Potential applications of Post-Consumer Vinyl Flex Banner (PCVFB) materials: sustainable management approach

ABSTRACT

In the present review, the consideration has paid on various possible applications of post-consumer polyvinyl chloride flex banners (vinyl flex banners), focusing on their process chemistry, process parameters, and methodologies. The vinyl flex banners are mainly composed of calcium carbonate, polyvinyl chloride resin, polyester fabric, plasticisers and additives. From the intensive literature search, it is observed that post-consumer vinyl flex banner (PCVFB) materials have the potential to use in various fields. The PCVFB materials can be reused as received for various possible applications, such as water-proof roof covers, vehicle covers, food grain covers, tarpaulins, sitting mats, bags, etc. Critically, they can be recycled by using suitable preparation process for different applications, such as footwear, geotextiles, canal linings, ropes, and pipes. Further, the PCVFB material can be used as one of the ingredients for concrete materials. To the finest of our information, it can be further suggested that there is a scope to prepare low-cost wood-plastic composites (WPC), and adhesive/glue material from PCVFB for diverse applications. The use of PCVFB for various possible applications can reduce the accumulation of solid waste and can provide a cleaner and greener environment.

Graphical Abstract

KEYWORDS:

• Sustainable management
• polyvinyl chloride
• flex banner
• recycling
• concrete material

1. Introduction

Communication plays a critical part in society because it is the establishment of all human connections. Open-air publicising has been broadly utilised for hundreds of years as a part of the marketing communication (Anup et al. 2018). Flex banners are the unavoidable canvassing tool of today’s cutting-edge innovation. High-quality printing and canvassing are presently possible and cheaply accessible in the form of ‘Digital Flex Banners’ (Saravanan and Sridhar 2015; Saravanan, Sridhar, and Vinitha 2015).

Flex banners are highly favoured for low-cost outdoor open-air marketing of products/brands and advancement of occasions worldwide. In the last one decade, the demand of flex banner has increased many folds in almost all cities and rural areas. It is digitally printed with a vast extent of rich colours to draw the attention of the individuals (Anup et al. 2018). Flex banner is utilised in nearly all sorts of occasions, such as for birthday celebrations, election campaigns, marriage functions, promoting new products etc. Due to its adaptability, uniform light transmission, hassle-free installation, water and ultraviolet (UV) resistance, resistance to solidifying climate and self-cleaning ability characteristics, it is widely used to make large-scale outdoor publicising signboards (Saravanan, Sridhar, and Vinitha 2015). Flex banners have been placed under the category of specialised textiles according to the Technology Upgradation Fund Scheme (TUFS) launched by the ministry of textiles, the Government of India (Technology upgradation fund scheme (TUFS) 2014).

Flex banners are made up of polyvinyl chloride (PVC) and polyester materials. PVC flex banners are commonly called as ‘vinyl flex banners’ (VFB). PVC has an amorphous structure with polar chlorine atoms in the molecular structure (Kavya and Umesh 2020). PVC is the third-most widely manufactured synthetic plastic polymer (after polyethylene and polypropylene) in the world. PVC is one of the abundantly used thermoplastic materials (Stichnothe and Azapagic 2013). The global production of PVC plastic is in the range of 35–40 million tons per year (Garcia et al. 2006; Yarahmadi, Jakubowicz, and Martinsson 2003; Braun 2001; Polyvinyl chloride 2020). PVC is used to process several short-life and long-life products due to its compounding versatility (Wenguang and La Mantia 1996; Matuschek, Milanov, and Kettrup 2000). Because of its excellent affordability, durability, and workability, PVC is extensively used for the preparation of various products, ranging from civil and construction materials to consumer products (Nakamura et al. 2009). The increasing consumption of PVC resulted in the increased quantity of used PVC items entering the waste stream. With the increased awareness of health and environmental issues, the recycling of PVC products has become demanding, and attempts have been made to recycle PVC materials (Sombatsompop and Thongsang 2001; Slapak, Van Kasteren, and Drinkenburg 1999; Saroj et al. 2018).

Pioneer Polyleathers Pvt. Ltd. is one of the leading industries in India to manufacture and offer a range of Frontlit and Backlit signage flex broadly utilised for computerised printing of flex banners. The Indian market is booming with 25% to 30% yearly increase of flex banners and is worth of around 550 crore rupees (Manufacture of PVC flex banner 2020). Cost-effectiveness is one of the essential factors that has been aiding the selection of flex banners over numerous businesses. Flex printing industries are inclined to develop permanent flex banners to make it cost-effective over other applications. Simple accessibility and quick deployment functionality are a couple of imperative factors favouring market growth (India flex banner market 2020).

