Review on eco friendly green polymers from biobased materials: Trends in biodegradable coating

Excerpt: Mixing biopolymers or biodegradable polymers with each other can improve their intrinsic properties.

Blends of Biodegradable Polymers

Mixing biopolymers or biodegradable polymers with each other can improve their intrinsic properties.

Starch-based blends

Starch is totally biodegradable and is an environmentally friendly material. In addition starch has a low cost. Nevertheless, since starch is highly sensible to water and has relatively poor mechanical properties compared to other petrochemical polymers, its use is limited. A solution may be to blend it with other synthetic polymers. Many biodegradable starch-based thermoplastic blends have been developed and studied extensively. A lot of research work deals with the development of blends of starch with synthetic biodegradable polymers. These blends present several advantages. The material properties can be adjusted to the needs of the application by modifying the composition. The blending process is low cost compared to the cost of the development of new synthetic materials. These kinds of blends are intended to be more biodegradable than traditional synthetic plastics.

Starch – PLA

The mechanical properties of blends of starch with PLA using conventional processes are poor due to incompatibility. An elongation increase can be achieved by using plasticizers or reacting agents during the extrusion process. Coupling agents like isocyanates have been used. The hydroxyl groups of starch could react with the isocyanate group resulting in urethane linkages and compatibilization of these systems. The effect of gelatinization of starch was also investigated[178]. It has been shown that in PLA/gelatinized starch blends, starch could be considered as a nucleating agent, resulting in an improvement of crystallinity in PLA blends and a greater superiority of mechanical properties.

Starch – PCL

To prepare films by using the film blowing technique, TPS was blended with PCL to adjust the rheological properties of the melt before the process. Novamont (Italy) produces a class of starch blend with different synthetic components. Its trade name is Mater-Bi. Four grades are available; one of them consists of PCL (Mater-Bi Z). The highest amount of starch allows the acceleration of the degradation of PCL. The behaviour of some PCL-modified starch blends has been studied. The addition of modified starch leads to an increase of the Young's modulus of PCL and a decrease in tensile strength and elongation at break values. The blend becomes less ductile[179]. Some synthetic polymers with lower biodegradabilty are used to control the rate of biodegradation according to the applications.

Starch – PBS

PBS was blended with granular corn starch[180]. By increasing the starch content it was shown that elongation at break and tensile strength decreased. The addition of starch fillers significantly improved the degradation rate.

Starch – PHB

Blends incorporating PHB or PHBV were previously reviewed. It was shown that poly (hydroxyalkanoate)s can form miscible blends with polymers which contain an appropriate functional group i.e. capable of hydrogen bonding or donor-acceptor interactions. The effect of blending starch in PHB was also studied. The properties of blend films with various proportions of starch are identical. A single glass transition temperature is obtained for all the samples, which are semi-crystalline. The tensile strength was optimum for a PHB/starch ratio of 70/30 (% wt/wt)[181].

In this particular case, an advantageous cost reduction and an improvement of mechanical properties compared to pure PHB are obtained.

Others blends

PHB or PHBV are brittle polymers. To improve their mechanical properties they are mixed with other biodegradable materials. When nucleating agents are added, smaller spherulites are formed, thus the mechanical properties are improved. In addition these properties depend on the processing conditions, morphology, crystallinity and glass temperature transition.

PLA – PCL

Many studies have been reported on PLA blends with various polymers. In most of systems, PLA and other polymers are immiscible. It is essential to compatibilize such blends to have good properties. Blends of PLA with PCL were prepared by melt blending and using in situ reactions. In this case an ester exchange reaction by alcoholysis was described. In EVOH/PLA blends, the hydroxyl groups of EVOH could react with the carboxyl group of PLA through an esterification reaction in the presence of catalyst. Reactive blending of PLA with ethylene copolymer gave an important improvement of mechanical properties of PLA. This was attributed to an interfacial reaction between the components[182].

PAL – PLA

Poly(aspartic acid-co-lactide) (PAL) was used to blend various polymers such as PLLA, PBS and PCL [183] in order to increase their biodegradability i.e. their degradation rate. In the case of PLLA, the mechanical properties of such blends were similar to that of non-blended PLLA but the hydrolysis rate of the PLLA was effectively enhanced. In the case of PCL melt blended with PAL, a sufficient percentage of poly (aspartic acid-co-lactide) to have an increase in degradation rate is 20%. PAL was shown to improve the thermal stability of PLA in PAL/PLA blend films.

