Search Results (18)

According to the global strategy of Green course, the production of sustainable textiles using different biodegradable fibres has immense potential for the development of sustainable products. Using one of the most sustainable biobased pure hemp and polylactide fibers yarns, four new biodegradable three-layer weft knitted fabrics with good thermal comfort properties were developed. The inner layer (worn next to the skin) and the middle layer of the knits were formed of hydrophobic polylactide fibers, the outer layer of different amounts (36–55%) of hydrophilic natural hemp fibers. Biodegradable polylactide fiber yarns were used as a replacement for conventional petroleum-based synthetic fibers. Natural hemp fibers are one of the most sustainable fibers derived directly from Cannabis sativa L. plants. The properties of the knitted fabrics were analysed and compared under thermoregulatory-moisture management, thermal resistance, air and water vapour permeability-properties. The results showed that all newly developed knits are ascribed to ‘moisture management’ fabrics according to the summary grading of all indices of moisture management parameters. In addition, it was found that the highest overall moisture management capability is related to the quantity of natural hemp fiber composition in different knitting structures. Based on the overall moisture management capacity (OMMC) index and thermal resistance values of developed knitted fabrics, the performance levels for these materials contacting the skin and intended for the intermediate layer were determined. Full article

In this study the influence of fabric weave (plain, twill, and panama) and weft type (flax and hemp yarns) on selected mechanical and comfort properties of six fabrics was analyzed. The results showed that tear and abrasion properties were most affected by the weave. The tensile properties of the linen fabrics were not significantly different when weft hemp yarns were used instead of flax. Fabrics with the same weave seemed to be equally resilient to abrasion regardless of the type of weft. By contrast, the hemp weft yarns favorized the physical and comfort properties of the investigated fabrics. For the same weave, the hemp–linen fabrics were slightly lighter and exhibited lower bulk density, significantly larger air permeability, and improved moisture management properties. Although the results of maximum thermal flux (Qmax) suggested a cooler sensation of the linen fabrics with panama and twill, the hemp–linen fabric with a plain weave seemed to be the optimal choice when a cool sensation was desired. Higher thermal conductivity values also suggested slightly better heat transfer properties of the hemp–linen fabrics, and these were significantly influenced by the weave type. The results clearly indicated the advantages of using hemp for improving physical and specific comfort properties of linen fabrics. Full article

Recyclable yarn has become increasingly significant because of growing environmental consciousness and the necessity to acquire or enhance the qualities of woven materials in the years to come. A cotton yarn’s tensile strength, rip strength, and permeability to air were examined to obtain the intended outcomes. The experiment was carried out on specimens with almost identical structures, and the impact of the weaving and various weft materials was evaluated. This endeavor aims to find the right blend or blends of regenerated fibers to substitute 100% cotton garments. The mechanical strength and physiological characteristics of Tencel textiles mixed with other regenerate cellulose yarns were compared to those of 100% cotton to attain the same or possibly superior end qualities. Thus, cotton fibers, viscosity, Tencel, modal, and hemp were used. Standard thread counts of 20 tex were used to make mixed plain woven textiles made of 100% cotton and 50:50 mixes of Tencel with other regenerating materials. The ergonomic qualities, such as air permeability, and mechanical characteristics (tension and tearing assets, pilling, abrasion resistance, and warp- and weft-wise) were assessed. It has been discovered that textiles combined with Tencel perform better than cotton ones. Consequently, it may be said that 100% cotton textiles can be replaced with a Tencel combination, using these regenerating fibers. Full article

Historically, cotton has been regarded as a highly sustainable material; however, thorough research indicates otherwise. The increasing levels of pollution and the need to address climate change have led towards a global search for sustainable alternatives. Plants with comparable chemical compositions, such as hemp, are attracting growing attention. The cultivation of hemp can be done with sustainable methods, thereby making it a viable alternative to cotton. This study investigates the mechanical, physical, and dyeing properties of 100% wet-spun hemp yarn in its natural and bleached state with the objective of incorporating its use in both technical and traditional textiles. Although significant academic literature is available on the properties of cotton, there is a noticeable lack of literature based on wet-spun hemp. This research suggests that the bleaching process positively affects wet-spun hemp yarn, thus making it suitable for use by the textile industries in various applications. Full article