Due to an exponential growth of plastic uses, the disposal of plastic waste has gained an increasing importance in recent years (Garcia et al. 2007; Burat, Guney, and Olgac Kangal 2009; Appala Naidu, Srikanta, and Bhanu Radhika 2020; Prabhakar et al. 2016). The PVC materials are non-biodegradable in nature, when burnt they release destructive gases that impact the wellbeing of the individuals, and can cause cancer and infertility (Hema Krishna and Swamy 2016; Flexi: The devil in the air 2014). PVC requires a temperature of around 300 °C to burn the flexi and moreover it raises the temperature of the surrounding environment. Concurring to specialists, the burning of PVC flex releases harmful pollutants like sulphates and nitrates, which are heavier than air and frame a thick blanket diminishing the supply of oxygen in the vicinity (Hema Krishna and Swamy 2016). The chlorine in PVC leads to the formation of dioxins and other chlorinated organic compounds that are subsequently released into the environment. Also, PVC leaches out gradually into the soil and contaminates it (Sadat-Shojai and Bakhshandeh 2011; Braun 2002; Ulutan 1998). As PVC is non-biodegradable, the appropriation of imaginative and environment-friendly strategies that encourage the reuse of the flex banners is extremely vital in the current scenario. The government of India had imposed the anti-dumping obligation on the import of the flex banners in 2010 so as to protect as well as to promote the local production (Anti-dumping duty on imports of PVC flex film from China 2016).

For a sustainable management of post-consumer vinyl flex banner (PCVFB) material, it can be reused and recycled for different possible applications, such as for making roofing sheets, covering sheets and additionally to plan value-added products like bags, sitting mats etc (Anup et al. 2018). The PCVFB material can be blended with concrete fixings to obtain low-cost concrete (Saravanan and Sridhar 2015). Various recycling strategies, such as mechanical recycling, thermal recycling and chemical recycling methods are being utilised to reuse the plastic materials (Maharana, Negi, and Mohanty 2007; Mehta, Biederman, and Shivkumar 1995; Scott et al. 1990). In mechanical recycling strategy, only the thermoplastic polymers can be used, since they can be re-melted and reprocessed into valuable end products. The drawbacks associated with this method are as follows: the heterogeneity of waste squanders and the deterioration of product properties in each cycle (Madalina 2017).

Sustainable management and viable utilisation of post-consumer waste have become the centre of attraction for research throughout the world. It includes the development of environment-friendly processes and products (Appala Naidu and Srikanta 2020; Akhilesh et al. 2019). The present review is embraced on the same line, that is, to reuse and recycle of PCVFB for various potential applications.

The present study is centred around the engineering perspectives of reuse and recycling of PCVFB for various applications. The other objective is to extricate and collate the information-like product properties, nature of the process, process operating parameters, test methods used in the reuse and recycling of PCVFB. For the benefits of the readers, the manuscript has been subdivided into segments indicating the areas of potential applications of PCVFB with a brief perspective and conclusion.

2. Preparation and composition of vinyl flex banners

PVC is one of the major ingredients used in making vinyl flex banners. PVC is available in two grades namely rigid and flexible. Commercial grade PVC is produced primarily by free-radical-initiated suspension and emulsion polymerisation of vinyl chloride (Ebewele 2000). The probable reaction scheme of synthesis of PVC polymer from the vinyl chloride monomer is shown in Figure 1.

Figure 1. Synthesis of PVC polymer from vinyl chloride

According to the United Nations Environment Programme (UNEP) report on ‘single-use plastic’, the flex banner is not listed as single-use plastic (use and throw) (Single-use plastics: A roadmap for sustainability 2018). A flex banner has the potential to reuse it again for various possible applications after its primary use. A flex banner is generally prepared by laminating a polyester fabric between two compounded PVC films, as shown in Figure 2. The commonly utilised flex banners are of 250 g per square metre (GSM) of which the top PVC film contributes around 100–120 GSM, bottom PVC film is of 85–95 GSM and the polyester fabric is about 39–45 GSM (Anup et al. 2018). The typical chemical composition of a PVC flex banner is given in Table 1.

Figure 2. Typical structure of a PVC flex banner

Table 1. Typical chemical composition of a PVC flex banner (Anup et al. 2018)

Major constituent	Composition (wt.%)
Calcium carbonate	36
Polyvinyl chloride (PVC) resin	33
Polyester fabric	18
Plasticisers	9
Additives	14

Based on production methods, PVC flex banner is classified into three types, namely, flex banner with knife scraping method, PVC flex banner with calendering method, and legal PVC flex banner.

