The effects of surface treated carbon fibers and CaCO<Subscript>3</Subscript> nanoparticles inclusions on the mechanical performances of PA6/ABS-based composites

The mechanical and morphological characteristics of PA6/ABS (60/40)-based hybrid composite containing HNO₃-treated short carbon fibers (HSCF) and CaCO₃ nanoparticles have been experimentally studied. A counter-rotating twin-screw extruder and an injection molding machine were employed to produce different samples containing 10 wt % of HSCF and 0, 2, 5 and 8 wt % of CaCO₃ nanoparticles. The SEM observations indicated high-quality adhesion between HNO₃-surface treated carbon fibers and PA6/ABS polymer matrix. In addition, the morphological studies showed that the inclusion of CaCO₃ nanoparticles caused a significant effect on the ABS particle dispersion in PA6/ABS matrix. The mechanical properties assessments revealed that the incorporation of 10 wt % HSCF into the PA6/ABS can significantly improve tensile strength (82%), tensile modulus (107%), flexural strength (98%), flexural modulus (104%) and impact resistance (24%). The inclusion of CaCO₃ nanoparticles, in the presence of 10 wt % HSCF, led to the noticeable improvements of tensile strength (128% for 2 wt % CaCO₃), tensile modulus (199% for 5 wt % CaCO₃), flexural strength (146% for 5 wt % CaCO₃), flexural modulus (204% for 5 wt % CaCO₃) and impact resistance (46% for 2 wt % CaCO₃). The surface treatment of carbon fibers, dispersion conditions of nanoparticles and ABS phase in polymeric matrix were found to be the major important factors affecting the mechanical properties.     

Synergic improvement of DGEBA/CSP/HBP composite on mechanical behavior

Hyperbranched polymer with amino end groups (HBPA) and core-shell particle (CSP, which is fabricated through grafting HBPA onto the surface of silica nanoparticle) were incorporated into an epoxy matrix to fabricate a high performance composite. The effects of CSPs contents on the mechanical properties of composites were studied, discussing the results from tensile, flexural, and impact tests. The composites revealed noticeable improvements in tensile strength, elongation, flexural strength and impact strength in comparison to the neat epoxy or epoxy/HBPA system. The glass transition temperature (T_g) was also improved by the addition of CSP. Field emission scanning electron micrograph (FESEM) indicated that HBPA could favorable improve the compatibility between CSP and epoxy matrix. And the toughening mechanisms were the synergic effect of shearing deformation, phase separation, crack propagation, crack deflection, and crack pinning.     

Glass fiber reinforced bismaleimide/epoxy BaTiO3 nano composites for high voltage applications

BaTiO₃/bismaleimide/epoxy/glass fiber reinforced composites were prepared using E-glass fiber (E-GF) and silane coated E-glass fiber (SC-EGF) separately as reinforcement. BaTiO₃ nanoparticles were prepared by hydrothermal method. Results show that the addition of BaTiO₃ nanoparticles has significant effects on the mechanical and dielectric properties of the composite. Both E-GF and SC-EGF reinforced BaTiO₃/bismaleimide/epoxy composites with 2 wt percentages of BaTiO₃ nanoparticles showed improved tensile strength, flexural strength and dielectric constant and those with 3% showed high dielectric strength indicating this composition is more adaptable for high voltage insulating applications. Dielectric constants and dielectric loss of the fabricated nanocomposites have been obtained at higher frequencies (in GHz) by using Vector Network Analyser at room temperature and was found to be highest for the BMI-Epoxy nanocomposite with 1% weight nanofiller.     

The synthesis and characterization of polyorganosiloxane nanoparticles from 3-mercaptopropyltrimethoxysilane for preparation of nanocomposite films via photoinitiated thiol-ene polymerization

