Short Glass Fiber Research Articles

The structure, composition and preparation of injection-molded composite materials based on glass-filled polysulfone

In the course of this study, compositions and designed structures for the polysulfone (PSF) and short glass fibers systems were calculated. Additionally, disperse-filled polymer composite materials (DFPCM) based on PSF-190 were classified in accordance with their respective structures, and the optimal amount of glass fiber (13.5–18.5 vol %) was determined. This article describes the production of DFPCM using PSF and a short glass fiber with a twin-screw extruder (Labtech Engineering Company LTD, model Scientific FIC 20-40). Furthermore, optimal mixing parameters for the creation of composites wherein the glass fiber length exceeds the critical length (lcr) were established. The critical length was calculated, and the curves for fiber size distribution of polysulfone composites were depicted, and a difference in fiber concentration between the dispenser and the extrusion head (up to ~10–15%) was found when the fiber content was at 18–25 vol %. For the first time, optimal parameters (which pertain to medium-filled dispersions) for the structure of DFPCM based on PSF and short glass fiber are able to be demonstrated.

Damage and damping of short-glass-fibre-reinforced PBT composites under dynamic conditions: Effect of matrix behaviour

The effect of a thermoplastic polyester elastomer (TPEE) on the damping properties and energy dissipation of PBT (polybutylene terephthalate) reinforced with short glass fibres is investigated in this study. Dynamic mechanical analysis (DMA) showed that tan δ increased significantly as a result of the incorporation of TPEE, especially for frequencies below 60 Hz. With increasing frequency, the storage modulus increased and the loss moduli decreased, with the loss modulus being higher for the TPEE composite. Tensile cyclic loading tests showed that more energy was dissipated during the first loading/unloading cycle for PBT TPEE composites than for PBT ones. Damage, characterized by degradation of the elastic modulus during sequential loading-unloading cycles, was analysed at strain-rates of 0.1, 0.2, 0.8 and 3.2 s−1. These experiments confirmed the DMA results and demonstrated that the TPEE composite dissipated more energy than the comparable PBT samples. SEM analysis showed that the incorporation of TPEE weakened the fibre-matrix interfacial bonding, especially in the ductile zones of the fracture surface. Moreover, localized deformation in the interface zone between glass fibres and the matrix was affected by the visco-damage behaviour, explaining the increase in the tan δ value for the TPEE composite.

Experimental In-Plane Shear Capacity of Clay Brick Masonry Panels Strengthened with FRCM and FRM Composites

Unreinforced masonry (URM) buildings, largely found in Euroasian regions, are particularly vulnerable to in-plane shear failures during seismic events due to the poor shear capacity of masonry walls. In the case of historical masonry buildings, the use of strengthening solutions with polymeric and polymer-modified matrices composites is not recommended since the breathability of the masonry could be reduced, leading to a fast and undesired degradation. In this paper, an innovative fiber-reinforced cementitious mortar (i.e., FRCM) system was used to improve the shear capacity of old-type solid clay brick masonry walls. An experimental program on 24 masonry panels subjected to diagonal compression tests was carried out. The innovative FRCM system consisted of a basalt grid embedded in an improved inorganic matrix, made of lime-based mortar reinforced with short glass fibers (i.e., Fiber-reinforced mortar, FRM). Two sets of specimens were tested, single-leaf masonry panels and double-leaf masonry panels, to investigate the typical configurations of load-bearing walls and partition walls. The effectiveness of the innovative FRCM system was investigated for both a conventional symmetric strengthening configuration and an asymmetric strengthening configuration with anchors, a solution often adopted in the case of internal/external interventions only. Furthermore, the response of masonry panels strengthened with only symmetric FRM with a slightly greater amount of short glass fibers embedded in the matrix was also investigated. The experimental outcomes outlined that panels reinforced with symmetric FRM achieved similar effectiveness in the shear strength increase to panels reinforced with symmetrical FRCM. Conversely, a reduced deformability was observed in FRM panels with respect to those strengthened with FRCM. The experimental results also allowed the quantification of the effectiveness of FRCMs in the case of asymmetric strengthening configurations. Finally, a comparison between experimental results and American Code provisions for FRCM-strengthened systems was reported.

