Advanced fibre-reinforced polymer (FRP) composites for structural applications

Raftopoulos

2017

J Therm Anal Calorim

Organic-inorganic hybrid materials, prepared via chemical synthesis route or physical blending of functionalized nanofillers within polymer matrix, have gained an increased attention in the recent years. Polyhedral oligomeric silsesquioxane (POSS) nanoparticles, due to their nanometer size and functionalization possibilities, are applied as effective modifiersboth chemical and physical, for polymer matrices, including polyurethanes (PU). In this work, we describe the synthesis and processing of polyurethane/POSS hybrid nanocomposites and discuss the influence of POSS moieties on the thermal properties of PU matrices. Glass transition, the crystallinity of the soft phase, as well as the order-disorder transitions are affected by the incorporation of POSS in the polyurethane structure. Direct polymer-POSS interaction, or -indirect-due to the suppression or enhancement of microphase separation by the POSS moieties are discussed in terms of topology of the polymeric structure with the key role of POSS functionalization.

Section: Polyurethane/poss Nanocompositessynthesis and Processingmentioning

confidence: 99%

Section: Polyurethane/poss Nanocompositessynthesis and Processingmentioning

confidence: 99%

Section: Polyurethane/poss Nanocompositessynthesis and Processingmentioning

confidence: 99%

Section: Polyurethane/poss Nanocompositessynthesis and Processingmentioning

confidence: 99%

See 2 more Smart Citations

The influence of POSS nanoparticles on selected thermal properties of polyurethane-based hybrids

Raftopoulos

2017

J Therm Anal Calorim

“…Due to their high strength and rigidity combined with low density, fiber-reinforced polymeric composites (FRP) are extensively used in a wide variety of fields, from sports equipment [1][2] to the automotive, civil engineering, [3][4][5] military, [6][7] aeronautics and aerospace [8][9][10] industries. The oldest thermoset polymers are phenolic resins.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and tribological properties of nanofilled phenolic-matrix laminated composites

Pelin¹,

Stefan²,

Dincă³

et al. 2017

Mater. Tehnol.

Phenolic-resin composites have attractive properties for applications in various fields from the wood and adhesive industry to the automotive, aeronautics and aerospace industries. The paper presents the obtaining of SiC-nanofilled phenolic-resin-based composites reinforced with a bidimensional fabric. Different contents of nanometric silicon carbide (0.5, 1 and 2) % mass fractions) were dispersed into the phenolic-resin matrix, using the ultrasonication method, to ensure the optimum dispersion. Several layers of the bidimensional fabric were impregnated with the obtained mixtures and the final laminated composites were obtained using high-temperature pressing, followed by a multistage temperature program. The obtained laminated nanocomposites were characterized with FTIR spectroscopy and evaluated in terms of mechanical and tribological properties. After mechanical testing, fracture cross-sections were characterized with SEM and optical microscopy. The results highlight the positive effect of the nanometric silicon-carbide addition to the phenolic-resin matrix of the laminated composites, in terms of mechanical and tribological performance, improving their strength, stiffness and abrasive properties. Keywords: laminated composites, tensile strength, flexural strength, nanometric silicon carbide, nanocomposites, friction coefficient Kompoziti fenolnih smol imajo mo`nosti raznovrstne uporabe na razli~nih podro~jih, tako na podro~ju lesne industrije, v industriji lepil, kot v avtomobilski in letalski industriji. Prispevek predstavlja pridobitev SiC fenolnih kompozitov na osnovi smole, oja~anih z bidimenzionalnimi vlakni. Razli~ne vsebine nanosilicijevega karbida (0,5, 1 in 2) % masnega odstotka, so bile razpr{ene z uporabo ultrazvo~ne metode v matrici, pridobljeni s smolo, da je bila zagotovljena optimalna disperzija. Ve~plasti bidimenzionalnih vlaken je bilo impregniranih s pridobljenimi me{anicami in kon~ni laminirani kompoziti so bili pridobljeni z visokotemperaturnim tla~nim pritiskanjem, kateremu je sledil ve~stopenjski temperaturni program. Pridobljeni laminirani kompoziti so bili preu~evani s FTIR-spektroskopijo in ovrednoteni glede na mehanske in tribolo{ke lastnosti. Presek zloma po mehanskem testiranju je bil preu~evan s SEM-mikroskopijo in opti~no mikroskopijo. Rezultati ka`ejo pozitiven u~inek dodatka nanometri~nih silicijevih karbidov, s smolo pridobljenih matric v ve~plastnih kompozitih, zaradi njihovih mehanskih in tribolo{kih lastnosti, in ker se tako izbolj{a mo~, togost in abrazivne lastnosti.

The Development of Epoxidized Hemp Oil Prepolymers for the Preparation of Thermoset Networks

Omonov

Patel

Curtis

2019

J Americ Oil Chem Soc

Epoxy thermosets comprised of plant oils along with simple curing agents are sustainable and environmentally friendly polymers. The curing agent selected, and its compatibility with epoxy monomers, strongly affects the curing kinetics, the extent of curing, and the final properties of an epoxy polymers. The goal of this work is to expand the application of epoxidized oils in formulating biobased thermoset polymer systems. Epoxidized hemp oil (EHO) was produced with 8% oxirane oxygen content (OOC) after 24 hours using in situ generated performic acid. Two model curing agents-one aromatic (trimellitic anhydride, TMA) and one biobased nonaromatic (citric acid, CA)-with similar molecular weights were selected to study the cure behavior of EHO in acetone. Both curing agents are insoluble in EHO. The prepolymerization curing reaction behavior was monitored via the OOC, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and gel permeation chromatography. It was demonstrated that at 50 C, the reaction of EHO with TMA was extremely fast to form esters of TMA, while the reaction of EHO with CA was slower and followed different pathways. The cured EHO/TMA epoxy network is rigid and has a high alpha relaxation temperature (T α ) of 89 C, which is associated with the glass transition temperature (T g ), while the cured EHO/CA network system is semirigid with a T α of 40 C. In addition, TGA analysis showed that the EHO/TMA resin system represents a more homogenous structure compared to the EHO/CA system, as indicated by the presence of lower-temperature decompositions of citric acid derivatives.Keywords Biobased epoxy thermosets Á Epoxidized hemp oil Á Citric acid Á Trimellitic anhydride Á Epoxy cure behavior J Am Oil Chem Soc (2019) 96: 1389-1403.