There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Biocomposites reinforced with natural fibers: 2000–2010

https://cyberleninka.org/article/n/768408.pdf

Mechanical properties of graphene and graphene-based nanocomposites

Natural fibers are getting attention from researchers and academician to utilize in polymer composites due to their ecofriendly nature and sustainability. The aim of this review article is to provide a comprehensive review of the foremost appropriate as well as widely used natural fiber reinforced polymer composites (NFPCs) and their applications. In addition, it presents summary of various surface treatments applied to natural fibers and their effect on NFPCs properties. The properties of NFPCs vary with fiber type and fiber source as well as fiber structure. The effects of various chemical treatments on the mechanical and thermal properties of natural fibers reinforcements thermosetting and thermoplastics composites were studied. A number of drawbacks of NFPCs like higher water absorption, inferior fire resistance, and lower mechanical properties limited its applications. Impacts of chemical treatment on the water absorption, tribology, viscoelastic behavior, relaxation behavior, energy absorption flames retardancy, and biodegradability properties of NFPCs were also highlighted. The applications of NFPCs in automobile and construction industry and other applications are demonstrated. It concluded that chemical treatment of the natural fiber improved adhesion between the fiber surface and the polymer matrix which ultimately enhanced physicomechanical and thermochemical properties of the NFPCs.

/pdf/a-review-on-natural-fiber-reinforced-polymer-composite-and-24eoqfvi7o.pdf

A Review on Natural Fiber Reinforced Polymer Composite and Its Applications

Polypropylene/calcium carbonate (PP/NPCC) nanocomposites were prepared using a co-rotating twin screw extruder at filler loadings of 5, 10 and 15 weight %. The impact strength and modulus of PP showed some improvement with the
incorporation of the nanofiller while the tensile strength deteriorated. SEM photomicrographs showed evidence of NPCC agglomeration within the PP matrix, indicating that the level of shear stress generated during melt compounding was far from adequate to break-up the nanofiller. WAXD results showed the appearance of I²-phase PP in the nanocomposites with 10 and 15 weight % NPCC. The influence of NPCC filler
on the crystallisation behaviour of PP were also investigated using a DSC. Incorporation of NPCC shifted the crystallisation exotherms of PP towards higher temperatures,
indicating that the nanofiller has acted as a nucleating agent for PP. The reduced values of half crystallisation times also implied that the introduction of NPCC has accelerated the crystallisation rate of PP.

The effect of calcium carbonate nanofiller on the mechanical properties and crystallisation behaviour of polypropylene

Polypropylene (PP)-based nanocomposites were developed by the incorporation of a novel nano-sized precipitated calcium carbonate (NPCC) nanoparticles and polyethylene-octene elastomer (POE). The NPCC filler loading selected were 10 and 15wt.% while the POE contents were varied between 0 and 30 wt.%. A slight decrease in the tensile strength of the PP nanocomposites was observed with increasing NPCC content. Results of impact strength indicated that the NPCC filler imparted some toughening effects on the PP and PP/POE blends. Maximum impact strength enhancement was achieved for the PP when blended with 30wt.% POE and filled with 15wt.% NPCC. However, the essential property balance between toughness and stiffness was still lacking in the nanocomposites developed. Differential Scanning Calorimeter results showed that NPCC acted as a nucleating agent for PP, increasing the crystallization temperature of PP by approximately 9 degrees C.

Properties and Structure of Polypropylene/ Polyethylene-Octene Elastomer/Nano CaCO 3 Composites

Polyamide-6 (PA6), acrylonitrile-butadiene-styrene (ABS), and their blends are an important class of engineering thermoplastics that are widely used for electronic and automotive industries. Many efforts have been made to improve the properties of both pure components and the blends. It was for this reason that the mechanical and rheological properties of PA6/ABS blend systems compatibilized by acrylonitrile-butadiene-styrene-maleic anhydride was studied. Short glass fiber was also used to enhance the compatibilized blends. The systems were prepared using a twin screw extruder. The specimens for mechanical test were molded using injection molding. The compatibilized blends showed higher mechanical properties compared to uncompatibilized blend. However, the impact strength reduced with the introduction of short glass fiber in the blends. The processing properties of the materials have been investigated using dynamic rheometer. The rheological measurements confirmed the increased in interaction between the blend components with the incorporation of compatibilizer. The incorporation of short glass fiber (SGF) into the compatibilized blends increased the storage and loss modulus as well as the viscosity of the blends.

Mechanical and Rheological Properties of PA6/ABS Blends - With and Without Short Glass Fiber

In this study, the properties of ethylene–vinyl acetate (EVA) and EVA filled with aluminum (aluminum trihydrate; ATH) and magnesium hydroxide (MH) as halogen-free flame-retardant materials were studied. Scanning electron microscopic analysis revealed that MH in EVA matrix is platy in structure, considerably broad size distribution and well homogeneously distributed, whereas ATH particles are smaller and much more homogeneous in size. Addition of ATH or MH to EVA had an impressive affection on the thermal aging and flame tests but impaired the blend mechanical properties. This research explored that in comparison with ATH, addition of MH to EVA blends was more efficient and suitable in all mechanical, thermal, and flammability tests.

Properties of ethylene–vinyl acetate filled with metal hydroxide

The main objective of this study was to investigate and compare the mechanical properties of poly(vinyl chloride) (PVC) composites filled with calcium carbonate (CaCO3), talc, and talc/CaCO3. Talc and CaCO3 with different grades were incorporated into the PVC matrix. To produce the composites, the PVC resin, fillers, and other additives were first dry-blended by using a laboratory mixer before being milled into sheets in a two-roll mill. Test specimens were prepared by compression molding, after which the mechanical properties of the composites were determined. Single and hybrid filler loadings used were fixed at 30 phr (parts per hundred parts of resin). Talc-filled composite showed the highest flexural modulus and the lowest impact strength, whereas uncoated, ground, 1-μm CaCO3 (SM 90) showed optimum properties in terms of impact strength and flexural modulus among all grades of CaCO3. It was selected to combine with talc at different ratios in the hybrid composites. The impact strength of the hybrid composites gradually increased with increasing SM 90 content, but the flexural and tensile properties showed an opposite behavior. Hybrid (10 phr talc):(20 phr SM 90)-filled PVC composite reached a synergistic hybridization with balanced properties in impact strength, as well as flexural and tensile properties. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers

Azman Hassan

Papers

The effect of calcium carbonate nanofiller on the mechanical properties and crystallisation behaviour of polypropylene

Properties and Structure of Polypropylene/ Polyethylene-Octene Elastomer/Nano CaCO 3 Composites

Mechanical and Rheological Properties of PA6/ABS Blends - With and Without Short Glass Fiber

Properties of ethylene–vinyl acetate filled with metal hydroxide

Mechanical properties of talc- and (calcium carbonate)-filled poly(vinyl chloride) hybrid composites†