Zbigniew Roslaniec

Surface modified multi-walled carbon nanotubes in CNT/epoxy-composites

Multi-walled carbon nanotubes (MWCNTs), produced by arc-discharge method, were treated with oxidising inorganic acids. The surface modification of the oxidised nanotubes (o-MWCNTs) was achieved by refluxing the tubes with multi-functional amines. The functionalised nanotubes were embedded in the epoxy resin and the resulting composite was investigated by transmission-electron microscopy (TEM). The functionalisation led to a reduced agglomeration and evidences are given for improved interaction between the nanotubes and the epoxy resin.

Nanocomposites based on multiblock polyester elastomers (PEE) and carbon nanotubes (CNT)

Polymer nanocomposites including those containing carbon nanotubes appear to be of particular significance. Polymer nanocomposites based on thermoplastic poly(ether-ester) elastomer and carbon nanotubes have been prepared and investigated. The nanocomposites are obtained (in situ) by introducing the fillers into the reaction mixture and the synthesis of copolymer by polycondensation in the molten state. The nanotubes are dispersed in 1,4-butanediol by ultrasonication. Physical properties of the resulting nanocomposites are studied using the DSC, DMTA, SEM and mechanical tensile tests.

Influence of intercalated organoclay on the phase structure and physical properties of PTT–PTMO block copolymers

Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT–PTMO) copolymer/organoclay nanocomposites were prepared by in situ polymerization. They showed an intercalated silicate structure, as determined by X-ray diffraction and transmission electron microscopy. The influence of intercalated organoclay on the two-phase structure and mechanical properties of PTT–PTMO block copolymer was examined by using DSC and tensile tests. The DSC results imply that the silicate layers (Nanofil 32) in PTT–PTMO act as nucleation agents and accelerate the crystallization of PTT hard phase during the cooling down process from the melt. The introduction of silicate layers does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase, and degree of crystallinity of the nanocomposites. As the organoclay loading in the nanocomposites increase, the enhanced tensile modulus and yield stress was observed. The cyclic tensile tests showed that obtained nanocomposites have values of permanent set comparable to the neat PTT–PMO copolymer.

Detailed study on interfacial interactions in epoxy composites cured with 1-buthylimidazole containing functionalized carbon nanotubes

This work provides a detailed information on the preparation process and characterization of functionalized multiwalled carbon nanotubes/Epidian 6 nanocomposites using ARES rheometer, TGA, and DSC measurements, with the imidazole derivative as a curing agent. Scanning electron microscopy of the fracture surfaces of the composites with a total nanofiller concentration below 0.5 wt.% reveals a uniform dispersion of MWCNT with only some minor agglomerates. At the same time, the TEM analysis of the composite with a total concentration of MWCNT–COOH higher than 0.5 wt.% confirmed the presence of carbon nanotube aggregates along with a large number of places without any presence of nanoparticles in the whole volume of the epoxy matrix. Mechanical tests (bending as well as dynamic mechanical analysis) show that compared with the neat epoxy resin, the bending strength of the composite was improved by about 30 and 21% after incorporating as little as only 0.1 and 0.2 wt.% MWCNT–COOH, respectively. The work presented hereby is a continuation of a previous study on epoxy-based nanocomposites with different types of multiwalled carbon nanotubes and it is a part of a wider project on precise charting of the influence of carbon nanotubes (particularly multiwalled carbon nanotubes) in the system of epoxy resin with 1-buthylimidazole, as a curing agent.

Influence of expanded graphite (EG) and graphene oxide (GO) on physical properties of PET based nanocomposites

Abstract This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization1, 2. In this study, nanocomposites based on poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.

