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Following their mechanical extraction, the fibers coming from the banana pseudo-stem are coarse and the inter fiber cohesive substances need to be removed before their transformation into textile y...

Antiviral textiles are one of the most promising areas of protective textiles. Antiviral textiles are important in the field of health and hygiene. They become an essential part of our daily-life when a pandemic situation arises. The present paper critically analyses and summarizes various researches of the production of antiviral textiles. Different classes of the virus, how the virus transmits and replicates, various antiviral agents for textiles and their working mechanism, and the application procedure of various synthesized and bio-based antiviral compounds on textiles have been discussed in this paper. Finally, the present paper compares the existing antiviral finishing on textiles in terms of its effectiveness, durability and skin-friendliness and, following that, discusses the possibilities of using antiviral textiles in various sectors.

Resistance to impact thrust is one of the most important requirement along with many others for defining suitable applications of any composite materials. In this present work, the influence of composite architecture and composite interfacial bonding strength on the impact performance of flax reinforced PP composites have been investigated. In this regard two different composite architecture through conventional film stacking method and through DREF (DR. E. Fehrer open-end friction spinning process) yarn consolidation method have been produced and to alter the fibre–matrix interfacial bonding the flax fibres are treated with MAgPP (Maleic Anhydride grafted Polypropylene). Finally, the notch Izod impact behaviour of all composite samples are evaluated and compared.

Recycling of thermoplastic composites has drawn a considerable attention in the recent years. However, the main issue with recycled composites is their inferior mechanical properties compared to the virgin ones. In this present study, an alternative route to the traditional mechanical recycling technique of thermoplastic composites has been investigated with the view to increase mechanical properties of the recycled parts. In this regard, the glass/polypropylene laminate offcuts are cut in different grain sizes and processed in bulk form, using compression moulding. Further, the effect of different grain sizes (i.e., different lengths, widths and thicknesses) and other process-related parameters (such as mould coverage) on the tensile properties of recycled aggregate-reinforced composites have been investigated. The tensile properties of all composite samples are tested according to ISO 527-4 test method and the significance of test results is evaluated according to Student’s t-test and Fisher’s F-test respectively. It is observed that the tensile moduli of the recycled panels are close to the equivalent quasi-isotropic continuous fibre-reinforced reference laminate while there is a noteworthy difference in the strengths of the recycled composites. At this stage, the manufactured recycled composites show potential for stiffness-driven application.

International audience; Retting of fibrous plants such as flax is an essential step in the extraction of fibre bundles and their transformation into textiles and reinforcement fabrics for use in garments and composites. Dew-retting is traditionally performed from Northwest France to the Netherlands, as the climate is highly favourable for this process. Hemp is a plant that can be grown almost all over Europe with a low environmental impact. A retting step is also required to facilitate the separation of the hemp fibres before their transformation into textiles for garments or for 1D to 3D reinforcement composites, which requires thoroughly separated fibres. Dew-retting is currently used in flax production zones. The present work demonstrates that dew retting can be conducted under different climates on different soils, from dry Mediterranean environments up to the cooler regions of eastern France. If the ternary combination of moisture, temperature and solar radiation is appropriate, field retting (dew-retting) can be as short as about three weeks. In less favourable conditions, such as in dryer areas or when retting is performed late in the season after seed maturity (cooler temperatures), it lasts longer, but it can reach suitable levels. When conducted with care and with proper monitoring of the retting level, the dew-retting process does impact neither the tensile properties of elementary hemp fibres (by degrading crystalline cellulose I) nor the tensile properties of unidirectional and injected composite materials. Consequently, if extracted with a suitable process such as scutching and hackling, fibres suitable for load-bearing composites can be produced from dew-retted hemp stems produced in a wide range of climates and locations, therefore not limited to the conventional “dew retting zone” of flax production areas.

The main objective of this work is to study the effect of composite architecture on the mechanical properties of flax reinforced polypropylene (PP) composites. In this context, two different hybrid yarn structures using flax and polypropylene (PP) fibres have been produced; one, through the friction spinning method and the other through thermal bonding of blended roving. The friction spun yarn (FSY) has a core-sheath type of yarn structure, whereas the thermally bonded roving (TBR) has a blended flax/ PP distribution in its structure. The flax content in both yarn structures is varied at 40 wt. %, 50 wt. % and 60 wt. %, respectively. Further, these hybrid yarns are consolidated to fabricate unidirectional composite samples and the resultant composites are tested accordingly. It is observed that the tensile and flexural strengths of all composite specimens increase with increasing flax content. While the impact strength of FSY-compressed composite decreases with increasing flax content and in case of TBR-compressed composite, it increases with increasing flax content. At constant flax content, the TBR-compressed composites demonstrate better tensile, flexural and impact properties than FSY-compressed composites.

In the present work, a novel, flax-polypropylene (PP) based twist-less, thermally bonded, flexible roving has been produced in a specially designed machine. Fibres in the roving are highly ...

International audience; 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.

In the present study, two distinguishable unidirectional composite structures have been produced using compression molding technique. Among these two, one is made through conventional film stacking (FSC) method while the other structure is made after consolidating the DREF spun hybrid yarns (DYC). In both cases, low twisted, MAgPP treated flax yarns are used as reinforcement and polypropylene (PP) is used as matrix. Effects of fibre content on both composite structures are studied at 40%, 50% and 60% flax contents respectively. It has been observed that irrespective of composite structure, the tensile and flexural properties of the composite samples increase with increasing flax content but the impact strength decreases with increasing flax content. However, at constant fibre volume fraction, the DYC composites demonstrate better properties than the FSC composites. This is mainly due to better fibre-matrix distribution and lower void content of the DYC composites than the FSC composites.

In the present work, the influence of interface and hybrid yarn structure on flax-PP based unidirectional composite properties have been studied thoroughly. Flax-PP based core-sheath structured DREF spun hybrid yarns are manufactured after varying the core yarn twist and sheath percentage at three different levels and using MAgPP treated and untreated flax yarn as core. These hybrid yarns are consolidated to manufacture unidirectional composite samples and the resultant composites are tested accordingly. It is observed that MAgPP treatment of the core flax yarn improves the tensile and flexural properties of the hybrid yarn reinforced unidirectional composites while impact strength decreases after the treatment. A negative impact on the tensile and flexural properties of the unidirectional composite samples is observed with increasing core twist and sheath content of the reinforcing hybrid yarn. The impact strength of the composite samples increases for similar changes in hybrid yarn parameters.

In this present study, thermally treated flax–polypropylene (PP) based hybrid yarns have been manufactured using DREF-3 spinning method for thermoplastic composite reinforcement. The effect of different process parameters such as core yarn twist level, sheath ratio and thermal treatment temperature on hybrid yarn properties has been studied thoroughly using Box–Behnken design. The DREF-3 spun hybrid yarn for composite reinforcement is optimized based on weavability performance, tensile behaviour and flexural rigidity. Further, degree of resin penetration inside DREF yarn-based unidirectional composite structures and their tensile properties are taken as parameters to judge the quality of composite. It has been observed that increase in sheath ratio, surface treatment temperature and decrease in core twist level resulted in enhancement of weavability of hybrid yarns and also in improvement in resin penetration inside composite structures.

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.

Flax-PP based thermally bonded roving (TBR) has a unique structure where the flax fibres remain twist-free and fully aligned along the roving axis. The present study describes an experimental investigation on the low velocity impact (LVI) behaviour of the TBR based woven fabric composites and compares the same with plain woven glass fabric reinforced PP composites (GRPC). Two different fabric architectures namely plain woven (PW) and unidirectional (UD) are fabricated using flax/PP based TBR. These TBR based woven fabrics and the glass fabric/PP sheets are consolidated in a compression moulding machine and the resultant composite-laminates are tested for their LVI behaviour. The impact test results revealed that the glass/PP composites absorb more energy and exhibit a higher peak load than both TBR based PW and UD fabric composites. However, the specific load and energy of all flax/PP composites are higher than the glass/PP composite. The damage tolerance of all composite laminates are evaluated by comparing their flexural strength before and after the impact. It is observed that the proportionate loss in flexural strength due to impact thrust is larger in case of glass/PP composites than all flax-PP composites.

In this review article, different approaches of enhancing flame retardancy of polymeric composite material and their effect on different composite properties are analysed critically. The mechanisms of fire spreading on composite materials are also discussed. Flame retardancy of polymeric composite material can be enhanced either by enhancing the fire performance of constituents of composite i.e. matrices and reinforcing agents or by providing a protective flame retardant (FR) coating around the composite material. Fire performance of reinforcing material is improved by treating with FR-chemicals while the fire performance of polymer matrices can be improved by incorporating micro and nano FR-fillers or by introducing FR-compound into polymer backbone. The flammability of micro and nano filler added polymeric composites and newly developed polymer derivatives and their effect on composite properties like mechanical, thermal have been discussed. However, the development of flame retardant polymer composite is still at nascent stage and for further development, it is necessary to work on the development of non-health hazardous, environment friendly flame retarding agents which will be able to enhance the fire performance of composite materials at very low concentration levels.

Natural fibre reinforced thermoplastic composite materials are becoming very popular in the material community due to several advantages of natural fibre and thermoplastic polymer. The demand of stronger and better composite than the existing ones is also increasing simultaneously with their growing popularity. However, natural fibre reinforced thermoplastics have some disadvantages associate with the poor fibre-matrix interaction, short length of the natural fibres and high melt viscosity of thermoplastic resins. All these factors decrease the ultimate mechanical properties of the natural fibre composites. However, the surface treatment of natural fibres, use of low twisted yarn and hybrid yarn during composite manufacturing significantly improve the mechanical properties of the natural fibre composites. The scope of all three approaches in determining composites mechanical properties have been reviewed here. Finally, the combined effects of interface and DREF spun hybrid yarn structure on the tensile and flexural properties of flax-PP based unidirectional composite specimen have been discussed in this chapter.

In the present study, an attempt has been made to convert sericin into film form and further make it insoluble by forming sericin–aluminum metal complex using alum salt, which may lead to some extent of cross-linking. After complex formation sericin becomes insoluble in warm water as well as thermal stability and tensile strength improves significantly with increasing alum content. Metal complexed sericin films show good antimicrobial property and both the pure and alum modified sericin (AM-Sericin) films show a very good oil barrier property. But after complex formation moisture content and swelling percentage of sericin film decreases quite significantly with increasing aluminum concentration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41400.