In this study, a novel compound lamination technique was applied to improve the mechanical properties of hemp fibre-reinforced polylactic acid composites. Polylactic acid fibres were blended with ...hemp fibres in a specific weight ratio in order to produce needled mats. Then, sections of the needled mat were stacked with several polylactic acid resin layers on either side, then formed hemp/polylactic acid composites through hot-pressing. The tensile and flexural properties of hemp/polylactic acid composites were tested according to ASTM standards. A multi-factor orthogonal analytical approach was adopted to discuss the effect of factors such as the hybrid ratio, forming temperature and pressure on mechanical properties of the developed green composites. The adhesion between the fibres and the matrix in the fracture surfaces and the thermal stability of the produced composites were observed via scanning electron microscopy and thermogravimetric analysis. The component analysis of composites was conducted by infrared spectra for confirming the contribution of polylactic acid. The results showed that adhesion between fibres and matrix was enhanced, as well as mechanical properties also improved, especially the tensile strength and flexural properties were obviously improved by utilizing this novel compounding technique.
The aim of this work was to improve mechanical properties of a biocomposite of polylactic acid (PLA) reinforcing with fibrillated methacrylate-silanized hemp fibre. The effect of hemp fibre on ...photo-oxidation and hydrolytic degradation of PLA was evaluated through a QUV accelerated weathering test. Incorporation of 20 mass% fibre filler into neat PLA matrix resulted in increased tensile and flexural modulus for 150% and 200%, respectively. The outdoor degradation of neat PLA and PLA biocomposites was simulated in a 30 days of QUV accelerated weathering test in accordance with ISO 11507 method B. Glass transition temperature (T
g
) was periodically recorded to measure the rate of degradation. Differential scanning calorimetry (DSC) analysis indicated that the degradation rate of the PLA matrix of the biocomposites tended to decrease proportionally to exposure time. The statistical regression method revealed a linear relationship between ln(M
n
) and lnT
g
(
R
2
= 0.96). The 20 mass% hemp/PLA biocomposite was mostly destroyed over neat PLA after 30 days. The rate of degradation tended to have a linear proportion with hemp content. The results of FTIR
13
C-NMR analysis confirmed that the substantial degradation of hemp/PLA biocomposites was due to the lignin content of the hemp fibre. The sensitivity of the PLA biocomposite to UVB light and moisture absorption accelerated photo-oxidation and hydrolytic degradation to the lowest molecular weight of PLA.
The main goal of this study was to improve the mechanical performance of polypropylene (PP) matrix composites through high hemp fibre content. In order to achieve high fibre content, the ...possibilities of different polymer sheet thicknesses and stacking arrangements were investigated. It was found that decreasing the overall thickness of fibre mats between two polymer sheets within the stacking arrangements of composites and so decreasing the distance the polymer needs to travel improved the fibre wetting and therefore improved the tensile properties. The strongest composite produced had a fibre content of about 60 wt%. At this fibre content, tensile strength and Young’s modulus of the composites were found to be 3.0 and 6.9 times, respectively, higher than the control samples (polymer only samples), while figures for flexural strength and flexural modulus were 3.4 and 3.6, respectively.
Plant-based hemp natural fibre-reinforced composites are sustainable in the view of the environment. However, these composites have not attracted many applications due to their less mechanical ...properties compared to the synthetic fibre-reinforced composites. The present work reports the hemp fibre-reinforced composite loaded with cellulose-based filler to improve their mechanical properties. At equal proportions of cellulose filler such as pistachio shell powder, teak wood powder, groundnut shell powder reinforced with the hemp fibre-reinforced epoxy composite, the improvement in the tensile strength, flexural strength, % of elongation and % of deformation is reported. The hemp fibre/epoxy composite loaded with 5 wt% of pistachio shell powder shows a 9.28% increment in tensile strength, 50.96 % increment in flexural strength compared to hemp fibre/epoxy composite. The hemp/epoxy composite loaded with 5 wt% teak wood powder particles shows enhancement in tensile, flexural by 31.56 %, 35.97%, respectively. The hemp/epoxy composite loaded with 5 wt% groundnut shell powder particles shows enhancement in tensile, flexural by 42.99 %, 83.99%, respectively.
•Potential of flax and hemp fibres as a feed additive for piglets was investigated.•Flax and hemp fibres exhibited antioxidant properties.•The fibres improved the weight gain, feed conversion, and ...antioxidant status of piglets.•Fibre at 2% has more favourable effect on intestine butyric acid than 1.5% of fibre.•The fibres did not affect the blood indices of piglets.
Weaning is a critical phase in intensive piglet production marked by the frequent occurrence of digestive disorders posing health and economic burden. To stave off such weaning-related problems, antibiotics and supplements containing high levels of ZnO are often used. In this study, we investigated whether natural fibres obtained from two plants known for their dietary fibre profile and antioxidant properties: flax (Linum usitatissimum L.) and hemp (Cannabis sativa L.), can serve as a health-promoting diet supplement. The study was conducted on a total of 191 Polish Large White piglets from 18 L, from their birth to 56 days of age. Piglets were divided by litters into six groups: W1.5, F1.5, H1.5, W2.0, F2.0, and H2.0. Groups W1.5, F1.5, and H1.5 received feed supplemented with 1.5% fibre from wood cellulose (W), flax (F), and hemp (H), respectively, while groups W2.0, F2.0, and H2.0 received feed with a higher 2.0% content of the same fibres. Flax and hemp fibres were characterised by a complex composition, antioxidant properties due to the presence of phenolic acids, and low risk of mycotoxin contamination. Flax fibre resulted in best weight gains and feed conversion ratio (P ≤ 0.05) of piglets, while hemp fibre had higher positive effect on antioxidant status (P ≤ 0.05) compared to the other two fibre additives. Neither flax nor hemp fibres had any adverse effect on the haematological and biochemical blood parameters. Piglets receiving a diet with 1.5% added fibre showed better growth performance, while diet supplementation with 2% fibre had a beneficial effect on the content of butyric acid in the small intestinal chyme (P ≤ 0.05). The results suggested that both flax and hemp fibres can be innovative feed additives for weaned piglets. However, further studies should be conducted in commercial farms, as the effects of dietary fibre could vary in more challenging environmental conditions.
