Preparation, mechanical properties and structural characterization of microfibrillar composites based on polyethylene/polyamide blends

There exist only few studies on the possibility to use the in-situ microfibrillar technology in HDPE/PA blends notwithstanding the good knowledge on the structure and properties of these blends. The main objective of this chapter is to summarize these studies in the field of the preparation, mechanical and structural characterization of HDPE/PA6 and HDPE/PA12 MFC materials. Along this presentation, the relationship between the mechanical properties and the structure of the MFCs on various length scales studied by various techniques will be discussed, as well.FCT grant SFRH/BPD/45252/2008 - to Nadya DenchevaFCT sabbatical grant SFRH/BSAB/812/2008 - to Zlatan DenchevHASYLAB at DESY , Hamburg,, Germany,Grant Number II-07-011 E

X-ray scattering studies on multiphasic polymer systems

The scope of the present chapter had to be limited to some recent studies on the application of synchrotron WAXS and SAXS in three particular multicomponent and multiphase polymer systems. The first system comprises materials that became known as microfibrillar reinforced composites (MFC) produced from oriented blends of thermoplastic semicrystalline polymers by conventional processing techniques. These materials belong to fiber-reinforced composites that have many important engineering applications but are notoriously difficult to study. As a second material system, the structure development during processing of an immiscible polymer blend of polypropylene (PP) and polystyrene (PS) was investigated by X-ray scattering techniques. Structure formation in polymers blends has been widely investigated in the last years, mainly in terms of the development of the size, shape, and orientation of the dispersed component under flow deformation. Further, the structure evolution and damage during stretching in the solid state of polymers blends is much less researched topic. Complementing, this second study, the structure evolution of the PP/PS blend was investigated by time resolved x-ray scattering in a synchrotron source. Finally, the third case reveals investigations on the structure of polymer nanocomposites developed during processing and also during stretching. Polymer nanocomposites are a recent class of materials, and very few studies have been published on the structure development in them.This work was supported by DESY and the European Commission under HASYLAB Projects 18DESYD-II-05-101 EC, DESY-D-II-07-011 EC and the FP6 contract RII3-CT-2004-506008 (IA-SFS). This work was also supported by FCT –Portuguese Foundation for Science and Technology through projectPOCTI/CTM/46940/2002 (MICROTEST) and POCI/CTM/57358/2004 (NANOFIBCO)

Manufacturing and properties of aramid-reinforced composites

The functional properties of the aramid-reinforced polymer composites depend primarily on the properties of the aramid reinforcing fibers, since the fraction of the fiber constituent in FRP is quite high, usually well above 30% by volume. The properties of the aramid fibers, in turn, depend on their chemical composition and manufacturing conditions: both of these determine the fibers physical structure and mechanical properties. The chapter will focus on these issues. Some specific problems related to the fiber-matrix nteraction.in aramid-containing FRP will also be addressed.Fundação para a Ciência e Tecnologia (FCT) - post-doctiral grant SFRH/BPD/45252/2008 (to Nadya Dencheva)Fundação para a Ciência e Tecnologia (FCT) - bolsa licença sabatica SFRH/BSAB/812/2008 (to Zlatan Denchev

Polyamide microcapsules and method to produce the same

National Patent application n.º 107879, data filled: 03.06.2014The invention relates to polyamide microcapsules prepared by means of activated anionic polymerization of lactams in a hydrocarbon solution containing organic or inorganic payloads in their cores and with porous polyamide shells. The capsules possess spherical or spheroid forms with average diameters in the range of 5-500 microns including payloads whose amount could vary from 0.05 to 50-60% of their weight which payload can include metals, metal oxides, carbon allotropes and/or their functionalized derivatives, clays, or any other polymeric or low molecular compounds that do not inhibit the polymerization process, being either soluble or insoluble in the reaction media. The microcapsules of the present invention can be used as obtained or can be transformed into molded parts of advanced thermoplastic composites comprising polyamide matrices reinforced by homogeneously distributed organic or inorganic reinforcements.Fundação para a Ciência e Tecnologi

Development and characterization of silicone/phosphorus modified epoxy materials and their application as anticorrosion and antifouling coatings

Epoxy resin is chosen for our present study owing to its exceptional combination of properties such as easy processing, high safety, excellent solvent and chemical resistance, toughness, low shrinkage on cure, good electrical, mechanical and corrosion resistance with excellent adhesion to many substrates. This versatility in formulation made epoxy resins widely applied for surface coatings, adhesives, laminates, composites, potting, painting materials, encapsulant for semiconductor and insulating material for electric devices. There are numerous paint/coating systems based on epoxy resin available for corrosion and fouling prevention. They however are not completely satisfactory in field applications, where high corrosion, fouling and flame resistance are required. The demand for epoxy resin as corrosion/fouling resistant coatings is restricted mainly due to its inferior characteristics like poor impact strength, high rigidity, and moisture absorbing nature besides inadequate flame retardant properties. It is for this reason that silicones and phosphorus-based compounds are used as modifier in this work by intercrosslinking network mechanism (ICN) to obtain epoxy resin with desired properties ideally suitable for field applications for preventing corrosion and fouling with flame retardantancy. The present work involves the development of solvent free silicone/phosphorus modified epoxy coating systems, since solvent free coating systems are widely used for numerous applications due to their lower cost per unit film thickness, freedom from fire and pollution hazard and ability to provide better performance. For the development of coating systems, epoxy resin (X) serves as base material, hydroxyl terminated dimethylsiloxane (HTPDMS) as modifier, aminopropyltriethoxysilane (APS) as crosslinking agent and dibutyltindilaurate (DBTDL) as catalyst. Polyamidoamine (A), aromatic amine adducts (B) and phosphorus-containing diamine (C) were used as curing agents. The study also describes the evaluation of corrosion resistant behaviour of unmodified epoxy and siliconized epoxy coatings by potentiodynamic polarization method, electrochemical impedance spectroscopy (EIS), salt-spray and antifouling tests. The results are discussed.CSIR. National Metallurgical Laboratory. Madras Centre. Fundação para a Ciência e Tecnologia