In the case of the knife-scraping method, the PVC slurry uniformly applied on both the sides of the base cloth, and then combined them through a drying process. The flex prepared in this process is generally shows high tensile strength and resistance to peeling. China is the major producer of this type of flex. In the calendering process, PVC powder and liquid plasticiser are mixed together, and then bonded with the cloth by using a hot roller under pressure. This method offers better surface flatness, and light transmission characteristics of the flex. However, most of the flex banners that are available in today’s market are prepared by laminating the PVC film on polyester cloth from both sides using hot rollers. The colour expression quality of these banners is excellent (Production processes of PVC flex banner 2020).

3. Applications of post-consumer VFB materials in domestic and automotive sectors

Flex banner is broadly utilised for open-air publicising as it is flexible, durable, economical and recyclable. After utilisation, flex banners carry a financial esteem as they can be reused for various applications as tarpaulin, roof covers, vehicle covers, food grain covers, bags, sitting mats, etc. Figure 3 shows the images of PCVFBs as received used for various field of applications. Imperatively, they can be recycled wherein the constituents are appropriately isolated and utilised for various applications, such as footwear, geotextiles, canal linings, ropes, pipes, etc. The recycling of PCVFB materials in various fields is shown in Figure 4.

Figure 3. Reuse of PCVFB materials in domestic and automotive fields

Figure 4. Recycling of PCVFB to prepare various value-added products

In 2013, Goonj (a non-governmental organisation, India) used a considerable amount of flex roll to cover the roof leakage of a school (shown in Figure 5) in the higher interiors of Gangotri in Uttarkashi, India. The school was spared from worry and misery wretchedness amid during the monsoons due to this flex for more than a year (This organization is using discarded flex banners to solve multiple problems in villages 2020). Amid the Uttarakhand floods when Goonj asked the masses to contribute their used flex, the same was put to numerous applications. Flexes were also used as sitting mats in various schools.

Figure 5. Applications of PCVFBs for roofing and mats (This organization is using discarded flex banners to solve multiple problems in villages 2020)

4. Applications of post-consumer VFB materials in construction field

PVC flex banner is not only a plastic squander available in plentitude, moreover it has a few exciting qualities that makes it an appropriate ingredient for use in the construction industry (Saravanan and Sridhar 2015; Saravanan, Sridhar, and Vinitha 2015). Significant research has been carried out in the field of construction to improve or modify the properties of concrete material by using post-consumer vinyl flex banner due to its unique qualities, such as flexibility, water resistance, high strength, high abrasion resistance, long life, etc. PVC flex banner is additionally cost-effective material as it is a waste material (Mishra and Jain 2019a, 2019b).

Saravanan et al. (Saravanan, Sridhar, and Vinitha 2015) have reported the 3 R’s (Reduce, Reuse, and Recycle) principles for successful utilisation of post-consumer vinyl flex banners (PCVFB) on qualitative basis. Because of the adverse effect of PCVFB on the environment, the authors suggested various reuse and recycling methods of PCVFB. To reduce the consumption of vinyl flex banners, the possible substitutes such as cotton canvas banners, LED boards and Nano 3D wall LCD were also suggested in the report. The recycling of PCVFB in the construction field was suggested in the report.

Saravanan and Sridhar (Saravanan and Sridhar 2015) have studied the preparation of low-cost concrete materials by fractional substitution of coarse aggregate with post-consumer VFB material. The PCVFB material was cut in to pieces of size within the range of 1 cm × 1 cm (1 cm²) to 2 cm × 2 cm (4 cm²). Within the ponder, the PCVFB loading was varied from 0 to 20% by weight to prepare the concrete material using a OPC-53 grade cement. The compressive strength of the concrete material was evaluated with and without PCVFB content, and the reported compressive strength values are shown in Table 2. The data show that the compressive strength of the concrete material decreased remarkably when the PCVFB loading was increased from 0% to 20% by weight. However, the decrement in compressive strength was insignificant up to 14 days when PCVFB content was used up to 10 wt.%. Around 12% decrease in 28 days strength was observed in the presence of 10 wt.% PCVFB. Therefore, it can be said that PCVFB content may be used up to around 10 wt.% to obtain low-cost concrete material with a reasonable decrease in the compressive strength of concrete materials.

Table 2. Effect of PCVFB loading on compressive strength of concrete materials

PCVFB loading (wt.%)	Compressive strength (N/mm^2)
	7 days	14 days	21 days	28 days
0	16.8	20.0	38.2	40.0
10	16.0	18.6	32.0	35.0
20	7.5	12.4	20.4	21.0

Mishra and Jain (Mishra and Jain 2019a) have studied the effect of PCVFB on concrete material properties. In the study, concrete cubes of standard size (150 mm × 150 mm × 150 mm) were used to investigate the water absorption and compressive strength characteristics of the cubes. PCVFB of 200 GSM was used as a wrapping material on the concrete surface. In the same work, concrete beams of standard size (150 mm × 150 mm × 700 mm) were also prepared from the same concrete mass to find the flexural strength of the concrete. PCVFB was wrapped around these beams using rubber-based carpet adhesive and dried in air for 2 days. The PCVFB wrapped beams were tested for flexural strength using universal testing machine (UTM) with a single point loading system.

The study showed around 75% (from 2.8 to 0.7 wt.%) reduction in water absorption capacity of the concrete cubes wrapped with PCVFB. The reduction in water absorption indicates that the improvement in the durability of the concrete material. The average compressive strength of unwrapped concrete cubes after 28 days of curing is around 27 N/mm². It is further mentioned that the wrapped concrete beams offered better flexural strength over unwrapped concrete beams. However, the flexural strength values of the concrete beams are not disclosed in the article.

Mishra and Jain, (Mishra and Jain 2019b) have studied the preparation of reinforced-cement-concrete (RCC) material with improved flexural strength using PCVFB and different steel wire meshes as pasting materials. The RCC beam specimens were prepared with a size of 150 mm × 150 mm × 700 mm. Different wire meshes and PCVFB were pasted over the surfaces of the RCC beams using rubber-based carpet adhesive and tile adhesive. In the study, four different types of concrete beams, namely plain RCC beams (RCC-Plain), RCC beams pasted with PCVFB on the surfaces of beams (RCC-PCVFB), RCC beams pasted with steel-chicken-mesh and PCVFB (RCC-PCVFB-SCM), and RCC beams pasted with steel-weld-mesh and PCVFB (RCC-PCVFB-SWM) were prepared. The prepared specimens were cured for 28 days before analysing, and the flexural strength of the specimens was carried out using UTM under centre-point loading, and the results are summarised in Table 3. The data show that the PCVFB pasted RCC material offered higher flexural strength over plain RCC material. The data further revealed that around 100% increase in the flexural load of the concrete material was obtained in the presence of both PCVFB and SWM materials with reference to RCC plain sample. Therefore, the PCVFB material could be used as an ingredient either in direct form or in combination with other ingredients to improve or modify the concrete properties.

Table 3. The effect of various pasting materials on the flexural strength of concrete materials

Sample type	Average load at failure (kN)	Increment in load capacity (%)
RCC-Plain (reference)	25.2	-
RCC-PCVFB	26.8	6.3
RCC-PCVFB-SCM	30.5	13.8
RCC-PCVFB-SWM	62.2	103.9

A comparative study is shown in Table 4 for the applications of PCVFB in concrete making with a similar kind of plastic waste, namely post-consumer expanded polystyrene (PCEPS). The waste EPS beads can be mixed with concrete to produce lightweight concrete materials for various applications, such as walls of low thermal conduction, bridge decks (Suhad et al. 2016; Kirti et al. 2017; Chandru et al. 2017). Therefore, the PCVFB has a potential to use as one of the ingredients of construction materials like PCEPS.

Table 4. A comparison between PCVFB and PCEPS blended concrete materials in terms of compressive strength (CS) and water absorption capacity (WAC)

Reference	VFB/EPS loading (wt.%)	CS after 28 days (MPa)	WAC (wt.%)	Remarks/comments
Saravanan and Sridhar, (Saravanan and Sridhar 2015)	Without VFB	40	-	CS decreased ~ 12% lack of information about the WAC of the materials
	10	35	-
Mishra and Jain, (Mishra and Jain 2019a)	Without VFB	27	2.8	lack of information on CS WAC reduced ~ 75%
	With VFB	-	0.7
Subhan (2016)	Without EPS	20.8	-	CS increased ~ 23% lack of information on WAC of the materials
	0.3% EPS	25.6	-
Trushna et al. (Trushna, Isha, and Kuldeep 2018)	Without EPS	46.5	-	CS increment ~ 7% lack of information on WAC
	0.2% EPS	49.5

From the literature pertaining to the potential applications of PCVFB in the construction field, it is observed that the PCVFB material can be used as one of the ingredients (so-called partial replacement of aggregate materials) of concrete mix to modify the properties of the concrete materials. The presence of PCVFB in concrete mix resulted in lowering the water absorption of concrete materials. A decreased trend in compressive strength of concrete materials is reported in the presence of PCVFB. However, the flexural strength of concrete increased. Although the authors have highlighted the advantages of using PCVFB in the construction field, the issues associated with the release of poisonous chemicals during the curing of concrete mass are not addressed explicitly.