The main objective of this study was to assess the effect of stearic acid vapour treatment on hemp fibre mats produced using dynamic sheet forming, and the potential use of these treated mats as ...reinforcement in polypropylene matrix composites. Stearic acid was successfully applied through vapour treatment, appearing to form a layer on fibre surfaces. It was found that the presence of stearic acid increased hydrophobicity and thermal stability of fibre mats. It was also found to increase thermal stability of polypropylene matrix composites as well as their strength.
Noil hemp fibre (NHF) is a kind of textile hemp fibre after deep degumming from scutched hemp fibre (SHF), mechanically-degummed hemp fibre. Both NHF and SHF with strong mechanical properties are ...good candidates as reinforcing fibres for plastics such as polypropylene (PP). The PP/NHF and PP/SHF composites were blended via internal mixing process. The effect of fibres on the morphology, thermal resistance and reinforcement of the composites were investigated. PP/NHF composites showed higher impact strength, lower flexural strength than PP/SHF at the corresponding loading because NHF has smaller diameter and better thermal resistance than SHF. Meanwhile, NHF has the similar reinforcement to tensile strength with SHF. The effect of maleic anhydride polypropylene (MAPP) on the fibre-resin interface bonding was also comparatively studied. With increasing amount of MAPP, the tensile, flexural and impact strengths of PP/NHF and PP/SHF increased, respectively. The morphology of PP/SHF and PP/NHF results well showed that MAPP improved the interaction of the fibres with PP through chemical adhesion.
Microwave assisted-degumming/retting of hemp stems was established and the changes in the components like cellulose, hemicellulose and lignin during microwave treatment were studied by near infrared ...(NIR) analysis of the fibres processed from the treated hemp stems. Pre-soaked hemp stems subjected to microwave assisted degumming/retting at various power levels showed significant increase in the cellulose content from 72.1% to 79.8% when compared with the control samples. The percentage of hemicellulose and lignin were the key factors in binding the fibres together, which showed significant decrease when subjected to microwave treatment. Hemicellulose decreased from 14.5% to 12.1% and lignin from 8% to 5.5%. These compositional changes proved the effect of microwave energy in fibre separation. Measurements of diameter distribution and tensile strength, and colorimetric analysis, were performed to verify the effect on the physical properties. Thirty five percent of control sample hemp fibre diameters were <23 μm whereas the microwave-assisted retted samples contained more than 50% of fibre diameter were <23 μm. Colorimetric tests and tensile strength tests did not show any specific trends but the results confirmed that the microwave energy did not have any significant influence in the changes of the physical qualities during the process. The above studies showed the efficiency of microwave treatments for the degumming of hemp fibres.
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•Hemp stems were subjected to microwave-pretreatment before decortication.•Found effective removal of impurities when compared to conventional method.•MW retting/degumming was found to be efficient and time saving when compared to other methods.•The process was optimized for maximum fibre quality.
In this study, a novel antibacterial hemp fibre grafted with quaternary ammonium groups (HF-GTA), were prepared by alkalization, oxidation, amination and quaternization multistage reactions. The ...chemical structure and micromorphology of the fibre were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and X-ray diffraction. The grafting and reaction mechanism proved to be successful, which indicated that the grafting reaction primarily occurred on the hydroxyl group of cellulose and hemicellulose in the hemp fibre, where it retained good fibrous morphology, thermal stability and hygroscopicity. HF-GTA exhibited the best antibacterial activity, where the antibacterial ratios against
and
were 95.41% and 99.64%, respectively. Even after washing 30 times, the antibacterial activity was retained at 89.78% and 91.12%, indicating that HF-GTA was endowed with good washing resistance. The antibacterial activity was owing to the electrostatic reaction reducing the electrochemical potential on the cell membrane, leading to the release of cytoplasmic substances and the dissolution of cells. This study is significantly important for guaranteeing textile quality and preventing disease transmission.
•Hemp-starch strong bond opposes loss of stiffness for reinforcement above 5%.•Achieved reinforcement twice matrix modulus below 10% of filler content.•Evolving interphase properties related to fibre ...packing and towards clustering.•Fibre content above 10% is inefficient using thermomoulding without mixing prestep.
Elasticity behaviour of a fully biopolymer composite is studied using both numerical and experimental approaches. Hemp fibre-starch composite is thermomoulded using a varied content of hemp fibres. On one end, mechanical testing reveals loss of stiffness due to limited load transfer with the increase of fibre content. On the other end, two-phase theories predict a reinforcement trend due to contrast of phase properties. In order to meet both ends, a numerical study is performed to study sensitivity of the predicted mechanical response to geometrical and mechanical considerations. Filler content, arrangement and interphase properties are some of the major studied effects. Interphases are accounted numerically to exhibit the mismatch of load transfer due to imperfect interface behaviour. Finite element results are discussed based on geometrical and mechanical considerations using a sensitivity analysis. Identification of interphase parameters for the tested experimental conditions is attempted successfully. The three-phase model is able to detect where the two-phase system approximation is valid. In addition, strong interphase properties are identified despite the apparent loss of stiffness. Such loss turns to be related to fibre clustering, which makes thermomoulding processing not suitable to achieve fibre volume contents above 10% if not combined with an energetic mixing stage.
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