On a theory of sandwich construction

The theory of sandwich construction developed in this paper proceeds from the simple assumption that the filling has only transverse direct and shear stiffnesses, corresponding to its functional requirements (§1). This supposition permits integration of the equilibrium equations for the filling (§2). The resulting integrals are used to study the compression buckling of a flat sandwich plate (§3). The formulae obtained are complex, but may be simplified in practical cases (§4). A second approach to sandwich problems is made in §5, where a theory of "bending" of plates is outlined. This generalises the usual theory, making allowance for flexibility in sheer. This approach is applied to overall compression buckling of a plate in §6, and agreement with the previous calculations is found. This suggests the possibility of calculating buckling loads for curved sandwich shells. A simple example, the symmetrical buckling of a circular cylinder in compression is worked out in §7. The theory developed would seem applicable to all cases of buckling of not too short a wave length (§8)

Modification of hemp shiv properties using water-repellent sol–gel coatings

For the first time, the hydrophilicity of hemp shiv was modified without the compromise of its hygroscopic properties. This research focused on the use of sol–gel method in preparation of coatings on the natural plant material, hemp shiv, that has growing potential in the construction industry as a thermal insulator. The sol–gel coatings were produced by cohydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) using an acidic catalyst. Methyltriethoxysilane (MTES) was added as the hydrophobic precursor to provide water resistance to the bio-based material. Scanning electron microscopy (SEM) and focused ion beam (FIB) have been used to determine the morphological changes on the surface as well as within the hemp shiv. It was found that the sol–gel coatings caused a reduction in water uptake but did not strongly influence the moisture sorption behaviour of hemp shiv. Fourier transformed infrared (FTIR) spectroscopy shows that the coating layer on hemp shiv acts a shield, thereby lowering peak intensity in the wavelength range 1200–1800 cm−1. The sol–gel coating affected pore size distribution and cumulative pore volume of the shiv resulting in tailored porosity. The overall porosity of shiv decreased with a refinement in diameter of the larger pores. Thermal analysis was performed using TGA and stability of coated and uncoated hemp shiv have been evaluated. Hemp shiv modified with sol–gel coating can potentially develop sustainable heat insulating composites with better hygrothermal properties

Industrial Hemp Fiber Planting Date Trial

Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and reemerging in worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The fiber has high tensile strength and can be used to create a variety of goods. Hemp consists of two types of fiber: bast and hurd. The bast fiber are the long fibers found in the bark of hemp stalks and are best suited for plastic bio-composites for vehicles, textiles, rope, insulation, and paper. The hurd fiber are short fibers found in the core of the stem and are suited for building materials, such as hempcrete and particle boards, bedding materials, and absorbents

Recent palaeoenvironmental evidence for the processing of hemp (Cannabis sativa L.) in eastern England during the medieval period

[FIRST PARAGRAPH] Hemp (Cannabissativa L.)— whose origins as a domesticated plant probably lie in C.Asia — has been cultivated in England since at least a.d.800 (and before this perhaps in the Roman Period), mainly for its ¿bre, which was used to make sails, ropes, ¿shing nets and clothes, as well as for the oil from hempseed. Hemp cultivation may have reached a peak during the early 16th century, when Henry VIII decreed that increased hemp production was required to supply the expanding navy. Evidence for the locations where the crop was cultivated and processed is available in several different forms, including written evidence in parish records and government reports, place-name evidence (e.g.Hempholme and some instances of Hempstead), and features on old maps, such as Hempis¿eld (hemp¿eld)

Industrial Hemp Fiber Variety Trial

Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and reemerging in worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The fiber has high tensile strength and can be used to create a variety of goods. Hemp fiber consists of two types: bast and hurd. The bast fiber are the long fibers found in the bark of hemp stalks and are best suited for plastic bio-composites for vehicles, textiles, rope, insulation, and paper. The hurd fiber are short fibers found in the core of the stem and are suited for building materials, such as hempcrete and particle boards, bedding materials, and absorbents

Effect of fibre treatments on interfacial shear strength of hemp fibre reinforced polylactide and unsaturated polyester composites

Surface treatment of hemp fibres was investigated as a means of improving interfacial shear strength (IFSS) of hemp fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/hemp fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated fibre samples. IFSS of UPE/hemp fibre samples increased for all treated fibres. This is believed to be due to the improvement of chemical bonding between the treated fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment fibre/UPE samples

Industrial Hemp Weed Control Trial

Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and reemerging worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The crop produces a valuable oilseed, rich in Omega-3 and other essential fatty acids that are often absent in western diets. When the oil is extracted from the seed, what remains is a marketable meal coproduct, which is used for human and animal consumption. The fiber has high tensile strength and can be used to create cloth, rope, building materials, and even a form of plastic. For twenty years U.S. entrepreneurs have been importing hemp from China, Eastern Europe, and Canada to manufacture travel gear, apparel and accessories, body care and cosmetics, foods like bread, beer, and salad oils, paper products, building materials and animal bedding, textiles, auto parts, housewares, and sporting equipment. Industrial hemp is poised to be a “new” cash crop and market opportunity for Vermont farms that is nutritious, versatile, and suitable for rotation with other small grains and grasses. To help farmers succeed, agronomic research on hemp is needed, as much of the production knowledge on this crop has been lost. In this trial, we investigated the impact of row spacing on yield and weed pressure

The Fate of Industrial Hemp in the 2018 Farm Bill – Will Our Collective Ambivalence Finally Be Resolved?

We are at a crossroads in the regulation of industrial hemp, and the 2018 Farm Bill is the time to decide which path we will choose. Congress has an opportunity to clear the path for farmers in the US to participate in this burgeoning market. With an estimated 25,000 uses, industrial hemp is one of those rare crops that has both food and agricultural uses. There is undoubtedly a market for hemp products. The Hemp Industries Association (HIA) estimates that US retail sales of hemp-based products was $688 million in 2016 – up from$573 million in 2015. Under the 2014 Farm Bill, Congress seemingly paved the way for industrial hemp to once again be grown in the US, as it granted authority for states to create industrial hemp pilot programs. However, the Drug Enforcement Administration’s (DEA) interpretation of the Controlled Substances Act (CSA) of 1970 still precludes farmers from fully participating in these programs. DEA claims that it has authority to regulate all species of Cannabis sativa under the CSA, and does not distinguish between marijuana and industrial hemp. In the 2018 Farm Bill, Congress has the opportunity to clarify that the definition of marijuana does not include industrial hemp, and by doing so simultaneously clarify (and limit) the scope of DEA’s authority. In order for farmers, processors and retailers to move forward, Congress must take this action, and therefore restrict DEA’s jurisdiction to marijuana. This is the only path forward for a thriving industrial hemp industry in the US

Industrial Grain Hemp Planting Date Trial

Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and reemerging in worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The crop produces a valuable oilseed, rich in Omega-3 and other essential fatty acids that are often absent in western diets. When the oil is extracted from the seed, what remains is a marketable meal co-product, which is used for human and animal consumption. The fiber has high tensile strength and can be used to create cloth, rope, building materials, and even a form of plastic. For twenty years, U.S. entrepreneurs have been importing hemp from China, Eastern Europe and Canada to manufacture travel gear, apparel and accessories, body care and cosmetics, foods like bread, beer, and salad oils, paper products, building materials and animal bedding, textiles, auto parts, housewares, and sporting equipment. Industrial hemp is poised to be a “new” cash crop and market opportunity for Vermont farms that is nutritious, versatile, and suitable for rotation with other small grains and grasses

Industrial Hemp Planting Date X Variety Trial

Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and reemerging worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The crop produces a valuable oilseed, rich in Omega-3 and other essential fatty acids that are often absent in western diets. When the oil is extracted from the seed, what remains is a marketable meal coproduct, which is used for human and animal consumption. The fiber has high tensile strength and can be used to create cloth, rope, building materials, and even a form of plastic. For twenty years, U.S. entrepreneurs have been importing hemp from China, Eastern Europe and Canada to manufacture travel gear, apparel and accessories, body care and cosmetics, foods like bread, beer, and salad oils, paper products, building materials and animal bedding, textiles, auto parts, housewares, and sporting equipment. Industrial hemp is poised to be a “new” cash crop and market opportunity for Vermont farms that is nutritious, versatile, and suitable for rotation with other small grains and grasses