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1.
In this study, microcapsules were prepared by spray drying and embedding hemp seed oil (HSO) with soy protein isolate (SPI) and maltodextrin (MD) as wall materials. The effect of ultrasonic power on the microstructure and characteristics of the composite emulsion and microcapsules was studied. Studies have shown that ultrasonic power has a significant impact on the stability of composite emulsions. The particle size of the composite emulsion after 450 W ultrasonic treatment was significantly lower than the particle size of the emulsion without the ultrasonic treatment. Through fluorescence microscopy observation, HSO was found to be successfully embedded in the wall materials to form an oil/water (O/W) composite emulsion. The spray-dried microcapsules showed a smooth spherical structure through scanning electron microscopy (SEM), and the particle size was 10.7 μm at 450 W. Fourier transform infrared (FTIR) spectroscopy analysis found that ultrasonic treatment would increase the degree of covalent bonding of the SPI-MD complex to a certain extent, thereby improving the stability and embedding effect of the microcapsules. Finally, oxidation kinetics models of HSO and HSO microcapsules were constructed and verified. The zero-order model of HSO microcapsules was found to have a higher degree of fit; after verification, the model can better reflect the quality changes of HSO microcapsules during storage. 相似文献
2.
30 wt% aligned untreated long hemp fibre/PLA (AUL) and aligned alkali treated long hemp fibre/PLA (AAL) composites were produced by film stacking and subjected to accelerated ageing. Accelerated ageing was carried out using UV irradiation and water spray at 50 °C for four different time intervals (250, 500, 750 and 1000 h). After accelerated ageing, tensile strength (TS), flexural strength, Young's modulus (YM), flexural modulus and mode I fracture toughness (KIc) were found to decrease and impact strength (IS) was found to increase for both AUL and AAL composites. AUL composites had greatest overall reduction in mechanical properties than that for AAL composites upon exposure to accelerated ageing environment. FTIR analysis and crystallinity contents of the accelerated aged composites support the results of the deterioration of mechanical properties upon exposure to accelerated ageing environment. 相似文献
3.
A kinetic model was developed, based on the power law of growth and Avrami’s nuclei growth concepts, to describe the heterogeneous
nature of pulping kinetics, taking into account the effects of chemical concentration and temperature. The general form of
the kinetic equation is first order with a time-dependent rate coefficient. The model was statistically tested using published
data obtained from delignification of lignocellulosic materials (hemp woody core, giant reed, wheat straw, cottonwood, bamboo
and flax fibres). The activation energies of the delignification range from 71 to 136 kJ/mol. The p-values obtained from the regression analysis are significantly small indicating that all the estimates of the model parameters
were significant with very high levels of confidence. The correlation coefficients R
2 for these models range from 0.76 to 0.98. 相似文献
4.
Pretreatments (water-soaking, pre-mercerization, mercerization under a pressure of 15 bars and steam explosion) were used
to improve the accessibilities and reactivities of celluloses of bleached flax, hemp, sisal, abaca and jute pulps for the
synthesis of methylcellulose. Degrees of crystallinity were determined by X-ray Diffraction (XRD) spectra. The iodine adsorption
accessibilities of pulps were low and accessible fractions ranged from 1.3 to 5.2%. Accessible fractions in amorphous cellulose
were calculated in the 5–18% range. The accessibilities of these pulps were hemp pulp > flax pulp > sisal pulp > jute pulp > abaca
pulp. Fourier Transform Infrared (FTIR) spectra showed that mean hydrogen bond strengths were weakened and relative crystallinity
indexes were decreased by pretreatments. The accessibility and reactivity of the abaca pulp were improved by water soaking,
mercerization under 15 bars pressure, steam explosion and preliminary mercerization, of which steam explosion and pre-mercerization
were the best treatments. Species was the main factor for the accessibility and reactivity. 相似文献
5.