PCL – chitin

PCL blends with chitin were prepared as biodegradable composites by melt blending. Increasing the amount of chitin has no effect on the melting or crystallization temperature. This was attributed to a non-miscible blend. Another blending route is solvent casting[184]. The degree of crystallinity of PCL decreases upon blending with chitin. Same results are obtained with PCL/chitosan blends. These blends are expected to have good mechanical properties.

Upcycling of carbon dioxide into sustainable polymers of high value

Carbon dioxide and epoxides can be copolymerized to deliver aliphatic polycarbonates. Polycarbonate polyols of low molecular weight may be suitable to prepare foams, coatings and adhesives, whereas high-molecular-weight polycarbonates may be used as rigid plastics or elastomers and Structures of Polymers from CO2 is shown in Figure 19[185].

Each year hundreds of millions of tons of plastics are produced from petroleum. Most of these plastics will remain in landfills for years to come or litter the environment posing significant health risks to animals; however, the average person's lifestyle would be impractical without them. One solution to this conundrum lies in biodegradable polymers. These polymers have the distinct advantage that over time they will break down. Professor Geoffrey Coates has developed innovative processes to synthesize plastics from inexpensive, bio renewable substances including carbon dioxide and carbon monoxide. This team has developed a new family of catalysts over the last decade that can effectively and economically turn CO2 and CO into valuable polymers. “Presidential Green Chemistry Award in 2012” by Professor Geoffrey Coates for this great work.

Dr. Geoffrey Coates headed research to create catalysts that can not only efficiently create these biodegradable polymers, but the polymers also incorporate the greenhouse gas and global warming contributor, CO2, and environmentally present ground-ozone producer, CO[186]. These two gases can be found or produced in high concentrations from agricultural waste, coal, and industrial applications as byproducts. Not only do the catalysts utilize these normally wasted and environmentally unfriendly gases, but they also do it extremely efficiently with high turnover numbers and frequencies in addition to good selectivity. These catalysts have been actively used by Novomer Inc. to make polycarbonates that can replace the current coating bisphenol A (BPA) found in many food and drink packaging. Novomer's analysis shows that if used in all cases, these biodegradable polymer coatings could not only sequester, but also avoid further production of CO2 in hundreds of millions of metric tons in just a single year[187].

Novomer is one out of 5 companies in world for striving to convert CO2 and CO into Cash. Recently it has launched carbon captured bio based polyols that can be used commercially in coatings, adhesives, sealants and elastomers.

Properties of biodegradable polymers

Even though biodegradable polymers have numerous applications, there are properties that tend to be common among them. All biodegradable polymers should be stable and durable enough for use in their particular application, but upon disposal they should easily break down. Polymers, specifically biodegradable polymers, have extremely strong carbon backbones that are difficult to break, such that degradation often starts from the end-groups. Since the degradation begins at the end, a high surface area is common as it allows easy access for the chemical, light, or organism. Biodegradable polymers also tend to have chain branching as this cross linking often decreases the number of end groups per unit weight. Crystallinity is often low as it also inhibits access to end groups. A low degree of polymerization is normally seen, as hinted at above, as doing so allows for more accessible end groups for reaction with the degradation initiator. Another commonality of these polymers is their hydrophillicity. Hydrophobic polymers and end groups will prevent an enzyme from easily interacting if the water-soluble enzyme cannot easily get in contact with the polymer [189].

Other properties of biodegradable polymers that are common among those used for medicinal usages include being:

  • Non-toxic
  • Capable of maintaining good mechanical integrity until degraded
  • Capable of controlled rates of degradation

A goal is not to elicit the immune response, and the products of degradation also need not to be toxic. These are important as biodegradable polymers are used for drug delivery where it is critical to slowly release the drug into the body over time instead of all at once and that the pill is stable in the bottle until ready to be taken. Factors controlling the rate of degradation include percent crystallinity, molecular weight, and hydrophobicity. The degradation rate depends on the location in the body, which influences the environment surrounding the polymer such as pH, enzymes concentration, and amount of water, among others. These are rapidly decomposed[190].

Advantages of biodegradable polymers

One major problem with plastic is that it often takes an extremely long time for it to break down once discarded, leading to massive problems with landfill waste and posing a danger to wildlife. Biodegradable plastics use alternate materials or specialized enzymatic or chemical reactions to break down the material quickly once exposed to the elements. This technology offers a number of advantages over traditional plastic materials.

Waste reduction

Plastic makes up around 13 percent of the waste stream, representing 32 million tons of waste. While around 9 percent of that plastic goes into recycling programs, the remainder enters landfills, where it takes up space for hundreds of years or more. Biodegradable plastics, on the other hand, may break down over the course of several months, depending on the materials involved and the conditions of their disposal. While not every form of landfill-friendly biodegradable plastic will completely break down, any reduction in the space required to dispose of this material will ease pressures on the waste stream.

Source reduction

Biodegradable plastics also help conserve petroleum supplies. Traditional plastic comes from heating and treating oil molecules until they turn into polymers, representing about 2.7 percent of America's petroleum consumption. Bioplastics come from natural sources, including crops like corn and switchgrass. While in some cases, the bioplastic material mixes with traditional plastic to give products more strength, any percentage that comes from a renewable source saves petroleum. As these technologies mature, they offer the capability of producing plastic packaging and items even after the world's oil has run out.

Energy savings

Biodegradable plastics can also represent a significant energy savings. For example, the corn-based plastic polymer PLA uses 65 percent less energy than creating a similar polymer from raw petroleum. In addition, it generates 68 percent fewer greenhouse gases during its manufacture, representing a significant environmental benefit.

Reduction in carbon emission

One of the main advantages of using biodegradable polymers to make plastic bags is the significant reduction in the carbon emissions that happen during the manufacturing process as compared to that of regular plastic. Not just that, since the materials used to create biodegradable plastics are plant based, minimal carbon is emitted during the composting process.

Eco-friendly disposable solution

Biodegradable plastics require composting or recycling to ensure proper breakdown of the plastic pieces to enable the natural composting process. The requirement to properly dispose/process biodegradable plastic products automatically reduces the amount of waste that would otherwise be sent to landfills.

Recyclable material

Apart from taking a significantly lesser time to breakdown as compared to regular plastic, biodegradable plastic can also be further recycled to create more plastic by products. The use of plant based oils to make biodegradable plastics also ensure its integrity (they contain no chemicals or toxins (such as Phthalates or Bisphenol A) compared to other types of plastics).

Plastic-eating bacteria

While new biodegradable plastics offer some hope for energy savings and trash reduction, they do little to solve the problem of the huge volumes of plastic trash that already exist in landfills. Specialized bacteria may hold the key to reducing already-existing plastic deposits, however. Several different types of bacteria have evolved the ability to consume hydrocarbons, giving them the capacity to "eat" plastic and hasten its decomposition. In some cases, microbes have developed this ability due to a lack of other nutrient options, and in other cases, scientists have been able to induce the ability in microscopic organisms. Further study will ensure that the bacteria and the byproducts produced are nontoxic, but this could represent one possible piece of the solution to the world's solid waste problems[191].

Disadvantages of biodegradable polymers

While biodegradable plastics have numerous advantages, they do have some drawbacks as well. As mentioned earlier,

  1. Biodegradable plastics need specific conditions to decompose, meaning the natural breakdown of this plastic will not occur if it is sent to the landfill along with other waste. A special composting system is required to ensure proper recycling/processing of biodegradable plastic bags.
  2. The other drawback to biodegradable plastics is that if they aren't disposed properly and mix with regular plastics, they become contaminated and cannot be used anymore. But, in spite of the minimal drawbacks of biodegradable plastic, it is still becoming a popular alternative to regular plastic, especially due to the growing awareness for environmental safety. Plus, the advantages of biodegradable plastics totally outweigh the disadvantages making it a better choice as compared to plastic polymers that have been used traditionally[191].

Global biodegradable polymer manufacturers

World Biodegradable polymer leaders in manufacture are given in the table 3. It is having data's like Trade name, Composition or name of the polymers, Company name, Country name and applications are mentioned in the table 3[192].

Applications

Biodegradable polymers can be processed by most conventional plastics processing techniques, with some adjustments of processing conditions and modifications of machinery. Film extrusion, injection moulding, blow moulding, thermoforming are some of the processing techniques used. The three main sectors where biodegradable polymers have been introduced include medicine, packaging and agriculture. Biodegradable polymers applications include not only pharmacological devices, as matrices for enzyme immobilization and controlled-release devices[193] but also therapeutic devices, as temporary prostheses, porous structure for tissue engineering.

Medical

Biodegradable polymers are also used as implantable matrices for the controlled release of drugs inside the body or as absorbable sutures. There are two types of polymers has been used in medical applications and one is Natural polymers another is Synthetic polymers.

