Polymers and Composites in the Consumer Packaged Goods Industry

December 2018

The consumer packaged goods industry, which is also known as the fast-moving consumer goods industry, manufactures and sells non-durable goods, usually at a low cost.

Packaged foods of all types (such as meats, fruits, vegetables, dairy products, baked goods, and TV dinners), beverages, cosmetics, personal hygiene products, over-the-counter drugs, dishwashing and laundry detergents, household cleaning solutions, and many other products that are used up relatively quickly and then discarded, are examples of non-durable goods.

Packaging is a branding mechanism and hence is important in marketing and selling non-durable goods.  For example, the distinctive images and designs on soft drink bottles sold by different manufacturers are remembered by consumers and become associated in their minds with the brand name.  The design of attractive and memorable labels is an important aspect of branding.  Shelf appeal is a major contributor to consumer engagement.  We will not, however, discuss this aspect of packaging any further in the present article.

A non-durable good usually has multiple levels of packaging during its lifecycle.  For example, eight PET bottles (primary packaging) containing a beverage may be enclosed in a cardboard box (secondary packaging) and sold together, and many such eight-packs may be shipped together inside a crate (tertiary packaging) from the factory to stores.  Another example is toothpaste in a squeezable tube (primary packaging), which is enclosed in a cardboard box (secondary packaging), which is in turn enclosed in a shipping crate (tertiary packaging) along with hundreds of other such cardboard boxes.  We will discuss the use of polymers and composites at all levels of packaging in this article.

Due to their amazing versatility, thermoplastic and thermoset polymers and their composites are widely used in packaging non-durable goods, in a vast range of packaging that meets different application requirements at acceptable cost.

The abilities to prepare blends of polymers, to incorporate many types of performance-enhancing additives, to prepare polymer matrix composites by incorporating reinforcing agents (such as fibers, platy fillers, and particulate fillers), to prepare laminates combining layers that provide different benefits, and to use adhesives and sealants (not discussed any further in this article) of various compositions when needed, all enhance the versatility of polymers far beyond the versatility provided by individual polymers on their own.

At Bicerano & Associates, our expertise in polymers and composites helps our clients to develop polymers and composites for any application they may require.

Performance, Price, and Regulatory Requirements

Non-durable goods must be packaged properly to protect them from perishing prematurely during transport, storage, or time on the shelf at a store.  Hence materials used for packaging non-durable goods must meet the performance requirements that would allow the enclosed product to remain usable for as long as possible.   The detailed performance requirements depend on the type of product that is being packaged.

Good mechanical properties are usually required.  The definition of “good mechanical properties” depends on the form of the packaging and on what the packaging is expected to accomplish.  Stiffness and impact resistance are usually required for rigid packaging containers such as PET bottles for beverages.  Tear and puncture resistance are usually required for flexible packaging films.  Semiflexible containers that can hold their shape while possessing sufficient flexibility to allow their contents to be squeezed out are usually preferred for ketchup and toothpaste.

In many instances, and especially with food and beverage packaging materials, it is important for the packaging material to provide a strong barrier to any one or more of gases such as oxygen and/or carbon dioxide, moisture, and organic molecules such as flavor and aroma molecules.

Transparency of the packaging material is often desired since it enables the quick visual inspection of the contents.

If a food item needs to be stored in a refrigerator or a freezer, its packaging material must be able to withstand cold temperatures and not lose its essential performance attributes.

If a food item will be cooked inside its container, the packaging material must be able to withstand high temperatures.  The temperature requirements for such packaging materials are often higher if the food item will be cooked in a conventional oven than if it will be cooked in a microwave oven.  However, if the food item will be cooked in a microwave oven, the packaging material must also meet the requirement of being microwave-safe.

Bottles used as containers for household products such as liquid drain openers must have a high level of resistance to aggressive chemicals.

The profit margins from the sales of non-durable goods are usually quite small.  The cost of the packaging material is, therefore, also usually an important factor.  Consequently, in general, the main material of construction of the packaging cannot be expensive.  It is, however, often possible to use very small amounts of expensive materials to impart essential performance attributes without raising the cost of the complete packaging material to prohibitively high levels.  The use of a very thin layer of expensive material with exceptional gas barrier performance in multilayer (laminate) films used in packaging highly perishable foods provides an example of such packaging designs.

If the product is a food, beverage, or drug, in addition to meeting technical requirements related to performance and being of acceptable cost, the packaging material must also obtain regulatory approval from agencies such as   the U.S. Food and Drug Administration (FDA) and/or similar regulatory agencies in foreign countries to be allowed for use.

Sustainability

The packaging materials remain, and must be disposed of, after non-durable goods are consumed.  Discarded packaging materials are major and well-recognized sources of pollution and environmental damage worldwide.  Trends towards enhancing the sustainability of the packaging used for non-durable goods are summarized below.  

Additional infrastructure and mechanisms are being put in place to increase the percentage of used packaging materials that gets recycled.  Most important in this regard is the implementation of increasingly more effective procedures and technology for the collection (or return) and sortation of used packaging materials.

“Designed for recycling” packaging materials that can be recycled with greater ease than the packaging materials they will replace are being developed.

New technologies for recycling used packaging materials in such a manner as to derive the highest possible value are being developed.  For example, chemical recycling methods have been developed to break down used PET bottles to their monomers which can then be polymerized to obtain a new generation of PET that can be used in the same applications as the first (virgin) generation of the polymer.  This is an essential step towards achieving the ideal target of closed-loop recycling.  By contrast, the use of traditional mechanical recycling methods leads to loss of quality so that the recycled PET can only be used in applications of lower value than the virgin polymer and after a few use-recycle-reuse cycles it cannot be used for any applications at all.

Biodegradable and compostable packaging materials are being developed.  The emerging materials even include edible packaging that the consumer may choose to either place in a compost pile or eat along with the food that the packaging contains.

Packaging materials derived from biobased feedstocks are being developed as alternatives to packaging materials derived from fossil fuel based feedstocks.  Most biodegradable and compostable polymers are derived from biobased feedstocks, and polymers derived from biobased feedstocks tend to be biodegradable and compostable more often than polymers derived from fossil fuel based feedstocks, so that the work described in this paragraph and the work described in the preceding paragraph are often complementary.

Work is in progress to develop “active” food packaging materials incorporating nanofiller particles with antimicrobial and/or antioxidant activity so that the package can inhibit and retard food spoilage even more effectively than would be expected from its barrier performance by itself.  The use of such active packaging materials will contribute positively to sustainability by reducing the amount of food that is discarded because of spoilage.

Premature disposal of food due to fear of spoilage both wastes food and generates additional packaging waste.  “Smart” or “intelligent” packaging materials that sense food spoilage and warn the consumer by changing color are under development.  Such packaging materials incorporate reactive nanoparticles that can serve as nanosensors and manifest visible changes to warn the consumer of spoilage of the packaged food.

Examples of Polymers and Their Applications

The following industry and application highlights provide a sampling of the vast range of applications of polymers and composites in the consumer packaged goods industry.

Poly(ethylene terephthalate) (PET):

PET is a mechanically strong, shatterproof, unreactive, transparent, lightweight, and reasonably priced thermoplastic polymer.  It is also resistant both to microorganisms and to biodegradation.  It is approved by regulatory agencies worldwide for food contact applications.  PET bottles and jars are used for food and beverage packaging throughout the world.

The packaging application of PET that is best-known by the general public is the use of PET bottles for beverages such as soft drinks, fruit juices, and water.  PET bottles and jars are also used in packaging many other foodstuffs, including salad dressings, butter, margarine, and cooking oils.  Furthermore, PET bottles and jars are also used in packaging cosmetics, personal hygiene products, over-the-counter drugs, dishwashing and laundry detergents, household cleaning solutions, and many other products.

Special “ovenable” grades contain additives that enhance the crystallinity and the strength of PET so that it can withstand the temperatures encountered during the use of microwave ovens and conventional ovens.  Such grades are used for takeout food containers and prepared food trays that can be microwaved or warmed in a conventional oven.  

Being much lighter and shatterproof are the major advantages of PET over glass. 

Not containing bisphenol-A is a major advantage of PET over bisphenol-A polycarbonate, which is used in baby bottles, reusable water bottles, and sippy cups, but is declining in its use and will hence not be discussed further. 

Not containing chlorine in its molecular structure and not using plasticizers such as phthalates are among the major advantages of PET over PVC.

PET is fully recyclable.  It is recycled in large quantities. 

As discussed above, the technology of PET recycling is going through a period of breakthrough innovation, with chemical recycling back into the monomers from which a new generation of virgin-quality PET can be synthesized gradually gaining broader use.

Glycol-modified PET (PETG):

PET is a homopolymer consisting of ethylene terephthalate repeat units.  A variant named glycol-modified PET (PETG) is a random copolymer that contains 1,4-cyclohexylidene dimethylene terephthalate repeat units along with the ethylene terephthalate repeat units. 

The 1,4-cyclohexylidene dimethylene terephthalate repeat units break the regularity of the PET chains, inhibiting crystallization and thus enhancing the impact resistance.  Unlike PET, PETG also offers the benefit of being RF-sealable.  Its disadvantages relative to PET are that it scratches more easily and that it can be weakened if exposed to UV rays. 

PETG is approved for and used in food and pharmaceutical packaging.  It is also used in many additional packaging applications.  While PET is much more widely used than PETG, PETG is preferred over PET for use in some packaging applications because of the different balance of properties and other features such as RF sealability that it provides.

Polypropylene (PP):

PP is an inexpensive, strong, impact-resistant, and lightweight thermoplastic polymer with a nonpolar (hydrocarbon) molecular structure.  It is resistant to many chemicals.  It can be used over a very wide temperature range so that PP packaging can be used both in microwave and in freezer applications without compromising its integrity.

PP is used widely in rigid containers for many foodstuffs and other non-durable goods.  Injection molding, thermoforming, and blow molding are used to manufacture packaging articles such as rigid PP bottles, jars, pots, and bottle tops.  Injection molded PP bottles can be used as containers for many liquid, powdered, or solid non-durable goods, including foodstuffs and both over-the-counter and prescription drugs.  PET (discussed above, the leader in soft drink bottles) and HDPE (discussed below, the leader in milk bottles) are its main competitors for use in bottles for non-durable goods. 

At the frontiers of research and development on PP bottles, it has been shown that the internal surface of a PP bottle can be modified to make it easier to remove all of the liquid contents (such as shampoo and oil).

PP is widely used in the form of a film.  Biaxial orientation enhances the tensile strength, puncture resistance, and clarity of PP films.  Hence biaxially oriented polypropylene (BOPP) films produced by extruding PP and stretching the extruded film both in the machine direction and in the transverse direction constitute the most frequently preferred version of PP films.  BOPP films provide moderate gas and organic (such as flavor and aroma) molecule barrier performance but higher barrier to water vapor due to the nonpolar structure of PP.  BOPP films can be used as overwraps, or to manufacture BOPP packaging products such as clear bags, pouches, and sealed wrapping, for use to package products such as snack foods, fresh produce, confectionery, biscuits, dried foods, other retail products, and artistic products.  BOPP films are also used as alternatives to paper for bottle labels.  BOPP films are easy to coat, print, and laminate, so that they can be readily imparted with an attractive appearance for use as a packaging material.

PP films are often used as one or more structural layer(s) in coextruded multilayer (laminate) films.  The use of a layer of more expensive barrier polymer such as PVDC or EVOH (which will both be discussed below) imparts excellent barrier properties to such multilayer films.  Non-polymeric layers are also sometimes used in such laminate designs, as in the use of a metalized (aluminum) surface treatment or lamination with aluminum foil to obtain both excellent gas barrier properties and UV barrier performance.

PP is fully recyclable.  It is recycled in large quantities.

It is important to remove odors and traces of food contamination for some highly demanding end uses of recycled PP.  Research is in progress to develop and implement improved decontamination processes.

Polyethylene (PE):

PE is an inexpensive, durable, and lightweight semicrystalline thermoplastic polymer with a nonpolar (hydrocarbon) molecular structure, good resistance to many chemicals, and low melting temperature.  Its low melting temperature makes melt processing economically favorable for PE compared with most other thermoplastics by reducing energy costs.  The nonpolar molecular structure of PE results in good moisture barrier. 

PE can be used to manufacture a broad range of packaging materials.  The fact that its molecular structure can be fine-tuned enhances its versatility.  High-density PE (HDPE), low-density PE (LDPE), and linear low-density PE (LLDPE) are all used in packaging applications.  The density increases with increasing percent crystallinity.  HDPE has the highest crystallinity and provides the most rigid products.  LDPE and LLDPE have lower crystallinity (lowest for LLDPE) and provide products that have higher elongation, and are softer, clearer (more transparent), and heat-sealable.

HDPE is used to manufacture rigid containers, most often by blow molding, for products ranging from milk bottles to shampoos and household cleaning solutions.  LDPE and LLDPE are used less often than HDPE in manufacturing containers.  Blow molding and injection molding are used most often for manufacturing containers from LDPE and LLDPE, especially for applications (such as squeezable bottles) where the container needs to be semiflexible.  LDPE and LLDPE are also preferred over HDPE if the container needs to be clear.

Packaging films are extruded from HDPE, LDPE, and LLDPE.  Extruded HDPE films provide excellent puncture resistance, low stretch, high tear resistance,  and good moisture protection, and are used to manufacture products such as packaging films, grocery bags, and garbage bags.  Extruded LDPE and LLDPE films provide higher stretch, and are used to manufacture films for both stretch wrapping and shrink wrapping, for uses such as bundling beverage bottles and food cans.

LDPE is also used to manufacture bags and tubes for packaging many different items.  Ziploc storage bags and freezer bags are the most familiar examples.

HDPE and LDPE are fully recyclable.  They are both recycled in large quantities.

Cyclic olefin copolymer (COC):

COC is an amorphous thermoplastic polyolefin.  In its neat form, COC offers high transparency, outstanding moisture barrier (four to five times better than LDPE), and high stiffness and strength, in applications that include food and pharmaceutical packaging.

COC is also used as a blending agent in polyolefin packaging films, where it provides higher modulus, greater heat resistance, and increased gas (O2 and CO2) barrier relative to LDPE, for bags, pouches, and thermoformed articles such as trays.   Such blends can be tailored to meet specific O2 and CO2 barrier levels required in fresh-produce packaging.  They are easily processed on conventional cast and blown film lines within standard polyolefin operating parameters.

COC can also provide moisture barrier performance to blister packs; typically in multilayer combinations with PP, PE, or PETG.

Polystyrene (PS):

Rigid expanded (foamed) PS is used as an extremely lightweight cushioning and thermal insulation material in packaging.  Cushioning protects the product that is being shipped from damage due to events such as impact resulting from being dropped accidentally or being handled carelessly.  Insulation protects products such as fresh fish and meats by maintaining the cool chain during shipment.

There are two different forms in which PS foams are used in packaging to provide cushioning during shipment while adding almost no weight to the shipment.  PS foam beads (sometimes referred to as “popcorn” or “peanuts” or “noodles”) are placed inside boxes and crates, as loose-fill materials, to fill the space that remains in the box or crate after a product is placed in it.  Extruded PS foam slabs are placed between the product and the inner surfaces of the box or crate, to immobilize the product and absorb impact energy.

Foam containers provided by restaurants for the takeout and delivery of food are also manufactured from PS foam.  In this very familiar application, the main role of the PS foam is to provide thermal insulation for the enclosed food.

Although PS is fully recyclable, and PS in its dense (not foamed) form is recycled in large quantities, the same statement cannot be made for foamed PS.  From 95% to 98% of foamed PS consists of air, so that only from 5% to 2% consists of PS, and it occupies 20 to 50 times as much volume as the volume occupied by its recyclable content.  For this reason, most local waste haulers do not accept foamed PS, so that it is usually not as convenient as dense PS to recycle, and it is recycled much less often.

Poly(vinyl chloride) (PVC):

PVC is inexpensive.  It possesses decent oxygen and water barrier properties, although its barrier properties are not as impressive as those of PVDC which will be discussed below.  It can be formulated to have a wide range of rigidity.  It can, therefore, be fabricated into various forms of packaging, such as rigid film, flexible film, cling film, and closures (end caps).  These forms of packaging are useful as blisters for foods and drug tablets, trays for foods as well as other products, shrink sleeves, transparent plastic boxes, packaging for disposable medical devices such as disposable syringes, packaging for cosmetics and personal hygiene products, and cling film for foods such as meat, fish, cheese, and vegetables.   Nonetheless, PVC is under attack due to serious environmental concerns, so that it is reasonable to expect the use of PVC as a packaging material to decline over time.

Although PVC is recyclable, in practice it is not recycled as frequently as most of the other common polymers to which a recycling code number has been assigned.  The main obstacle to the more widespread recycling of PVC is that the full range of PVC products encompasses many different formulations, incorporating many different additives (often including phthalate plasticizers), so that PVC products cannot be separated easily for recycling to manufacture recycled products of good quality.

Poly(vinylidene chloride) (PVDC):

PVDC is a semicrystalline thermoplastic polymer.  Despite generic designations such as “PVDC films” or “PVDC wraps” commonly used for them, such films and wraps are usually not manufactured from homopolymers of vinylidene chloride.  They are, instead, usually manufactured from copolymers of vinylidene chloride with a small percentage (such as 15%) of vinyl chloride to reduce the melting temperature of the crystalline phase and thus to make the polymer easier to process in the melt without thermal degradation.  Other comonomers can also be used for this purpose as alternatives to vinyl chloride. 

Copolymers of vinylidene chloride are melt-processed most often by extruding them into film or coextruding them to form the barrier layer of a multilayer (laminate) film. 

PVDC food packaging and household wrap films were developed by Dow Chemical and sold for a long time under the tradename of SARAN.  Such films can also be used for packaging cosmetics and drugs.  The rights to the SARAN tradename are now owned by S. C. Johnson & Son which no longer manufactures PVDC films but instead uses this tradename for its polyethylene food wrap.  Other companies continue to manufacture and sell PVDC packaging films, but such films are not as prominent as they were a few decades ago.

The degree of crystallinity of PVDC films can be increased by orienting the films.  Uniaxial orientation results in anisotropic films whose properties differ along the direction of orientation and perpendicular to that direction.  Biaxial orientation results in films whose properties are identical in both directions.

The main advantages of PVDC films are their self-adhesion capability and their very low permeability to all types of molecular species (gases, water vapor, and organic molecules).  The excellent gas barrier slows down the entry of oxygen from air into the package and thus helps protect the wrapped food from spoilage.  The excellent water vapor barrier provides further protection under many use conditions.  The excellent barrier to organic molecules helps the wrapped food retain its flavor and aroma. 

PVDC films also have several disadvantages:

  • They are considerably more expensive than PE and PP packaging films. Hence they are often not used alone but instead laminated as a thin layer with cheaper films.  In such laminate films, the PVDC layer provides outstanding barrier performance while the structural properties are derived from the layers of cheaper film.
  • Their relative difficulty of melt processing is another disadvantage of PVDC films.
  • Environmental concerns raised by the presence of a large weight percentage of chlorine in their compositions have created another major limitation, as sustainability has become an issue of increasing concern worldwide.

The use of aqueous dispersions of PVDC is a more recently introduced manufacturing option.  Such dispersions enable food and drug manufacturers to benefit from the exceptional barrier properties of PVDC without needing to deal with the challenges it presents during melt processing.  Aqueous PVDC dispersions can be applied on various types of substrates.  The resulting PVDC coatings enhance the barrier performance significantly.  Such a PVDC-coated substrate can thus ensure the freshness of foods or preserve the efficacy of drugs for a much longer period than the uncoated substrate would have been able to do.

Ethylene vinyl alcohol (EVOH):

EVOH is also a very important flexible semicrystalline thermoplastic oxygen barrier polymer for the protective packaging of foods and any other goods for which excellent barrier performance is of critical importance.  It also provides excellent barrier to organic (such as flavor and aroma) molecules.

EVOH is obtained by reacting vinyl acetate with ethylene to obtain an ethylene vinyl acetate copolymer which is then converted to EVOH by a saponification process step.  The mole percentage of ethylene in the starting monomer mixture typically ranges from 27% to 48% and determines the composition of an EVOH copolymer.   

Both the processing characteristics and key aspects of the performance of EVOH depends on the percentage of repeat units bearing hydroxyl (–OH) groups.  The optimum copolymer composition of any given EVOH product is a result of a tradeoff between two conflicting factors.  The first factor is that, the larger the percentage of repeat units bearing –OH groups, the higher the cohesive energy density and hence the gas barrier performance.  The second factor is that the larger the percentage of repeat units bearing –OH groups, the higher the melting temperature of the crystalline phase (and hence the greater the difficulty of processing) and also the greater the moisture sensitivity.

The degree of crystallinity of EVOH films can be increased by orienting the films, exactly as was summarized above for PVDC films.

EVOH is used in the form of films as well as in rigid or semi-rigid retortable food containers where it provides the barrier performance of a laminate whose other layers provide the structural properties. 

The main limitation of EVOH is that, because of its high content of -OH groups which have the ability to form hydrogen bonds, it has relatively high moisture sensitivity.  Hence it is not as advantageous as PVDC in applications involving significant exposure to moisture.

EVOH films and PVDC films used to be major competitors in the past.  The environmental concerns raised about PVDC films have led to the relative decline of their use so that EVOH films are more popular than PVDC films nowadays.

Semicrystalline aliphatic polyamides (nylons):

Nylons are semicrystalline polymers.  They are strong, sanitary, and of reasonable cost.  They provide a good barrier to penetration by oxygen. 

The most commonly used chemical compositions are the Polyamide 66 and Polyamide 6 homopolymers and the Polyamide 6/66 copolymers.  The processing characteristics and the performance attributes of fabricated articles (such as packaging films) change over this composition range, requiring some tradeoffs but allowing the selection of different optimum compositions for different applications.

Nylons are often used as components of multilayer (laminate) food packaging films (such as meat or cheese wrappings and sausage sheaths).  Such laminate films include a layer of a polymer such as EVOH that possesses exceptional barrier properties.  The laminate films are also useful in packaging other non-durable goods.

Nylons can also be used in rigid packaging materials.

Nylons can also be used in oven (roasting) bags thanks to their high heat resistance and chemical resistance, provided that the oven temperature and/or the duration of exposure to elevated temperatures in the oven are not too extreme for the bags to withstand.

Additional advantages of nylons in packaging applications include the facts that they can be processed quite easily either by coextrusion as a layer in a laminate or by thermoforming, and that they possess excellent abrasion resistance.

Amorphous semi-aromatic polyamides:

Selar™ PA is an amorphous semi-aromatic polyamide that was developed by DuPont.  The molecular structure of the first product commercialized long ago under this tradename was reported to be poly(hexamethylene isophthalamide).

Selar™ PA product grades provide unique oxygen barrier properties when wet or chilled, making them optimum for use in preserving the flavors of refrigerated foods and beverages.  They offer the clarity of glass, but with lower weight and better impact resistance, when used in bottles, jars, and other rigid structures.  

Some Selar® PA product grades are suitable for blending with semicrystalline barrier polymers such as Polyamide 6 and EVOH at percentages sufficient for enhancing the processability of these other barrier polymers without decreasing the barrier performance.

Polyethersulfone and polyphenylsulfone:

Polyethersulfone and polyphenylsulfone are high-performance specialty thermoplastics.  They combine good chemical resistance with high heat deflection temperature.  They are used in baby bottles (their only non-durable goods packaging application), as well as in food processing and service items such as microwave trays and food service trays.

Cellulosics:

Cellulose is the most abundant biopolymer on our planet.  Cellophane is a thin, transparent, and completely biodegradable film or sheet manufactured from regenerated cellulose. 

Cellophane is useful for food packaging due to its low permeability to air, oils, greases, bacteria, and water.  It has, therefore, been used as a food packaging material for nearly a century.  Its utilization has decreased in recent decades, however, due to the increasing availability of packaging options that are often preferable to cellophane.   The fact that the cellulose regeneration process generates polluting byproducts has probably contributed to this decline by creating the perception that cellophane is not an especially environmentally friendly packaging material despite being biobased and biodegradable. 

The leading-edge cellulosic packaging technology of today has advanced far beyond the old cellophane technology.  The advances in this technology, combined with the growing focus on increasing the utilization of biobased and biodegradable packaging materials, suggest that new cellulosic packaging materials based on more advanced technologies are likely to lead to a comeback by cellulosic packaging materials as replacements for some packaging materials derived from fossil fuel based feedstocks. 

NatureFlex™ from Futamura is a commercialized example of the use of new technologies to manufacture cellulosic packaging materials.  NatureFlex™ uses cellulosic films derived from renewable wood pulp that is sustainably harvested.  It provides suitable packaging for a wide variety of food service products; such as takeout, confectionary, and bakery items.  It is resistant to grease, oil and fats, and both microwave-safe and conventional oven-safe.  NatureFlex™ films have a coating that can be tailored to provide varying degrees of moisture barrier.

Research is in progress to develop nanocellulose and cellulose composites providing air and moisture barrier and thermal insulation to replace plastics in packaging materials such as boxes for shipping fish.

Research is in progress to develop a biodegradable material made from cellulose, derived from tree fibers, and chitin, derived from crab shells, that has the potential to replace flexible plastic packaging for food.

Poly(lactic acid) (PLA):

PLA is a biobased, renewable, recyclable, and compostable semi-synthetic polyester.  It is produced by polymerizing monomers prepared by a fermentation process.  Hence microorganisms produce the monomers but synthetic polymer chemistry is then used to produce the polymers from these monomers.

PLA is already being used in a number of packaging applications today; such as fruit and vegetable packaging in supermarkets, single-use shopping bags, and disposable drinking cups at concerts and sports events.

The shelf lives of fresh fruits and vegetables can be extended as a result of the water permeability of PLA which allows moisture to pass more easily through the film so that it is not trapped inside the packaging.

Carrier bags manufactured from bioplastics represent more sustainable alternatives to conventional fossil fuel based bag types.  For example, PLA-based compounds are excellent material choices for single-use shopping bags.  They have a lower carbon footprint and they can replace traditional fossil fuel based shopping bags. 

In countries where organic waste is collected, shopping bags that are biobased and compostable can be used to collect organic waste, making them dual use bags.   Dual use also reduces the number of bags that are littered or end up in landfills.

PLA drinking cups are already being used at major sports stadiums, festivals and concert halls.  Such densely populated events are ideally suited to PLA cups because their closed-loop collection systems allow for easier collection of a single-material stream, which can then be recycled into new cups.

Polyhydroxyalkanoates (PHAs):

PHAs are microbial polyesters.  They are produced by bacteria that accumulate them as energy storage materials when cultured by using suitable nutrients in suitable environmental conditions.  They are biobased, renewable, and compostable.   They have a lower carbon footprint than fossil fuel based polyesters.

The applications of poly(3-hydroxybutyrate) and random copolymers of 3-hydroxybutyrate with repeat units such as 3-hydroxyvalerate and/or 3-hydroxyhexanoate include food packaging and storage bags, packaging films, bottles and other containers (such as cups), lids, shopping bags, and shipping materials.

Polymer matrix nanocomposites: 

The exfoliation and dispersion of clay nanoplatelets parallel to the plane of a polymeric film introduces tortuosity to the path of a penetrant molecule and thus greatly enhances the barrier performance of the film.  The scientific literature shows this benefit of platy nanofillers.   News reports and press releases, mostly dating back to the 2000s but also repeated in recent review articles, refer to several companies commercializing nanocomposite barrier packaging materials that incorporate clay nanoplatelets into polyamide matrices.  We have not, however, been able to find any such products in the current online product literature of any of these companies.  Furthermore, the MatWeb database lists some of these product grades but states that they were discontinued.  It appears, therefore, that such products are probably no longer commercially available.

Work is in progress to develop “active” food packaging materials incorporating nanofiller particles with antimicrobial and/or antioxidant activity so that the package can inhibit and retard food spoilage even more effectively than would be expected from its barrier performance by itself.  The use of such active packaging materials will contribute positively to sustainability by reducing the amount of food that is discarded because of spoilage.

Premature disposal of food due to fear of spoilage both wastes food and generates additional packaging waste.  “Smart” or “intelligent” packaging materials that sense food spoilage and warn the consumer by changing color are under development.  Such packaging materials incorporate reactive nanoparticles that can serve as nanosensors and manifest visible changes to warn the consumer of spoilage of the packaged food.

Call Bicerano & Associates Consulting, LLC at (912) 235-2238 or use our online form or email us at info@polymerexpert.biz today!

Go to top