Mechanical and Interfacial Properties of Flax Fiber-reinforced Plastic Composites Based on a Chemical Modification Method

Hongguang Wang,HAO WU,Lanjie Yang,Guanglong Yu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

Due to growing interest in environmental protection, eco-friendly fibers with high specific strength and low costare widely used to reinforce matrix materials. Flax fiber is a natural renewable plant fiber that originates from the phloem offlax. Flax fibers not only have the characteristics of other natural fibers but also have the outstanding mechanical properties ofnatural fibers. However, due to the large amount of hydrophilic hydroxyl groups on the surface, the hydrophilic absorption offlax fibers is large, and the wet-heat durability of the composite is poor, which limits the use of flax fiber as a reinforcementmaterial in civil engineering applications. In this study, based on the research results of flax fiber, a flax fiber sheet wasgrafted with multiwalled carbon nanotubes, a silane coupling agent and nano-TiO2 particles. The effect of different treatmentmethods and process parameters on the mechanical and interfacial properties of flax fiber-reinforced plastic (FFRP)composites materials was studied. The results show that the FFRP composites grafted with multiwalled carbon nanotubeshave higher tensile strength and interlaminar shear strength than those grafted with the same content of nano-TiO2 particles. Flax fiber composites with improved interfacial properties can be obtained by grafting flax fiber sheets, but the content ofparticles on the flax fiber surface should not exceed 2.0 wt.% of nano-TiO2 and multiwalled carbon nanotubes. Under thistreatment, the FFRP composites have improved properties, such as tensile strength, interlaminar shear strength and glasstransition temperature.

Thermal Characterization of Alkali Treated Kenaf Fibers and Kenaf-Epoxy Composites

Levi Gardner,Troy Munro,Ezekiel Villarreal,Kurt Harris,Thomas Fronk,Heng Ban 한국섬유공학회 2018 Fibers and polymers Vol.19 No.2

Chemical treatment of natural fibers is a well-defined means of mechanical property improvement in natural fiberreinforced composites. An understanding of mechanical and thermal properties in these media is essential for evaluating heat transfer, thermal degradation, and overall performance of these composites over their product lifetime. However, very little information is available illustrating the effect of such treatment on the thermal properties of kenaf composites. Also, no study to date has reported the thermal conductivity of individual kenaf fibers. This study reports the effects of fiber treatment (in 6 % NaOH) on thermal transport in unidirectionally oriented kenaf-epoxy composites and individual kenaf fibers. The effective thermal conductivities and thermal diffusivities of chemically treated fiber composites show a general increase over untreated fiber composites (0.210 to 0.232 W/m/K at 28 ℃, 0.206 to 0.234 W/m/K at 200 ℃). This improvement may be attributed to improved interfacial contact between the fibers and epoxy matrix shown in microstructural images after chemical treatment. The thermal conductivity of individual fibers was evaluated at room temperature using two techniques. Results from both techniques showed slight increases after chemical treatment (0.58±0.53 to 1.0±0.13 W/m/K and 1.2±0.54 to 1.6±0.28 W/m/K) but lacked statistical significance. Any improvement in surface crystallinity after chemical treatmentdoes not appear to affect overall fiber thermal conductivity. A better understanding of thermal transport in kenaf fibers and composites enables better estimation of the performance of these composites in different applications. Moreover, the thermal conductivities of individual fibers are useful in understanding the fiber’s contribution to conduction in different fiber reinforcement configurations.

The Fiber Orientation Distribution of Injection Molded Long Fiber Reinforced Polymeric Composites

Kim, Hyuk,Ann, Jongyoon,Yoon, Sungun CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.1

The characteristics of fiber-reinforced plastic composites depend on the quantity and shape of fibers. During a injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no study on the measurement of fiber orientation using image processing. In this study, the effects of fiber length, fiber content, matrix, and molding condition on the fiber distribution and by using image processing technique, a method is achieved for quantitative visualization of fiber orientation of a product which is injection molded of long fiber reinforced polymeric composites. Using the burning method, fiber content distribution in products and the effects of fiber content by weight on the fiber orientation functions are discussed.

A Novel Study on Thermal Stability of Camphor Soot Reinforced Coir Fibers

T. Raghavendra,Panneerselvam Kavan 한국섬유공학회 2018 Fibers and polymers Vol.19 No.7

Thermoplastics, reinforced with lignocellulosic fibers are usually processed at lower temperatures ranging from 100 oC to 160 oC. Further increase in temperature leads to the degradation of the fibers mechanical properties. Camphor soot reinforced coir fibers (CSRCF) based on the osmosis technique were prepared, in this study. Parameters using Design of Experiments (DOE) varied and the process is investigated for varied camphor soot concentrations (0.5, 1.0 and 1.5 wt. %), time (4, 8 and 12 hrs.) and temperature (30, 40 and 50 oC) with three levels for each parameter (L9 Orthogonal array). Relative camphor soot content in the coir fiber (RCSCF) and tensile strength are vital objective functions. Tensile tests were conducted on tensometer according to DOE, and based on analysis of variance (ANOVA). The optimal results from ANOVA were established by charting the main effect plots. The optimal combination of parameters for CSRCF were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared radiation (FTIR). Further, scanning electron microscope (SEM) equipped with an energy dispersion spectroscope (EDS) examined and compared neat fibers. The results showed a considerable increase in tensile strength by about 37 % for CSRCF compared to neat fibers. XRD revealed that crystallinity index was slightly reduced for modified fibers. The TGA result reveals that thermal stability of the modified fibers improved by 15 % compared to neat fibers. FTIR analysis revealed that modified fibers experienced peak diminishing in OH, CH stretching and carbonyl groups. The Morphology study of neat and CSRCF were examined using SEM with EDS analysis which revealed 94 % carbonaceous compounds in a cross examination of modified fibers compared to the cross section of a neat coir fiber (64 %).

Correlating the Fineness and Residual Gum Content of Degummed Hemp Fibres

Beltran, Rafael,Hurren, Christopher J.,Kaynak, Akif,Wang, Xungai The Korean Fiber Society 2002 Fibers and polymers Vol.3 No.4

It is well known residual gum exists in degummed or rotted hemp fibers. Gum removal results in improvement in fiber fineness and the properties of the resultant hemp yams. However, it is not known what correlation if any exists between the residual gum content in retted hemp fibers and the fiber fineness, described in terms of fiber width in this paper. This study examined the mean width and coefficient of variation (CV) of fiber width of seventeen chemically rotted hemp samples with reference to residual gum content. The mean and CV of fiber width were obtained from an Optical fiber diameter analyser (OFDA 100). The linear regression analysis results show that the mean fiber width is directly proportional to the residual gum content. A slightly weaker linear correlation also exists between the coefficient of variation of fiber width and the residual gum content. The strong linear co-relation between the mean of fiber width and the residual gum content is a significant outcome, since testing for fiber width using the OFDA is a much simpler and quicker process than testing the residual gum content. Scanning Electron Microscopy (SEM) reinforces the OFDA findings. SEM micrographs show a flat ribbon like fiber cross-section hence the term \"fiber width\" is used instead of fiber diameter. Spectral differences in the untreated dry decorticated skin samples and chemically treated and subsequently carded samples indicate delignification. The peaks at $1370cm^{-1}$, $1325cm^{-1}$, $1733cm^{-1}$, and $1600cm^{-1}$ attributed to lignin in the untreated samples are missing from the spectra of the treated samples. The spectra of the treated samples are more amine-dominated with some of the OH character lost.cter lost.

하이브리드 섬유 보강 콘크리트의 휨인성 및 휨인장 강도에 관한 실험적 연구

趙勇範,朴弘用 明知大學校 産業技術硏究所 2009 産業技術硏究所論文集 Vol.28 No.-

Fiber reinforced concrete is increasing used in practice because of its excellent cracking resistance. There are various types of fiber such as steel fiber, glass fiber, synthetic fiber and organic fiber. Many trials to add more than two types of fiber to concrete mix have been being made to enhance ductility and maximum load bearing capacity as well as cracking resistance. Recently, a new type of polyolefin fiber having a good mechanical properties is developed, and it needs to examine a possibility for the new fiber to be used as a reinforcing fiber with other types of fiber or by itself. The objective of this study is to find out flexural toughness and tensile strength of concrete reinforced with steel and polyolefin fibers. Four point beam tests were performed with 324 specimens following two standard tests methods: KS F 2566 and ASTM 1399-02. From the test results, the effects of volume fraction of fibers, and aspect ratio of steel fiber on the toughness and tesile strength were found, and the optimal ratio of steel fiber to Dolvolefin fiber was suggested.

섬유 보강콘크리트의 피로특성 및 내충격성

이봉학,윤경구,홍창우,김동호,최의규 강원대학교 부설 석재복합신소재 제품연구센터 1999 석재연 논문집 Vol.4 No.-

본 연구에서는 강섬유보강콘크리트의 각종 물성 실험 및 휨피로와 충격시험을 통하여 강섬유 보강콘크리트의 우수성을 입증하였다. 각 유형별 휨강도 특성은 Hooked 형이 Crimped 형보다 큰 휨강도를 나타내었으며 또한 형상비가 클수록 큰 강도발현을 보였다. 휨인성 평가에 있어서는 섬유 형상에 관계없이 섬유 혼입량의 증가에 따라 월등한 에너지 흡수능력을 나타내었으며 Hooke형이 Crimped 형보다 뛰어난 에너지 흡수능력을 갖고 있음을 확인하였다. 정적극한강도에 대한 휨피로수명은 보통 콘크리트는 약 53%정도로 나타났으며 강섬유 보강 콘크리트는 약 54∼65%정도를 나타내었다. 또한 충격에 대한 평가는 섬유 혼입량의 증가에 따라 큰 충격저항성능을 발휘하지는 않았으나 초속경시멘트를 사용한 경우가 보통 시멘트를 사용한 경우와 비교하여 매우 우수한 충격저항성을 갖고 있음을 확인하였다. This paper is conducted on the flexural fatigue test and the impact test to find the mechanical properties of steel fiber reinforced concrete. Experimental investigation is examined according to fiber contents(0, 0.4, 0.7, 1.0, 1.5%), fiber aspect ratio(58, 60, 83), fiber type (hooked, crimped fiber), and cement type(normal portland & rapid-set cement). The principal results obtained through this study are as follow; toughness, impact resistance and fatigue resistance tend to considerably increase with fiber contents, fiber aspect ration, and hooked fiber is improved better than crimped fiber. Concrete using rapid set cement is increased strength properties compared with concrete using normal portland cement, but relative strength properties behavior and fatigue resistance show a tendency to decrease a little.

Surface Morphologies and Internal Fine Structures of Bast Fibers

Wang H. M.,Wang X. The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.1

Fiber surface morphologies and associated internal structures are closely related to its properties. Unlike other fibers including cotton, bast fibers possess transverse nodes and fissures in cross-sectional and longitudinal directions. Their morphologies and associated internal structures were anatomically examined under the scanning electron microscope. The results showed that the morphologies of the nodes and the fissures of bast fibers varied depending on the construction of the inner fibril cellular layers. The transverse nodes and fissures were formed by the folding and spiralling of the cellular layers during plant growth. The dimensions of nodes and fissures were determined by the dislocations of the cellular layers. There were also many longitudinal fissures in bast fibers. Some deep longitudinal fissures even opened the fiber lumen for a short way along the fiber. In addition, the lumen channel of the bast fibers could be disturbed or disrupted by the nodes and the spi­rals of the internal cellular layers. The existence of the transverse nodes and fissures in the bast fibers could degrade the fiber mechanical properties, whereas the longitudinal fissures may contribute to the very rapid moisture absorption and desorption.

Physcial and Fiber Properties of TMP and CTMP from Kenaf Cultivated at Reclaimed Land of Korea

SEUNG-LAK YOON,YASUO KOJIMA,DONG-HA CHO,NAM-HUM KIM,MIN-JOONG KIM,MYOUNG-KU LEE 한국펄프·종이공학회 2006 한국펄프종이학회 기타 간행물 Vol.- No.-

Fiber characteristics and fiber distribution of thermomechanical pulp(TMP), bisulfite chemithermomechanical pulp(bisulfite CTMP), neutral sulfite chemithermomechanical pulp(neutral sulfite CTMP) from kenaf(Hibiscus cannabinus L., Malvaceae) cultivar Tainug-2 cultivated in the reclaimed land of Korea were examined to use effectively nonwood fibers as an alternative raw material sources for papermaking. Yields of TMP and CTMP from kenaf were lower than those of TMP from hardwoods and CTMP from softwoods and hardwoods. Bark fibers of kenaf cultivar Tainung-2 ranged 2.04 to 2.30 ㎜ long and 18.7∼19.7㎛ width. Core fibers averaged 0.63 to 0.80 ㎜ long and 29.5∼31.4㎛ wide. Coarseness of bark fiber was higher than that of core fiber, and fiber from TMP were higher than those from both bisulfite CTMP and neutral sulfite CTMP. Curl indexes of bark fibers were higher than those of core fibers. However curl indexes were not significantly affected by the pulping conditions. Short fiber distributions were higher in core fibers from TMP and CTMP and long fiber distributions were higher in bark fibers. There was no significant difference in fiber distribution of whole and core fibers obtained from TMP and CTMP. Fibers from neutral sulfite CTMP, however, exhibited a little higher long fiber distribution. Distinct difference in anatomical characteristics was found between core and bast fibers of kenaf plant. Parenchyma cell, pith parenchyma cell and vessel were observed in core fibers and bast fiber in bast sections.

Mechanical Properties of PP/Glass Fiber/Kenaf/Bamboo Fiberreinforced Hybrid Composite

안승국 한국섬유공학회 2021 Fibers and polymers Vol.22 No.5

The present study deals with the effect of hybrid ratio on the mechanical properties and thermal properties ofkenaf, bamboo fiber-reinforced hybrid polypropylene (PP) composites. The present work deals with the fabricating andcharacterization of PP/glass fiber/kenaf/bamboo fiber-reinforced composite. The composite of PP reinforced with kenaf,bamboo fiber and kenaf/bamboo fiber was made using injection molding technique. Different fiber loadings of 100, 75, 50,25, 0 wt% kenaf/bamboo composites were also prepared. Scanning electron microscopy (SEM) were performed for nonmixedfiber and mixed compounds. By observing FE_SEM, the random directionality of fiber direction was reduced as theKF content increased, thus improving the physical characteristic value. Moreover, since the kenaf and bamboo were mixedwith the pp, PP/glass fiber/kenaf/bamboo fiber-reinforced composite had better physical, morphological and mechanicalproperties. However, variations in tensile and impact properties depend on the mixing ratio. The mechanical properties of PP/glass fiber/kenaf/bamboo fiber-reinforced composite compared with those of non-mixed stand-alone were also measured. The mechanical properties were higher when 75 wt% kenaf/bamboo fibers were mixed. And the calculation of the volumefraction also showed the tendency of increasing mechanical properties according to the increasing proportion of fibers.