Natural Polymers

Proteins are the major components of many tissues and thus they have been extensively used as biomaterials for sutures, haemostatic agents, scaffolds for tissue engineering and drug delivery systems. Gelatin was used for coatings and microencapsulating various drugs for biomedical applications. It has also been employed for preparing biodegradable hydrogels.Chitin and its derivatives have been used as drug carriers and anti-cholesterolemic agents, blood anticoagulants, anti-tumor products and immune adjuvants. More recently some studies have shown the anti- oxidative and radical scavenging activities of chitosans. Chitin, collagen and poly-L-leucine have been used to prepare skin substitutes or wound dressing[194]. Alginate gels have been extensively used in controlled release drug delivery systems. Herbicides, microorganisms and cells have been encapsulated by alginates. PHB is suitable for biomedical applications. It is used in drug carriers and tissue engineering scaffolds. Fibrin used in tissue engineering, drug delivery, surgical sealant and surgical Glue in many surgeries like cardio vascular, orthopedic and Dental..Etc. and Pictures of Natural Polymers in Medical Applications are shown in figure[195].

Synthetic polymers

Synthetic polymers are widely used in biomedical implants and devices because they can be fabricated into various shapes. In this area interest in biodegradable polymers has increased. PGA and PLA can be considered as the first biodegradable polymers used in biomedical applications. Due to their good mechanical properties, PGA and PLLA have been used as bone internal fixation devices. They also have excellent fiber forming properties and thus PGA was used to prepare absorbable sutures and PLLA to replace ligament and non-degradable fibers. Non-woven PGA fabrics have been investigated as scaffolding matrices for tissue regeneration. As PDLLA has lower mechanical properties and faster degradation rate than PLLA, it is often used in drug delivery systems and scaffolding matrices for tissue engineering. PLGA has shown to have a good cell adhesion and could be used for tissue engineering applications[196]. PLGA is used as polymeric shell in nanoparticules used as drug delivery systems.

Other polyesters like PBS, PPDO, PCL and their copolymers are also utilized as biomedical materials. PCL is used as a matrix in controlled release systems for drugs, especially those with longer working lifetimes. PCL has a good biocompatibility and is used as scaffolds for tissue engineering. PBS is a promising substance for bone and cartilage repair. Its processability is better than that of PGA or PLA. It has higher mechanical properties than PE or PP. Its insufficient biocompatibility could be enhanced by plasma treatment. PPDO was used to prepare the first monofilament sutures. They have a lower risk of infection when used and are thus more interesting than multifilaments. PPDO was also used as fixation screws for bones[197].

Polyurethanes and poly (ether urethane) s have good biocompatibility and mechanical properties and have thus been used as medical implants. Polyanhydrides have been investigated in controlled release devices for drugs treating eyes disorder. They have been used as chemotherapeutic agents, local anesthetics, anticoagulants, neuro-active drugs and anticancer agents. Pictures of Synthetic Polymers in Medical Applications are shown in figure 22[198].

Packaging

In everyday life, packaging is another important area where biodegradable polymers are used. In order to reduce the volume of waste, biodegradable polymers are often used. Besides their biodegradability, biopolymers have other characteristics as air permeability, low temperature sealability and so on. Biodegradable polymers used in packaging require different physical characteristics, depending on the product to be packaged and the store conditions.

Due to its availability and its low price compared to other biodegradable polyesters, PLA is used for lawn waste bags. In addition, PLA has a medium permeability level to water vapor and oxygen. It is thus developed in packaging applications such as cups, bottles, films[199]. PCL finds applications in environment e.g. soft compostable packaging. Biodegradable polymers used in food packaging are given in the Table 4[200].

Several polysaccharide-based biopolymers such as starch, pullulan and chitosan, have been investigated as packaging films. Starch films have low permeability and are thus attractive materials for food packaging. When composed of proteins and polysaccharides, the films have good mechanical and optical properties, but they are very sensitive to moisture. They also have poor water barrier properties. When composed of lipids, films are more resistant to moisture. The problem is their opacity. Moreover they are sensitive to oxidation. The current trend in food packaging is thus the use mixtures of different biopolymers. Chitosan was used in paper-based packaging as a coating, to produce an oil barrier packaging. Results showed that chitosan coatings can be used as fat barriers, but the treatment cost was relatively high compared to the fluorinated coatings usually used. Chitosan based films have proven to be effective in food preservation and can be potentially used as antimicrobial packaging[201].

PHB has been used in small disposable products and in packing materials. Bucci[202] investigated the use of PHB in food packaging, comparing it to PP. The deformation value of PHB was about 50% lower than that of PP. PHB is more rigid and less flexible than PP. The performances of PHB tend to be lower than those of PP under normal freezing conditions. Nevertheless at higher temperatures PHB performed better than PP.

In 2002, DuPont and EarthShell commercialized food packaging and containers composed of starch and Biomax. APACK is a thermoformed packaging based on starch, from Switzerland. Pictures of Synthetic Polymers in Packaging Applications are shown in figure 23[203]. In packing industry PLA is most widely used biodegradable polymer and the cycle of PLA in nature. Pictures of PLA cycle in nature shown in Figure 24 [204].

Agriculture

For this application, the most important property of biodegradable polymers is in fact their biodegradability. Starch-based polymers are the most used biopolymers in this area. They meet the biodegradability criteria and have a sufficient life time to act.

Plastic films were first introduced for greenhouse coverings fumigation and mulching in the 1930s. Young plants are susceptible to frost and must be covered. The main actions of biodegradable cover films are to conserve the moisture, to increase soil temperature and to reduce weeds in order to improve the rate of growth in plants. At the end of the season, the film can be left into the soil, where it is biodegraded. Another application bases on the production of bands of sowing. It is bands which contain seeds regularly distributed as well as nutriments. In the field of geotextiles, we can mention the use of textiles based on biopolymers for filtration and drainage and the use of the geogrilles[205].

Biodegradable polymers can be used for the controlled release of agricultural chemicals. The active agent can either be dissolved, dispersed or encapsulated by the polymer matrix or coating, or is a part of the macromolecular backbone or pendent side chain. The agricultural chemicals concerned are pesticides and nutrients, fertilizer, pheromones to repel insects. The natural polymers used in controlled release systems are typically starch, cellulose, chitin, aliginic acid and lignin.

In horticulture threads, clips, staples, bags of fertilizer, envelopes of ensilage and trays with seeds are applications mentioned for biopolymers. Containers such as biodegradable plant pots and disposable composting containers and bags are other agricultural applications. The pots are seeded directly in the soil, and break down as the plant begins to grow.

In marine agriculture, biopolymers are used to make ropes and fishing nets. They are also used as support for the marine cultures[206]. Pictures of Biodegradable Polymers in Agriculture Applications are shown in Figure 25[207].

In mulching and low-tunnel cultivation, to enhance sustainability and environmentally friendly agricultural activities, a promising alternative is the use of biodegradable materials. Agricultural films placed in the soil are susceptible to ageing and degradation during their useful lifetime, so they need to have some specific properties.

When starch is placed in contact with soil microorganisms, it degrades into nontoxic products. This is the reason why starch films are used as agricultural mulch films. Mater-Bi based biodegradable films were developed and tested. Water and high temperatures do not affect the mechanical behavior of the biodegradable films. Negative effects on the elongation at break were obtained with a high dose of UV radiation[208].

Edible coating

Nowadays, fruits and vegetables are highly demanded in the market because of its nutritional value. Fruits and vegetables have short shelf life due to its perishable nature. About 30% fruits and vegetables are affected or damaged by insects, microorganisms, pre and post harvesting conditions during transport and preservation. Preservation of fruits and vegetables is a big challenge for world. Edible coating is an effective method to solve this problem. It provides protective edible covering to fruits and vegetables. It is beneficial for consumers and environment. Today herbal edible coatings are used as a nutraceutical and beneficial for consumer health. Edible coatings are of different types such as hydrocolloids, lipids and plasticizers. These have good barrier properties to O2, CO2, moisture and water vapour.

Edible coatings are defined as the thin layer of material which can be consumed and provide a barrier to oxygen, microbes of external source, moisture and solute movement for food. In edible coating a semi permeable barrier is provided and is aimed to extend shelf life by decreasing moisture and solute migration, gas exchange, oxidative reaction rates and respiration as well as to reduce physiological disorders on fresh cut fruits[209].

Properties of edible coatings are based on their molecular structure, molecular size and its chemical composition[210]. These properties are as follows:

a. Edible coatings have good barrier properties to water, moisture, O2, CO2, and ethylene.

b. It improves appearance and mechanical handling to maintain structure and colour of Fruits and Vegetables.

c. Edible coating contains active components such as antioxidants, vitamins etc., they enhance nutritional composition of Fruits and Vegetables without affecting its quality.

d. These coatings provide a protective covering on Fruits and Vegetables and enhance their shelf life

Different types of Edible coating

Edible coating materials are produced with a variety of natural substances. Those natural substances are given below. Types of biodegradable polymers are used in edible coatings shown in the Table 5[211].

a Polysaccharide-based

b. Protein-based

c. Waxes-based,

d. Fatty acids-based

e. Composites-based

Applying methods of edible coating

Edible coatings should be applied on fruits and vegetables by different methods. Those methods are given below. Biodegradable polymers used in edible coatings are given in the Table 6[212].

a. Dipping

b. Brushing

c. Extrusion

d. Spraying

e. Solvent casting

Herbal Edible Coatings: A new concept

Herbal edible coating is a new technique for food industry. It is made from herbs or combination of other edible coatings and herbs, most common herbs used in Edible coatings are such as Aloe vera gel, Neem, Lemon grass, Rosemary, Tulsi and Turmeric. Herbs have antimicrobial properties, it consists vitamins, antioxidants and essential minerals.

As recently Aloe vera gel is widely used in coating on Fruits and Vegetables, because of its antimicrobial property, it also reduces loss of moisture and water. Ginger essential oil, clove bud oil, turmeric neem extract, mint oil, other essential oil and extracts are also used in edible coating of Fruits and Vegetables. Herbs are natural source of vitamins, minerals, antioxidants, beneficial for health act as a nutraceutical and medicines[213]. Pictures of Biodegradable Polymers in Edible Coatings are given in the table Figure 26[214].

Automotive

The automotive sector aims to prepare lighter cars by use of bioplastics and biocomposites. Natural fibers can replace glass fibers as reinforcement materials in plastic car parts[215]. We await the development of the bio-composite materials. For example the PLA is mixed with fibers of kenaf for replace the panels of car doors and dashboards (Toyota Internet site). Starch-based polymers are used as additive in the manufacturing of tires. It reduces the resistance to the movement and the consumption of fuel and in fine greenhouse gas emissions (Novamont Internet site).

Toyota has typically used bio-based polypropylene/polylactic acid (PP/PLA) composite derived from plant material. They have developed a new plant-derived bio-based plastic more suitable for auto interiors than other bio-based plastics. Table 7 shows the list of vehicles containing bio-based plastics. Toyota began using the new material in the luggage compartment liner of the new Lexus CT200h hybrid-electric compact car. This is the world's first use of a bio-based polyethylene terephthalate (PET) resin in the auto industry. Biodegradable polymers applications used in Automotive are shown in Table 7[216] and Figure 27 shows an example of eco-plastic usage in Lexus HS 250h [216].

In this table7 and Figure 28 the Car Model and Parts are highlighted in green colors represent those are made with biobased polymers.

Electronics

PLA and kenaf are used as composite in electronics applications. Compact disks based on PLA are also launched on the market by the Pioneer and Sanyo groups. Fujitsu Company has launched a computer case made of PLA[217].Pictures of Biodegradable Polymers in Electronic Coatings are shown in Figure 28[218].

Construction

PLA fiber is used for the padding and the paving stones of carpet. Its inflammability, lower than that of the synthetic fibers, offers more security. Its antibacterial and antifungal properties avoid allergy problems. The fiber is also resistant to UV radiation. Pictures of Biodegradable Polymers in Constructions are shown in Figure 29[219].

Sports and leisure

Some fishing hooks and biodegradable golf tees (Vegeplast, France) are based on starch. PLA fiber is used for sports clothes. It combines the comfort of the natural fibers and the resistance of synthetic fibers. Pictures of Biodegradable Polymers in Sports shown in figure 30[219].

Other applications

Biotechnological applications

Chitin acts as an absorbent for heavy and radioactive metals, useful in wastewater treatment.

Applications with short-term life character and disposability

Aliphatic polyesters like PLA, PBS, PCL and their copolymers are used as biodegradable plastics for disposable consumer products, like disposable food service items (disposable cutlery and plates, for example). Other products are diapers, cotton stalk and sanitary products.

Unusual applications

There are a lot of other applications which do not fit into any of the previous categories. Thus combs, pens (Begreen from Pilot Pen or Green Pen from Yokozuna), and mouse pads made of biodegradable polymers have also been invented, mostly for use as marketing tools.

Food Industry

Biodegradable polymers can be used to modify food textures. Due to its non toxicity, alginate has been used as a food additive and a thickener in salad dressings and ice creams. Chitin and chitosan are used as food and feed additives[220]. PLA (semi-synthetic polymers) is used for compostable food

Global biopolymers market analysis

As there is need for eradication of polymers, there is increase in growth of industries for Biopolymers. Biopolymers have found wide acceptance in various industries, on account of its distinguished environment friendly properties. Biopolymers are now an important part of every sector Food tech, nanotech, chemistry, medical, agriculture etc.

There is an increase of 20% (approx.) in the production of biopolymers products and bioplastics per year. Market of around 1.2 million tones in 2011 may see a five-fold increase in production volumes by 2016, to almost 6 million tones shown in chart-1[221]. By 2020 Bioplastics production could rise to 12 million tones.

Global production capacities of biodegradable polymers in different segments namely packaging, Consumer goods, Automotive & transport, Building & construction, Textiles, Agriculture & horticulture, Electrics & electronics and others market by 2022 are given in the below chart 2 [222].