Microstructural analysis of short glass fiber reinforced thermoplastics based on x-ray micro-computed tomography

As a result of the injection molding process, short glass fiber reinforced thermoplastics (SFRT) exhibit complex microstructures with fibers of different length and orientation as well as spatially varying fiber volume fractions. Their mechanical and functional performance can therefore only be predicted and ensured based on precise knowledge of said microstructure. To that end, x-ray micro-computed tomography (μCT) is commonly employed, with analysis software most-often yielding the fiber orientation tensors but lacking more detailed results. In order to increase the quality of the microstructural data, more accurate analysis techniques are necessary that include single fiber information for detailed correlations of microstructural parameters. In this work, a novel algorithm is suggested that relies on an iterative single fiber segmentation and merging procedure to obtain the fiber characteristics: orientation, location, radius and length. The algorithm is implemented in an efficient manner in Python, making heavy use of parallelization techniques. It is then applied to μCT scans and artificially generated 3D data of short glass fiber reinforced polyamide 6.6 with fiber mass fractions of 35%. The algorithm has been validated using reference data, commercial software and experimental fiber length data from an incinerated specimen and was shown to be both robust and accurate.

On the investigations of nano and micro-sized particles of Boric acid as a solid lubricant in PAEK composites

The attempt to explore the tribo-potential of micro-particles and nano-particles of Boric acid, a well know solid lubricant with a layer lattice structure is first time reported in this work using high performance poly (aryl-ether-ketone) (PAEK) as a matrix, short glass fibers (GF) as a reinforcement and graphite as a primary solid lubricant. The tribo-performance evaluation in a pin on disc configuration under high pressure and velocity conditions confirmed very low μ and specific wear rates (around 0.04–0.08 and 2–8 × 10−16 m3 (Nm) respectively for these composites. Slight deterioration in performance due to particles was analyzed based on the degradation chemistry of boric acid at high temperature. The test results were discussed by considering the surface properties, i.e., material removal and film transfer formation. Scanning electron microscopy, energy dispersive x-ray analysis and Raman spectroscopy on worn surfaces was performed to understand wear mechanisms.

Static and fatigue behaviors of short glass fiber–reinforced polypropylene composites aged in a wet environment

In this paper, a new experimental study of the bending static and fatigue behaviors of a composite material reinforced with 40% by mass of short glass fibers (type E) and polypropylene matrix is presented. The composite material is obtained in the form of plates by an injection process, which inevitably affects the distribution of the fibers and therefore the behavior of the material studied. To do this, several techniques are implemented on specimens by cutting them in transverse and longitudinal directions. The effect of aging in distilled water at 40℃ on the mechanical characteristics is studied under static and fatigue loading conditions. The static tests, three-point flexure up to failure, allow us to choose the levels of stress for the fatigue tests. The endurance curves as a function of the number of cycles are plotted by adapting the end-of-test criteria N5, N10, and N20, which represent a rigidity drop of 5%, 10%, and 20%, respectively. An interpretation of the Wöhler curve equations defined for the end-of-test criteria allows defining the kinetics of material damage. The results highlighted the influence of distilled water on the mechanical behavior and the lifetime of the material. We also perform macroscopic observations of fracture and microscopic facies in order to identify the damage mechanisms of the composite material.

Fracture behaviour of MOD restorations reinforced by various fibre-reinforced techniques – An in vitro study

PurposeThe aim was to evaluate the fracture resistance of various direct restorative techniques utilizing different fibre-reinforced materials for restoring deep class II. MOD cavities in molar teeth. Material and methodsTwo hundred forty intact mandibular third molars were randomly divided into twelve groups (n = 20). Except for the control group (G12), deep mesio-occluso-distal (MOD) cavities were prepared all other groups. After adhesive treatment and rebuilding the missing interproximal walls with composite, the specimen were restored with different fibres and a final occlusal layer of composite as follows: composite only (G1), short fibre-reinforced composite (SFRC) (G2), glass fibre net (GFN) on the base of the cavity bucco-lingually (BL) and SFRC (G3), SFRC and GFN on top of it BL (G4), SFRC and occlusal splinting with GFN (G5), GFN circumferentially and SFRC (G6), polyethylene fibres (PF) on the base of the cavity BL and composite (G7), composite and PF on top of it BL (G8), composite and occlusal splinting with PF (G9), PF circumferentially and composite (G10), transcoronal splinting with PF (G11). Fracture-resistance for the restored teeth were tested using universal-testing machine. Fracture thresholds and fracture patterns were measured and evaluated. ResultsThe transcoronal splinting (G11) yielded the highest fracture resistance among the restored groups. Groups 1, 3 and 4 showed significantly lower fracture resistance values compared to intact teeth. ConclusionIncorporating polyethylene or a combination of short and bidirectional glass fibres in certain positions in direct restorations seems to be able to restore the fracture resistance of sound molar teeth.

