HEMP FIBRE FOR HIGH-QUALITY APPLICATIONS

La fibra di canapa europea è l'unica fibra naturale con una certificazione di sostenibilità. La qualità della fibra è influenzata principalmente da genotipo, tecniche agronomiche, epoca di raccolta e metodo di macerazione. L'obiettivo principale della tesi è delineare le pratiche agronomiche e di post-raccolta per migliorare l'estrazione e la qualità della fibra, con particolare attenzione alla produzione di canapa multiuso ritardando la raccolta fino alla maturazione dei semi. Le prove di densità, fertilizzazione azotata e varietali sono state condotte in differenti ambienti Europei. La procedura di decorticazione standardizzata è stata confrontata con la linea longitudinale di estrazione della fibra per applicazioni di alto valore aggiunto. I test su bio-compositi di canapa sono stati effettuati con fibra pettinata per confrontarne le proprietà tra genotipi, epoca di raccolta e metodi di macerazione. I risultati di questa indagine suggeriscono che i) la densità di semina e la concimazione azotata ottimale sono tra 90-150 piante m-2 e 30-60 kg N ha-1; ii) le nuove varietà dallo stelo giallo presentano un'alta efficienza di decorticazione e una ridotta contaminazione da canapulo nella fibra, iii) la fibra di canapa, con proprietà comparabili a quelle del lino, si è dimostrata adatta per applicazioni in compositi di alto valore.European hemp fibres are the only natural fibre with an established sustainability certification. Hemp fibre quality is affected by genotype, agronomic techniques, harvest time and retting method. The main objective of this thesis is to outline the agronomic and post-harvest practices for improved fibre extraction and fibre quality, with special attention to multipurpose hemp production delaying the harvest from the flowering stage until seed ripening is complete. Planting density and nitrogen fertilization trials and variety trials were conducted in contrasting environments in Europe. Stems were decorticated following a standardised procedure and longitudinal hemp line for textile and high-added values application was compared with lab-scaled decortication. Impregnated fibre bundle tests were carried out with hemp hackled fibre bundles to compare composites and back-calculated fibre properties between genotypes, harvest times and retting methods. Results of this investigation suggest that i) optimum plant density and nitrogen fertilization are between 90 and 150 plants m-2 and 30 and 60 Kg N ha-1 respectively; ii) new yellow stemmed varieties are characterized by high decortication efficiency and relative high cleanness of the extracted fibre and iii) long hemp fibre, having properties comparable to those of flax, proved to be suitable for high-tech composites applications

Study of solutions to optimize the extraction of hemp fibers for composite materials

Fibres from hemp stems can be extracted through different mechanical processes following dew or water retting etc. Extraction processes generally have a significant impact on mechanical and morphological properties of the fibres. In this study, hemp fibres are extracted following three different ways. In the first route hemp fibres are extracted from FUTURA 75 variety stems by performing scutching, hackling and microwave degumming. A second batch of fibres of the same variety was extracted by scutching and hackling after an initial microwave degumming treatment. In the third route, the same variety of hemp fibres are extracted from dew retted stems grown at Piacenza (Italy). Finally, the mechanical properties of single fibres as well as the fineness of technical fibres of all types of extracted fibres are evaluated and compared and the interest of the microwave degumming for hemp stem is evaluated

Comparing flax and hemp fibres yield and mechanical properties after scutching/hackling processing

Increasing the production of high-performance natural fibres that minimise their impact on the environment is a challenge that flax (Linum usitatissinum L.) cannot address alone. In flax traditional production territories, hemp (Cannabis sativa L.) can be a complementary source of high added value fibres if their yield of long line fibres can be maximised to levels equivalent to the one of flax. The objective of the present work was to establish process parameters maximising the long line fibre yield using flax dedicated scutching and hackling devices. A lab-scale scutching/hackling device was used to establish sets of process parameters which best improve the long fibre scutching yield and as a consequence minimise the production of tow fibres. Decreases in straw processing transfer and beating speeds during scutching were necessary so that to be less aggressive on the straw and fibres. Very high long fibre yields were obtained after scutching and hackling at the laboratory scale (18 % of the hemp straw mass). These very high results, combined to high straw yield production in the field indicate that hemp can be a very productive source of high-performance fibres as these ones showed tensile properties completely suitable for a textile use as well as for load bearing composite materials. If the potential of high production yields and high mechanical and morphological properties was demonstrated at the lab-scale, this one should be improved at the industrial scale. Suggestions to reach this goal are provided to prevent too high transformation of long fibres into tows and to keep the mechanical potential maximum. When using optimised parameters and a lab-scale scutching/hackling device, it was demonstrated that hemp has the potential for providing equivalent amounts of long fibres per hectare than flax with tensile properties about 20 % lower than the ones of flax

Management of patients with early-stage colon cancer: guidelines of the Italian Medical Oncology Association

About 75% of colorectal cancers are diagnosed as early stage, in which radical surgery is achievable. In the last decade, in Italy, the overall incidence of colorectal cancer has remained stable, while mortality gradually decreased, which is attributable to early diagnosis and improved medical, surgical and locoregional treatments. The Italian Medical Oncology Association formulated guidelines to manage early-stage colon cancer, including screening, diagnosis, treatment and follow-up, which we herein present

Hemp Sowing Seed Production: Assessment of New Approaches in North-Italy

Bottlenecks occur as the cultivated area increases and the inappropriate mechanization methods hinder the stable supply of seeds for hemp multiplication. Moreover, the seeds ripen scalarly, and a timely stabilization is required to impede a germinability reduction. The study coupled the delayed sowing of a non-specific hemp variety to a harvesting system allowing for the collection of seeds with other threshing fractions. The final goal was the identification of an innovative route integrating agronomic and mechanical aspects for the improvement of the supply chain of seed production. To this aim, harvesting trials were carried out on the variety Futura sowed at the end of June in North Italy and were collected with a combine equipped with a separator developed for the recovery of threshing residues. The shortening of the growth cycle did not affect the plant height (173 cm on average). The effective working time of the combine was 57% of the total working time and the field efficiency was 1.14 ha h−1, a good performance considering that in our work the seeds was threshed simultaneously to the harvest operation. Seed losses were found to be mostly at the expense of the mowing and threshing system (sector B) but remained below 5%. The separation system allowed for the rescue of 492.20 kg ha−1 (DW basis) of high-value threshing residues

Optimizing Hemp Fiber Production for High Performance Composite Applications

Hemp is a sustainable and environmental friendly crop that can provide valuable raw materials to a large number of industrial applications. Traditionally harvested at full flowering for textile destinations, nowadays hemp is mainly harvested at seed maturity for dual-purpose applications and has a great potential as multipurpose crop. However, the European hemp fiber market is stagnating if compared to the growing market of hemp seeds and phytocannabinoids. To support a sustainable growth of the hemp fiber market, agronomic techniques as well as genotypes and post-harvest processing should be optimized to preserve fiber quality during grain ripening, enabling industrial processing and maintaining, or even increasing, actual fiber applications and improving high-added value applications. In this paper, the effect of genotypes, harvest times, retting methods and processing on the yield and quality of long hemp for wet spun yarns was investigated. Conventional green-stem varieties were compared with yellow-stem ones on two harvesting times: at full flower and seed maturity. Scutching was performed on un-retted stems and dew-retted stems, the un-retted scutched fiber bundles were then bio-degummed before hackling. Both scutching and hackling was performed on flax machines. Quality of hackled hemp, with particular reference to its suitability for high performance composites production, was assessed. The results of fiber extraction indicate that yellow-stem varieties are characterized by higher scutching efficiency than green-stem varieties. Composites strength at breaking point, measured on specimens produced with the Impregnated Fiber Bundle Test, was lower with hemp obtained from stems harvested at seed maturity than at full flowering. On average, back-calculated fiber properties, from hackled hemp-epoxy composites, proved the suitability of long hemp fiber bundles for high performance composites applications, having properties comparable to those of high quality long flax