This article describes the synthesis of modified silica nanoparticles (SiO₂-MPTMS) via the condensation reaction carried out between silanol moieties of silica nanoparticles and the trialkoxy silyl groups of (3-mercaptopropyl) trimethoxysilane (MPTMS). Then, SiO₂-MPTMS nanoparticles in certain amounts (0.5 wt %, 1 wt %, 2.5 wt % and 5 wt %) were incorporated into thiol-ene resins consisting of bisphenol A glycerolate dimethacrylate and trimethylolpropane tris(3-mercaptopropionate) to prepare nanocomposite films via the photoinitiated thiol-ene polymerization in presence of 2,2-Dimethoxy-2-phenylacetophenone 99% as a photoinitiator. Fourier transform infrared spectroscopy, dynamic light scattering, scanning transmission electron microscopy, thermal gravimetric analyzer, and X-ray photoelectron spectrometer were employed to characterize SiO₂-MPTMS nanoparticles. It was revealed that the nanosilica surface was successfully grafted by MPTMS with the grafting ratio of 22.9%. Properties of the nanocomposite films such as decomposition temperature, thermal glass transition temperature, tensile strength, hardness, and particle distribution were investigated and the results were compared with each other and neat film. The addition of MPTMS-modified silica particles did not improve the thermal stability of the films. In scanning electron microscopy study, it was seen that 2.5 wt % of these nanoparticles used as additives were about 200 nm in size and dispersed homogeneously in the polymer matrix. The increase in tensile strength of nanocomposite films compared to the neat film was measured as 77.3% maximum.     

Filled grades of chemically modified poly(ethylene terephthalate)

Structural phases and blends properties of glass fiber filled reactive PET/R‐PE blends (85/15 and 75/25 wt/wt) were studied in a chemical modification involving reactive extrusion with a ricinyl‐2‐oxazoline maleate. The present method offers compatible heterogenous blends with the structure stabilized at microphase level and with advantageous macroscopic properties, viz., impact and tensile resistance, processability. The most important effects of glass fiber reinforcement are increases in strength (tensile and flexural) and stiffness (flexural modulus).     

The potential use of electrospun polylactic acid nanofibers as alternative reinforcements in an epoxy composite system

This pilot study elaborates the development of novel epoxy/electrospun polylactic acid (PLA) nanofiber composites at the fiber contents of 3, 5, and 10 wt % to evaluate their mechanical and thermal properties using flexural tests and differential scanning calorimetry (DSC). The flexural moduli of composites increase remarkably by 50.8 and 24.0% for 5 and 10 wt % fiber contents, respectively, relative to that of neat epoxy. Furthermore, a similar trend is also shown for corresponding flexural strengths being enhanced by 31.6 and 4.8%. Fractured surface morphology with scanning electron microscopy (SEM) confirms a full permeation of cured epoxy matrix into nanofiber structures and existence of nondestructive fibrous networks inside large void cavities. The glass transition temperature (T_g) of composites increases up to 54–60 °C due to embedded electrospun nanofibers compared to 50 °C for that of epoxy, indicating that fibrous networks may further restrict the intermolecular mobility of matrix in thermal effects. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 618–623     

Mechanical and thermal properties of poly-ether ether ketone reinforced with CaCO3

CaCO₃/PEEK (poly-ether ether ketone) composites were prepared on a twin-screw extruder with different mass ratio of CaCO₃/PEEK from 0% to 30%. Four types of particles were used as filler in PEEK matrix. The influence of surface treatment with sulfonated PEEK (SPEEK) of the particles on the mechanical and thermal properties of the composites was studied. The experiments included tensile tests, flexural tests, notched Izod impact tests, TGA, DSC and SEM. The modulus and yield stress of the composites increased with CaCO₃ particles loadings. This increase was attributed to the bonding between the particles and the PEEK matrix, as can be proved by the SEM pictures of tensile fracture surface of the composites. The impact strength of the composites was modified by the SPEEK coated on the CaCO₃ particle surface. DSC experiments showed that the particle content and surface properties influenced the glass transition temperature (T_g) and melting temperature (T_m) of the composites. The T_g increased with the content of fillers while T_m decreased. In this study the fillers treated were found to give better combination properties, which indicated that SPEEK played a constructive role in the CaCO₃/PEEK composites.     