This study investigates the influence of a hot press process on the properties of hemp fiber-reinforced organo sheets. Plain-woven fabric made from hemp staple fiber yarns is used as textile reinforcement, together with a recycled poly-lactic acid (PLA) matrix. Process pressure and temperature are considered with three factor levels for each parameter. The parameter influence is examined based on the B-factor model, which considers the temperature-dependent viscosity of the polymer, as well as the process pressure for the calculation of a dimensionless value. Increasing these parameters theoretically promotes improvements in impregnation. This study found that the considered recycled polymer only allows a narrow corridor to achieve adequate impregnation quality alongside optimal bending properties. Temperatures below 170 °C impede impregnation due to the high melt viscosity, while temperature increases to 185 °C show the first signs of thermal degradation, with reduced bending modulus and strength. A comparison with hemp fiber-reinforced virgin polypropylene, manufactured with identical process parameters, showed that this reduction can be mainly attributed to polymer degradation rather than reduction in fiber properties. The process pressure should be at least 1.5 MPa to allow for sufficient compaction of the textile stack, thus reducing theoretical pore volume content to a minimum. Full article

Plant fibres are promising candidates to replace synthetic fibres in polymer matrix composites. However, there is still an important issue to overcome: the poor quality of adhesion at the fibre/matrix interface. Many surface treatments of plant fibres have been developed, most of them based on non-environmentally friendly processes. In this paper, a 100% natural treatment is proposed. Hemp yarns are immersed in tap water until the natural growth of limestone beads attached to their surface occurs. The morphology analysis reveals that these calcium carbonate crystals have a nanoneedle architecture, with hemp fibres acting as nucleators for these highly ordered coral-like structures. Tensile tests on ±45° woven hemp/epoxy composites show that the presence of CaCO₃ beads improves the adhesion quality of the fibre/matrix interface and, therefore, increases Young’s modulus value. Full article

This paper aims to study the tensile behavior of a woven [0/90]₇ hemp/Elium composite after three different conditionings: “Ambient storage”, “Saturated at 60 °C” and “15 wet/dry cycles”. Instrumented repeated progressive tensile loading tests were carried out and showed an unexpected increase in the secant modulus for the aged samples at the end of the test. An in-situ micro-CT tensile test was then performed on a “15 wet/dry cycles” aged sample. The analysis of the tomographic images showed the damage development with interfacial debonding and matrix cracks in the specimen volume, and also the decrease in the curvature radius of the warp yarns during tensile loading facilitated by the plasticization of the resin. Finite element calculations were thus performed and demonstrated that the increase in the modulus is directly linked to the straightening of warp yarns, showing that the evolution of the modulus on a macroscopic scale can be explained by the deformations of the yarns on a microscopic level. These results allow us to better understand the mechanical behavior and the damage mechanisms that occur in biocomposites during tensile testing after water aging. Full article

Hemp is finding a strong renewal of interest in the production of fine fibers for garment textiles. This resource of long-line fibers would come as a complement to the highly demanded flax fibers, whose large production in the north-west of Europe cannot be extended. In Normandy, where a complete industrial value chain exists for flax, it is intended to adapt it to hemp, and this was demonstrated from the field to the scutched fibers with a complete value chain. In this region, early harvesting is necessary to leave enough time for dew-retting and permit dry storage of stems before mid-September. An early-flowering variety (USO-31) was harvested using dedicated hemp equipment to obtain a 1 m parallel and aligned windrow that can be further processed by flax equipment. The scutching process as well as the fiber’s morphological and mechanical properties were particularly studied. Adapted scutching process parameters with reduced advancing speed and beating turbine velocity led to long fiber yields of about 18% of the stem mass. Stem yields were reaching about 6 tons/ha leading to a production of 1.1 tons/ha of long fibers. The tensile properties of the long fibers were highly sufficient for textile applications, and their thickness after hackling was in the range suitable for the production of fine yarns. Compared to other crops grown in Normandy, the hemp as produced in this 2020 case study provides good incomes to the farmer, higher than traditional crops such as wheat or barley, and the results of this study should encourage farmers to grow hemp for textile purposes. Full article

