Application of Natural (Plant) Fibers Particularly Hemp Fiber as Reinforcement in Hybrid Polymer Composites - Part II. Volume of Hemp Cultivation, Its Application and Sales Market

ABSTRACT The paper is a second part of a multi-aspect analysis of whether it is feasible and practical to use (plant) natural fibers processed into fabrics and mats as homogeneous or hybrid reinforcement in polymer composites used in various industrial sectors. The paper presents the volume of hemp cultivation worldwide, in Europe and in Poland 2016–2022. It also sets out the percentage share of hemp application in nine industrial sectors. The presented statistics includes total volume of industrial hemp stalks market, which is a by-product of hemp farming in the main geographical regions of the world and in Poland. The paper gives examples of current sales of hemp at the USA market, with sales until 2022. The paper discusses the possibility of using industrial hemp as “noble reinforcement that is fully recyclable” of a new generation of polymer structural composites which can be applied in modern sectors of bulky structures, including sea-going vessels.


Introduction
EU stringent ecological recommendations on environmental protection and sustainable development require producers to replace synthetic materials that are not biodegradable with composite materials that would quickly break down naturally or which can be utilized using energy recycling methods.Several fibrous plants have been thoroughly examined over the past decades: jute, flax, ramie (Chinese grass), coir (outer husk of coconut), hemp, abaca/manila (fiber obtained from bananas), sisal (a species of Agave native to Mexico), kenaf (Hibiscus cannabinus), bagasse and bamboo.Many of their products are used in various industrial sectors, including textile, chemical (everyday products), automotive industry (reinforcement in polymer composites), machine, arms, civil engineering and energy industries.By contrast, plant fibers have so far had little use in the aerospace industry and, in particular, in the ship-building industries.
On the ground of thorough analyses of chemical, physical and mechanical properties of plant fibers and their examination in agricultural, ecological and economic terms we singled out one plant that would meet all various requirements (Scheibe, Urbaniak, and Bledzki 2023).It is hemp, also known as industrial hemp.It is cultivated in over 50 countries in various parts of the world for food, seeds, fiber and shives, which find various applications in different industrial sectors.The last six years have witnessed a steady increase of hemp production which has many (a minimum of 25,000) applications in many branches of industrial production.

Volume of industrial hemp production in the world, Europe and Poland
The main hemp-producing countries are located in Asia (China, India, South Korea, Mongolia and to a lesser degree Thailand and Japan), North America (Canada and USA), South America (Brazil) and Europe (France, Lithuania, Poland, Estonia, Italy, the Netherlands, Romania, Germany and to a smaller degree Austria, Denmark, Czech Republic, Croatia, Slovenia and Belgium).China is the leader of hemp agriculture in Asia (114,000 ha in 2022).Canada heads American market (137,000 ha in 2022) while France is the largest European producer (42,100 ha for 70,200 ha grown in Europe in 2022) (Global Industrial Hemp Market Report 2022).
According to data in 2022 published by EIHA, China (Asia), Canada, USA and Europe accounted for approximately 29.1%, 35.0%, 6.6% and 17.9% of the world's production of all hemp.Over the five (2016-2022) years, these parts of the world have seen a systematic increase of demand for hemp products (Figure 1).The most conducive conditions for industrial hemp production can be found in France, Italy, the Netherlands, countries along the southeast parts of the Baltic Sea (Lithuania, Estonia and Poland), Romania and Germany.When EU changed its policy on diversification of farming products, these countries started to increase the volume of industrial hemp cultivation (Figure 2) to use hemp products in many industrial sectors.
Between 2016 and 2022, France was the European leader of hemp production (according to EU data from 2022), with their farming volume accounting for approximately 30.5% of all European production.Over the last three years, there has been a fast (69.5%) but not evenly distributed increase of industrial hemp production in EU countries.The fastest growth was recorded in Lithuania, Estonia, Italy, the Netherlands, Romania and Germany (Figure 3).The slower growth in Austria, Latvia, Croatia, Finland, Czech Republic, Bulgaria, Denmark, Ireland, Slovenia and Belgium was shown in Figure 3 as the others EU countries.Hungary and the UK are also large industrial hemp producers.However, no data is available in public data sources.In 2012, Poland farmed industrial hemp on only 530 ha.During the two successive years, the figure went down to 107 ha.Owing to changes in European farming subsidy system, there was a sudden increase of hemp cultivation since 2015 up to 6,777 ha in 2017.The area of hemp cultivation decreased in 2018 and 2020 by approximately 7% and 8%, respectively.It was due to lower subsidies for hemp cultivation: 572.00 PLN for 1 ha in 2015 compared to only 127.16 PLN for 1 ha in 2020, i.e. 22.2% of the initial subsidy.The forecast increase of the area of hemp production up to 6,370 ha in 2022 (Figure 4) accounts for increasing technological possibilities of processing industrial hemp stalks into homogeneous and long fibers and into yarn (Pokora-Kalinowska 2020).

Application of industrial hemp in industry
Jack Herer, an American enthusiast of Cannabaceae plant family and one of the world's most knowledgeable people on the subject, demonstrated that hemp is an exceptional fibrous species that can produce seeds, fibers and shives (Herer 1992).According to Renée Johnson, the world's hemp market involves over 25,000 introduced hemp applications in nine industrial sectors, including textile, medical, personal hygiene (medicinal, pharmaceutical, cosmetic and hygiene products), food, agriculture (seeds and animal care), pulp and paper, automotive industry (biofuels, renewable energy, biocomposites), civil engineering (building materials), furniture and other industries (Johnson 2018).Based on available publications on hemp industry and based on thorough analysis of hemp application in social, technological, economical and legal terms in the nine main industrial sectors, a compilation of hemp share in the world's market was made taking 2022 data as the benchmark (Figure 5).
As shown in Figure 5, the largest share of hemp application is for textile industry (22.8%) and food and personal hygiene sectors (slightly over 17.7% and 19.7%, respectively).The animal care industry takes about 13.3%.These sectors cover a total of approximately 73.5% of hemp application which shows their role in human and animal lives worldwide (Report 2023).A thorough literature review over the period of last decade and analysis of hemp properties were used to produce a compilation of  hemp application in ten selected industrial sectors (Table 1) (Freedom 2019;PILiK 2020;Promhuad et al. 2022;Strzelczyk 2018;Świechowska 2019;Szymek 2014;Tarnowski 2018a).

Total industrial hemp market volume in the world
The hemp market volume of hemp understood to be a fibrous plant common in various parts of the world is discussed in terms of final product value, with applications in generic industrial sectors in line with even more stricter environmental legislation.To comply with the regulations, the final product must be 100% biodegradable.Analyses on worldwide hemp market in our opinion are carried on four main economy segments: agriculture (cultivation volume, crop yield in a defined geographical region of the world), industry (ability of the plant's industrial use to produce given market products in terms of their production cost), consumption (supply and demand of products in nine generic industrial sectors) and environmental protection (ability of a product to be fully decomposed/utilized after its life cycle is completed).
During the 2010s, many scientific-research centers all over the world processed their local data and analyzed technological trends for most continents and countries of: North America (USA, Canada), Europe (the UK, Germany, France), Asia-Pacific (China, India, Japan), North and South America (Brazil), Middle East and Africa.Biomass figures given in analyses of industrial hemp straw are proportionally correlated to the amount of useful waste processed for energy generation purposes.Figure 6 shows the size of the industrial hemp straw market, and thus biomass production in thousands of tonnes, in the main geographic regions of the world in 2016-2022 [China (274-798) [China (274-798), USA (416-180), Canada (260-1067), Australia-Egypt-India . . .(259-314), Europe (253-491)].The total increase worldwide was 1462-2850.
The Polish market of industrial hemp straw between 2012 and 2022 (predicted data) rose quickly starting from 2015 to 2017.2017 was the peak with 47,44 tonnes of hemp biomass.The slight decrease of 2018 and 2022 was due to changes in hemp cultivation area (Figure 7).
The wide-ranging alternative use of industrial hemp in generic industrial sectors (Table 1) is mainly owing to their extraordinary chemical, physical and mechanical properties.This correlates with constant increase of their application in manufacturing new generations of plastics, including polymer composites.Statistical analysis of developmental trends conducted mainly in North America (USA and Canada) between 2018 and 2019 in terms of micro-and macro-economic area of supply and demand for hemp and intermediate products confirmed a steady, long-term increase of consumer demand for industrial hemp products (Report 2023).Total sales of hemp food and medicinal products in the USA where hemp market is very developed constituted almost a half of 320 million US dollars of the total hemp product sales in 2013.For example, the volume of hemp in the USA, by product, over the last ten years increased by almost 430% in 2022 (Figure 8).
"2018 Hemp Farming Act" removed hemp from illegal crop list at the federal level and enabled farmers to grow it in all US states.In early 2022, the hemp volume widening in the USA, by product, in million US dollars between 2016-2022 was developed (Figure 9).
Analysis of the three main products, i.e. seeds, fiber and shives, hemp market (Figure 9) in the USA and in other geographical regions of the world, shows that between 2016 and 2022 seeds account for 63% of the total market.Over the same 7 years, hemp fiber constituted 32% and shives only 10% of the total market.

Development of structural polymer composites reinforced with natural (plant) fibers in industrial applications -overview
The wide variety of fibrous crops cultivated for over five thousand years would certainly provide ample opportunity to use them in a number of ways in many sectors of industry.Hemp, in particular, can find many applications owing to its resistance to putrefactive processes.Hemp has been commonly used to produce: textile fibers (fabrics, including structural fabrics), ropework (nets, trawls, different types of rope), green fibers produced following decortication of industrial hemp stalks (mats and insulation materials) (Freedom 2019).No.

Generic industrial sectors that make use of industrial hemp
Properties and application of industrial hemp 5.2.4.Non-wood paper for wound dressing 5.2.5.
Biofuels and renewable energy 6.1.1.
Second-generation biofuels (hemp fuel used as replacement of oil) 6.1.2.
Composite materials for car interior 6.2.2.
Composite materials for car chassis 6.2.3.
Composite materials for public transport vehicle bodies 6.2.4.
Interior elements of vessels 7.
Materials used for prefabricated bulky elements 8. Furniture 8.1.
Mats and upholstery filling material 9.
Hot house growing medium 9.2.
Road building materials 9.4.
Composite interior design materials for rail vehicles 9.5.
Hemp essential oil used as insect repellent Research conducted in the USA in the 1910s/1920s on the application of natural fibers as the alternative reinforcement of construction polymer composite led to the creation of fully recyclable composite material with application in many components used in the automotive industry.At the end of the 1920s in Germany, the Saxon car company Dampfkraftwagen (DKW) in Zschopau started producing passenger cars.Due to the significant increase in the production of these relatively cheap and popular cars and the growing problems with elements made of plastic reinforced with a filler in the form of ground wood waste, in the years 1955-1959 in the GDR, the VEB Automobilwerk Zwickau factory produced AWZ P70 cars based on the technological solutions of the previously produced DKW F8 car, the successor of which in the following years until 1991 was the TRABANT P50.The Germans added a filler in the form of compressed cotton products and cotton post-production textile waste to the composite resin (Sonntag and Barthel 2002).Meanwhile, in North America (USA), at the turn of the 1930s/1940s, in the factories of Henry Ford, engineer, entrepreneur and founder of the Ford Motor Company, was created a prototype of a passenger car made of a polymer composite reinforced with a mixture of paper and soybean shells.The cooperation between Henry Ford and the botanist George Washington Carver led to the creation of a fully functional and the first ever car made from hemp and soybean shells.The automobile was driven with bio-fuel made from industrial hemp.The prototype was presented to the public on 13 August, 1941, i.e. over 80 years ago (Suddell and Evans 2005).
Research conducted at the turn of 20 th c. in Europe, e.g. in Germany (wide-ranging studies at University of Kassel (Bledzki, Gassan, and Lucka 2000;Specht 2007;Specht and Bledzki 2007;Specht et al. 2002Specht et al. , 2004Specht et al. , 2006) ) or Poland (mainly at Institute of Natural Fibers and Medicinal Plants in Poznan (Kaczmar and Pach 2007;Kozlowski 2012;Kozlowski, Wladyka-Przybylak, and Kicinska Jakubowska 2008;Zimniewska, Wladyka-Przybylak, and Mankowski 2011), mainly concerned the possible application of natural (plant) fibers, including hemp fibers, in industrial use.Industrial hemp was investigated as a possible replacement of mineral (glass) fibers in automotive industry.
Particular attention in Europe and USA was paid to thermoplastic composite materials commonly used to fit road vehicle interiors.One of the trends in the area of designing structural polymer composites developed in the 1990s was research into applications of polymer reinforcing materials such as wood flour and natural fibers, i.e. cotton, jute, kenaf.In Poland, the trends focused mainly on commonly available flax and marginally accessible hemp (Kaczmar and Pach 2007;Specht 2007;Specht and Bledzki 2007;Zimniewska, Wladyka-Przybylak, and Mankowski 2011).
The research showed that replacement of mineral (glass) fibers with natural (plant) fibers (flax, hemp, less often kenaf, sisal, wood) decreased composite density and mass by approximately 54-56%, given insignificant reduction of mechanical properties.Thermoplastic composites reinforced with natural fibers were demonstrated to have much greater ability to absorb impact energy, had no dangerous sharp edges or splinters following damage or cracking, had better sound absorption and were safer to use in standard exploitation.A combination of these features proved to be a decisive factor in common application of natural fibers in thermoplastic composites, mainly in automotive industry.The ecological aspect proved to be of great importance as natural fibers can be recovered using energy recycling.The advantages of thermoplastic composites reinforced with natural fibers and exceptional biological, technical, economic and ecological properties of hemp compared to other fibrous crops led to further research on their potential use in structural polymer composite materials for applications in large scale products.Compared to other natural (plant) fibers, industrial hemp is characterized with exceptional resistance to decay, low density, relatively high durability.It is readily accessible, cheap and can be fully energy recycled.
The disadvantages of natural fibers, including hemp, are relatively high moisture absorption and limited potential for fiber wetting by the polymer, which has an adverse effect on structural connections with the polymer matrix and reduces the composite's mechanical strength.
The conducted research shows that structural polymer composites produced with chemically modified industrial hemp fibers (alkalization) and improved polypropylene coating (pro-adhesive agent) had tensile strength and Young's modulus greater by approximately 20%.The effect was achieved when fibers constituted 30% of the composite's mass (Kaczmar and Pach 2007;Zimniewska, Wladyka-Przybylak, and Mankowski 2011).

Conclusions
It should be noted that the implementation of the EU framework program under the name H2020, implemented in 2013-2020, the use of universal design of technological processes based on Technology Readiness Levels and the launch of the production of products in the ecological aspect and recycling of existing products in terms of environmental protection, as well as the adoption and approval in December 2015 by the European Commission of the circular economy package, promoting innovative solutions ensuring an adequate level of environmental protection, clearly indicated the need to solve the global problem of disposal and/or recycling of reinforced GF and CF fibers from endof-life polymer structures reinforced with these fibers.
It is important to be able to replace synthetic (mineral) fiber reinforcement with an alternative material, i.e. natural (plant) fibers, given environmental regulations, strength and quality requirements of structural elements.Most tested fibrous plants turned out to be useful for implementation in such materials.Natural fibers and particularly hemp (Cannabis sativa L.) are characterized by significantly lower density and therefore mass, lower production and application costs in the manufacturing of polymer composites, compared to synthetic (mineral, e.g.glass) fibers.Primarily, natural fibers are renewable and environment friendly.
A thorough review of the size of industrial hemp cultivation in Poland, Europe and in the world, the fact that the plant has a variety of applications in general industries and the determination of the supply and demand market for hemp in Poland and in the world indicate the need for intensive continuation of multi-faceted research on their use in advanced technologies polymer composites.Such composites can be used to produce bulky structures, e.g.elements of hulls of selected vessels or their individual structural elements of superstructures.

Figure 1 .
Figure 1.Major industrial hemp crops in the world in 2016-2022 (source: own elaboration, 2023 in connection with (Global Industrial Hemp Market Report 2022).

Figure 6 .
Figure 6.The size of the industrial hemp stalks market in major regions of the world in 2016-2022 (source: own elaboration, 2023, with reference to fig. 1).

Figure 7 .
Figure 7.The size of the fiber industrial hemp stalks market in Poland in 2012-2022 (source: own elaboration, 2023, with reference to fig. 4).

Figure 8 .
Figure 8. Size of the total consumer market for industrial hemp and cannabis in the USA, by product, 2013-2022 (USD million) (Report 2020, 2023).