44 research outputs found
BĂ©ta-polipropilĂ©n alapĂş keverĂ©kek előállĂtása Ă©s szerkezet-tulajdonság összefĂĽggĂ©sek meghatározása = Preparation of beta-polypropylene based blends and determination of their structure-properties relationships
A kutatásunk az alábbi tĂ©materĂĽleteket fogta át: 1. Az izotaktikus polipropilĂ©n (iPP) bĂ©ta-mĂłdosulatát tartalmazĂł keverĂ©kek előállĂtása 2. BĂ©ta- gĂłckĂ©pzĹ‘k összehasonlĂtĂł vizsgálata 3. A maleinsav-anhidriddel mĂłdosĂtott polipropilĂ©n (MAPP) alapĂş kompatibilizátorok bĂ©ta-kristályosodási hajlama 1. Az alábbi gĂłckĂ©pzĹ‘mentes Ă©s bĂ©ta-nukleált keverĂ©keket állĂtottuk elĹ‘: iPP/random iPP, iPP/szĂĽndiotaktikus polipropilĂ©n, iPP/poli(vinilidĂ©n-fluorid), iPP/poliamid-6 Ă©s iPP/MAPP. Meghatároztuk a keverĂ©kek kristályosodási Ă©s olvadási jellemzĹ‘it, valamint szupermolekuláris Ă©s fázisszerkezetĂ©nek jellegzetessĂ©geit. Kimutattuk, hogy bĂ©ta-polipropilĂ©n alapĂş keverĂ©kek előállĂthatĂłk, ha az adalĂ©k polimernek nincs alfa-gĂłckĂ©pzĹ‘ hatása. Alfa-gĂłckĂ©pzĹ‘ hatásĂş polimeradalĂ©kok esetĂ©n kompatibilizátor segĂtsĂ©gĂ©vel az adalĂ©k polimer alfa-gĂłckĂ©pzĹ‘ hatása mĂ©rsĂ©kelhetĹ‘. 2 Ă–t ismert bĂ©ta-gĂłckĂ©pzĹ‘ összehasonlĂtĂł vizsgálata során megállapĂtottuk, hogy gĂłckĂ©pzĹ‘ hatĂ©konyság növekedĂ©sĂ©vel a bĂ©ta-szelektivitás csökken. Az egyik bĂ©ta-gĂłckĂ©pzĹ‘ parciálisan oldĂłdik az iPP ömledĂ©kben. Ennek a bĂ©ta-kristályosodásra Ă©s szupermolekuláris szerkezetre gyakorolt hatását kĂsĂ©rletileg demonstráltuk. 3. Kimutattuk, hogy a kĂĽlönfĂ©le MAPP tĂpusok bĂ©ta-polipropilĂ©n alapĂş keverĂ©kekben hatĂ©kony kompatibilizátorkĂ©nt alkalmazhatĂłk, annak ellenĂ©re, hogy bĂ©ta kristályosodási hajlamĂşk a maleinsav-anhidrid tartalom növekedĂ©sĂ©vel megszűnik. A MAPP adalĂ©kok a bĂ©ta-gĂłckĂ©pzĹ‘ polimerfázisonkĂ©nti megoszlásában alapvetĹ‘ szerepet játszanak. | Our research have dealt with the following topics: 1. Preparation of beta-polypropylene based blends. Isotactic polypropylene (iPP) blends were prepared: iPP/rPP, iPP/sPP, iPP/MAPP, iPP/PVDF, iPP/PA-6, iPP/PTT, and iPP/sPS. The crystallisation and melting characteristics and the feature of their morphology were studied. It was demonstrated that beta-iPP based blends with high beta content can prepared, if the additive polymers have no alpha nucleating ability. The alpha-nucleating effect of the semicrystalline additive polymers can be moderate or eliminated by adding compatibilisers. 2. Comparison of beta-nucleating agents. The efficiency and selectivity of five beta-nucleating agents (Ca-pimelate, Ca-suberate prepared, commercial gamma-quinacridone and N,N?-dicyclohexyl-2,6-naphtalene-dicarboxamide (NJ Star) and an experimental compounds) were compared. We demonstrated that the selectivity of nucleators decreases with increasing their nucleating efficiency. It was found that N,N?-dicyclohexyl-2,6-naphtalene-dicarboxamide is partially soluble in iPP melt. The influence of its solubility on the crystallisation, the polymorphic composition and the supermolecular structure of iPP were demonstrated. 3. Beta-crystallisation ability of polypropylene based compatibilizators (MAPP). We have shown that the MAPP-s with different maleic anhydride content can be applied as efficient compatibilisers in blends studied. It was also found that MAPP-s modified the encapsulation of the beta-nucleating agent with additive polymer and influenced the polymorphic composition of in the beta-nucleated iPP blends
Különböző béta-gócképzők hatása az izotaktikus polipropilán kristályosodására
