TY - CONF A1 - Krüger, Simone A1 - Goering, Harald A1 - Stark, Wolfgang A1 - Bayerl, H. A1 - Brinkmann, P. T1 - Thermo Analytical Investigations of Phenol Moulding Compound Curing - Potential for Post-Cure Optimisation T2 - 3rd International Thermoset Conference CY - Iserlohn, Germany DA - 2005-04-21 KW - Post curing KW - High pressure DSC KW - DMA KW - Reaction kinetic KW - Phenolic resin PY - 2005 SP - 219 EP - 225 PB - Fachhochschule Südwestfalen - Hochschule für Technik und Wirtschaft CY - Iserlohn AN - OPUS4-7453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang T1 - Investigation of the curing behaviour of carbon fibre epoxy prepreg by dynamic mechanical analysis DMA N2 - Carbon fibre prepregs have found widespread application in lightweight constructions. They are based on a carbon fibre fabric impregnated with reactive epoxy resin. Measurements were carried out using commercially available prepreg material. For Dynamic Mechanical Analysis (DMA), a single cantilever measuring device was applied. The DMA results were refined by additional DSC measurements. The measurements were carried out with dynamic heating in the temperature range -90 to 280 °C. The heating rates were 1 and 2 K/min, respectively. A glass transition of the uncured material (Tg0) near 1 °C, and crosslinking-induced vitrification and devitrification at the maximal glass transition temperature of the cured material (Tgmax) in the temperature range 220 to 230 °C were found. The activation energies for the glass transitions were determined using an Arrhenius plot. By detailed consideration of the influence of the frequency on the DMA data, indications for gelation were deduced. KW - CRP KW - Prepreg KW - Carbon fibre KW - Epoxy KW - DMA KW - DSC KW - Glass transition KW - Crosslinking KW - Vitrification KW - Devitrification PY - 2013 U6 - https://doi.org/10.1016/j.polymertesting.2012.11.004 SN - 0142-9418 VL - 32 IS - 2 SP - 231 EP - 239 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-27584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mc Hugh, Jarlath A1 - Döring, Joachim A1 - Stark, Wolfgang A1 - Guey, J. L. T1 - Relationship between the Mechanical and Ultrasound Properties of Polymer Materials T2 - 9th European Conference on NDT CY - Berlin, Germany DA - 2006-09-25 KW - Ultrasound KW - DMA KW - Epoxy KW - Modulus KW - tan delta KW - High temperature PY - 2006 SN - 3-931381-86-2 SP - 1(?) EP - 9(?) PB - European Federation for Non-Destructive Testing CY - Berlin AN - OPUS4-14065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Jaunich, Matthias T1 - Investigation of ethylene/vinyl acetate copolymer (EVA) by thermal analysis DSC and DMA N2 - Two types of commercially applied Ethylene/Vinyl Acetate Copolymers (EVA) for encapsulation of photovoltaic modules were investigated by the thermal analysis methods of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) in the temperature range from -150 °C to 200 °C. Glass transition, crystal melting and cross-linking were analyzed. The aims of the investigations were to gain more information for incoming goods control and to get information about the whole temperature dependent material properties in the investigated temperature range, starting at very low temperatures up to the crosslinking temperature region. KW - EVA KW - Thermal analysis KW - DSC KW - DMA KW - Glass transition KW - Crystal melting KW - Cross-linking PY - 2011 U6 - https://doi.org/10.1016/j.polymertesting.2010.12.003 SN - 0142-9418 VL - 30 IS - 2 SP - 236 EP - 242 PB - Elsevier Ltd. CY - Amsterdam [u.a.] AN - OPUS4-23206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Stark, Wolfgang A1 - Bohmeyer, W. ED - Karbhari, V.M. T1 - Non-destructive evaluation (NDE) of composites: using ultrasound to monitor the curing of composites N2 - Typical composite materials for lightweight construction consist of a fibre (glass or carbon) reinforced thermosetting matrix. The impregnation of the fabric is made with liquid resin – usually epoxy resin or unsaturated polyester resin are used. The main processing methods are resin transfer moulding (RTM) and prepreg technology often used in combination with autoclave curing. After shaping, the resin must be cured. The final properties of the produced parts depend on the curing degree and the final glass transition temperature. Analytical methods and the use of ultrasound for online cure monitoring in the manufacturing process are introduced. Examples for the application of ultrasonic cure monitoring for the production of composite parts for traffic systems are also covered. KW - Epoxy KW - DSC KW - DMA KW - Kinetic KW - Autoclave KW - Curing KW - Glass transition KW - Curing behaviour KW - Curing degree KW - Rheology KW - Differential scanning calorimetry KW - Dynamic mechanical analysis KW - Sound velocity KW - Sound damping KW - Resin transfer moulding KW - RTM KW - Prepreg PY - 2013 SN - 978-0-85709-344-8 SN - 978-0-85709-355-4 U6 - https://doi.org/10.1533/9780857093554.1.136 SN - 2052-5281 SN - 2052-529X N1 - Serientitel: Woodhead publishing sereies in composites science and engineering – Series title: Woodhead publishing sereies in composites science and engineering VL - 43 IS - Part 1 / Chapter 7 SP - 136 EP - 181 PB - Woodhead Publishing Ltd CY - Cambridge, UK AN - OPUS4-28848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Jaunich, Matthias A1 - McHugh, J. T1 - Carbon-fibre epoxy prepreg (CFC) curing in an autoclave analogue process controlled by dynamic mechanical analysis (DMA) N2 - Carbon fibre prepregs have found widespread application in lightweight constructions. They are based on a carbon-fibre fabric impregnated with reactive epoxy resin. DMA measurements under temperature conditions similar to an autoclave programme were carried out using commercially available prepreg material with a high glass transition temperature. The characteristic of the temperature programme was a dynamic heating segment at 1.5 K/min followed by a longer isothermal segment at 180 °C. The courses of the storage modulus E', loss modulus E'' and tanδ were recorded. The measuring frequency was varied between 1 Hz and 33.3 Hz. Gelation and vitrification are assigned. The influence of the measuring frequency on the time to vitrification and the correlation with DSC are discussed. The reaction does not end even after 10 h curing at 180 °C, which is interpreted as the slow cessation of the reaction caused by vitrification. KW - Prepreg KW - CFC KW - Curing KW - DMA KW - DSC KW - Autoclave KW - Gelation KW - Vitrification KW - Glass transition PY - 2013 U6 - https://doi.org/10.1016/j.polymertesting.2013.09.014 SN - 0142-9418 VL - 32 IS - 8 SP - 1487 EP - 1494 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-29479 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -