Introduction

The first industrial scale generation of plastics commenced in the 1940. The finished plastic consists of repetitive units of monomer incorporated with several other chemicals to procure its desired scheme, color, flexibility and other properties. These chemicals are collectively known as additives, which pertaining upon their functions has been classified into different major groups. Different amount of additives utilized for plastic generation. The main components of a plastic product is made up from 58% plasticizers, 3% heat stabilizers, 8% FRs, 9% blowing agents, 12% colorants and 7% others. Global plastic generation reported around 230 and 299 Mt in 2009 and 2013 respectively, 3.9% rise from 2012. Around 280 Mt plastics released by 2012, 90% was devoted to LDPE, HDPE, PP, PVC, PS and PET products. More than one third of this rate is applied for packing usages like plastic bags and another third for housing appliances like plastic pipes and vinyl cladding, 10% end up in the oceans. It has been estimated that approximately 60-80% of the total marine debris are contributed to plastics by around 80% of the plastic litter gets back to terrestrial sources; whereas 18% is aligned with fishing industry. In 2010, 192 coastal countries produced about 275 million metric tons of plastic wastes, of which 4.8-12.7 million metric tons were forecasted to release the ocean that over 5 trillion plastic pieces are currently afloat at sea. Over half of plastic wastes manufactured in Europe are land filled. The main applications for plastics in particular have been house ware, packaging, toys and construction usages. There are 7 kinds of plastics which are low-density, durable, formable and low-cost materials which do not decay, corrode, or dissolve, owning to their properties, are extensively employed in variety of fields, sectors and industries such as PET, HDPE, PVC, LDPE, PP, PS and etc.

Materials and plastics applications

The biomedical applications of plastics encompass their utilization as heart valves, vascular grafting materials, orthopedic implants, artificial organs, disposable syringes, dialyzing sets, pouches for blood transfusion, dextrose, saline and other life-saving fluids during surgery, contact lenses, dentures intrauterine devices, blood transfusion sets, various kinds of catheters, dialyzing units, hypodermic devices, and similar injection devices, splinters, braces, films and protective clothes, containers, bags for blood, blood products, nutritional products and diagnostic agents etc. Plastic film wraps and covers animal feed (forage) and grain to prevent spoiling. Products applied for this aim encompass bale wrap, bunk silo covers, silage and grain bags. Plastic substitutes for plywood, roof shingles, sidewalk pavers, garbage bags, reusable shopping bags, parking garage bumpers, deck lumber, other non-weight-bearing lumbers, as well as new agricultural plastic products such as baling twine, nursery pots, irrigation tubing are some of the end-products from mechanical recycling. Agricultural plastics can also be chemically added into crude oil, waxes, bituminous products, fuels & other petrochemical applications. Because most agricultural plastics are white or black or a combination of both, and because of residues (soil, plant debris, silage or chemicals), recycled agricultural plastics are not generally utilized as feedstock for products with strict color or other technical demands. LDPE and LLDP Reutilized for film, maple tubing and irrigation tubes. HDPE procures flexible rigid plastic applied for pesticide and dairy chemical containers, irrigation pipe, and nursery pots. PPas a more brittle rigid plastic assigned for small nursery pots, woven into bags for feed, nutrients and agricultural inputs. PS employed for planting plugs and trays. The bitumen modification using plastics-based additives (different plastics wastes, namely HDPE and LDPE, EVA, SBS, ABS and crumb rubber) would permit additive products to be formed at very low costs, while also culminating the use of waste plastics disposed into environment. With regard to e-waste amounts come out globally reported around 41.8 Mt by 2014, it is expected to rise to 50 Mt in 2018 at an annual expansion rate about 5%. Plastics, besetting approximately 20% of the total WEEE, encompass 5% FRs and 15% non-Frs. WEEE plastics can be possessed over 15 various kinds of engineering plastics, comprising ABS, HIPS, PE, PP, PS, SAN, PU, PA, mixtures of PC/ABS and incorporations of HIPS/PPO. Based on a direct analysis conducted in order to identify the plastic constituents of WEEE around 3400 items have been distinguished such as cooling appliances, small WEEE, CPUs, copying equipment, printers, CRT monitor sand CRT televisions were realized with the analysis finding about 6 t of plastics with variety of polymer kinds. PS, ABS, PC/ABS, HIPS and PP obtained to be pioneers and dominants types and the integrated rates of both HIPS and ABS were determined approximately 55% of the total WEEE plastics content. The plastics make up for each computer has been reported about 13.8 lb that the largest volume is associated to PVC consumed mainly in cabling and computer housing, although recently most computer moldings are being designed of ABS. The EU Union commissioned to dispose 9.5 Mt of WEEE in 2008, and forecasted quantities would be 12.3 Mt by 2020 with a rapid culminating rate in China. The recycled plastic in WEEE, respectively weighted 19 200, 124 200, 364 900 and 130 300 tons in 2009 to 2012 in China.

