Combination of plasma treatment and solgel chemistry for enhanced rubber / fibre adherence Kristina Klinkhammer, Esther Rohleder, Maike Rabe, Eberhard Janssen Aachen-Dresden-Denkendorf Deutsches Fachkolloquium Textil 28.-29.03.2017, Aachen
Content textile reinforcement material properties application standard functionalisation aim of the project plasma technology sol-gel technology results summary
Textile Reinforcement textile reinforcement are embedded in a second material, e.g. rubber increase stability and durability of a product many different application Cam-, V-belts conveyor belts hose tyres
Reinforced plastic - material textile material: polyester polyamide 6.6 (nylon) p-aramide other materials for embedding matrix: natural rubber synthetic rubber ( e.g. VP, SBR) plastics (e.g. PU, PVC, PE)
Reinforced plastic - properties textile reinforcement are embedded in (rubber) matrix to enhance product properties rubber properties differ from textile properties, e.g. surface morphology flexibility E modulus low reactivity and low polarity of textile fibres need for chemical functionalisation for better adherence
Reinforced plastic - properties material polyethylenterephthalat (PET) E modulus (N/mm²) 2800-3000 PA6 3000 / 1000 PA66 3100 / 1100 aramide 59000-100000 natural rubber 50 SBR 10 PU 20-220 PVC 3000 PE 720-1100
Reinforced plastic - functionalisation standard for water based systems: RFL (resorcinol formaldehyde latex) RF resin preparation: 1. reaction between resorcinol and formaldehyde RF resin (binds to fibre) 2. introduction of latex (rubber-like, bonds to rubber by covulcanization) 3. dipping of fibres in RFL 4. heat treatment (drying 130-170 C, curing 190-240 C)
RFL - problems formaldehyde: reclassified from class 2 to class 1B (carcinogenic) US and EU impact on regulations currently discussed resorcinol: evaluating endocrine disruptive properties done in 2016 (in CoRAP) impact on future regulations open great interest to substitute RFL dip
Research project - aims adhesion improvement between textile reinforcement and rubber matrix substitution of RFL dip use of more environmental friendly chemicals combination of plasma and sol-gel-chemistry
Surface functionalisation - plasma technology Plasma (fourth state of matter) nature: thunderbolt, solar wind artificial: by electrical discharge ionised gas neutral and electrical charged species (electrons, ions, neutral particles) www.wikipedia.de
Plasma technology types of plasma atmospheric pressure plasma: pressure: approx. 1 bar energy: electric discharge Corona / DBD 5 100 khz DBD (dielectric barrier discharge) rel. high temperature high process gas consumption low pressure plasma: pressure: 0.5 mbar energy: RF-Generator homogenous reactions low temperature low process gas consumption closed circuit: toxic gases possible
Surface functionalisation sol-gel technology originally: wet-chemical process for surface functionalisation 1. hydrolysis: R R RO Si OR OR + H 2 O H + / OH - RO Si OH OR 2. condensation: RO R Si OH OR + HO R Si OR OR - H 2 O R Si RO O OR R Si OH OR precursors: XR -Si-(OR) 3 with X = functional group R = alkyl or aryl, R = mainly CH 3 or CH 2 CH 3 OR crosslinking and film formation X special functions of the film
Sol-gel-technology - film formation sol application via padding, drying and polymerisation fibre fibre fibre drying : evaporation of the solvent (water, ethanol) increase of sol concentration condensation of particles and film formation (polymerisation)
Experimental a) conventional dryer (oven) aqueous dispersion of silane (mix) application b) plasma material: polyester fibres for embedding in rubber silanes with different functionalities: alky, amino, vinyl, mercapto, glycidoxy, drying and condensation (polymerisation): oven or plasma
Analytics hydrophilicity (droplet test) functional groups (KMnO 4 ) elemental composition (EDX) surface morphology (REM) adhesion (peel test)
Results: hydophilicity / hydrophobicity droplet test: absorption time of water droplet hydrophilic: short absorption time plasma decreases absorption time
Detection of functional groups: KMnO 4 Adsorbance 3 2,5 2 1,5 1 0,5 0 350 450 550 650 wave lengths (nm) violett solution becomes clear by reaction with double bonds and other functional groups
Results: REM / EDX Si localised around fibres and in interspaces
Results: REM / EDX coating with 10% vinylsilane
Results: REM / EDX coating with 4% vinylsilane
Results: peeltest samples
Results: adhesion name functionalisation treatment adhesion force (N/25mm) raw PES raw PES none none 106 RFL (standard) oven 185 MG33 glycidoxy silane oven 118 MG34 glycidoxy silane plasma 182 MG127 amino silane plasma 189 plasma treatment of functionalised fibres results in higher adhesion than oven heating variation of chemical concentration / variation results in high adhesion force
Summary polyester fibres were functionalised with silanes and treated with plasma or in the oven plasma treatment shows clear advantages in comparison to oven treatment the finishing is located around the fibres and in interspaces high adhesion forces comparable to RFL dip are achieved
Acknowledgment Thanks to German Federal Ministry of Education and Research (BMBF) for financial support (grant no. 03X0129B). Many thanks to the colleagues and students of FTB at Niederrhein University of Applied Science: Noman Mughal, Alexandra Glogowski and Anne Hartmann
Contact Dr. Kristina Klinkhammer, phone: +49 (0)2161-186 6042 Dr. Esther Rohleder, phone: +49 (0)2161-186 6008 Prof. Dr. Maike Rabe, phone: +49 (0)2161-186 6110 Prof. Dr. Eberhard Janssen, phone: +49 (0)2161-186 6042 Niederrhein University of Applied Sciences Research Institute for Textile and Clothing (FTB) Richard-Wagner-Str. 97 41065 Mönchengladbach Germany