The United Kingdom has consistently been the largest producer of biopolymer and the synthetic plastic market is engrained in the UK and world economy, but now the focus has been shifted to Bioplastics as plastics are having many adverse effects. The biopolymer market is miniscule in comparison to the plastics marketplace; however, bioplastics are gaining in capital and popularity. Europe is the 2nd biggest market for biopolymers, consuming more than one-third of the total global demand for biopolymers.

Bioplastic award

The 12th Global “Bioplastics Award 2017” has been won by MAIP Srl for a newly developed PHBH. 'I am NATURE: the first Bio-Technopolymer' by MAIP (Italy).

'I am NATURE' is a special PHBH based compound, available in tailor made grades and suitable for high temperature applications. It offers a sustainable solution preserving the technical properties of a traditional thermoplastic material. Maip has developed different bioplastics that are sold under the name of I am NATURE for several years. These PHBH based grades are compounded with natural fillers and additives of vegetal origin as well as functional components for specific requirements.

The main properties that were achieved, allow the definition of the new I am NATURE as an actual Bio-Technopolymer that also allows to eliminate the painting (because of its good mass colourability) dramatically reducing the carbon footprint of the component. The switch covers were officially introduced to the market in Europe in September 2017 and Picture of switch cover is shown in figure 31[223].

Biobased material Award

“The Innovation Award 2018” Bio-Based Material of the Year Winner was ARCTIC Biomaterials (FI) for PLA reinforced with biodegradable glass fibre. Arctic Biomaterials is a company producing biodegradable plastic solutions for the medical and technical industries. The bioresorbable glass fiber reinforced PLA materials produced with ABM composite technology enable us to fulfill customer needs in demanding applications in an environmentally friendly way[224].

Eco-friendly biodegradable paint

It is clear that eco-friendly and non-toxic varieties of paints come at a higher cost than regular paints, but that they do last long. They also benefit you and your family's health, as well as the environment.

The shift to low/zero-VOC paints is seen not only because of an environmentally conscious industry but with an industry that understands that consumers are increasingly buying green-labelled products. Thus, it is necessary that consumers understand what a green label means. Green Seal Certifications (International), EcoMark Scheme (in India) are standards prevalent in the market for green paints. The EcoMark, conferred by Bureau of Indian Standards (BIS), has the following standards for water-based coatings:

  • 5% or less VOC
  • Absence of metals like Mercury and its compounds, Lead, Cadmium, Chromium VI and their oxides
  • Less than 10 milligrams per kilogram free formaldehyde
  • Absence of chemicals like halogenated solvents, benzene, poly-aromatic hydrocarbons and other aromatic hydrocarbons

Some of the biodegradable paint manufactures are namely PPG, Asian Paints, Berger Paints, Dulux India, and Kansai Nerolac…etc.

PPG launched new bio-based wall paint for the professional and consumer market. The latest bio- based wall paint to be introduced in the market is the “Sigma Air Pure”. It is made via the Decovery bio-based technology of DSM. It is a bio-based wall paint that comes with an effect of air purification. The revolutionary paint is made explicitly for interior walls, and it is meant to enhance the air climate behind closed doors by filtering, neutralizing, and removing over three-quarters of formaldehyde from the air inside a room.

Sigma Air Pure paint is made from a unique resin. Through the Decovery resin technology, a resin that matched the specific needs of the paint was developed, giving it distinct characteristics from other bio-based wall paints. The technology aids paint manufacturers to produce paints that are sustainable. It also utilizes several renewable components that enable the customizing of solutions to suit the individual needs of clients and the market at large.

Sigma Air Pure paint has made bio-based wall paints even more acceptable. Both the consumer and professional markets are embracing this renewable resin. These resins are generated from renewable sources like agricultural waste, starch, sugars, and natural oils. They play the role of fossil ingredients, which are the source of binder resins used in the manufacture of conventional paints that are water and solvent borne. Decovery resins technology used in the production of Sigma Air Pure paint is eco-friendly. Reports show that these bio-based wall paints have been developed under extra creativity and relentless dedication. To date, they have been used to solve the issues and challenges experienced by professionals and common paint consumers[225].

Future trends and challenges in biopolymers

Biopolymers and Bioplastics are available for the last decade or so has the potential to reduce the petroleum consumption for plastic by 15%-20% by 2025. Improved technical properties and innovations open new markets and applications with higher profit potentials in automotive, medicine and electronics. Biopolymers & Bioplastics are biodegradable and can be made from a wide range of different plants. When Biopolymers & Bioplastics companies change their strategy from just replacing current products to new applications, product conceptions and production processes, profitability and salability increase dramatically. In 2025, Europe will count for 31% share, USA for 28% share and Asia will be the major market with 32% share of the total global demand. Asia has the advantage that genetically modified plants are easier to realize and new outlets for agriculture are faster to build up. Biopolymers & Bioplastics markets are growing at 8% -10% pa. Biopolymers & Bioplastics cover approximately 10% -15% of the total plastics market and will increase market share to 25% -30% by 2020. The market itself is huge, and has reached over US$1 billion in 2007 and is expected to cross US$10 billion by 2020. A growing number of companies are foraying into and investing in this segment. New applications and innovations in the automotive and electronics industry lead to market boom. Over 500 Biopolymers & Bioplastics processing companies are currently on stream, with the figure expected to grow beyond 5000 by 2025. Nowadays, biobased polymers are commonly found in many applications from commodity to hi-tech applications due to advancement in biotechnology and public awareness.

The main concerns for humans in the future will be energy & resources, food, health, mobility & infrastructure and communication. There is no doubt that polymers will play a key role in finding successful ways in handling these challenges. Polymers will be the material of the new millennium and the production of polymeric parts i.e. green, sustainable, energy-efficient, high quality, low- priced, etc. will assure the accessibility of the finest solutions round the globe[226].

Conclusions

Biodegradable polymers have received much more attention in the last decades due their potential applications in the fields related to environmental protection and the maintenance of physical health. At present only few groups of the mentioned biopolymers are of market importance. The main reason is their price level, which is not yet competitive. The future of each biopolymer is dependent not only on its competitiveness but also on the society ability to pay for it. The future outlook for development in the field of biopolymers materials is promising.

To improve the properties of biodegradable polymers, a lot of methods have been developed, such as random and block copolymerization or grafting. These methods improve both the biodegradation rate and the mechanical properties of the final products. Physical blending is another route to prepare biodegradable materials with different morphologies and physical characteristics.

To provide added value to biodegradable polymers, some advanced technologies have been applied. They include active packaging technology and natural fiber reinforcements. Recently different studies have been reported concerning the use of nanoclay with biodegradable polymers, especially with starch and aliphatic polyesters. Nano-biocomposites or bio-nanocomposites are under investigation.

Opportunities for research

Opportunities for research in this subject are enormous. Again to reduce the carbon emission we have to go for next generation Biobased green polymer system.

Work continues in the development of the biodegradable polymers due to ever increasing demand and effective use in various applications. The biopolymer industry has been enhancing its arena to a point where it is economically competitive with the conventional plastic industry

The inexpensive nature of the renewable resource feed stocks is encouraging researchers and industry officials to invest time to further develop these processes. As the production of biopolymers expands, so too will the services associated with it. As a general summary, it may be stated that time will lead to greater economic strength for the incorporation of biopolymer materials into society.

Microbial grown plastics are scientifically sound and a novel approach but the infrastructure needed to commercially expand their use is still costly and inconvenient to develop. It is the right time for scientist and researchers to explore the hidden potential of natural wealth existing as polymer and fiber, to utilize them and develop biodegradable polymer for the development of science and technology while sustaining the pollution free environment.

To improve the properties of biodegradable polymers, a lot of methods have been developed, such as random and block copolymerization or grafting.

These methods improve both the biodegradation rate and the mechanical properties of the final products. Physical blending is another route to prepare biodegradable materials with different morphologies and physical characteristics.

Future researches should include the

i. Development of biopolymer with less prices compare to conventional polymers.

ii. Development of Bio–based Green Composites polymers with good physical and mechanical properties compare to conventional polymers.

iii. Development of new trend in biopolymers is Nano-biocomposites or bio-nanocomposites

iv. Easy industry commercialization process for biopolymers with more productivity.

v. Development of Bio based and efficient and environment friendly green polymers for coating systems Researchers all around the world may conduct extensive research in this area to find the commercial applications of these systems for actual implementation and Picture of green polymers shown in figure 33[227].

Acknowledgment & Dedication

The author takes this opportunity to thank PPG Asian Paints management team and special thanks Mr. K.S. Samuel and Mr. Sanjeev Karn for their Motivation, suggestion and feedback during the course of the reviewing the paper.

This review paper work is dedicated to those who (it may be individual, Industry, Academic center, Government, NGO, country…etc.) care about natural resources like Water, Air, Soil and Environment…etc. and want to save the natural resources from pollution.

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R Kanchana

PPG Asian Paints Pvt.Ltd, Research & Development Centre, SIPCOT Industrial Park, Plot no L10, Phase II, Mambakkam Post, Sriperumbudur, Kanchipuram, Chennai – 602 105