TY - THES

T1 - Dynamic-mechanical Characterization of Tailor-made Elastomers for Damping Applications

AU - Karall, Jürgen

N1 - embargoed until 02-03-2025

PY - 2020

Y1 - 2020

N2 - Elastomers are used in various applications and spread all over the industries. Common approach of using elastomers originates as it offers a deformable and elastic behavior, frequently underestimating its possible damping capacity up to now. Mass spring systems are still state of the art while having new opportunities to counter various problems arising from that. Especially damping in a low frequency range needs high mechanical loss factors to work properly. Different industries benefit out of that for damping vibrations and impacts as being a major issue for various areas of application. For example, antivibration gloves, ear-tips, rail-systems, damping elements, audio applications and many more. In this regard trans-polynorbornene (t-Pnb) offers the possibility to adjust the thermomechanical properties in terms of damping (mechanical loss factor tan δ up to 3), glass transition temperature from -40 to +40° C and tensile strength up to 50 MPa for the specific requirements in application. In this thesis various components of t-Pnb are investigated in terms of their thermomechanical behavior and modification potential under consideration of environmental influences such as UV-radiation, elevated temperature and contact media. Dynamic mechanical analysis (DMA) is used for the investigation of the thermomechanical properties. The application properties of t-Pnb are adjustable concerning type and quantity of the plasticizing process oil added to the t-Pnb polymer. Adding other polymeric components such as liquid silicone rubber, thermoplastics, rubbers or hydrocarbon resins may change the application properties as well. Depending on the application requirements in terms of thermomechanical properties as well as related stiffness and damping behavior the compound can be tailor made to a certain extent. In this study five different materials with various contents of different process oils and various additional thermoplastic components are investigated. The nomenclature was selected according to the materials Shore A hardness degree: PNB13, PNB25, PNB50, PNB65 and PNB70. The results show different thermomechanical behavior with significant alterations in glass transition temperature Tg, elastic modulus and damping properties indicated by the max. value of tan δ. While the t-Pnb formulations with components such as refined-aromatic-extract (RAE) process oil, Resin or other polymeric additives have Tg values of about room temperature or above, formulations with paraffinic oil (PA) show Tg values of around -20°C. The Tg varies over a wide range and the results generally show the underlying structure property correlations which are decisive for property adjustment. In addition, the characteristic typical frequency dependency of the material was investigated. Concerning application relevant external influences, no significant influence of UV-radiation or elevated temperature treatment on the glass transition temperature and elastic modulus was observed. Exempt was compound PNB65 with paraffin process oil. The immersion in the specific contact medium sebum being an artificial ear wax, showed significant influence on the properties of the materials at elevated temperatures. However, using specific additives kept the glass transition range stable. Moreover, after material aging a significant loss in the damping capacity was noticeable for all materials investigated.

AB - Elastomers are used in various applications and spread all over the industries. Common approach of using elastomers originates as it offers a deformable and elastic behavior, frequently underestimating its possible damping capacity up to now. Mass spring systems are still state of the art while having new opportunities to counter various problems arising from that. Especially damping in a low frequency range needs high mechanical loss factors to work properly. Different industries benefit out of that for damping vibrations and impacts as being a major issue for various areas of application. For example, antivibration gloves, ear-tips, rail-systems, damping elements, audio applications and many more. In this regard trans-polynorbornene (t-Pnb) offers the possibility to adjust the thermomechanical properties in terms of damping (mechanical loss factor tan δ up to 3), glass transition temperature from -40 to +40° C and tensile strength up to 50 MPa for the specific requirements in application. In this thesis various components of t-Pnb are investigated in terms of their thermomechanical behavior and modification potential under consideration of environmental influences such as UV-radiation, elevated temperature and contact media. Dynamic mechanical analysis (DMA) is used for the investigation of the thermomechanical properties. The application properties of t-Pnb are adjustable concerning type and quantity of the plasticizing process oil added to the t-Pnb polymer. Adding other polymeric components such as liquid silicone rubber, thermoplastics, rubbers or hydrocarbon resins may change the application properties as well. Depending on the application requirements in terms of thermomechanical properties as well as related stiffness and damping behavior the compound can be tailor made to a certain extent. In this study five different materials with various contents of different process oils and various additional thermoplastic components are investigated. The nomenclature was selected according to the materials Shore A hardness degree: PNB13, PNB25, PNB50, PNB65 and PNB70. The results show different thermomechanical behavior with significant alterations in glass transition temperature Tg, elastic modulus and damping properties indicated by the max. value of tan δ. While the t-Pnb formulations with components such as refined-aromatic-extract (RAE) process oil, Resin or other polymeric additives have Tg values of about room temperature or above, formulations with paraffinic oil (PA) show Tg values of around -20°C. The Tg varies over a wide range and the results generally show the underlying structure property correlations which are decisive for property adjustment. In addition, the characteristic typical frequency dependency of the material was investigated. Concerning application relevant external influences, no significant influence of UV-radiation or elevated temperature treatment on the glass transition temperature and elastic modulus was observed. Exempt was compound PNB65 with paraffin process oil. The immersion in the specific contact medium sebum being an artificial ear wax, showed significant influence on the properties of the materials at elevated temperatures. However, using specific additives kept the glass transition range stable. Moreover, after material aging a significant loss in the damping capacity was noticeable for all materials investigated.

KW - trans-polynorbornene

KW - norsorex

KW - high damping

KW - elastomer

KW - resonance frequency

KW - insulation

KW - aging effects

KW - glass transition temperature

KW - tan delta

KW - Elastomere

KW - hohe Dämpfung

KW - trans-Polynorbornen

KW - Norsorex

KW - Resonanzfrequenz

KW - Dämmung

KW - Alterungseffekte

KW - Glasübergangstemperatur

KW - tan delta

M3 - Master's Thesis

ER -