Shives Research Articles

Manufacturing Particleboard Using Hemp Shiv and Wood Particles with Low Free Formaldehyde Emission Urea-Formaldehyde Resin

Abstract In order to better use the hemp shiv in manufacturing particleboard panels, tests for determining the mechanical and physical properties of this particleboard were performed according to the Chinese standard for wood-based paneling. The results showed the following. (1) The properties of the particleboard are optimal, with a 1:1 ratio of hemp shiv to wood particles; hemp shiv and wood particles actually strengthen each other when particleboard is made from a mixture of hemp shiv and wood particles. (2) The low density and the low mechanical properties of fiber cell walls were both advantages for the hemp shiv used to manufacture the particleboard panels.

Development and study of fully biodegradable composite materials based on poly(butylene succinate) and hemp fibers or hemp shives

The use of natural fibers to reinforce polymers is an established practice, and biocomposites have gained an increased interest in areas such as automotive, construction, and agriculture. The purpose of the present work was the preparation and study of fully biodegradable (“green”) composite materials using poly(butylene succinate) (PBSu) as polymeric matrix and hemp fibers and shives as fillers. Composites containing 15, 30, 50, 60, and 70 wt% of fillers were prepared by melt mixing in a twin screw extruder. The composites were studied using Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimeter while the dispersion and interfacial adhesion were studied with scanning electron microscopy. From mechanical properties measurements, it was found that tensile and impact strength are both affected by the type and the amount of the used filler. The degree of crystallinity of PBSu was found to decrease by increasing the filler content, although that both fillers can act as nucleating agents. Finally, the degradation rate during enzymatic hydrolysis and soil burial increased in all biocomposites by increasing the filler content. PBSu/hemp shive composites showed higher biodegradation rates than PBSu/hemp fiber composites. POLYM. COMPOS., 37:407–421, 2016. © 2014 Society of Plastics Engineers

Innovative Use of Biomass Based on Technical Hemp in Building Industry

This article discusses about the possibility of using industrial hemp as a source of natural fibres for purpose of construction. The technical hemp (Cannabis Sativa) is the source of two types of fibres; bast fibres (used mainly in the paper and textile industries) and woody fibres - hurds. In recent decades hemp hurds have experienced a renaissance in use in the construction industry. This material is waste resulting from the processing of hemp stem on bast fibres. For the purposes of construction it has potential thanks to their exceptional thermal insulation, antiseptic, acoustic and mechanical properties. One of the aspects of using hemp products in building industry is that these materials are environmentally friendly in comparison to the used conventional materials (such as conventional insulating materials with polymer matrix or based on mineral wool).In this article, the lightweight composites based on hemp hurds (as a biomass) and nonconventional binders MgO-cement are tested. The physical and mechanical properties of the composites hardened in indoor condition (28, 60, 90, 180 days) are studied. The results of the obtained parameters (density, water content, compressive strength, thermal conductivity coefficient) of hardened composites are presented.

Racking performance of timber studwork and hemp-lime walling

Hemp-lime is a natural, sustainable low carbon insulating material. It is formed from three main constituents: hemp shiv; lime based binder; and, water. Its use within the construction industry is a relatively recent development. In the UK hemp-lime is most widely used for solid wall insulation in conjunction with structural timber studwork, either cast in situ or more recently innovative prefabricated panels. Current design practice assumes that the hemp-lime does not contribute towards the structural capacity of the wall. Previous work by the authors has confirmed that hemp-lime significantly benefits vertical load bearing capacity of the timber studs. This paper presents research that has been undertaken to establish the enhancement hemp-lime provides to the in-plane racking strength of timber studwork framing. Laboratory testing was undertaken on a series of timber studwork frames both with and without hemp-lime. It was found that the hemp-lime significantly increases both the racking strength and stiffness.