Determination of cannabinoids in hemp food products by use of headspace solid-phase microextraction and gas chromatography–mass spectrometry 总被引:4,自引:0,他引:4
Lachenmeier DW Kroener L Musshoff F Madea B 《Analytical and bioanalytical chemistry》2004,378(1):183-189
A fully automated procedure using alkaline hydrolysis and headspace solid-phase microextraction (HS-SPME), followed by on-fiber derivatization and gas chromatographic–mass spectrometric (GC–MS) detection has been developed for determination of cannabinoids in hemp food samples. After addition of a deuterated internal standard, the sample was hydrolyzed with sodium hydroxide and submitted to direct HS-SPME. After absorption of analytes for on-fiber derivatization, the fiber was placed directly into the headspace of a second vial containing N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), before GC–MS analysis. Linearity was good for
9-tetrahydrocannabinol (THC), cannabidiol, and cannabinol; regression coefficients were greater than 0.99. Depending on the characteristics of the matrix the detection limits obtained ranged between 0.01 and 0.17 mg kg–1 and the precision between 0.4 and 11.8%. In comparison with conventional liquid–liquid extraction this automated HS-SPME–GC–MS procedure is substantially faster. It is easy to perform, solvent-free, and sample quantities are minimal, yet it maintains the same sensitivity and reproducibility. The applicability was demonstrated by analysis of 30 hemp food samples. Cannabinoids were detected in all of the samples and it was possible to differentiate between drug-type and fiber-type Cannabis sativa L. In comparison with other studies relatively low THC concentrations between 0.01 and 15.53 mg kg–1 were determined. 相似文献
6.
In biotechnology, strong emphasis is placed on the development of wet chemical analysis and chromatography to separate target
components from a complex matrix. In bioprocessing, the development of single compound biosensors is an important activity.
The advantages of these techniques are their high sensitivity and specificity. Inline or online monitoring by means of spectroscopy
has the potential to be used as an “all-in-one” analysis technique for biotechnological studies, but it lacks specificity.
Multivariate curve resolution (MCR) can be used to overcome this limitation. MCR is able to extract the number of components
involved in a complex spectral feature, to attribute the resulting spectra to chemical compounds, to quantify the individual
spectral contributions, and to use this quantification to develop kinetic models for the process with or without a priori
knowledge. After a short introduction to MCR, two applications are presented. In the first example, the spectral features
of hemp are monitored and analysed during growth. MCR provides unperturbed spectra on the activity of, for example, lignin
and cellulose during plant development. In a second example, the kinetics of a laccase enzyme-catalysed degradation of aromatic
hydrocarbons are calculated from UV/VIS spectra. 相似文献
7.
Raw and refined flax, hemp, abaca, sisal, jute and ramie fibres are dipped into N-methylmorpholine N-oxide (NMMO)–water with various contents of water and into hydroxide sodium (NaOH)–water. The swelling and dissolution mechanisms
of these plant fibres are similar to those observed for cotton and wood fibres. Disintegration into rod-like fragments, ballooning
followed or not by dissolution and homogeneous swelling are all observed as for wood and cotton fibres, depending on the quality
of the solvent. Balloons are not typical of wood and cotton and they seem to be present in all plant fibres. Another interesting
result is that the helical feature seen on the balloon membrane is not related to the microfibrillar angle. Plant fibres are
easier to dissolve than wood and cotton. This is not related to the molar mass of the cellulose chain. Raw plant fibres keeping
most its non-cellulosic components do not show the formation of balloons.
Patrick Navard is a Member of the European Polysaccharide Network of Excellence (EPNOE) 相似文献
8.
The present work aims to investigate the local deformation mechanisms around a yarn in an eco-composite. Different hemp yarn orientations and two types of epoxy resin were tested. Full-field measurements were realised with the digital image correlation technique on specific single yarn composites, either on the face of the specimens, or on the edge. The tensile tests were performed under an optical microscope to give sufficient precision, and a numerical model was developed. The experimental results showed high heterogeneities in strain fields which increase with the applied stress level. The comparison with the underlying microstructure and the numerical model enabled us to study the influence of the yarn on the mechanical behaviour. The local constitutive behaviour of the different constituents of the specimens could be approached by these analyses. These results constitute a complete and original database on hemp/epoxy interface mechanical behaviour. 相似文献
9.
10.
Alain Bourmaud Antoine Le DuigouChristophe Baley 《Polymer Degradation and Stability》2011,96(10):1732-1739
The integration of the environmental problem in the design of industrial products leads us to incorporate vegetal fibres and recycled polymers into composite materials. The aim of this work is to study the behaviour and the environmental interest of a recycled PP/hemp fibre after several injection cycles. The mechanical and rheological behaviour of recycled PP/hemp composite was first studied by using tensile, dynamical mechanic analysis and rheological measurements. Then, to better understand the influence of the recycling, a morphology study was carried out on composites by using optical and electron microscopy. Finally, we investigated the environmental advantages of our composite thanks to a simplified environmental assessment. Our results highlighted the environmental interest of using a recycled matrix to prepare composites reinforced with vegetal fibres and the interesting properties of this material after recycling. 相似文献