using an injection molding machine. The filler sizes and shapes were measured using dynamic image ...
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Cross-Linked Hydrophobic Starch Granules in Blends with PLA
(2018-04-17)
The majority of native starch is used in the food sector and in the paper industry. Only a small amount is used in polymer engineering. One reason for the reluctance of the plastics processing industry to use starch as a filling material in polymer blends is the unsatisfactory mechanical behavior of starch when combined with thermoplastics. Another reason is the hydrophilicity of starch. In order to make these materials capable of competing, an amelioration of the mechanical properties is compulsory. By means of ...