scholarly journals Impact of Alkali and Silane Treatment on Hemp/PLA Composites’ Performance: From Micro to Macro Scale

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 851
Author(s):  
Percy Festus Alao ◽  
Laetitia Marrot ◽  
Michael David Burnard ◽  
Gregor Lavrič ◽  
Mart Saarna ◽  
...  
Keyword(s):  
Structural Changes ◽  
Negative Impact ◽  
Silane Treatment ◽  
Hemp Fiber ◽  
Hemp Fibers ◽  
Structural Alterations ◽  
Fiber Properties ◽  
Macro Scale ◽  
Locally Grown ◽  
Composite Properties

This study investigated the effect of hemp fiber pretreatments (water and sodium hydroxide) combined with silane treatment, first on the fiber properties (microscale) and then on polylactide (PLA) composite properties (macroscale). At the microscale, Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy investigations highlighted structural alterations in the fibers, with the removal of targeted components and rearrangement in the cell wall. These structural changes influenced unitary fiber properties. At the macroscale, both pretreatments increased the composites’ tensile properties, despite their negative impact on fiber performance. Additionally, silane treatment improved composite performance thanks to higher performance of the fibers themselves and improved fiber compatibility with the PLA matrix brought on by the silane couplings. PLA composites reinforced by 30 wt.% alkali and silane treated hemp fibers exhibited the highest tensile strength (62 MPa), flexural strength (113 MPa), and Young’s modulus (7.6 GPa). Overall, the paper demonstrates the applicability of locally grown, frost-retted hemp fibers for the development of bio-based composites with low density (1.13 to 1.23 g cm−3).

Optimization and characterization of flavonoids extracted from Cannabis sativa fibers

2021 ◽  
pp. 004051752110277
Author(s):  
Qilu Cui ◽  
Jiawei Li ◽  
Chongwen Yu
Keyword(s):  
Chemical Structure ◽  
Cannabis Sativa ◽  
Ethanol Concentration ◽  
Extraction Process ◽  
Test Results ◽  
Hemp Fiber ◽  
Hemp Fibers ◽  
Structure Surface ◽  
Degumming Process

In this paper, the extraction process of flavonoids from hemp fibers was studied. Response surface methodology (RSM) analysis of the extraction parameters indicated that optimized results would be ethanol concentration 76 vol.%, bath ratio 1:50, and reaction time 139 min; therefore, an optimal extraction rate of flavonoids of 0.2275% can be obtained. The chemical structure, surface morphology and element composition of flavonoid extracts were analyzed. The test results indicated that hemp extract contains flavonoids, which can be used to extract flavonoids from hemp fiber, so as to comprehensively develop hemp fiber and reduce the discharge of waste liquid in the traditional degumming process.

scholarly journals Hemp Fiber Reinforced Red Mud/Fly Ash Geopolymer Composite Materials: Effect of Fiber Content on Mechanical Strength

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 511 ◽  
Author(s):  
Eyerusalem A. Taye ◽  
Judith A. Roether ◽  
Dirk W. Schubert ◽  
Daniel T. Redda ◽  
Aldo R. Boccaccini
Keyword(s):  
Fly Ash ◽  
Mechanical Strength ◽  
Red Mud ◽  
Fiber Reinforced ◽  
Brazilian Tensile Strength ◽  
Hemp Fiber ◽  
Hemp Fibers ◽  
The Matrix ◽  
Geopolymer Composites ◽  
Scanning Electron

Novel hemp fiber reinforced geopolymer composites were fabricated. The matrix was a new geopolymer based on a mixture of red mud and fly ash. Chopped, randomly oriented hemp fibers were used as reinforcement. The mechanical properties of the geopolymer composite, such as diametral tensile (DTS) (or Brazilian tensile) strength and compressive strength (CS), were measured. The geopolymer composites reinforced with 9 vol.% and 3 vol.% hemp fiber yielded average DTS values of 5.5 MPa and average CS values of 40 MPa. Scanning electron microscopy (SEM) studies were carried out to evaluate the microstructure and fracture surfaces of the composites. The results indicated that the addition of hemp fiber is a promising approach to improve the mechanical strength as well as to modify the failure mechanism of the geopolymer, which changed from brittle to “pseudo-ductile”.

Structural Changes on Charring Woods of Dichrostachys and Salix from Southern Africa: The Effect of Moisture Content

IAWA Journal ◽  
1986 ◽  
Vol 7 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Juliet Prior ◽  
K. L. Alvin
Keyword(s):  
Moisture Content ◽  
Southern Africa ◽  
Structural Changes ◽  
Initial Increase ◽  
Dichrostachys Cinerea ◽  
Chemical Changes ◽  
Structural Alterations ◽  
Wood Pyrolysis ◽  
Effect Of Moisture ◽  
Physical And Chemical

Air-dried and saturated cubes of fully developed wood of Dichrostachys cinerea (Leguminosae) and Salix subserrata (Salicaceae) were charred for 60 minutes at 400°C. An initial increase in moisture content caused few structural alterations in Salix but in Dichrostachys it resulted in considerable ray distension and massive deformation of non-gelatinous fibres. An attempt is made to correlate these observations with the physical and chemical changes known to occur during wood pyrolysis.

scholarly journals The effects of simulated microgravity on skeletal muscle of Japanese quail: transmission electron microscopic study

2011 ◽  
Vol 80 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Katarína Holovská ◽  
Viera Almášiová ◽  
Viera Cigánková ◽  
Peter Škrobánek
Keyword(s):  
Skeletal Muscle ◽  
Japanese Quail ◽  
Structural Changes ◽  
Simulated Microgravity ◽  
Negative Impact ◽  
Electron Microscopic ◽  
Giant Mitochondria ◽  
Transmission Electron ◽  
Muscle Tissues ◽  
And Control

The aim of the present study was to investigate the effects of simulated microgravity (hypodynamia) on the structure of the skeletal muscle (m. gastrocnemius) in developing Japanese quail by transmission electron microscopy. Samples of muscle tissues from experimental (n = 28) and control (n = 28) birds were collected at day 7, 14, 28, 42 and 56 of age. The structure of m. gastrocnenmius was changed depending on hypodynamia length. The first extensive structural changes were found on day 14 of age. The mitochondria were enlarged and the spaces between the myofibrils were slightly extended compared to control. The sarcomeres were irregular and lipid droplets occurred in the sarcoplasm. Further developmental changes occurred on day 28 of age. Mitochondria fused into the giant mitochondria which frequently exceeded the length of one sarcomere. Moreover, at 42 days of age, beside the above mentioned changes, sarcoplasmic reticulum was dilated and the number of mitochondrial cristae was reduced. However, the structure of m. gastrocnemius on day 56 was less damaged compared to the damage observed on day 42 of age. Presented results indicate that the continuous stay of male Japanese quail under simulated microgravity has a negative impact on the structure of m. gastrocnemius, but also the ability of muscle tissue to cope with these specific conditions.

STRUCTURAL CHANGES IN THE JUDICIAL SYSTEM OF THE UZBEK SSR(For example, 1930-1938.)

2021 ◽  
Vol 4 (2) ◽  
pp. 33-39
Author(s):  
Dilshod P. Komolov ◽  
Keyword(s):  
Working Conditions ◽  
Structural Changes ◽  
Negative Impact ◽  
Ethnic Composition ◽  
Judicial System ◽  
District Court ◽  
Historical Sources ◽  
Poor State ◽  
Archival Documents

Based on the analysis of archival documents and historical sources, this article highlights such provisions as the negative impact of structural changes in the judicial system of the Uzbek SSR from 1930 to 1938, the level of professionalism of judges, ethnic composition, the economically poor state of the courts, insufficient working conditions for full-fledged activity. It also talks about violations in the judicial system and the factors that led to staff turnover.Index Terms: people’s court, district court, verdict, decision, collegium, personnel problems

Investigation of the Mechanical Behavior of Natural Vegetable Fibers Used in Composite Materials for Structural Strengthening

2021 ◽  
Vol 888 ◽  
pp. 15-21
Author(s):  
Ivelina Ivanova ◽  
Jules Assih ◽  
Dimitar Dontchev
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Fiber Composite ◽  
Low Cost ◽  
Weight Ratio ◽  
Synthetic Fiber ◽  
Engineering Structures ◽  
Hemp Fiber ◽  
Plant Fibers ◽  
Hemp Fibers

This research aims at studying the mechanical properties of industrial hemp fibers and promoting their use as a reinforcing composite material for strengthening of civil engineering structures. Natural hemp fibers are of great interest due to the following advantages they have: low cost, high strength-to-weight ratio, low density and non-corrosive properties. The use of plant fiber composite materials has increased significantly in recent years because of the negative reduction impact on the environment. For example, the tendency to use renewable resources and their possibility for recycling. They cause fewer health and environmental problems than synthetic fibers. Natural fibers, in addition to environmental aspects, have advantages such as low densities, i.e. have low weight, interesting mechanical properties comparable to those of synthetic fiber materials, and last but not least, low cost. Composites based on natural plant fibers can be used to reinforce or repair reinforced concrete structures, as shown by research on flax fiber composites. These concretes specimens strengthened with biocomposite materials have very good resistance to bending and significantly increase the rigidity of the structure. The results show that the hemp fiber reinforcement has significant effects on the strengthening and increase in flexural strength from 8% to 35 %.

scholarly journals Studies on Hemp and Recycled Aggregate Concrete

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Samer Ghosn ◽  
Nour Cherkawi ◽  
Bilal Hamad
Keyword(s):  
Mechanical Properties ◽  
Fiber Length ◽  
Plain Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Silane Treatment ◽  
Hemp Fiber ◽  
Fiber Treatment