CaCO3/PEEK复合体系的力学行为和热行为研究

以聚醚醚酮和碳酸钙复合体系为研究对象,考察了偶联剂和填料添加量对复合材料力学行为和热行为的影响.发现磺化聚醚醚酮作为偶联剂能有效地改善材料的力学性能,提高基体树脂的玻璃化转变温度,降低基体树脂的熔点,有助于改善聚醚醚酮的加工条件     

Properties and morphologies of UV‐cured epoxy acrylate blend films containing hyperbranched polyurethane acrylate/hyperbranched polyester

The properties and morphologies of UV‐cured epoxy acrylate (EB600) blend films containing hyperbranched polyurethane acrylate (HUA)/hyperbranched polyester (HPE) were investigated. A small amount of HUA added to EB600 improved both the tensile strength and elongation at break without damaging its storage modulus (E′). The highest tensile strength of 31.9 MPa and an elongation at break around two times that of cured pure EB600 were obtained for the EB600‐based film blended with 10% HUA. Its log E′ (MPa) value was measured to be 9.48, that is, about 98% of that of the cured EB600 film. The impact strength and critical stress intensity factor (K_1c) of the blends were investigated. A 10 wt % HUA content led to a K_1c value 1.75 times that of the neat EB600 resin, and the impact strength of the EB600/HPE blends increased from 0.84 to 0.95 kJ m^?1 with only 5 wt % HPE addition. The toughening effects of HUA and HPE on EB600 were demonstrated by scanning electron microscopy photographs of the fracture surfaces of films. Moreover, for the toughening mechanism of HPE to EB600, it was suggested that the HPE particles, as a second phase in the cured EB600 film, were deformed in a cold drawing, which was caused by the difference between the elastic moduli of HPE and EB600. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3159–3170, 2005     

Enhanced surface free energy of UHMWPE fibers and its interfacial adhesion behavior to PI resins

Mechanical properties of composites made up of ultra‐high‐molecular‐weight polyethylene (UHMWPE) fiber, polyimide (PI), and TiO₂ particles were investigated. The hybrid composite of 20 vol% of UHMWPE fiber with TiO₂ showed tensile strength greater than UHMWPE fiber/PI composite. A positive hybrid effect in tensile strength is obtained. It is observed that addition of small amount of TiO₂ to UHMWPE fiber/PI increased the tensile strength of the composite by 28%. With increase in TiO₂ loading to 1 to 3 vol%, the impact strength of the hybrid composite is increased from 55 KJ/m² to 69 KJ/m². This maximum value is more than one and a half times greater than the impact strength of neat UHMWPE fiber/PI composite.     

Effect of nitrile butadiene rubber/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/YSZ fillers for PMMA denture base on the thermal and mechanical properties

This study is to investigate the effect of nitrile butadiene rubber (NBR as impact modifier) together with Al₂O₃/YSZ (toughening) as filler loading in PMMA denture base on the thermal and mechanical properties. PMMA matrix without fillers was mixed between PMMA powder and 0.5 mass% of BPO, and it is used as the control group. The liquid components consist of 90% of methyl methacrylate (MMA) and 10% as the cross-linking agent of ethylene glycol dimethacrylate. The denture base composites were fabricated by incorporating PMMA powder and BPO and fixed at 7.5 mass% NBR particles and filler loading (1, 3, 5, 7 and 10 mass%) of Al₂O₃/YSZ mixture filler by (1:1 ratio) as the powder components. The ceramic fillers were treated with silane (γ-MPS) and the powder/liquid ratio (P/L) according to dental laboratory practice. The TGA data obtained show that the PMMA composites have better thermal stability compared to unreinforced PMMA, while DSC curves show slightly similar Tg values. DSC results also indicated the presence of unreacted monomer content for both reinforced and unreinforced PMMA composites. The fracture toughness, Vickers hardness and flexural modulus values were statistically increased compared to the unreinforced PMMA matrix (P?<?0.05).     

Effect of fiber length and composition on mechanical properties of carbon fiber‐reinforced polybenzoxazine

The mechanical strength and modulus of chopped carbon fiber (CF)‐reinforced polybenzoxazine composites were investigated by changing the length of CFs. Tensile, compressive, and flexural properties were investigated. The void content was found to be higher for the short fiber composites. With increase in fiber length, tensile strength increased and optimized at around 17 mm fiber length whereas compressive strength exhibited a continuous diminution. The flexural strength too increased with fiber length and optimized at around 17 mm fiber length. The increase in strength of composites with fiber length is attributed to the enhancement in effective contact area of fibers with the matrix. The experimental results showed that there was about 350% increase in flexural strength and 470% increase in tensile strength of the composites with respect to the neat polybenzoxazine, while, compressive properties were adversely affected. The composites exhibited an optimum increase of about 800% in flexural modulus and 200% in tensile modulus. Enhancing the fiber length, leads to fiber entanglement in the composites, resulted in increased plastic deformation at higher strain. Multiple branch matrix shear, debonded fibers and voids were the failures visualized in the microscopic analyses. Defibrillation has been exhibited by all composites irrespective of fiber length. Fiber debonding and breaking were associated with short fibers whereas clustering and defibrillation were the major failure modes in long fiber composites. Increasing fiber loading improved the tensile and flexural properties until 50–60 wt% of fiber whereas the compressive property consistently decreased on fiber loading. Copyright © 2008 John Wiley & Sons, Ltd.     

Mechanical properties of plasma‐treated carbon fiber reinforced PTFE composites with CNT

This paper is concerned with the effects of the plasma surface treatment and the addition of CNT on the mechanical properties of carbon fiber/polytetrafluoroethylene (PTFE) composite. The tensile and flexural strength of composites containing CNT and plasma‐treated carbon fibers improved. The flexural strength first decreases with respect to the CF content. The flexural strength increases to 179 MPa for the plasma‐treated composite as compared with 167 MPa for the neat carbon fiber composites. The overall improvement is thus nearly 8%.     

The investigation of the friction and wear properties of surface‐treated carbon fiber/SiO2 reinforced PMMA composites

The mechanical properties of SiO₂ filler particles on carbon fibers have been under discussion for several decades; the diverse models, and the properties of the components relevant to retention, are critically reviewed in the first part of this study. In addition, to gain an insight into some possible combined effect of the carbon fiber/poly(methyl methacrylate) (CF/PMMA), interfacial adhesion strength and the tensile properties and dielectric strength of the hybrid composites were studied. Simple modified rules of mixtures are used to estimate the fiber efficiency factors for the strength and modulus of the hybrid composites. Except, with the increasing fraction of CFs in PMMA, the weld line area's elongation percent is decreased. Whereas for case of SiO₂, the 10 wt% is the threshold for micro injection molded weld line tensile strength and dielectric strength turning from decrease trend to increase. Same as CF, elongation of micro weld line samples is in general lower than neat PMMA as well, due to the addition of SiO₂ particles.     

Ultrasound technique as a tool for high-rate incorporation of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> in NiCo layers

NiCo–Al₂O₃ composite coatings were prepared by electrodeposition in a sulfamate plating bath containing Al₂O₃ particles to be co-deposited under sonication. For reliable determination of the microstructure, detailed studies on composite cross-sections were carried out by energy-dispersive spectrometer (matrix composition, particle content) and FE-SEM/electron backscattered diffraction data (particle distribution, grain size), accompanied by XRD analyses concerning texture, lattice parameter, grain size, and residual stress. The NiCo matrix with a Co/Co + Ni ratio up to 0.4 is a face-centered cubic solid solution with <100> and <110> fiber textures. The distribution of the particles (size 250 nm) was well-dispersed and enhanced up to 15 wt.% by ultrasound application during plating. Vickers hardness increased up to 50% by dispersion hardening. First-order residual stress in the matrix increased with rising Co content, thus decreasing wear resistance and revealing the complex of composite properties with partially opposite effects.     

Crystallization and melting behavior of PP/nano-CaCO<Subscript>3</Subscript> composites with different interfacial interaction

The effect of different interfacial interaction on the crystallization and melting behavior of PP/nano-CaCO₃ composites was investigated using differential scanning calorimetry, X-ray diffraction and polarized optical microscope. The results indicated that nano-CaCO₃ acted as heterogeneous nuclei for PP crystallization. There existed a synergistic effect of heterogeneous nucleation between nano-CaCO₃ and compatibilizer for PP crystallization, which was proved by increasing the crystallization rate and decreasing the fold surface free energy as well as favoring the formation of β-crystal of PP. However, this synergistic effect was dependent on the interfacial interaction between PP and compatibilizer. The increased miscibility between compatibilizer and PP favored this synergistic effect.     

The β-nucleated ternary composites of polypropylene/nano-CaCO3/short poly(ethylene-terephthalate) fiber

A serial of β-nucleated polypropylene (β-PP)/nano-calcium carbonate (nano-CaCO₃)/ short poly(ethylene-terephthalate) (PET) fiber composites were prepared using extrusion blending. Maleic anhydride grafted PP (PP-g-MA) was used to modify the compatibility. The relationships among components, structure, and properties of the PP composites were studied. The results show that adding nano-CaCO₃ improved the mechanical properties of the materials. Adding PET fiber increased the rigidity and toughness but the tensile strength decreased. PP-g-MA modified the compatibility of the components of the composites. Both PET fiber and nano-CaCO₃ had nucleation effect on the PP crystallization and slightly induced the formation of β crystals. Ternary β-PP/nano-CaCO₃/PET fiber composites contained high β-crystal content, and the compatibilizer exhibited synergy effect with β nucleating agent to further increase the β-crystal content in the blends. Mo’s method could satisfactorily describe the nonisothermal crystallization behavior of ternary composites, whereas Jeziorny and Ozawa methods failed to do the same ideally.     

Nanocomposites of poly(ethylene terephthalate‐co‐ethylene naphthalate) with organoclay

Poly(ethylene terephthalate‐co‐ethylene naphthalate) (PETN)/organoclay was synthesized with the solution intercalation method. Hexadecylamine was used as an organophilic alkylamine in organoclay. Our aim was to clarify the intercalation of PETN chains to hexadecylamine–montmorillonite (C₁₆–MMT) and to improve both the thermal stability and tensile property. We found that the addition of only a small amount of organoclay was enough to improve the thermal stabilities and mechanical properties of PETN/C₁₆–MMT hybrid films. Maximum enhancement in both the ultimate tensile strength and initial modulus for the hybrids was observed in blends containing 4 wt % C₁₆–MMT. Below a 4 wt % clay loading, the clay particles could be highly dispersed in the polymer matrix without a large agglomeration of particles. However, an agglomerated structure did form in the polymer matrix at a 6 wt % clay content. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2581–2588, 2001     

Epoxy nanocomposites co-reinforced by two dimensionally different nanoscale particles

Comprehensive high-performance epoxy nanocomposites were prepared by simultaneous incorporating montmorillonite (MMT) and nanoSiO₂ into epoxy. Mechanical tests and thermal analyses showed that the epoxy/MMT/nanoSiO₂ nanocomposites obtained considerable improvement over basic epoxy in tensile modulus, tensile strength, flexural modulus, flexural strength, notch impact strength, glass transition temperature, and thermal decomposition temperature. X-ray diffraction measurements and transmission electronic microscopy observations revealed that the layered structure of MMT was completely exfoliated into two-dimensional nanoscale mono-platelets. These 2D mono-platelets formed intermingled structure with the zero-dimensional nanoSiO₂ spheres in the nanocomposites. This study suggests that employing the synergistic reinforcement effect of two dimensionally different nanoscale particles is one pathway to success in developing comprehensive high-performance polymer nanocomposites.     

A study of PP/PET composites: Factorial design,mechanical and thermal properties

Due to the economic importance of polypropylene (PP) and polyethylene terephthalate (PET), and the large amount of composites made with PP matrix and recycled PET as reinforcing material; an investigation was performed regarding the mechanical and thermal behavior of PP composites containing recycled polyethylene terephthalate fibers (rPET). Interfacial adhesion between the two materials was achieved by adding a compatibilizer, maleic anhydride grafted polypropylene, PP-g-MA. Mechanical behavior was assessed by tensile, flexural, impact and fatigue tests, and thermal behavior by HDT (Heat Deflection Temperature). Fractured surfaces and fiber were investigated by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. Tensile strength, tensile modulus, flexural strength, flexural modulus and HDT increased after rPET fiber incorporation while strain at break, impact strength and fatigue life decreased. Addition of compatibilizer increased tensile strength, flexural strength and flexural modulus, fatigue life and HDT while tensile modulus, strain at break and impact strength decreased. However, at low fiber content, the impact strength increased, probably due to nucleation effects on PP.