Thermoplastic elastomers containing 2D nanofillers: montmorillonite, graphene nanoplatelets and oxidized graphene platelets

Abstract This paper presents a comparative study on which type of platelets nanofiller, organic or inorganic, will affect the properties of thermoplastic elastomer matrix in the stronger manner. Therefore, poly(trimethylene terephthalate-block-poly(tetramethylene oxide) copolymer (PTT-PTMO) based nanocomposites with 0.5 wt.% of clay (MMT), graphene nanoplatelets (GNP) and graphene oxide (GO) have been prepared by in situ polymerization. The structure of the nanocomposites was characterized by transmission electron microscopy (TEM) in order to present good dispersion without large aggregates. It was indicated that PTT-PTMO/GNP composite shows the highest crystallization temperature. Unlike the addition of GNP and GO, the introduction of MMT does not have great effect on the glass transition temperature of PTMO-rich soft phase. An addition of all three types of nanoplatelets in the nanocomposites caused the enhancement in tensile modulus and yield stress. Additionally, the cyclic tensile tests showed that prepared nanocomposites have values of permanent set slightly higher than neat PTT-PTMO.

Nanocomposites based on polymer blends: enhanced interfacial interactions in polycarbonate/ethylene-propylene copolymer blends with multi-walled carbon nanotubes

Abstract In this article, the phase separation in the melt blended polycarbonate (PC) and ethylene propylene copolymer (EPC) has been studied with dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). Two glass transition temperatures on the tan δ curves were detected. This confirms the immiscibility of PC and EPC phases. Different content of multi-walled carbon nanotubes (MWCNTs) were added to the PC/EPC blends and the interfacial adhesion between MWCNTs and PC/EPC blend were shown using transmission electron microscopy (TEM). The MWCNTs were located in the PC phase and at the interfaces of PC and EPC phases. Moreover, the storage modulus (E′) of polymer blends was changed by the increasing content of EPC elastomer and MWCNTs. The value of E′ of PC decreased with an incorporation of EPC. While, along with an addition of MWCNTs in the PC/EPC blends an increase of E′ was visible. The strong interfacial interactions between the matrix and MWCNTs played the main role in increasing the values of the E′ of the nanocomposites.

Oxygen barrier properties and melt crystallization behavior of poly(ethylene terephthalate)/graphene oxide nanocomposites

Poly(ethylene terephthalate) nanocomposites with low loading (0.1-0.5 wt%) of graphene oxide (GO) have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2-3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt%) showed almost similar values of the long period (L = 11.4 nm for neat PET and L = 11.5 nm for PET/0.5GO).

Broadband Dielectric Spectroscopy of Nanocomposites Based on PVDF and Expanded Graphite

Nanocomposites based on poly (vinylidene fluoride) (PVDF) and expanded graphite (EG) were prepared by non-solvent precipitation from solution with different EG concentrations. Films were obtained by compression molding and their structural and dielectric properties studied. From Wide Angle X-ray Scattering (WAXS) experiments, it can be assessed that for all EG concentrations the -crystalline phase of PVDF is the predominant crystalline form. However, for composites with high nanoadditive content, higher than 3 wt.%, the -crystalline phase is also detected. Dielectric spectroscopy results showed that the nanocomposites present both high dielectric constant and electrical conductivity at low percolation threshold.

Morphology and mechanical properties of polyamide 12 (PA12)/poly(vinylidene fluoride) (PVDF) blends

Morphology and mechanical properties of polyamide 12 (PA12)/poly(vinylidene fluoride) (PVDF) blends The morphology, thermal and mechanical properties of polyamide 12 (PA12)/poly(vinylidene fluoride) (PVDF) blends were investigated. These polymers are engineering, semi-crystalline polymers which are reciprocally immiscible. Differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM) were used to characterize the polymeric materials. Mechanical properties were examined by static tensile test. The investigations demonstrate that blends with higher amount of PVDF, with the morphology of two co-continuous semicristalline phases, exhibit better mechanical properties. The blends with small content of PVDF and prepared by extrusion show the morphology of small separated domains of PVDF and full continuous PA phase. The morphology of these blends is different than the blends prepared by internal mixer and have better mechanical properties too. Thus they can be used in particular applications without a compatibilizing agent.