Az izotaktikus polipropilĂ©n (iPP) a szabályos tĂ©rszerkezetű, az u.n. sztereoreguláris polimerek elsĹ‘ Ă©s ma is legfonto-sabb kĂ©pviselĹ‘je. Az iPP-t Natta Ă©s munkatársai [1] állĂtot-ták elĹ‘ a Ziegler által felfedezett katalizátor segĂtsĂ©gĂ©vel. Zieglert Ă©s Nattát korszakalkotĂł tudományos munkásságu-kĂ©rt Nobel dĂjjal tĂĽntettĂ©k ki. Napjainkban az iPP az egyik legnagyobb mennyisĂ©gben gyártott műanyag. A világ po-lipropilĂ©n gyárainak kapacitása 2007-ben elĂ©rte az Ă©vi 47 milliĂł tonnát. Hazánkban a Tiszai Vegyi Kombinátban 280 ezer tonna iPP-t állĂtanak elĹ‘ Ă©vente. Nagy műszaki-gazdasági jelentĹ‘sĂ©gĂ©nek Ă©s tudományos Ă©rdekessĂ©gĂ©nek köszönhetĹ‘en az iPP-vel kapcsolatos polimerkĂ©miai Ă©s –fizikai, valamint műanyagtechnolĂłgiai kutatások rendkĂvĂĽl szĂ©leskörűek Ă©s szakirodalmuk nagyon gazdag
Robustness Study of a Tensile Modulus Prediction Model for Semicrystalline Polymers
This work presents a robustness study of a previously developed empirical model that links Young's modulus to two key parameters of crystalline structure; crystallinity and lamellae thickness. The reliability of this modulus prediction model was tested by using different calorimeters and different polypropylene grades as well. Small samples were fabricated from injection-molded bars from different locations of the specimens in order to check the effect of structural inhomogeneity originated by the dynamic processing conditions. In addition, the standard deviation and consequently the accuracy of the prediction was tested by repeated calorimetric measurements. The crystalline structure and melting characteristics were measured by differential scanning calorimetry (DSC). The tensile properties of studied specimens were evaluated by standardized tensile tests. Although, the accuracy and reliability of the prediction model is dependent on the instrument used for thermal analysis, reasonably good agreement was found between the predicted and measured values in most cases. However, we may note that only well-calibrated calorimeters are suitable for reliable prediction of the modulus
Effect of N,N'-Dicyclohexyl Terephthalic Dihydrazide on the Crystallization and Properties of Isotactic Polypropylene
Application of nucleating agents is a common way to manipulate the structure and properties of crystalline polymers. Our goal was to synthesize N,N'-dicyclohexyl terephthalic dihydrazide (DCTDH) and study it from the viewpoint of applicability as a nucleating agent for isotactic polypropylene (iPP). We used differential scanning calorimetry to investigate the efficiency of DCTDH in samples containing the nucleating agent in a wide concentration range. We used polarized light microscopy to study the crystalline morphology developed in the presence of this nucleating agent. To characterize the mechanical properties of the nucleated samples, we performed tensile and impact tests on injection molded specimens. DCTDH proved to be a non-soluble α-nucleating agent in iPP, with a saturation concentration around 300 ppm. The nucleating agent has a significant effect on the crystalline structure of iPP, microspherulitic structure forms in its presence. Owing to the different structure, a considerable change in the mechanical properties is observable: with increasing nucleating agent content the tensile modulus increases, while impact resistance has a maximum value around 300 ppm nucleating agent content
Szakmai tevékenység az MNTA TTK Polimer Fizikai Kutatócsoportjában és a BME Műanyag és Gumiipari Laboratóriumában
A Muanyag- Ă©s Gumiipari LaboratĂłrium aktĂvan rĂ©szt vesz a Budapesti Muszaki Ă©s Gazdaságtudományi
Egyetem vegyészmérnök és biomérnök képzésében, valamint az országban egyedülálló módon
elindĂtottuk az önállĂł Muanyag- Ă©s SzáltechnolĂłgiai Mesterszak-ot. Az oktatás mellett, kutatĂłcsoportunk