Structure and molecular dynamics in metal-containing polyamide 6 microparticles

The data presented in this study are available on request from the corresponding author.Polymer microparticles are used in additive manufacturing, separation and purification devices, biocatalysis, or for the recognition of biomolecules. This study reports on the effect of metal fillers on the structure and molecular dynamics of polyamide 6 (PA6) microparticles (MPs) containing up to 19 wt.% of Al, Cu, or Mg. These hybrid MPs are synthesized via reactive microencapsulation by anionic ring-opening polymerization in solution, in the presence of the metal filler. 13C high-resolution solid-state NMR (ssNMR) spectroscopy is employed as the primary characterization method using magic angle spinning (MAS) and cross-polarization (CP)/MAS. Depending on the metal filler, the ssNMR crystallinity index of the MP varies between 39–50%, as determined by deconvolution of the 13C MAS and CP/MAS spectra. These values correlate very well with the crystallinity derived from thermal or X-ray diffraction data. The molecular dynamics study on PA6 and Cu-containing MP shows similar mobility of carbon nuclei in the kHz, but not in the MHz frequency ranges. The paramagnetic Al and Mg have an observable effect on the relaxation; however, conclusions regarding the PA6 carbon motions cannot be unequivocally made. These results are useful in the preparation of hybrid microparticles with customized structures and magneto-electrical properties.This research was funded by Fundação para a Ciência e Tecnologia (FCT), project UID/CTM/50025/2019. N. Dencheva is also grateful for the personal program contract CTTI-51/18-IPC. FMO wishes to thank the AdvaMTech—Ph.D. Program in Advanced Materials and Processing for the Ph.D. grant PD/BD/114372/2016 (FCT)

Single polymer laminate composites by compression molding of knitted textiles and microparticles of polyamide 6: Preparation and structure-properties relationship

Knitted reinforced single polymer laminate composites based on polyamide 6 (KSPCsPA6) were produced bycompression molding of polyamide 6 microparticlesMPs()PA6powder-coating annealed PA6 Rib or Jersey knittedtextile structures. TheMPsPA6were synthesized by solution/precipitation activated anionic ring-opening poly-merization ofε-caprolactam. The tensile properties ofKSPCsPA6were studied in relation to the knitted re-inforcement architecture,fiber volume fraction, ply orientation and stacking orders. The tensile stiffness andstrength of the newly preparedKSPCsPA6withfiber content of 15% showed significant improvements as com-pared to the neat anionic PA6 matrix and to commercial hydrolytic PA6 (HPA6). The mechanical behavior of theKSPCsPA6was correlated with the geometry parameters of the knitted reinforcements, the polymorph content ofthe samples and their crystallinity indexes determined by differential scanning calorimetry and wide-angle X-raydiffraction. The fracture behavior of KSPCsPA6was investigated by electron microscopy complemented by si-mulation studies.All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. This work was partially financed by FEDER funds through the Competitiy Factors Operational Program - COMPETE and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER-007136. SDT thanks FCT for his PhD Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT through the strategic projects LA25/2013-2014 and UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant

NOVEL HYBRID COMPOSITES FROM HIGH DENSITY POLYETHYLENE REINFORCED BY NANOCLAY-FILLED POLYAMIDE 6 FIBRILS

Abstract Polyamide 6 filled with nanosized, montmorillonite (o-MMT/PA6) is nowadays one of the most common polymer nanocomposites with plate-like reinforcement in industrial applications. This work reports on the preparation and characterization of a new type of hybrid composite materials as an attempt to avoid the disadvantages of o-MMT/PA6 and MFCs

Microstructural-mechanical properties relationship in single polymer laminate composites based on polyamide 6

This paper studies theflexural and the impact properties of polyamide 6-based knitted reinforced single polymercomposites (KSPCs) prepared by compression molding of powder-coated textile structures. To prepare matrixcomponent, polyamide 6 microparticles (MPs) were synthesized by activated anionic ring-opening poly-merization ofε-caprolactam in solution and then used for powder-coating of the knitted structures. The influenceof the reinforcements' architecture, plies orientation, stacking order andfiber content on thefinal mechanicalproperties of KSPCs were investigated. Rib1 × 1 and Jersey knitted structures were selected as reinforcementsand treated by a stretching-annealing procedure to modify their mechanical properties. The anisotropic tensileand compression properties imparted by the knitted structures were found to be the major factors determiningthe impact andflexural behavior of KSPCs. Moreover, reinforcement's crossover points, the plies orientation andthe presence of a transcrystalline layer at the matrix-reinforcement interface were identified as relevant para-meters. The fracture mechanism of KSPCs was linked to the morphology and crystalline structure of the resultingcomposites and investigated by simulation andfinite element analysis of knitted reinforcemenents.This work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER 007136. SDT thanks FCT for his Ph.D. Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT in the frames of the stra tegic project UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant. All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund