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High‐load bearing bone replacement composite was produced from poly(lactic acid) (PLA), surface modified hydroxyapatite (HA) and glass fiber (GF). Composition dependence and other salient properties of the composites were investigated with respect to the mechanical and dynamic mechanical performance of the composites. Incorporation of modified HA facilitates dispersion, improves bonding, as well as induce heterogeneous nucleation in the PLA matrix. On the other hand, GF greatly influenced the mechanical properties of the composite. The effectiveness coefficient, C, and adhesion factor, A, showed that incorporation of hybrid HA/GF filler helps to improve interfacial interaction due to increased bonding among the components, which produced remarkable enhancement in mechanical performance. For instance, tensile and flexural modulus of the PLA‐HA‐GF composite was raised by 86% and 82%, respectively. In addition, whereas incorporation of HA alone resulted in decreased impact strength (IS) of PLA, the IS of the PLA‐HA‐GF composite improved by 42%. Furthermore, damping of the ternary composite was reduced by 34% whereas the storage modulus is 1273 MPa higher than neat PLA. Therefore, hybrid HA/GF reinforced PLA offers alternative possibility for the fabrication of composites suitable for use in bone replacement and other orthopedic applications requiring high‐load bearing materials. [ABSTRACT FROM AUTHOR]

Glass fiber (GF) and hydroxyl‐functionalized multi‐walled carbon nanotubes (MWCNTs)‐reinforced polyester‐based composites were prepared by solution casting technique. Unsaturated polyester (UPE) was mixed separately with a fixed amount (0.5 wt%) of hydroxyl‐functionalized MWCNTs and GF (5.0 wt%). Multi‐walled carbon nanotubes (MWCNTs) were functionalized with hydroxyl functional group (OH) prior to the fabrication of the composites. The structural properties were evaluated by Fourier transform infrared spectroscopy. The mechanical properties of the composites, like tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were also evaluated. The surface of the samples was observed by the field‐emission electron microscopy. In addition, the thermal stability was assessed by thermogravimetric analysis and differential scanning calorimetry. The dynamic thermal mechanical analysis was also performed to assess the performance of the composites at elevated temperature. A comparative analysis of the composites prepared with GF and hydroxyl‐functionalized MWCNTs was described. Result analysis showed that hydroxyl functional group‐based MWCNTs is more effective for improving the properties of the composites, compared to the others. POLYM. COMPOS., 40:E1235–E1242, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In this study unsaturated polyester resin (UPR) was reinforced with different concentration of pre-dispersed multiwalled carbon nanotube (MWCNT). The rheology, structural analysis, fracture behavior, morphology, and thermal analysis of nanocomposites were carried out as a function of MWCNT content. Shear thinning behavior exhibited distinguishable dispersion quality of 0.3 wt% MWCNT in UPR matrix. Structural analysis reveals that MWCNT enhanced the nucleation of nanocomposites. The crystallinity of nanocomposites was increased by 71% after incorporation of 0.3 wt% MWCNT. Bending strength (BS) and bending modulus (BM) of nanocomposites were increased as well as 0.3 wt% MWCNT exhibited crack shielding in nanocomposites. The glass transition ( Tg) and melting transition ( Tm) of nanocomposites was increased by 6°C and 10°C respectively as compare to neat UPR. Additionally thermal stability of 0.3 wt% MWCNT incorporated nanocomposites was significantly improved as compare to UPR and nanocomposites which contained 0.1 and 0.5 wt% MWCNT. POLYM. COMPOS., 38:E462-E471, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Structural, mechanical, thermal, and electrical properties of low-loaded (0−1.5 wt%), untreated, and treated (with heat and nitric acid) multiwalled carbon nanotubes (MWCNTs)/poly (lactic acid) (PLA) nanocomposites have been studied. Among all synthesized composites, acid-treated 1.0 wt% MWCNTs reinforced PLA shows superior tensile strength and modulus to those shown by other samples. All nanocomposites including the pure PLA exhibit the orthorhombic β-form crystalline structure with low degree of crystallization, as demonstrated by X-ray diffraction study. Differential scanning calorimetry (DSC) of injection molded samples, respectively, reveals an enhancement of PLA crystallinity by 8% and 14% for untreated and treated nanotubes, relating to the observed improvement in mechanical properties. Nanocomposites show double melting behavior when crystallized nonisothermally by DSC, whilst the pure PLA shows single melting character. Thermogravimetric analysis discloses that the MWCNTs-loaded sample degraded faster than PLA. Surface resistivity of the nanocomposites is found to be dropped drastically by a factor of 1013 with a low loading of MWCNTs (1.5 wt%). A detailed discussion and correlation of the observed structures and properties are presented in this study. POLYM. ENG. SCI., 54:317-326, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract: Copper nanoparticles (CuNPs) have been synthesized under chemical reduction and in aqueous medium where polyvinyl alcohol (PVA) played a role as a stabilizer. From Transmission electron microscopy (TEM) images analysis, calculated average size of the synthesized CuNPs was 3.5nm. The synthesized CuNPs were loaded in the oil palm empty fruit bunch (EFB) natural fibers. Surface of the fibers were modified by cationic agent (CA). The existance of hydroxyl group in fibres exhibit negative charge and inhibit the PVA surrounded negatively charged on CuNPs. Several types of composites were developed using hand mixing process by varying the fiber types. The developed composites were formulated using untreated empty fruit bunch fibers (UF) and CuNPs loaded EFB fibers (NF) with commercially available unsaturated polyester resin (UPER). The UF, NF, UPER and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), x-ray diffactometer (XRD), differential scanning calorimetry (DSC), tensile strength test, etc. The results from biodegradation study showed that significant weight loss was not observed for virgin resin (VR) and VR-NF nanocomposite whereas, the VR-UF composite showed ca. 13.3% weight loss at 90 days, reflected to preferential degradation of the natural fibers. [Copyright &y& Elsevier]

Jute fabrics (hessian cloth) reinforced thermo-set composites were prepared by using urethane acrylate oligomer solutions (50–90% by weight) followed by UV radiation. It was found that 70% oligomer-treated jute fabrics performed the best results. The monomer hexanediol diacrylate (HDDA) was used as a coupling agent for jute fabrics and found potential on the performance of the composites. Urea was incorporated with 30% HDDA to monitor its effect on the properties and 1% urea showed the best mechanical properties of the composites. Water uptake and dielectric properties of the composites were also performed. [ABSTRACT FROM PUBLISHER]

The major challenge for natural fiber composites is their inherent poor adhesion between fiber and the matrix, high moisture absorption, and UV degradation. Lignin and hemicelluloses are the major composites of natural fiber which are responsible for UV degradation and moisture absorption, respectively. In this study, the lignocelluloses (oil palm empty fruit bunch) were treated with alkaline peroxide to separate lignin and hemicelluloses. Composites were produced with treated and untreated fibers using up to 45% fiber with polypropylene matrix using twin-screw extruder followed by injection molding. To improve the interfacial bonding, maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the formulation. Properties of composites were evaluated using tensile testing, flexural testing, impact testing, SEM, and FTIR. The tensile, flexural, and impact properties were found to be improved with alkaline peroxide-treated fiber composites compared to untreated fiber composites. Addition of coupling agent (MAPP) also found to provide improved properties of composites. [ABSTRACT FROM AUTHOR]

Degradable phosphate glass fiber is a synthetic fiber and silk is one of the strongest natural fibers. In this study, composites are fabricated from PP reinforced with phosphate glass fiber and silk fiber using compression molding. Tensile testing, flexural testing and impact testing are carried out to evaluate the composites mechanical properties. It has been found that silk fiber composites provided higher tensile strength (46 MPa), bending strength (50 MPa), and impact strength (17 kJ/m2) compared to glass fiber composites which are respectively 39 MPa, 46 MPa, and 8 kJ/m2. Degradation studies are carried out by accelerated weathering as well as by natural weathering. After weathering, the mechanical properties are evaluated and it has been found that phosphate glass fiber/PP composites degrade more rapidly compared to silk/PP composites. [ABSTRACT FROM AUTHOR]

In this study, polyester-kenaf fiber composites were prepared by adding various percentages of kenaf fiber in unsaturated polyester resin and subsequently cross-linked using methyl ethyl ketone peroxide and the accelerator cobalt octanoate. Liquid natural rubber (LNR) (3%) was added as a toughening agent. Kenaf fibers were treated with sodium hydroxide solution to improve the interfacial bonding between the fiber and the matrix. The mechanical properties of the composites were evaluated by impact and flexural testing. Environmental stress cracking resistance (ESCR) of composites in acid and base medium was also studied. Bonding mechanisms were assessed by scanning electron microscope and Fourier transform infrared analysis. It was found that the addition of LNR increased the impact strength and fracture toughness. Alkali fiber treatment was found to provide better impact and flexural strengths to the composites. Measurement of ESCR shows that the composite with acid medium has the fastest diffusion rate, followed by that with base medium, and then without medium. [ABSTRACT FROM AUTHOR]