Effect of Hemp’S Soluble Components on the Physical Properties of Hemp Concrete

Lime hemp concrete is a sustainable building material made with hemp shiv and lime. In this research, pozzolans are added to the lime binder. Hemp shiv contains water soluble constituents including pectic polysaccharides which can dissolve in the mixing water. Sugars and pectins are known to retard clinker hydration in portland cement. This research studies whether the hemp soluble components impact lime-pozzolan paste reactions thus affecting the properties of hemp concrete with lime-pozzolan binder. Physical tests and microstructural analyses were undertaken to determine how the water soluble hemp constituents influence the hydration reactions responsible for setting and hardening of lime-pozzolan pastes. The effect of hemp particles on a lime-pozzolan binder was also investigated using microstructural analysis. Physical testing evidenced that the hemp’s soluble constituents do not alter ultimate strength however, they delay pozzolanic reaction retarding setting and early strength development. The microstructural analysis of lime-pozzolan pastes agreed with the above, evidencing that the hemp delays the formation of hydrates, in particular calcium silica hydrates. The halt of the pozzolanic reaction by the hemp particles was clear at the hemp interface, where few hydrates were evident. This suggests that the properties of the hemp particles including their high suction (which removes water at the interface) and their high porosity (which assists CO2 diffusion) contribute to the halt of the pozzolanic reaction.

Suitability of magnetic nanoparticle immobilised cellulases in enhancing enzymatic saccharification of pretreated hemp biomass.

BackgroundPrevious research focused on pretreatment of biomass, production of fermentable sugars and their consumption to produce ethanol. The main goal of the work was to economise the production process cost of fermentable sugars. Therefore, the objective of the present work was to investigate enzyme hydrolysis of microcrystalline cellulose and hemp hurds (natural cellulosic substrate) using free and immobilised enzymes. Cellulase from Trichoderma reesei was immobilised on an activated magnetic support by covalent binding and its activity was compared with that of the free enzyme to hydrolyse microcrystalline cellulose and hemp hurds on the basis of thermostability and reusability.ResultsUp to 94% protein binding was achieved during immobilisation of cellulase on nanoparticles. Successful binding was confirmed using Fourier transform infrared spectroscopy (FTIR). The free and immobilised enzymes exhibited identical pH optima (pH 4.0) and differing temperature optima at 50°C and 60°C, respectively. The K M values obtained for the free and immobilised enzymes were 0.87 mg/mL and 2.6 mg/mL respectively. The immobilised enzyme retained 50% enzyme activity up to five cycles, with thermostability at 80°C superior to that of the free enzyme. Optimum hydrolysis of carboxymethyl cellulose (CMC) with free and immobilised enzymes was 88% and 81%, respectively. With pretreated hemp hurd biomass (HHB), the free and immobilised enzymes resulted in maximum hydrolysis in 48 h of 89% and 93%, respectively.ConclusionThe current work demonstrated the advantages delivered by immobilised enzymes by minimising the consumption of cellulase during substrate hydrolysis and making the production process of fermentable sugars economical and feasible. The activity of cellulase improved as a result of the immobilisation, which provided a better stability at higher temperatures. The immobilised enzyme provided an advantage over the free enzyme through the reusability and longer storage stability properties that were gained as a result of the immobilisation.

Changes in the Properties of Composites Caused by Chemical Treatment of Hemp Hurds

Changes in the Properties of Composites Caused by Chemical Treatment of Hemp Hurds

Fractionation of hemp hurds by organosolv pretreatment and its effect on production of lignin and sugars.

Fractionation of hemp hurds into its three main components, cellulose, hemicellulose, and lignin, was carried out using organosolv pretreatment. The effect of processing parameters, such as temperature, catalyst concentration, reaction time, and methanol (MeOH) concentration, on the dissolution and recovery of hemicellulose and lignin was determined. More than 75% of total hemicellulose and 75% of total lignin was removed in a single step with low amounts of degradation products under the following conditions: 165 °C, 3% H2 SO4 , 20 min reaction time, and 45% MeOH. Enzymatic hydrolysis of the residual pretreated biomass yielded up to 60% of cellulose-to-glucose conversion. The maximum recovery of the main components was obtained at a combined severity factor value of around one. Characterization of pretreated biomass and isolated lignin was carried out with FTIR and 2D (13) C-(1) H correlation HSQC NMR spectroscopy, the latter technique providing detailed structural information about the obtained methanol organosolv lignin (MOSL). Results suggested that xylopyranoside is the major carbohydrate associated with hemp lignin. The chemical properties of MOSL samples in terms of their phenolic group content and antioxidant capacity were also investigated. The results showed that MOSL samples have a high phenolic group content and antioxidant capacity relative to Klason lignin.

Single-step fermentation of agricultural hemp residues for hydrogen and ethanol production

We have investigated a one-step fermentation process using purified hemp cellulose (PHC), hemp fibres (HF), and hemp hurds (HH), compared to reagent-grade α-cellullose (AC) for ethanol and hydrogen production by Clostridium thermocellum. Exponential phase growth and production rates on PHC were comparable to those observed with AC. Net production of ethanol for AC (8.47 mM) was only slightly higher than PHC (6.56 mM), but significantly higher than HF (5.48 mM) and HH (3.52 mM), while the final hydrogen yield was comparable for AC (12.70 mM), PHC (11.01 mM), HF (10.91 mM), and HH (4.72 mM). End-product yields were dependent on the intrinsic cellulosic content as well as the presence of other polymers present in substrate biomass. Rates of ethanol and hydrogen production were similar in early log phase but varied in mid-log, and accessibility to cellulose was shown to determine yield and metabolic flux distribution. Our data suggest that improving the accessibility of the cellulolytic bacterium, C. thermocellum, to cellulose fibres has a greater effect on increasing the yield of fermentation products than simply increasing the concentration of cellulose in the substrate.

Design and multi-physical properties of a new insulating concrete using sunflower stem aggregates and eco-friendly binders

In the interests of sustainable development, building materials using lignocellulosic aggregates like hemp concretes are more and more used in green construction. This type of concrete made of plant aggregates has particularly attractive thermal and hygroscopic properties. The hemp produced by agricultural holdings represents 10,000 ha in France whereas sunflower production is about 700,000 ha. The purpose of the article is to bring scientific elements which demonstrate that aggregates from the sunflower stem can be valorised in the same way as hemp hurd for the manufacturing of building materials. This study could encourage the development of new outlets for agricultural crops. Moreover, the sunflower aggregates could be available at low costs and promote a local economy as compared to hemp hurd. The experimental program includes the physical and thermal characterisation of the raw materials and the design of concrete where aggregates, obtained from an industrial grinding process, are associated with a binder. The characterisation of the aggregates mainly consists of the granulometric study by image analysis, the water absorption and the determination of thermal properties using especially the hot wire method. Two binders are used to prepare cylindrical specimens of sunflower concrete. Two kinds of mixture are tested in compression after 60 days, in thermal conductivity and capillary water absorption. The first one, called wall mixture, has a binder on aggregates mass ratio of 2 (B/A = 2) and the second mixture, called roof mixture, has a B/A mass ratio of 1. Hot wire test results demonstrate for the wall mixtures an average dry thermal conductivity of 0.096 ± 0.003 W m−1 K−1 for the two binders. Compression results show an average compressive strength value at 60 days of 0.50 ± 0.1 MPa for the wall mixtures and 0.10 ± 0.01 MPa for the roof mixtures after an average 17 % strain. The results obviously show that the sunflower concrete reaches thermal and mechanical properties very close from those of hemp concrete. The capillary absorption test confirms the high absorbent potential of the sunflower aggregates but also the role of the binder towards the water uptake behaviour of lignocellulosic concretes.

Novel sustainable hemp-based composites for application in the building industry: Physical, thermal and mechanical characterization

• Novel hemp-based composite materials were developed for the building sector. • Low and medium density composites were designed for thermal insulation. • High density composites were designed for resisting physical–mechanical stress. • The panels have enhanced environmental sustainability and impact on human health. • All the panels exhibit promising thermal, physical and mechanical properties. In this study, novel hemp-based composite materials, designed for building application as components of a multi-layer wall plug for concrete, steel or wood structures, providing both thermal insulation and physical–mechanical resistance, are presented and characterized. Composite panels were produced by bonding hemp hurds with a novel hybrid organic–inorganic binder. The panels were then characterized in terms of physical–microstructural properties (bulk density, water absorption, swelling in thickness and weight loss after immersion in water, microstructural features by means of scanning electron microscope and stereo optical microscope observation), thermal properties (thermal conductivity, reaction to fire) and mechanical properties (compressive strength, flexural strength, tensile strength, resistance to axial withdrawal of screws). The panels exhibited promising physical, thermal and mechanical characteristics, generally comparable to those of commercially available products. In addition, the novel composites have the advantage of a significantly low environmental impact (thanks to the nature of both the dispersed and the binding phase) and no negative effects on human health (contrary to many commercial materials, responsible for emission of formaldehyde). All things considered, the novel composites seem like very promising materials for application in the building industry. Further tests to assess the physical–mechanical durability of the panels are currently in progress.