a polimerek feldolgozásához és alkalmazási területeihez kapcsolódóan végez szerteágazó
kutatómunkát
Influence of Graphene Oxide Incorporation on Resorcinol-Formaldehyde Polymer and Carbon Aerogels
Resorcinol-formaldehyde based polymer hydrogels with various graphene oxide (GO) content were synthesized using Na2CO3 as catalyst at pH=6 conditions. After supercritical drying they were converted to carbon aerogels in nitrogen atmosphere. The heat treatment not only pyrolysed the polymer gel, but also reduced GO. The GO added varied within 0-14% related to the mass of resorcinol which resulted in the reinforcement of the polymer matrix. The texture of the polymer and the carbon aerogels were characterized and compared in the nanoscale using SEM and TEM imaging, X-ray diffraction (XRD) and low temperature nitrogen adsorption measurements. The transition from polymer to carbon state was studied by thermogravimetry. In agreement with reference works in the GO range studied the morphology was not affected by the GO content either in the polymer or in the carbon form. The direct current (DC) conductivity however linearly increased with the added GO and already 10 % doubled the conductivity of the plain carbon aerogel
A molekula szerkezet és a gócképzés hatása a homo- és random polipropilén minták optikai tulajdonságára
Jelen munka során vizsgáltuk kĂ©t oldĂłdĂł gĂłckĂ©pzĂ´ hatását az optikai tulajdonságokra kilenc homo- Ă©s random kopolimer esetĂ©ben. A minták etilĂ©n tartalma 0 Ă©s 5,3 m/m% között változott. A láncszabályosságot lĂ©pcsĹ‘s izoterm kristályosĂtással (SIST) vizsgáltuk, mĂg az optikai jellemzĹ‘ket homályosság (haze) mĂ©rĂ©ssel határoztuk meg. A kristályosodási Ă©s olvadási jellegzetessĂ©geket differenciális pásztázĂł kalorimetriával (DSC) jellemeztĂĽk. Az eredmĂ©nyekbĹ‘l megállapĂthatĂł, hogy a lamella vastagságnak Ă©s a kristályosságnak nincs hatása a homályosságra. MennyisĂ©gi összefĂĽggĂ©st állĂtottunk fel a homályosság Ă©s a kristályosodási csĂşcshĹ‘mĂ©rsĂ©klet között, amely kapcsolatban áll a kristályosodás alatt kialakult szupermolekuláris egysĂ©gek mĂ©retĂ©vel. Az összefĂĽggĂ©s paramĂ©terei fĂĽggnek a polimer molekula szerkezetĂ©tĹ‘l. Mind az etilĂ©n tartalom, mind a láncszabályosság erĹ‘sen befolyásolja
az optikai tulajdonságok függését a gócképzéstôl. A nagy etilén tartalmú (>2 m/m%) minták
jelentôsen eltérnek a többi polimer viselkedésétôl, ennek ellenére a homályosság hasonló
képpen függ a láncszabályosságtól minden minta esetében
Determination of nucleus density in semicrystalline polymers from non-isothermal crystallization curves.
The present study introduces a new calculation method for obtaining nucleus density formed during non-isothermal crystallization of semicrystalline polymers. Isotactic polypropylene homopolymer (iPP) was used as a semicrystalline model polymer and its crystalline structure was modified using highly efficient nucleating agents or different cooling rates in order to manipulate nucleus density (N) within a wide range. The melting and crystallization characteristics were studied by calorimetry (DSC) and the nucleus density was calculated from the crystallization curves recorded under non-isothermal conditions at constant cooling rate. The nucleus density was correlated to the optical property, in fact to the haze index of injection molded plaques in order to qualify the calculated values of N. It was found that N increases more orders of magnitude in nucleated samples and correlates strongly to the optical properties. These observations are according to our expectations and indicate clearly the reliability of the proposed calculation approach