Environmental exposures to plastics

Plastic particles can be perceived in marine environment in the water columns, on beaches and on the seabed either directly or indirectly due to fragmentation of larger plastic litter. The plastics introduced to the environment are ingested and swallowed by sea turtles that led to a distinguished problem to them and ambient in Northeast Brazil. Also, hydroids and diatoms joined on the pellets of plastic run up in a neuston net, plastic particles exhibited an abundance of life posed with the particles, resulting in use of the term Plastisphere in new microscopic observations as well as emerging hazardous pollutants emissions such as PCBs. Main inputs of plastics come into view from ship produced litter, thrown from recreational activities or litter introduced into the sea via rivers, municipal drainage networks, sewer, solid waste disposal, coastal landfill operations accidently lost, carelessly handled and or packing materials. Plastic nano-particles can be released to aquatic food chain either as plastic waste degraded to the micro and nano-size, or as manufactured nano-sized plastic particles via algae and bacteria and then digested by fish, mammals and etc. The micro- and nano-size plastics employed in consumer products like cosmetics, ship breaking commodities and industries are dissipated directly into the oceans by surface runoff and then takes place some transformations and alterations via macromolecular interplays, and physical, chemical and biological. Environmental durability is the main reason of extensively dispersion of plastic particles in the oceans, beaches and in surface waters globally. Variety of marine animals diseases have been manifested by recent surveys such as entanglement, ingestion, suffocation, general debilitation, internal and external wounds, suppurating skin lesions and ulcerating sores, blockage of the digestive tract and etc over 250 marine species (for instance crustaceans, fish, sea-turtles, sea-birds, sea-otters, pin-nipeds, sirenians and cetaceans) by entanglement and ingestion in the Mediterranean Sea. More recently, in the Mykonos Island in Greece Sea over 100 plastic in its stomach of whales that led to death. Remains small plastics figured out in the sperm whale stomach emerged from greenhouse (cover material of greenhouse, flower pot, hosepipe, plastic burlap, rope and plastic mulch of greenhouse) general debris (dishwater plastic pot, hanger, mattress, plastic carafe, small plastics, spray plastic pot, tub of ice-cream and bag) cephalopods beaks (cephalopods beaks and total plastic items).The toxicity bioassay of PET, PVC, LDPE, HDPE, PC, PP and PS leachates to barnacle nauplii had confirmed that at all concentration levels, mortality was less than 30% except PS leachates at 0.10 m²/L and statistically significant toxicity to its larvae at 0.50 m²/L. The most and least toxic leachates were observed at 0.50 m²/L, for PVC, LDPE, PC, PP and PS respectively. Plastic nano-particles (70 nm PS particles) effect tested on Daphnia magna, it resulted mortality, a lower reproduction rate and a significant slump in body size. It was discernes increased generation of pseudo feces, and particles aggregation to gills of blue mussel, Mytilus  edulis exposed to PS nano-particles (30nm) metabolic fluctuations, disturbed fat metabolism, arisen ethanol, inosine/adenosine and lysine concentrations in liver and muscles by feed exposer for fishes respectively.

Plastic disposal rates

Conventional plastics compose approximately 9% of the global’s oil and gas production, 5% as feedstock and about 4% for the energy exploited in production. At present 74 % of post -consumer plastic wastes in Europe is either incinerated or delivered to landfill sites. Majority of consumer plastic commodities are made to be disposable after single-use or have a short usage life except many long-term usage plastics like water pipes, electric cables, household products, and electronics casing. (Table 1)

In Europe Post-consumer plastic wastes production is around 25 Mt per year, of which 6.6 Mt are recovered mostly via mechanical recycling, 8.9 Mt are used for energy conversion targets and 9.6 Mt are disposed to landfill sites. Around 2.8 Mt per year of plastic wastes is disposed in Canada.

Plastic processing and techniques

Plastics origin gets back to raw materials comprising petroleum, natural gas, carbon, common salt and etc. Nowadays, plastics are nearly thoroughly derived from petrochemicals released from fossil oil, of which around 4% is exploited for plastic generation at the global areas. Taking into attention of the environment impact and human sanitation, disposing of PSW to landfill envisaged to be an insurmountable trouble due to legislative impediments, rising outlay, the allowing culminating of greenhouse gases emissions and the insensible bio-degradability of them and etc. The outlays for polymer synthesis and processing claim circumstances such as [1] the accessibility of the raw material [2] scale up practice of the synthesis [3] non-toxicity, and [4] melt and/or solution processing techniques considering green chemistry, which forces strict shaping and scheming instructions on the chemical structure of monomers and polymers. Feedstock can be either processed in the state of a powder that can withstand the operational processes to make up a solid framework, or deposited in situ as a thin film on an electrode through electrochemical polymerization. Post-synthesis can be fulfilled through of the soluble polymer formation: dopant complex, redesign and reproduction by plasma facilities.

The term BPs usually besetting both plastics those are bio and fossil-derive in three various aspects [1] bio-based and non-biodegradable [2] bio-based and biodegradable or [3] fossil-based and biodegradable. BP sare bio-based products, usually easy biodegradable, extracted from renewable resources (bio starch and starch mixtures (74.5%); fermentation (13%) and petrochemicals products (12.5%)) are receding the conventional oil and petrochemicals industries as a central core of bio-economy. Vegetable fats and oils, corn starch, pea starch or micro biota are pioneered as raw ingredients for BPs generation. BPs are as a prominent option to impede some environmental impacts induced by the utilization of fossil-based conventional plastics. Petroleum based plastics are extensively utilized due to their unique mechanical characteristics, low outlay, light weight and high energy efficiency, their stability, durability and bio-chemical inertness. BPs generation practices comprise [1] produced from BMS: corn, potato, wheat, rice, beets, cellulose, starch etc. [2] renewable resources: PLA, PGA, PCL [3] Microorganisms or genetically modified: PHAs, PHB, PHBV [4]. Mixtures with biodegradable polymers: PVOH, PCL. Many plant proteins have been combined into plastics, besetting proteins from wheat, corn, soy, cottonseed, sunflower, linseed and rapeseed. Upon disposal in bio-bins and envisaged to a bioactive ambient, BPs will dissociate to natural compounds such as CO₂, H₂O, humic matter, and biomass. New agricultural crops, using nutrients from compost and stabilizing CO₂, will synthesis new polymer building networks and monomers. Valorization of wastes from Posidonia Oceanica (Mediterranean endemic seaweed) resulted to generate a BP composite by incorporation of a bio-based PE extracted from sugar cane as matrix recently. Bio-based HDPE matrix was employed for injection molding. Therefore, in order to promote the environmentally friendly nature of the wood plastic composites, recycled plastics and BPs can be utilized as matrices which cause to analogous mechanical properties comparison to virgin or petro-chemical based polymers even in an industrial scale. The various commercial grades of green PE procure identical characteristics with petroleum-derived PE grades but with a prominent environmental achievements, bereavement of protruding CO₂, it stabilizes around 2.5 t CO₂/t polymer, while typical CO₂ output gas of a petroleum-derived PE are approximately 2.1 t CO₂/t polymer. But one of the most significant restrictions to widespread industrial implementation of emerging BPs such as PLA and PHA is that they do not afford the flexibility and impact resistance of petroleum-based plastics like PP or high-density PE. PU foams, its semi-rigid and rigid foams plastics are provided utilizing vegetable oil derivatives, castor oil, and modified soy-based oil respectively.

The present technologies for recycling PSW could be embedded into four major categories such as [1] Primary (re-extrusion, containing middle-cost) by injection moulding [2] Secondary (mechanical, containing middle-cost) via cutting/shredding, milling and grinding [3] Tertiary (chemical, usually high cost) using pyrolysis, gasification, hydrogenation, catalytic cracking, condensation polymers, smelting by blast furnace, degradation, incineration, hydrolysis, glycolysis, hydroglycolysis, aminolysis and fractionation [4] Quaternary (Energy recovery, usually low-cost. The mechanical recycling as a kind of physical treatment of PSW can only be conducted on single-polymer plastic, e.g. PE, PP, PS, etc supported by separation, washing and sorting facilities for PSW. Separation method is operated via manual, selective dissolution and flotation, hydro-cyclone, melt filtration, liquid-fluidized bed, X-ray fluorescence, laser-induced plasma spectroscopy, magnetic density, sink-float, tribo-electrostatic and etc. Plastics flotation is an appropriate practice, which offers advantages such as cost-effective and higher separation rates, particularly for same and analogous density plastics. The near-infrared and x-ray sorting techniques and hydro-mechanical purification practices for WEEE plastics recycling can scale up approximately 98% purity from mixed scrap composing ABS, PC/ABS, PC and HIPS. Re-extrusion recycling prosecutes the re-return of scrap, industrial or single-polymer plastic parts to procure products of same properties so it is a well-known and dominant procedure to retrieve of the PSW according to the layout depicted by (Figure 1)

The potential energy value of plastics is approximately 40 MJ/kg, usually rich in H₂ and may thus be employed as cheap and abundant H₂ storages. A potential energy resource for fuel supply is non-recyclable waste plastics.

Coming into view the novel enzymatic dissociation modules assigning plastic hydrolases with immense quantities of plastic de-polymerization is discernible also for white rot fungus to breakdown the ordinary LDPE at a greater rate for up to 90 days. Pseudomonas species slowly undergo the plastics breakdown process like PE. Current process is supported via some biotechnological practices in order to transform PET to PHA sand then degradation by Pseudomonas. Therefore, the successful enzymatic dissociation is only feasible for BPs.

Sustainable feedstock problems

At present the annual BPs generation is about 1 Mt, but posed to rise around 6-12 Mt in 2020 via modern technical progresses. BPs generation using sustainable biomass feedstock and renewable energy encountered to biomass deficiency and other resources as well as above named disadvantages. In fossil-free resources nations, the petroleum-based plastics manufacturing must be changed to assigning other feed stock to supply human demands in terms of plastics production. However, all plastic generation is going on to become electricity-based in the EU by 2050. Keeping constant generation rates of plastics, it claims a huge annual demand of electricity, input gases and feedstock in the EU. This results that a thoroughly conversion to electricity-based plastics is feasible from a resource and technology point of view and the generation outlays can be descended to reasonable values using Plasmatron or electricity produced from renewable sources. Another fossil-free option for procuring plastics is to exploit renewable electricity, H₂O and gases like CO₂ as a feedstock through carbon capture and nuclear options.

Conclusion

Comparison of virgin and regenerated PVC and municipal properties of model polymers before and after recycling techniques for LDPE, HDPE and PP based on impact strength by falling weight, thermal shrinkage, appearance after heating at 150^oC, strength of welder corners and tensile stress at max load and at yield, elongation at break, elastic modulus revealed same, analogues and close performance properties. Also, findings were similar for PC/ABS plastics in terms of strain at break, tensile, charpy impact, aesthetic inspection, candle frame, vertical burn and impact tests. Studies reported that even a very short time plasma treatment of the surface of recycled carbon fiber procured oxygenated functional groups on the surface and resulted in fortified adhesion and promoted the surface activity. These characteristics can assist to recede the disadvantages by refraining mechanical and chemical characteristics to levels approaching those of fresh carbon fiber-reinforced plastics. Rising the compatibility of different rigid and flexible products in injection molding process by plasma treatment designed low-cost PP, ABC and various plastics and polymers as well as cut down one third of outlays.

Acknowledgements

Thanks go to Editor in chief and manager of plastic surgery and modern techniques journal so that offering to publish current editorial.