The Use of Sapropel in Development of Effective Thermal Insulating Materials

This paper presents investigations of thermal conductivity, tensile strength and compressive stress at 10% deformation of effective thermal insulation composites made from hemp shives and sapropel. Images of hemp shives and hemp composite microstructure obtained by scaning electron microscope (SEM) are analised. The paper presents properties of composite from seven compositions. Composite forming mixture contains different amount of sapropel as well as paper production wastes (PPW) obtained in paper processing industry.

Thermal, Moisture and Energy Performance of a Hempcrete Test Structure in the Northern Prairie Climate of Manitoba, Canada

The processing of industrial hemp, cannabis sativa, results in three basic constituents seed, fibre, and hurd. Within Manitoba the main focus is with seed and oil products. When considering the entire plant approximately 60-70% is the predominantly cellulose woody core called the hurd. A combination of hemp hurd, a binder and water in various proportions is used in the construction of buildings referred to as hempcrete. Hempcrete is used as an environmental barrier providing resistance to heat transfer and to manage moisture of the building envelope. Engineering and architectural designers practicing in the field of non-conventional material applications have clearly indicated a need for design data. This paper presents a portion of research data collected over the past 18 months from a 23.8 m2 (256 ft2) test building on the campus of the University of Manitoba at the Alternative Village. The design temperatures for this location range from-35°C to +32°C. The structure was built using 300 mm thick pre-fabricated hempcrete panels. In addition to indoor and exterior ambient conditions, the temperature is monitored at 40 locations within the envelope - at the interior, middle and exterior providing a profile through the wall system. Similarly, the relative humidity is monitored within the wall and used in conjunction with a sorption isotherm to estimate the moisture content within the assembly. The building is kept at a constant temperature during the heating season with the energy consumption monitored continuously. This building is one of several on the test site that are all identical in terms of size and configuration. This paper will provide a comparison between the thermal, moisture and energy performance of the hempcrete structure and a conventional wood frame, batt-insulated building that represents the vernacular construction in Manitoba.

Comparatve Study of Mycelial Growth and Carpophore Yield of Agrocybe aegrerita (Brig.) Sing. on Selected Agricultural and Textile Industry Wastes as a Cultivation Substrate

In modern mushroom cultivation, the most important issue is to obtain possibly highest yields which are consistent with high quality of the carpophores. Agrocybe aegerita is an edible mushroom valuable due to medicinal properties. The aim of the performed investigation was to evaluate the mycelium growth and yielding of A. aegerita on agricultural and textile industry wastes. The subject of the studies was two strains of black poplar mushroom i.e. AE11 and AE06. The experiment showed that no statistically important differences between the mycelia growth of the investigated strains occurred. The mycelial growth was the best on straw of Miscanthus gigantheus, Miscanthus sinensis and Miscanthus sacchariflorus. The two investigated strains differed significantly with respect to their yield on the investigated substrates: wheat straw, M. sacchariflorus and P. virgatum mixture as well as flax and hemp shives mixture. The best sub- strate for the cultivation of A. aegerita AE11strain was mixture of flax and hemp shives while M. sacchari- florus and P. virgatum mixture for AE06. The content of dry matter was the highest on flax and hemp shives for both investigated strains.

Structural benefits of hempcrete infill in timber stud walls

Hempcrete is a bio-composite mix made up of hemp shives, lime, cement and water. Extensive research has shown that it has good thermal and acoustic insulation properties, and can passively regulate humidity in a built environment. However it has low compressive strength and modulus of elasticity and so cannot be used as a direct load bearing material. It is often used as an infill material in timber stud walls. The objective of this study was to determine if the hempcrete infill has sufficient strength and stiffness to act as lateral bracing and prevent weak-axis buckling of the timber studs.Seven timber walls were constructed (both half scale – 1200 mm high; and full scale - up to 2133 mm high) with varying column dimensions. Five of the walls were infilled with hempcrete of two different densities (313 kg/m3 and 715 kg/m3). Two walls were not infilled and were baseline tests. All walls were tested in compression. It was found that high density hempcrete (715 kg/m3) not only prevents weak-axis buckling o...

