TY - JOUR A1 - Waniek, Tassilo A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - The influence of water released from particles in epoxy‐based nanocomposites N2 - AbstractRecent studies have hypothesized that the reinforcing effects of boehmite nanoparticles (BNPs) in polymer nanocomposites (PNCs) are partly related to the particles themselves and partly to the water released from the BNP during curing. In this work, PNCs made from dried BNP (dBNP) with concentrations up to 15 wt% are investigated to differentiate particle and water related effects. The observed trend of the storage modulus in dynamic mechanical thermal analysis measurements was found to be independent of the drying procedure. Stiffness maps from intermodulation atomic force microscopy showed that dBNP leads to a stiffening of the interphase surrounding the particles compared with the unaffected epoxy matrix, while a softer interphase was reported for PNCs with as received BNP. A slight decrease in the glass transition temperature was observed by broadband dielectric spectroscopy related to a lowered crosslink density due to the particles. A significantly higher decrease was reported for PNCs with BNP, attributed to water influencing the curing process. In conclusion, the stiffening of PNC with BNP is related to the particles themselves, while the release of water causes the formation of a soft interphase in the vicinity of the particles and a significant decrease in crosslink density. KW - AFM stiffness of interface KW - Aluminium oxide hydroxide KW - Boehmit nanoparticle KW - Glass transition temperature KW - Broadband dielectric spectroscopy KW - Crosslink density control KW - Structure–property relationship KW - Nanocomposites KW - Thermoset PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606772 DO - https://doi.org/10.1002/app.55937 SN - 0021-8995 SP - 1 EP - 16 PB - Wiley AN - OPUS4-60677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tang, S. A1 - Wachtendorf, Volker A1 - Klack, Patrick A1 - Qian, Lijun A1 - Dong, Y. A1 - Schartel, Bernhard T1 - Enhanced flame-retardant effect of montmorillonite/phosphaphenanthrene compound in an epoxy thermoset N2 - A phosphaphenanthrene and triazinetrione group containing flame retardant (TAD) is combined with organically modified montmorillonite (OMMT) in epoxy resin thermosets (EP) to improve the performance of the flame-retardant system. When only 1 wt% OMMT/4 wt% TAD is introduced into the EP, the limited oxygen index (LOI) rises from 26% to 36.9% and a V-0 rating is achieved in a UL 94 test. The decomposition and pyrolysis products in the gas phase and condensed phase were characterized using thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The influence on the decomposition of EP, such as the increase in char yield, is limited with the incorporation of OMMT; a large amount of the phosphorus is released into the gas phase. The flame-retardant effect evaluation based on cone calorimeter data testified that OMMT improves the protective-barrier effect of the fire residue of OMMT/TAD/EP on the macroscopic scale, while TAD mainly causes flame inhibition. The fire residues showed a corresponding macroscopic appearance (digital photo) and microstructure (scanning electron microscope [SEM] results). The protective barrier effect of OMMT and the flame-inhibition effect of TAD combined to exert a superior flame-retardant effect, resulting in sufficient flame-retardant performance of OMMT/TAD/EP KW - Flame retardant KW - Nanocomposite KW - DOPO KW - Thermoset KW - Epoxy resin KW - TG-FTIR PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-388865 DO - https://doi.org/10.1039/c6ra25070j SN - 2046-2069 VL - 7 IS - 2 SP - 720 EP - 728 AN - OPUS4-38886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang T1 - Investigation of curing behaviour of melamine/phenolic (MP) thermosets N2 - Commercially available melamine/phenolic (MP) moulding compounds used for manufacturing electro installation parts were investigated by laboratory thermal analysis methods: Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) and Dielectric Analysis (DEA). The results were compared with on-line measurements in a compression mould using incorporated dielectric and ultrasound sensors. Softening and cross-linking behaviour were analyzed. For on-line process monitoring, only the ultrasound method worked well. The dielectric method was distorted by water formed as a by-product from the poly-condensation reaction. KW - Thermoset KW - Melamine KW - Phenol KW - Moulding compound KW - Cross-linking KW - DSC PY - 2010 DO - https://doi.org/10.1016/j.polymertesting.2010.05.008 SN - 0142-9418 VL - 29 IS - 6 SP - 723 EP - 728 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-20982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Goering, Harald A1 - Michel, U. A1 - Bayerl, H. T1 - Online monitoring of thermoset post-curing by dynamic mechanical thermal analysis DMTA N2 - Thermosetting moulding compounds are synthetic materials which can be easily formed in the molten state and achieve high temperature stability due to a cross-linking process which takes place during manufacture. To ensure thermal and mechanical properties, post-curing of moulded phenolic resin components is necessary for high quality applications. In the industrial practice, post-curing time-temperature-programs are heuristically acquired. In this paper, dynamical mechanical thermal analysis is employed to determine optimal post-curing conditions for injection moulded parts from phenolic resin. KW - DMTA KW - Moulding compound KW - Thermoset KW - Phenolic resin KW - Post-curing PY - 2009 DO - https://doi.org/10.1016/j.polymertesting.2009.02.005 SN - 0142-9418 VL - 28 IS - 6 SP - 561 EP - 566 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-19822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Bartusch, Jürgen A1 - Döring, Joachim A1 - Mc Hugh, Jarlath T1 - Making cure visible: monitoring the crosslinking process using integrated ultrasound sensors N2 - A special ultrasonic measuring system was developed to monitor the cross-linking process, enabling interaction with the manufacturing process in order to optimise part quality and reduce cycle times. KW - Thermoset KW - Ultrasound sensors KW - Mould KW - Rtm KW - Gelation KW - Vitrification PY - 2008 SN - 1639-965X IS - 38 SP - 64 EP - 66 PB - JEC CY - Paris AN - OPUS4-18610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -