Editorial

Additives in the 21st Century: Minor Components OrTransforming Ingredients?

Roger AvakianChief Technology OfficerPolyOne Corporation

Avon Lake, Ohio 44012

This question is especially poignant in the first decade of the 21st Century, where new developments initially con-

ceived early in the 20th Century, then discovered and researched in the latter part of that Century, are now becoming

reality. The term ‘‘additive’’ is being redefined by recent advances in technology, namely, nanotechnology and bio-

derived polymers and additive systems. These new additive technologies and others are transforming the importance of

minor ingredients from beneficially influencing the characteristics of entire compositions into radically changing those

characteristics, many times yielding properties beyond prediction.

The first ‘‘enhancer’’ role that had a major effect on a new polymer was the introduction of hindered amine light sta-

bilizers (HALS) during the 1970s. The use of this technology allowed the embryonic polypropylene industry to have out-

standing outdoor weathering performance allowing use in outdoor furniture, ropes, etc. The HALS additive technology

moved polypropylene resin from simply an interior application polymer to an outdoor one, vastly multiplying its poten-

tial markets.

Fast forward 30 years. We are no longer using additives to limit an undesired effect or enhance an existing one. We

are now entering the ‘‘Age of Additives’’ where the additive itself dramatically alters the inherent properties of the poly-

mer compound itself. A good example of this behavior is the way that the incorporation of minor amounts of carbon

nanotubes changes a normally insulating polymer into a conductive one.

Additives technology in this Century will play a key role in developing materials that successfully address the key

materials science challenges facing industry and its consumers, for example, the emergence of bio-derived polymers. As

with other technologies, their ‘‘market pull’’ and speed of introduction will be influenced highly by the market trends/de-

mographic changes in the 21st Century. The factors of oil scarcity, global warming, growing energy needs, and increased

population exist in a tension not before experienced in the world and will cause material scientists and technologists to

design more sustainable materials, processes, and applications. For example, who can doubt the increased use of bio-

derived polymers for both environmental and supply reasons? There is a bit of irony to this rhetorical question, because

it was only the scarcity of natural rubber in the 1940s that drove the industry toward synthetic resins. Now, with the

feedstock supplies of petroleum in question, either physically or financially or environmentally, bio-derived polymers

return to prominence after 60 years of being on the margins of polymer chemistry research.

The drive for more security and personal identification in our lives and commerce will combine to make polymeric

materials ‘‘smarter’’ and ‘‘responsive;’’ additives will help enable these ‘‘smart materials.’’

In another arena, as global mobility of both people and products increases, the demand for clean water and protection

from infectious diseases will increase and be met with polymeric materials transformed by new additives containing anti-

bacterial or antiviral agents. In that circumstance, form of the product will follow its function, but the product will be

transformed with protections unimaginable a few years ago.

Nanotechnology in the 21st Century promises to be the biggest technical revolution seen in human history. The ability

to build materials from ingredients engineered on an atomic scale will bring the ultimate ability to tailor materials and

properties in polymer compounds to an extent never before possible. The molecule-by-molecule construction of ingre-

Correspondence to: R. Avakian; e-mail: roger.avakian@polyone.com

DOI 10.1002/vnl.20087

Published online in Wiley InterScience (www.interscience.wiley.com).

� 2006 Society of Plastics Engineers

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2006

dients will create new materials which will address biological, chemical, or physical needs when placed in a matrix and

molded into a product. Because these ingredients will inevitably be minor in amount, but major in importance in the

polymer compound, the ‘‘additive’’ will become, indeed, the ‘‘star of the show.’’

The influence of nanotechnology is already being felt in the additives arena at levels that are comparable to the load-

ings of colorants and pigments used in thermoplastics and thermosets today, namely in the 0.1 to <10 wt% range.

Although still in its infancy, nanotechnology is already commercial in such additives as nanoclays and nanoparticles on

the inorganic side of the ledger, and carbon nanotubes and ‘‘Buckyballs’’ on the organic side of the ledger.

For example, a nanoclay concentrate is available at 40–60 wt% loading and can be incorporated during compounding

the blend of ingredients. Often, incorporation at the time of molding, where the conventional polymer compound is

being formed into the final product, can be carried out with the ‘‘game changer’’ addition of the nano-based concentrate.

This technical achievement of altering a physical property so dramatically via addition of a concentrate is comparable to

the advent of color concentrates �30 years ago which have become so commonplace today. One advantage of this con-

centrate approach is that the same base resin matrix can now be carried in inventory with a variety of concentrates of

transforming additives, each of them having a dramatically different effect on the final product.