Currently, there are increased interests in growing grain and fiber hemp (Cannabis sativa L.) as well as in large-scale hemp products. Cannabis has been grown/utilized for thousands of years as a fiber, grain, and drug/medicinal plant. However, the strict control of cannabis cultivation to combat illegal use, the spread of new yarns and oilseeds, and the advent of cheap synthetic fibers caused a decreased/eliminated hemp production. Hemp has been banned in most of the world for more than seven decades; it missed out on the Green Revolution and the adoption of new technologies and varieties, creating a knowledge gap. After the 2014 and 2018 Farm Bill in the USA, hemp became legal and the land grand universities launched research programs. The ability to utilize the entire plant for multiple purposes creates opportunity for the market to value hemp products. Hemp production technology varies depending on the type of hemp cultivated (grain, fiber, or cannabinoids), soil characteristics, and environmental factors. Hemp has the potential to be a very sustainable and ecologically benign crop. Hemp roots have a significant potential for absorbing and storing heavy metals such as lead, nickel, cadmium, and other harmful substances. In addition, hemp has been proven to be an excellent carbon trap and biofuel crop. Hemp has the ability to successfully suppress weeds, and it is generally regarded a pesticide-free crop. The purpose of this paper is to examine historic and recent industrial hemp (grain and fiber) literature, with a focus on hemp agronomy and utilization. Full article

FRCM is a strengthening system based on composite material made of a cementitious matrix and fabrics. This strengthening system has been studied and researched, obtaining analytical predictive models where it is common to assume full composite action between components. Through using non-typical materials for these composites, it has been seen that, in some cases, the previous assumption cannot be taken. In this situation, traditional analytical models such as ACK or tri-linear ones do not offer a reasonable prediction. This work researches the behavior of synthetic and naturally coated vegetal-FRCM with partial interaction through the characterization of the materials through tensile tests. Yarns, meshes and different FRCM coupons were manufactured and mechanically tested using different types of coatings and fabrics. The use of colophony and Arabic gum as natural coatings provided similar mechanical properties to the cotton and hemp yarns and meshes conformed. Partial interaction was found when using epoxy as a natural resin to coat the reinforcement while maintaining the mechanical properties in the same order of magnitude. A new two-stage model is proposed to fit stress–strain mechanical test, and it is reliable and accurate for cotton specimens. Full article

The objective of this work was to assess the possibility of dyeing a substrate composed of non-textile industrial hemp using natural dyes from common madder (Rubia Tinctorum L.) and calendula (Calendula Officialis) and tannin and alum as mordants. The substrate used for the dyeing had a 25/75 hemp/cotton composition. The hemp raw material is an agricultural by-product that was subjected to mechanical and chemical treatments in order to cottonize the fibers, blend them with cotton, and thus obtain first 40-tex open-end yarns and then a knitted fabric. The latter was subjected to different dyeing conditions by varying the dye, mordant, and method for its application, type of water, and rinsing after dyeing. Measurements of the difference (ΔE) and intensity (K/S) of color and fastness to washing and rubbing were carried out. The results showed that dyeing of a non-textile residual hemp substrate is possible, and that calendula is a good option for dyeing it with tap water, tannin-alum set in a meta-mordanting process, and rinsing after 24 h. In this way, a contribution has been made to the circular economy of the textile industry through the use of more sustainable sources and products. Full article

The composite group investigates endlessly the features of natural fiber/thermoplastic matrix composite materials to improve recyclability, use of renewable sources, and reduce material costs. In this context, the development and use of biodegradable polymers for composites is considered one of the important strategies for reducing environmental challenges. Here, axially oriented fibers incorporated in conforming matrices make up fiber-reinforced composites. Due to the high viscosity of molten Poly(ε-caprolactone) (PCL), impregnating into reinforced fiber strands is challenging. So, continuous hybrid flax and hemp fibers were produced using a braiding technique by considering the fiber aspect ratio (AR). The resulting braided yarns were parallel aligned with PCL filaments before being compression molded into unidirectional composite laminates. The flax and PCL blend had better mechanical properties than the other produced composites. Temperatures for the glass transition, melting, and crystallization, were much greater than for neat PCL. However, mechanical properties were barely altered due to the ductile nature of PCL. Full article

Over the last several decades, Cannabis sativa L. has become one of the most fashionable plants. To use the hemp potential for the development of a sustainable textile bio-product sector, it is necessary to learn about the effect of the processes creating hemp’s value chain on fibre properties. This review presents a multi-perspective approach to industrial hemp as a resource delivering textile fibres. This article extensively explores the current development of hemp fibre processes including methods of fibre extraction and processing and comprehensive fibre characteristics to indicate the challenges and opportunities regarding Cannabis sativa L. Presented statistics prove the increasing interest worldwide in hemp raw material and hemp-based bio-products. This article discusses the most relevant findings in terms of the effect of the retting processes on the composition of chemical fibres resulting in specific fibre properties. Methods of fibre extraction include dew retting, water retting, osmotic degumming, enzymatic retting, steam explosion and mechanical decortication to decompose pectin, lignin and hemicellulose to remove them from the stem with varying efficiency. This determines further processes and proves the diversity of ways to produce yarn by employing different spinning systems such as linen spinning, cotton and wool spinning technology with or without the use of the decortication process. The aim of this study is to provide knowledge for better understanding of the textile aspects of hemp fibres and their relationship to applied technological processes. Full article

Hemp and flax fibers are among the most interesting vegetable fibers that can be used to reinforce polymeric matrices. In line with the global environmental requests, the use of these fibers especially coupled with thermoforming polymers are increasing more and more in order to expand their applications and replace synthetic fibers and thermosetting plastics. However, one of the major limitations of vegetable fibers is their poor adhesion with polymeric matrices that is often overcome by fibers chemical treatments or by using coupling agents within the matrix. Aiming to produce polypropylene (PP) bio composite laminates reinforced by hemp and flax fibers without additional process steps, this paper deals on the study of their production via the compression molding technique by using woven fabrics characterized by a large mesh size able to ensure a mechanical anchoring between fibers and matrix. Two different forming strategies that differ in the time required for reaching the maximum values of compression pressure and in the dwelling time at this value were used in order to investigate how the yarn impregnation was affected by them. To expand the applications of composites under investigation, tensile, bending, Izod, heat deflection temperature (HDT) and bearing tests were carried out. The results highlighted how the use of a waiting time before the reaching of the maximum moulding pressure allowed a better matrix flow within the vegetable yarn leading to higher mechanical performances. Full article

The present work investigates the potential of developing bio-composites based on thermoplastic polymers reinforced with natural fibres by using hybrid yarns. The hybrid yarns were produced by the wrapping technique, in which a multifilament of polyamide 11 (PA11) was wrapped around an untreated low-twisted hemp roving to produce a yarn with sufficient tenacity and stiffness for the next step of weaving. The tensile behaviour of the wrapped yarns was identified both in the dry- and thermo-state. Then, two different fabrics were woven and tested to study the influence of yarn densities and weave diagrams on the tensile and flexural properties. At this fabric scale, properties of fabrics made from hybrid yarns were compared with those of fabrics from a previous study made from 100% hemp roving. Composites made from these fabrics, with stacking of two cross-plies, were produced by thermocompression and characterised regarding mechanical strength. Full article