3D printing has attracted a lot of attention over the past three decades. In particular the Fuse Filament Fabrication (FFF) technique, general materials require low shrinkage during cooling and viscous behavior during extrusion through a nozzle. Semi-crystalline thermoplastics and their composites are of the relevance of new materials for 3D printing. However, the crystalline structures, for instance, may have a favorable impact on their printability. In this study, polypropylene/organoclay nanocomposites were prepared by melt extrusion using a twin-screw extruder. The effects of organoclay on the thermal, rheological and morphological properties were studied to evaluate the possibility of using the polypropylene/organoclay nanocomposites as the FFF 3D printing feedstock. Dioctadecyl dimethyl ammonium chloride (D18) was successfully used to modify the clay surfaces, providing a good dispersity and wettability of organoclay in the PP matrix.
Kenaf cellulose fiber was extracted from kenaf locally grown in Thailand as a potential local renewable resource for the cellulose fiber. In this study, the biodegradable polymer composites, poly(butylene succinate) (PBS)/cellulose fiber composites with different types of cellulose were prepared. The kenaf fiber treated with hydrochloric acid (KTH), extracted cellulose fiber (EC), and commercial cellulose fiber (CC) were selected as alternative renewable fillers in the PBS (the biodegradable polymer). Regarding the fiber characteristics, the aspect ratio of the EC (11.5) was found to be higher than that of the CC (6.1). In a similar manner, the EC contained 65.9% crystallinity, which was higher than that of the CC (37.0%) and the KTH (58.9%). Moreover, the EC exhibited higher thermal stability (Td[Max] = 362.9°C) than the CC (Td[Max] = 302.0°C) and the KTH (Td[Max] = 353.8°C). For PBS/cellulose fiber composites, the rheological, tensile, and thermal properties were studied. The rheology results revealed that the addition of the fiber changed the PBS microstructure. The EC fiber dispersion in the PBS seemed to be better than the others; however, the KTH fiber dispersion was poor. The addition of the fiber raised the elastic moduli of the composites by 5‐26%; however, it reduced the tensile strengths (by 14‐53%) and the decomposition temperatures (by 1‐2%). Furthermore, the addition of the fiber slightly affected the crystallization temperatures and melting temperatures of the composites. The yellowness and whiteness of the composites were marginally reduced. The composite with the EC fiber showed a significant improvement in the elastic modulus as compared to the composite with the CC fiber, while the tensile strength and the strain at maximum stress were comparable. Thus, according to the rheological, thermal, and tensile properties of the composites, the EC fiber showed a possibility of using as an alternative reinforcement material from a local renewable resource.
ABSTRACT:The aim of this research was to investigate the behaviors of epoxy resin blended with epoxidized natural rubber (ENR). ENRs were prepared via in situ epoxidation method so that the obtained ENRs contained epoxide groups 25, 40, 50, 60, 70, and 80 mol %. The amounts of ENRs in the blends were 2, 5, 7, and 10 parts per hundred of epoxy resin (phr). From the results, it was found that the impact strength of epoxy resin can be improved by blending with ENRs. Tensile strength and Young's modulus were found to be decreased with an increasing amount of epoxide groups in ENR and also with an increasing amount of ENR in the blends. Meanwhile, percent elongation at break slightly increased when ENR content was not over 5 phr. In addition, flexural strength and flexural modulus of the blends were mostly lower than the epoxy resin. Scanning electron microscope micrograph of fracture surface suggested that the toughening of epoxy resin was induced by the presence of ENR globular nodules attached to the epoxy matrix. TGA and DSC analysis revealed that thermal decomposition temperature and glass transition temperature of the samples were slightly different.
This study fabricated polylactic acid (PLA)/kenaf cellulose ber biocomposite laments via meltextrusion process. Kenaf cellulose bers (KF) were chemically extracted from locally grown kenaf plants and used as reinforcement. Moreover, the KF was then treated with tetraethyl orthosilicate (TEOS), socalled KFs, to improve the compatibility between the bers and PLA matrix. Also, the plasticizers (polyethylene glycol) were incorporated to enhance the owability and processability of the biocomposites. The melt viscosities of the biocomposites increased as the solid KF and KFs were loaded. However, they were signi cantly decreased with the addition of plasticizers. The combined use of the plasticizers and TEOS treatment improved tensile strength, Young's modulus and elongation of the biocomposites compared to the neat PLA. The obtained PLA/KFs biocomposite materials are proved to be a mechanical-improved material, which offers the opportunity for customized and rapid prototyping of biocomposite products.
Herein, carboxymethyl cellulose nanocomposite films incorporated with graphene oxide and reduced graphene oxide were successfully prepared by a novel approach for the first time, and their alternative properties compared with the original carboxymethyl cellulose films were disclosed.
For carboxymethyl cellulose/reduced graphene oxide film preparation, sodium borohydride was used as a chemical reducing agent. The carboxymethyl cellulose films were prepared by using a solvent casting method, followed by an acid treatment to decrease the water solubility (98%) while enhancing
the tensile strength (15%) and elastic modulus (32%) of the original carboxymethyl cellulose films. Overall, the addition of 1.0 wt% graphene oxide and reduced graphene oxide to the treated films increased the water solubility, water absorption, tensile properties and electrical conductivity.
Particularly, the electrical conductivity was predominantly enhanced 1.3×105 times with graphene oxide and 2.2×105 times with reduced graphene oxide compared to the treated carboxymethyl cellulose film. The electrical conductivity of the treated carboxymethyl
cellulose film also increased with an increase in reduced graphene oxide. The effects of reduced graphene oxide on the water solubility, water absorption, tensile properties and electrical conductivity of the treated carboxymethyl cellulose film were more pronounced than those of graphene
oxide, especially for the electrical conductivity. In conclusion, graphene oxide and reduced graphene oxide might be alternative nanofillers for improving the carboxymethyl cellulose film properties. For the future applications, carboxymethyl cellulose/reduced graphene oxide films prepared
by using this approach might be employed as alternative materials in electronic packagings and electrochemical biosensors.
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