Lightweight Composites Based on Rapidly Renewable Natural Resource

Over the last few years, a number of researchers have been involved in investigating the exploitation of natural fibres as load bearing constituents in composite materials. The use of such materials in composites has increased due to their relative cheapness, their ability to recycle and their mechanical and physical properties. Composites based on natural fibbers have many advantages over their synthetic counterparts owing to their low cost, low density, high specific strength and stiffness, excellent sound- absorbing and high impact energy absorption. The technical hemp as fast-growing plant has prospect in the construction field in accordance with the principles of sustainable development. A special attention is paid to the use of fibrous hemp as well as hemp hurds (nonfibrous fraction hemp stalk) in the building materials preparing in various forms, such as insulation boards, mass-spraying hempcrete for the production of lightweight composites, where it is in the role of filler. The presence of surface impurities and the large amount of hydroxyl groups make plant fibbers less attractive for reinforcement of composites. Incompability of interface between fibres and matrix, the tendency to form aggregates during processing and poor resistance to moisture can be eliminated by physical/chemical treatments of fibbers and/or matrix or the use of coupling agents. In this paper, some aspects of durability of hardened composites based on chemically modified of hemp hurds slices and MgO-cement as binding agents after long termed storage in deionised water by testing on some important material properties as water absorbability, thermal conductivity coefficient, apparent density and compressive strength was studied.

Experimental Research Regarding the Tensile Properties of some Polypropylene Based Biocomposites Reinforced with Hemp Shives

The paper analyzes the tensile behavior of some new biocomposite materials based on polypropylene reinforced with hemp shives for different volume fractions and sizes. The aim of this study is to make a comparison between the tensile properties of these materials and to determine in which way the values of the tensile strength and tensile modulus are influenced by the volume fraction and dimensions of the reinforcement elements. The analyzed materials are new materials based on renewable and recyclable resources and from this point of view these materials have a less harmful impact on the environment compared to the conventional composites. By analyzing the tensile properties of polyproylene based biocomposites reinforced with hemp shives it can be observed in which way these materials could replace conventional materials in various fields of applications.

Performance of Hemp-Starch Concrete Composite

This paper presents a possibility of making up a vegetable concrete by using starch and hemp shives. The results obtained by test show that this type of environmental material has a lower density, a lower thermal conductivity, and better acoustic properties. The mechanical performance of the starch-hemp concrete depends on the material density, binder/hemp shive ratio and mix composition. The advantageous of thermal and acoustic properties of the material make it good future in the building construction.

Properties monitoring of fibrous composites based on hemp hurds with different mean particle size

In this paper, the effect of mean particle length of hemp hurds on compressive strength and other parameters of fibrous-composites is studied. Hemp hurds of various origin (Hungarohemp LTd, Nagylak, Hungary; Hempflax, Netherlands) with a wide particle size distribution were used in the experiments. Six samples of hemp hurds with various mean particle length (from 7.3 mm to 39.9 mm) were used for the preparation of fibrous composites based on MgO-cement as a binder. Bulk density, compressive strength, thermal conductivity and water absorbability of fibrous composites after 28 days of hardening were tested. The impact of men particle length of hemp hurds slices on values of bulk density, compressive strength and water absorbability of hardened composites was confirmed.

Relationship to reducing sugar production and scanning electron microscope structure to pretreated hemp hurd biomass (Cannabis sativa)

Lignocellulosic biomass is a highly rigid and recalcitrant structure which requires pretreatment to loosen chemical bonds to make accessible monomeric sugars for biofuel production. In this study, locally available biomass, that is hemp (Cannabis sativa), a low cost feedstock for ethanol production, has been used for the production of fermentable sugars. Hemp hurd biomass (HHB) was exposed to five different pretreatments which included dilute acid (H2SO4), alkaline (NaOH), alkaline peroxide, hot water and one stage dilute acid (H2SO4). Different pretreatments resulted in loosening and degradation of HHB structure thus facilitating enzymatic saccharification at optimized parameters (pH–4.8 and 50 °C). The changes in the reactive groups (hydroxyl or acetyl) of the HHB were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Scanning electron microscopy (SEM) was employed to characterize the surface morphology of untreated and treated HHB. Finally, enzymatic saccharification demonstrated maximum yield of total sugars (743 mg g−1) that are suitable for biofuel production.