Polymer-polymer Microfibrillar Composites: Effect of Nanofillers on Structure and Properties

Microfibrillar composites (MFCs) are advantageous polymer-polymer composites with in situ formed reinforcing fibrils. The range of applications of MFCs is limited by their low thermal resistance and me-chanical parameters of polymeric microfibres, which are formed by melt or cold drawing of the polymer blend. This study addresses improving MFCs based on HDPE matrix with 20% polyamide 6 microfibrils using organophilized montmorillonite. The complex effect of the nanofiller on the structure and parameters of the MFCs is investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3545

Effect of an organoclay on the reaction-induced phase-separation in a dynamically asymmetric epoxy/PCL system

The addition of layered silicates can significantly affect the phase behaviour of both immiscible thermoplastic blends and partially miscible thermoset systems that undergo reaction-induced phase separation (RIPS) during curing. This study focuses on the phase behaviour of polycaprolactone (PCL)/epoxy in the presence of organically modified montmorillonite (oMMT). Due to the high dynamic asymmetry caused by the differences in the molecular weights and viscosities of the PCL and the uncured epoxy, the critical point is localised at low PCL concentrations, as indicated by the pseudophase diagram. The addition of oMMT to the system led to the marked shift of the critical point towards higher concentrations of PCL, with an increase in the oMMT content occurring as a consequence of the preferential localisation of the clay in the epoxy phase, making this phase more dynamically slow. Significant changes in morphology, including phase inversion of the PCL/epoxy systems caused by the presence of oMMT, were recorded for PCL concentrations ranging from 10 to 30%

Теоретико-методологічні основи розуміння механізму правового регулювання

Метою цієї статті є аналіз напрямів наукових досліджень, що у своїй єдності формують теорію механізму правового регулювання (МПР), розкриття теоретикометодологічних проблем, які мають місце при осмисленні МПР, визначення та систематизація методологічних підходів до розуміння МПР

Effect of layered silicates on the thermal stability of PCL/PLA microfibrillar composites

This paper reports on an investigation of the influence of the presence of two different clays, Cloisite 15A and Cloisite 30B, and fibre drawing on the degradation behaviour and kinetics of PCL/PLA composites. It was found that the type of clay significantly influenced the mass loss behaviour of the composites because of physical interactions between the clay and the polymer chains and degradation volatiles. Melt drawing of the composite films, however, had little influence on the degradation behaviour of the investigated samples.This work was supported by Czech Science Foundation (Grant No 13-15255S)

The effect of halloysite modification combined with in situ matrix modifications on the structure and properties of polypropylene/halloysite nanocomposites

The effect of various modifications/intercalations of halloysite and the combination of these modifications with in situ PP matrix modification was investigated with respect to the structure and properties of the polypropylene/halloysite nanocomposites. Hexadecyl-tri-methyl-ammonium-bromide (HEDA), 3-aminopropyltrimethoxysilane and urea were used as the intercalators/modifiers. The best intercalation was found for urea, although an unexpected insignificant impact on the mechanical properties also resulted as a consequence of the urea polarity and the significant decrease in PP crystallinity. However, the simultaneous application of 4,4!-diphenylmethylene dimaleinimide (DBMI) brought about an increase in the mechanical behavior by increasing the halloysite/PP affinity as a result of in situ matrix modification. This effect was further supported by coupling between the PP and halloysite (HNT) in the system containing urea-intercalated HNT. This can be explained by the occurrence of a urea-supported reaction between the imide ring of DBMI and the OH groups of the HNT, which resulted in the best mechanical behaviors achieved in this study

Interfaces study of all-polysaccharide composite films

Films made of xylan (X) and quaternized chitosan (QC) were prepared and the interactions of the polysaccharides on interfaces were discussed. According to elemental analysis, the X film contained also cellulose (31%) which could not be separated from the water suspension. The QC sample was soluble in water due to the presence of quaternized glucosamine units (4%) despite the presence of equal amounts of chitosan (CS, 48%) and chitin (CT, 48%). According to mechanical tests on QC/X = 1/3 composite film, the modulus and tensile strength values were the best from all mixtures measured, but still not better than on the film from X. We assume this is due to the sorption of xylan onto the surface of insoluble cellulose fibrils in the X film. Cyclic voltammetry indicates that the incorporation of X into the QC film decreases the overall positive charge provided by the QC. The X composite with net negative charge is indeed a barrier against the diffusion of ferricyanide anions. Based on TG/DTG/DTA analysis, the onset temperatures (OT) are decreasing with increasing X content in the blended films. X and QC films exhibited the highest OT values in comparison with the blended samples. The lowest OT temperature was observed at QC/X = 1/3. We think it is due to the thermocatalytic effect of the 4-O-methyl-D-glucuronate in X and the QC quaternary groups on the thermolysis–thermo-oxidation mechanism. According to AFM, the QC/X = 1/3 film exhibited the largest roughness values on both sides of the films, likely due to having the highest density of electrostatic interactions. XRD profiles of the films indicate some crystalline residues of cellulose in the xylan component as well as some chitin in the QC component. We assume that the properties are the result of the combination of the electrostatic interactions of carboxyl and quaternary groups of the soluble components of X and QC bonded to the surface of insoluble cellulose fibrils by hydrogen bonds. This probably results in both synergistic and antagonistic effects expressed by the improved or diminished values of determined properties.Acknowledgements We gratefully acknowledge funding from State programs #2003SP200280203 and 2003SP200280301; Slovak Granting Agency VEGA (Project Nos. 2/7030/7, 2/0087/11, 2/0007/13 and 2/0100/14). We thank Eva Hadzimov? for performing the TG/DTG/ DTA experiments. This contribution is also the result of the project implementation: Centre of Excellence for White-Green Biotechnology, ITMS 26220120054, supported by the Research & Development Operational Program funded by the ERDF. P.K. thanks Qatar University for QUUG-CAM-2017-1 grant funding.Scopu