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3D-Printed PLA Filaments Reinforced with Nanofibrillated Cellulose

Journal of Renewable Materials 2020年第7期8卷 759-772页

作者： Matea Perić Robert Putz Christian Paulik wood K Plus-competence center for wood Composites&wood Chemistry Kompetenzzentrum Holz GmbHLinzA-4040Austria Institute for Chemical Technology of Organic Materials Johannes Kepler University LinzLinz4040Austria

In the current study poly(lactic acid)PLA composites with a 3 wt%and 5 wt%of nanofibrillated cellulose(NFC)were produced by 3D-printing *** enzymatic pretreatment coupled with mechanical fibrillation in a twin screw extruder was used to produce high consistency *** electron microscopy(SEM)equipped with Fibermetric software,FASEP fiber length distribution analysis,Furrier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),tensile tests,impact tests and differential scanning calorimetry were used to characterize NFC and PLA/NFC *** results of the fiber length and width measurements together with the results of the SEM analysis showed that enzymatic hydrolysis coupled with a twin screw extrusion could effectively reduce the diameter and length of cellulose *** produced NFC consisted of microand nanosized fibers entangled in a characteristic *** on the FT-IR analysis,no new bonds were formed during the enzymatic hydrolysis or fibrillation *** TGA analysis confirmed that produced NFC can be used in hightemperature extrusion processing without NFC *** the PLA/NFC composites preparation the NFC agglomerates were formed,which negatively influenced PLA/NFC composites impact *** slightly improved tensile strength and elastic modulus were reported for all composites when compared to the neat *** elongation at break was not affected by the NFC *** significant differences in thermal stability were detectable among composites nor in comparation with the neat ***,the crystallinity degree of the composite containing 5 wt%NFC was increased in respect to the neat PLA.

关键词： Nanofibrillated cellulose enzymatic hydrolysis twin screw extruder poly(lactic acid) 3D-printing

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Influence of Co-Catalyst Concentration on the Formation of Active centers and the Polymerization Rate in Catalytic Ziegler Natta Ethene Slurry Polymerization

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材料科学与工程（中英文A版） 2012年第7期2卷 511-518页

作者： Heinrich Trischler Martin Ruff Christian Paulik Institute for Chemical Technology of Organic Materials Johannes Kepler University Linz Altenbergerstrasse 69 4040 LinzAustria competence center wood kplus gmbh Altenbergerstrasse 69 4040 Linz Austria

The influence of co-catalyst triethylaluminium (TEAL) concentration on polymerization rate for standard Ziegler-Natta catalyst systems has been studied. By applying the simple polymerization rate model it is found that the co-catalyst concentration can be positively correlated with the number of active centers C*. This finding is confirmed by the fact that a deactivated catalyst can be reactivated by additional co-catalyst injection. It also is shown that co-catalyst concentration mmol·dm-3 should be used in ethene slurry polymerisation to qualify the behavior of Ziegler-Natta catalysts and not the commonly used co-catalyst/catalyst (Al/Ti) molar ratio.

关键词：催化剂浓度助催化剂聚合速率活性中心淤浆聚合 Ziegler-Natta 纳塔乙烯

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EFFECT OF DEEP COLD TREATMENT ON TWO CASE HARDENING STEELS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 1-7页

作者： C.H.Surberg P.Stratton K.Lingenhle V-Research center of competence for Tribology and Technical Logistics gmbh DornbirnAustriap The Linde Group UnterschleiβheimGermany Lingenhle Technology gmbh FeldkirchAustria

Although cold treatments have been used to reduce the retained austenite in the cases of carburised steel for many years, there is little data on deep cold temperatures below -70℃ or treatment times longer than an hour or two. This study set out to determine the effects of such deep cold treatments at temperatures -150℃ for 24 h. The study investigated the effects of deep cold on the microstructure, hardness profile, residual stress and internal oxidation on two typical carburising steels, 16MnCr5 and 21NiCrMo2. The study found that for both 16MnCr5 and 21NiCrMo2 carburised to a case depth of approximately 0.8 mm, the longer and colder the deep cold treatment, the more the austenite retained in the case was converted to martensite and the harder it became. After low temperature tempering, the hardness difference was smaller, but still significant. In both steels, the case appeared more refined and homogeneous after deep cold treatment. Deep cold treatment had a negligible effect on the core properties of either steel.

关键词： Carburised steel Deep cold Retained austenite

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Simulation of Mould Level Velocities During Continuous Casting of Round Bloom Strands With Mould-Electromagnetic Stirring

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Journal of Iron and Steel Research International 2012年第S2期19卷 884-887页

作者： BARNAMartin JAVUREK Mirko REITER Jurgen WATZINGER Josef KAUFMANN Bernhard HACKL Gemot Institute for Fluid Mechanics and Heat Transfer Johannes-Kepler-University-Linz Voestalpine Stahl Donawitz gmbh and Co KG Siemens VAI Metals Technologies gmbh and Co Voestalpine Stahl gmbh RHI AG Technology Center Leoben

In modern continuous casting of round steel blooms rotating electromagnetic fields are commonly employed to improve the product ***-electromagnetic stirrers(M-EMS)are used to excite a rotary motion along the solidification front in the liquid *** velocities lead to a better strand surface quality as well as enhancing the transition from columnar to equiaxed *** the usage of electromagnetic stirrers is widespread,not all effects are fully known or *** to harsh conditions at the plant,measurements are scarce and *** model experiments-an established alternative for investigating continuous casting of steel-cannot be used due to the low electrical conductivity of *** with liquid metals like mercury,Galinstan or wood’s metal are either expensive or difficult to *** numeric simulations are essential to gain a better understanding of the processes involved in continuous casting with electromagnetic *** numeric simulations should always be validated with experiments and/or *** the velocity field inside the liquid core of the bloom cannot be measured at the caster,the velocity at the mould level can be measured by dipping a nail into *** skull forming at the tip of the nail is directly linked to the occurring surface *** measurements can then be compared with numeric simulations of the nail dipping *** numeric model is restricted to the upper part of the *** lower part of the strand is also taken into account through adjusted boundary conditions(velocity field *** from a simulation of the whole strand).In this work the influence of the stirring field strength on the simulation results will be *** the future these nail dipping simulations will be validated with plant *** can then to a certain extentvalidate the simulation of the strand with M-EMS too,as it serves as the basis for the nail dipping model.

关键词： continuous casting of steel mould-electromagnetic stirring velocity measurements finite volume method

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