Abstract This paper reports on the first phase of a multi-phase research program conducted at the American University of Beirut (AUB) on “Hemp and Recycled Aggregates Concrete” (HRAC). HRAC is a new sustainable concrete material where hemp fibers are incorporated in the mix, the coarse aggregate content is reduced by 20% of the concrete volume, and 50% of the natural coarse aggregates (NCA) are replaced by recycled concrete aggregates (RCA), thus saving on natural resources and addressing the problem of waste material disposal. The effect of the new material on concrete consistency and hardened mechanical properties was studied. Also, few durability tests were conducted. Variables included percentage replacement of NCA by RCA (0 or 50%), maximum size aggregate (10 or 20 mm), hemp fiber length (20 or 30 mm), and hemp fiber treatment (alkali or silane or acetyl). Fiber characterization tests were conducted including morphology, crystallinity, and thermal analysis. The tests indicated that alkali and acetyl fiber treatments were better than the silane treatment in removing impurities on the fiber surface. Also, alkali and acetyl treatments have increased the crystallinity of the fibers while silane treatment decreased it. Results of mechanical properties tests showed that while HRAC has considerable lower compressive strength and modulus of elasticity than plain concrete, the flexural strength and splitting tensile strength are not significantly affected. The flexural stress–strain behavior of HRAC is ductile as compared to the brittle behavior of the plain concrete beams indicating positive impact on toughness and energy dissipation. The durability tests indicated that whereas HRAC mixes have higher absorption than plain concrete, they have better thermal properties and their resistance to freeze–thaw cycles is comparable to plain concrete. All test results were not significantly affected by fiber length or fiber treatment.

Hemp Fiber Reinforced Geopolymer Composites: Effects of NaOH Concentration on Fiber Pre-Treatment Process

2020 ◽  
Vol 841 ◽  
pp. 166-170
Author(s):  
Phattharachai Maichin ◽  
Teewara Suwan ◽  
Peerapong Jitsangiam ◽  
Prinya Chindaprasirt
Keyword(s):  
Treatment Process ◽  
Solution Concentration ◽  
Alkaline Treatment ◽  
The Self ◽  
Hemp Fiber ◽  
Natural Materials ◽  
Hemp Fibers ◽  
Naoh Solution ◽  
Pre Treatment ◽  
Geopolymer Composites

High demand for using parts of natural materials, e.g., cores, fibers or leaves, as alternative additives are being increased. The main reasons are that natural materials can be served as renewable and eco-friendly choices such a sustainable development. Nevertheless, some limitations of applying those natural products, such as biodegradation, UV degradation, or weak bonding, are raised and need to be modified before further handling. One of the modification techniques for bio-based materials is chemical treatment by using alkaline solution (alkalization). Treatment process allows the plant's fiber to have fewer impurities as well as to increase the bonding on its contacting surface area. This research focuses on (i) effects of NaOH solution concentration on the pre-treatment properties of hemp fibers and (ii) self-treatment behavior of hemp fiber in geopolymer composites. The results show that the concentration of NaOH solution directly affected the pre-treatment process of hemp fiber as higher concentration from 1, 3, 5, 8, 10 to 12 Molar provided more vanishing level of fiber impurities, indicated by Contact Angle (CA) measurement and Fourier Transform Infrared (FT-IR) Spectroscopy analysis. With the concept of alkaline treatment, the self-treatment process was therefore applied for hemp fiber incorporated in alkaline-activated geopolymer matrix. The results illustrate the self-treatment behavior of hemp fiber in geopolymer composites, which could improve the final performances of the hardened products without conventional pre-treatment process.

Characterization of Hemp Fiber Using Microwave-Assisted Extraction (MAE) Pretreatment

2010 ◽  
Vol 148-149 ◽  
pp. 1594-1599
Author(s):  
Guo Jun Han ◽  
Li Jun Qu ◽  
Xiao Qing Guo
Keyword(s):  
Low Cost ◽  
Microwave Assisted Extraction ◽  
X Ray Diffraction ◽  
Acid Pretreatment ◽  
Hemp Fiber ◽  
Hemp Fibers ◽  
Microwave Assisted ◽  
Assisted Extraction ◽  
Short Period ◽  
Index Contrast

The main objective of this paper was to investigate a low cost pretreatment method, namely microwave-assisted extraction(MAE) pretreatment, which could be applied to hemp degumming with low environmental impact. Degumming index, contrast of different pretreatment methods, transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fiber tensile testing were used to characterise the effect of pretreatment on hemp fibers. In this paper, the results of degumming effect were given comparing MAE pretreatment with acid pretreatment for hemp degumming. It was found that the MAE pretreatment could remove non-cellulosic compounds from hemp bundles effectively with very short period of time. Meanwhile, seen from SEM micrographs, the fibers pretreated by MAE were cleaner than that of fibers pretreated by acid. These results suggested that MAE pretreatment was higher efficiency and more environmental friendly than traditional pretreatment methods.

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