Fabrication and Investigation on Impact, Hardness and Water Absorption Properties of Short Sisal and Glass fibre Reinforced Hybrid Thermoplastic Composites

Fabrication and Investigation on Impact, Hardness and Water Absorption Properties of Short Sisal and Glass fibre Reinforced Hybrid Thermoplastic Composites

Fabrication and Investigation on Tensile and Flexural Properties of Short Sisal and Glass fibre Reinforced Hybrid Thermoplastic Composites

Fabrication and Investigation on Tensile and Flexural Properties of Short Sisal and Glass fibre Reinforced Hybrid Thermoplastic Composites

Improving fracture toughness of epoxy resin composites by magnetic particles modified short glass fiber

In this paper, magnetic nanoparticles were loaded on the surface of short glass fibers by solvent thermal method to prepare magnetic short glass fibers (MSGF) that has orientation response to a weak magnetic field (0.12T), and further MSGF/epoxy resin (EP) composites were prepared. Scanning electron microscope, X-ray diffractometer, infrared spectroscopy and vibration sample magnetometer were used to characterize the samples before and after loading magnetic nanoparticles on the surface of SCF. The effects of MSGF particle content and magnetic field on the fracture toughness of MSGF/EP composites and the toughening mechanism were investigated. The results show that γ-Fe2O3 nanoparticles surface loaded MSGF are successfully achieved using solvothermal synthesis method under the 240 °C with ferric acetylacetonate as iron source and ethanol as solvent. With the optimum MSGF content of 3wt%, when MSGF are oriented along the direction perpendicular to the crack growth under magnetic field, compared to that of pure epoxy resin, the fracture toughness Kic and Gic of the composite materials with magnetic orientation are increased by 54.4% and 138.5%, respectively, and increased by 20% and 43.9% than that of MSGF/EP composites without magnetic orientation, respectively. The main mechanisms of toughening epoxy resin by MSGF include debonding, pulling-out, bridging and deflecting crack.

Short phosphate glass fiber - PLLA composite to promote bone mineralization.

The clinical application of composites seeks to exploit the mechanical and chemical properties of materials which make up the composite, and in researching polymer composites for biomedical applications the aim is usually to enhance the bioactivity of the polymer, while maintaining the mechanical properties. To that end, in this study medical grade Poly(L-lactic) acid (PLLA) has been reinforced with short phosphate-based glass fibers (PGF). The materials were initially mixed by melting PLLA granules with the short fibers, before being extruded to form a homogenous filament, which was pelletized and used as feedstock for compression moulding. As made the composite materials had a bending strength of 51 MPa ± 5, and over the course of eight weeks in PBS the average strength of the composite material was in the range 20-50 MPa. Human mesenchymal stromal cells were cultured on the surfaces of scaffolds, and the metabolic activity, alkaline phosphatase production and mineralization monitored over a three week period. The short fiber filler made no significant difference to cell proliferation or differentiation, but had a clear and immediate osteoinductive effect, promoting mineralization by cells at the material surface. It is concluded that the PLLA/PGF composite material offers a material with both the mechanical and biological properties for potential application to bone implants and fixation, particularly where an osteoinductive effect would be valuable.

Effect of continuous elongational flow on structure and properties of short glass fiber reinforced polyamide 6 composites

Abstract Short glass fiber (SGF) reinforced polyamide 6 (PA6) composite is an important thermoplastic engineering plastic with excellent properties such as high toughness, high strength, self-lubrication and corrosion resistance. However, due to the characteristics of difficult to disperse and easy to break of the fibers during processing, the application range of the PA6/SGF composite is limited. An innovative twin-eccentric rotor extruder (TERE), which can generate continuous elongation flow, is applied to fabricate the PA6/SGF composites in different fiber content and rotor speed. The fiber length remains good and the fibers are well dispersed in the polymer matrix so that the residual fibers after burn-off form a network interlock structure. That is, the TERE based on continuous elongational flow not only disperses the glass fibers effectively, but also reduces the fiber breakage. Under the action of elongation flow field, the fiber agglomerates undergo a periodic convergence-divergience effect, which forces the fiber agglomerates to separate from each other and disperse homogeneously in the polymer matrix. Interestingly, the charpy impact strength of the composites prepared by the TERE is about double that prepared by the twin-screw extruder (TSE) at each fiber content, which can be attributed to the more efficient fiber dispersion and longer fiber retention length. The thermal oxygen aging property, fatigue property, and creep property analysis also indicate that the TERE has a better dispersion effect than the TSE, and the fibers retain a longer length in the PA6 matrix, thereby providing more excellent service properties.

Validation of micromechanics models including imperfect interfaces for short fiber thermoplastic composites

Micromechanics models proposed by Nairn et al. and Hashin, which can treat imperfect bonded interfaces between fibers and polymer matrix, are evaluated for use in predicting the equivalent stiffness of a short fiber reinforced thermoplastic composite. Treatment of the imperfect interfaces is fundamentally important to address differences of interface connections that affect the mechanical properties of the composite. We first compare the Nairn–Hashin (NH) models with the Mori–Tanaka (MT) model under the condition of a perfect interface. Elastic moduli calculated from the NH models almost agree with that from the MT model. The NH models are then evaluated using elastic moduli measured for randomly fiber-oriented films of short glass fiber reinforced polypropylene. By considering the imperfect interface parameters estimated from pull-out tests of a single glass fiber embedded in a polypropylene matrix, the NH models predict the measured elastic moduli.

Effect of tensile rates on thermal and mechanical properties of porous PTFE composites

ABSTRACTTo achieve polymer‐matrix composites for sealing materials with thermostability and toughness, PTFE composites filled with short glass fibers (SGFs) were hyperthermal stretched to prepare a substrate material with high thermal stability and porosity. The effects of various tensile rates on the thermal and mechanical properties and morphologies were investigated. The results revealed that the thermal stability could be improved slightly and the thermal expansion coefficient of composites increased by the tensile rate. Through observing the morphologies, tensile process produced cavities and the increased tensile rate had negligible effects on porosity, which also could be proved by density test. From mechanical properties analysis, stretched composites exhibited that the tensile strength increases first and then decreases with the increased tensile rate. Although the variation tendency of Young's modulus is similar to that of tensile strength, which is smaller than that of unstretched composite. When the tensile rate reached 50 mm·min−1, the tensile strength and Young's modulus of the stretched composites increased by 65 and 9% to maximum, respectively. Meanwhile, elongation at break and shore hardness decreased. The thermal and mechanical properties improvement could be ascribed to the strain‐induced crystallization and crystal alignment. In addition, the interplanar spacing and grain size were inversely proportional to the tensile rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48175.

Influence of screw configuration and processing temperature on the properties of short glass fiber reinforced polypropylene composites

Short glass fiber reinforced polymers are used in many different applications due to their good property profiles. These properties are directly correlated with the fiber length present in the final composite, which can be influenced through the process. Therefore, the aim of this work was to investigate the influence of processing temperature and screw configuration in compounding on the properties of glass fiber reinforced polypropylene. On the one hand, the barrel temperature was varied between 180°C and 260°C and, on the other hand, four different screw configurations were applied using a standard temperature profile. Specimens were produced by injection molding, which were tested via mechanical characterization, density, and fiber length measurements as well as morphology through microscopical analysis. We found, that with higher barrel temperatures and screw configurations bringing lower shear into the melt the glass fiber length is preserved better, thus resulting in improved composite properties. Also the interfacial interaction is not influenced within the investigated parameters, as was checked via the application of a micromechanical model in composite strength. POLYM. ENG. SCI., 59:1552–1559 2019. © 2019 Society of Plastics Engineers

Exploring the tribo-potential of nano and micron-sized particles of potassium titanate in PAEK based composite

Structural and mechanical integrity, as well as friction and wear performance of a composite designed for tribological application (hereafter called as tribo-composite) depends on a precise selection and potent combination of fillers, fibers, and polymer matrix along with right processing technique. Modern day research is primarily focused on exploring the suitability and potential of new ingredients, which are better than the conventional ones, in enhancing the friction and wear performance of a tribo-composite. In-depth laboratory scale study on the tribo-performance evaluation of these ingredients is a key to explore their potential and use at an industrial level. Particles of potassium titanate (KT) is one of such ingredients which helps in reducing wear of friction materials. However, its role in influencing the wear performance of anti-friction materials is still unexplored. In the present work, the potential of KT particles (10 wt%) in two sizes (micron and a combination of micrometer and nanometer, 7 + 3 wt%) has been evaluated. In all, three tribo-composites based on two fixed ingredients viz. polyaryletherketone (PAEK) and short glass fibers (GF-30 wt%) were developed. The first composite contained 10 wt% graphite, while the other two composites contained additional 10 wt% KT particles. It was observed that KT particles acted as a solid lubricant despite not having a layer-lattice structure. Tribo-composites with nanoparticles of KT as a filler proved more effective at severe sliding conditions (PVlimit 168 MPa m s−1) compared to that filled with micron-sized particles (PVlimit 112 MPa m s−1 respectively). Based on this study, it was concluded that KT proved as a filler having the potential to enhance the tribo-performance of PAEK based composites and nano-sized particles proved more efficient compared to the micro-sized one.

Optimization of graphite contents in PAEK composites for best combination of performance properties

Graphite is one of the most widely used solid lubricants in both, anti-friction and friction materials. The influence of particles in the composite mainly depends on its size, amount, its combination with fibers and other fillers etc. No efforts were done to optimize the amount of graphite to achieve very low friction and wear. A series of Polyaryl ether ketone (PAEK) composites with GF (short glass fibers) and increasing amount of graphite particles (10, 15, 20 and 25 wt %) were developed and characterized for various properties such as physical, mechanical, thermal along with adhesive wear performance in severe operating conditions (high pressure and velocity (PV)). Inclusion of graphite led to deterioration in strength and modulus but increase in thermal conductivity. The composites showed very low μ (friction coefficient) in the range of 0.04 and K0 (specific wear rate) (∼2 × 10−16 m3/Nm). Composite with 15 wt % graphite proved to be significantly superior by showing highest PVlimit value (154 MPa m/s) and very low μ (0.04) and K0 (1.91 × 10−16 m3/Nm). The typical inferences were supported by various techniques such as Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), 3D profilometer, Raman spectroscopy on the worn surfaces.

Improved interlaminar shear strength of glass fiber/epoxy composites by graphene oxide modified short glass fiber

Improving the interlaminar shear strength (ILSS) of composites is vital for the application of laminated composites. In this work, graphene oxide (GO) modified short glass fibers (GO-modified SGFs) was employed to intercalate into glass fiber/epoxy (GF/EP) composites to improve their ILSS. The effects of GO-modified SGFs and SGFs on the ILSS of composites were compared. The GF/EP composites were prepared by compression molding. The results showed that the ILSS of GF/EP composites increased by 12.5% and 18.4% after intercalation of SGFs and GO-modified SGFs, respectively. GO significantly increased the surface roughness of SGFs, and improved the interfacial adhesion between SGFs and EP.

Effect of Nanographite Type on Structure and Mechanical Properties of Hybrid Composites of Poly(ethylene terephthalate) Filled with Short Glass Fibers and Nanographite

Abstract—The paper presents the results of comparative studies of the structure and rheological and strength properties of poly(ethylene terephthalate) (PET) filled with hybrid micro- and nanofillers—short glass fibers (GF) and nanographite (nG) of two types—expanded graphite (EG), prepared by hydrolysis of sodium-intercalated graphite, and thermally expanded graphite (TEG), prepared by thermal shock treatment of sulfuric acid intercalated graphite in air. The GF concentration varied within 15–60 wt %, and that of nG, from 0.4 to 3 wt %. The composites were produced by reactive compounding using a corotating twin-screw extruder (screw diameter 35 mm, L/D = 40). It is established that the nG preparation method strongly influences the structure and properties of the composites. EG, unlike TEG, displays improved dispersibility in the polymer, helps to increase the proportion of GF with an average length exceeding the critical length, and reduces PET degradation, which increases the strength characteristics of PET/GF/EG hybrid composites in comparison to PET/GF/TEG at a high GF content of 45–60 wt %. The hybrid composites also demonstrate accelerated PET crystallization and a synergetic increase in the elasticity modulus.

Damage Identification in Various Types of Composite Plates Using Guided Waves Excited by a Piezoelectric Transducer and Measured by a Laser Vibrometer.

Composite materials are widely used in the industry, and the interest of this material is growing rapidly, due to its light weight, strength and various other desired mechanical properties. However, composite materials are prone to production defects and other defects originated during exploitation, which may jeopardize the safety of such a structure. Thus, non-destructive evaluation methods that are material-independent and suitable for a wide range of defects identification are needed. In this paper, a technique for damage characterization in composite plates is proposed. In the presented non-destructive testing method, guided waves are excited by a piezoelectric transducer, attached to tested specimens, and measured by a scanning laser Doppler vibrometer in a dense grid of points. By means of signal processing, irregularities in wavefield images caused by any material defects are extracted and used for damage characterization. The effectiveness of the proposed technique is validated on four different composite panels: Carbon fiber-reinforced polymer, glass fiber-reinforced polymer, composite reinforced by randomly-oriented short glass fibers and aluminum-honeycomb core sandwich composite. Obtained results confirm its versatility and efficacy in damage characterization in various types of composite plates.