5. Further scope of the potential applications of post-consumer VFB in other fields

In addition to the above-mentioned applications of post-consumer VFB materials, to the finest of our information, there may be other potential areas like, preparation of low-cost and environment-friendly wood-plastic composites (WPC) (Chun et al. 2018; Koay et al. 2018), preparation of adhesive materials using PCVFB (Akhilesh et al. 2019; Guido et al. 2015). Sagar et al. (Sagar et al. 2018) have studied the preparation of value added composite products using recycled PCVFB. In the study, plastic composite panels were prepared for indoor and outdoor applications by using PCVFB and recycled PVC cable materials. It is reported that 100% recycled banners showed a tensile strength of 6.5 MPa, whereas the composite products showed small reduction in tensile strengths property. The reported value of flexural strength of the fabricated panels are 6, 3.5, and 1.5 MPa, respectively, with the addition of 0, 50, and 75% of cable material in the composites. Though there is no research article found on the preparation of wood-PCVFB composites, this may be a probable field of application of PCVFB in near future.

Preparation of low-cost adhesives from recycled VFB is another potential area. Kaushal et al. (Kaushal et al. 2018) and Appala et al., (Appala Naidu et al. 2021) have studied the preparation of adhesives from recycled polymers using various solvents. The adhesives are suitable for binding cardboard and plywood types of materials. The similar method can be used to prepare adhesive from PCVFB. The probable process flow diagram of the preparation of adhesive materials from PCVFB is shown in Figure 6. Currently we are working on the preparation of adhesive from PCVFB materials. Detailed characterisation of the product is not completed yet and we are in the process of completing the study for scientific communication.

Figure 6. Probable steps for the preparation of adhesive using PCVFB

5. Conclusions

In the present review, consideration has paid on various possible applications of post-consumer polyvinyl chloride flex banners (PCVFB), focusing on their process chemistry, process parameters, and methodologies. From the intensive literature search, it is observed that PCVFB materials have the potential to use in various fields. PCVFB materials can be reused for various applications, such as waterproof roof covers, food grain covers, tarpaulins, sitting mats, bags, etc. Critically, PCVFB can be recycled for making footwear, geotextiles, canal linings, ropes, and pipes.

Further, PCVFB materials could be used as one of the ingredients of concrete materials to alter the properties of the concrete mix. The presence of PCVFB in concrete mix resulted in lowering the water absorption capacity and compressive strength of concrete materials. However, the flexural strength of PCVFB mixed concrete increased as reported in one article. Though a few authors have highlighted the points of interest of using PCVFB in the construction field, the issues associated with the release of poisonous chemicals during the curing of concrete mass are not addressed explicitly. It is also observed that the detailed characterisation of the concrete products prepared with PCVFB is not unveiled. Furthermore, the information pertaining to the reuse and recycle of PCVFB material for various applications is scarce.

To the best of our knowledge and understanding, there may be other fields like preparation of low-cost wood-plastic composites (WPC) and preparation of adhesives, where PCVFB can be used suitably for diverse applications. The use of PCVFB for various possible applications can reduce the accumulation of solid waste and can provide a cleaner and greener environment. We believe that the information reported in the present review will be useful to the business visionaries/analysts to design a suitable process for mitigating the global problems associated with waste generation and its proper management.

Nomenclature

Table

3D	Three-dimensional
CAGR	Compound annual growth rate
GSM	Gram per square meter
kN	Kilonewton
LCD	Liquid crystal display
LED	Light-emitting diode
OPC	Ordinary Portland cement
PCVFB	Post-consumer vinyl flex banner
PVC	Polyvinyl chloride
RCC	Reinforced-cement-concrete
SCM	Steel-chicken-mesh
SWM	Steel-weld-mesh
TUFS	Technology upgradation fund scheme
UTM	Universal testing machine
UV	Ultraviolet
WPC	Wood-plastic composites
wt.%	Weight percent

Acknowledgments

The authors express their gratitude to B.V. Raju Institute of Technology (BVRIT) - Narsapur, Medak Dist., and BITS-Pilani Hyderabad Campus for providing the necessary support for the present study.

Disclosure statement

No potential conflict of interest was reported by the author(s).