Additionally, nanofibers, nanowires, and other nanosized structures too numerous to mention here are also beginning

to be employed in plastics as additives at concentrations in low levels of weight percent but which change the entire

property profile of the plastic. For example, carbon nanotubes are commonly used to impart electrostatic dissipative and

in some cases electrically conductive properties to highly insulative polymers. The resin is transformed with a bit of the

magic ingredient. Application areas include imparting electrostatic paintability to plastic automotive parts, electrostatic

dissipative properties to polymeric fuel lines, and EMI/RFI shielding properties to plastic enclosures. A unique applica-

tion is the use of carbonaceous SWNT (single-walled nanotubes) to provide electrical conductivity to a cathodic protec-

tion, anti-corrosion primer coating for metal substrates.

Nanoparticles are similarly gaining acceptance in coatings and plastics where their unique electromagnetic radiation

absorption spectra can be used to absorb either UV radiation or to absorb/reflect IR radiation. The former property is

being used to design very robust UV packages for polymers where nonmigration and/or low volatility is required, such

as in food-approved packaging and high-temperature polymers, respectively. Other nanoparticles are being used to

change the melt rheology of traditional polymers by allowing them to flow more easily. Two companies have recently

announced nanoparticle technology developments to improve the overall processing of various polymers and to help

reduce flow marks and improve pigment dispersion.

However, the challenge always remains to disperse these high-surface-area, high-aspect-ratio materials in a uniform

manner and to make sure that the proper amount of interaction of the dispersed nanomaterial within the matrix polymer

is achieved. As this decade progresses, the development of better nanomaterial masterbatches that address these issues of

dispersion and adhesion will need to be addressed successfully.

More stunning additive technologies can be anticipated from the exciting interface between nanotechnology and mate-

rials derived from renewable resources. The clock on additive engineering is being restarted with bio-derived materials,

after years of work with synthetic resins.

Initially, our traditional polymers such as polyolefins, polyamides, and polyesters were developed in the mid-20th

Century when oil and natural gas were plentiful and inexpensive. Development of synthetic polymers superior to natural

products derived from ‘‘mined polymer feedstocks,’’ i.e., oil, was actually a major technological achievement by the

Allies during World War II. This achievement was brought about by concerns for natural rubber supplies held by the

Axis nations. It is ironic that the converse situation now exists, where we need to diminish our dependence on foreign

oil. Thus, ‘‘harvested polymer feedstocks’’ hold the potential to be a renewable matrix polymer source, much needed as

the global demand for oil and natural gas increases, supplies tighten, and prices escalate.

Bio-derived polymer compound ingredients have not been totally absent from the landscape. Where a natural feed-

stock existed and yielded a viable product on the basis of its properties, not its source, that naturally occurring ingredient

established itself in the industry.

Many people are not aware that millions of pounds of a bio-derived additive, ESO, or epoxidized soybean oil, are

used today for the plasticization of poly(vinyl chloride) (PVC), one of the largest commodity plastics in the world. Many

PVC formulations could not be made without this stabilizing plasticizer. This is a very good example of an additive that

is cost effectively derived from a renewable resource and chemically transformed to create its stabilizing functionality. It

has been used successfully for over 50 years and is based on soybeans grown domestically.

Another bio-derived polymer stabilizer additive that has been introduced in recent years is based on renewable rape-

seed oil from Canada. Similarly, Vitamin E, derived from corn in the Midwest, is being used as a processing stabilizer

in polyolefin packaging applications, in some cases as a scavenger for undesired byproducts of polyolefin compounding

that alter the taste of the product in the package.

In each of these examples, the additives have typically been used at levels of <10 wt% and in some cases <1 wt%

but have had a major effect on the entire composition. In the past, stabilizers have had a large effect on thermal aging

152 JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2006 DOI 10.1002/vnl

performance or color development upon processing in levels of <1 wt%, but other additives such as reinforcements have

required >10 wt% and typically 30 wt%.

I foresee the unveiling of the 21st Century as bringing even more examples to this premise of the additive becoming

the star of the show, whereby additives will actually define the property profile of a material, doing so even at homeo-

pathic levels. These new additives could become the ‘‘vitamins’’ and ‘‘hormones’’ of our new polymeric materials, domi-

nating the performance properties of the compound even though being employed at very low levels of weight concentra-

tion. With the matrix polymer work having been done in the 20th Century, indeed, the ‘‘New Age of Additives’’ is now

upon us in the 21st Century.

Additives are no longer ‘‘add ons’’ or ‘‘enablers’’ but are now ‘‘transformers,’’ providing the basis for polymer per-

formance and helping us to address our global needs of better energy efficiency and materials sustainability.

DOI 10.1002/vnl JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2006 153