Some Nanocomposite Forms

Some Nanocomposite Forms

Nylon 6 Nanocomposites

Nylon 6 nanocomposites containing 2 wt% Nanomer are currently available from two
commercial sources, Honeywell Engineered Polymers & Solutions and Bayer AG. Four percent loaded products are under development. Currently available products feature dry-as-molded (DAM) strength improvements of 30% and heat distortion increases double those of neat nylon. As loading increases, so too do strengths and HDT’s.

Mechanical Properties of Nylon 6 Nanocomposites

Nanomer (Wt.%)	Flexture Modulus (Mpa)	Tensile Modulus (Mpa)	HDT (°C)
0%	3404	3117	56
2%	4374	4220	125
4%	4578	4897	131
6%	5388	5875	136

Since real world uses of nylon require performance at moderate-to-high humidity, dry-asmolded values are not indicative of actual service requirements. Fortunately, comparisons of nanocomposite performance vis-a-vis neat nylon are even better under humid conditions. Percent Improvement For Commercial Products Versus Neat Nylon 6

Gas permeability also improves with Nanomer loading. Current commercial products deliver about 50% (2X) improvement in barrier to oxygen. At higher loadings the reduction exceeds 3X. Because Nanomers promote rapid crystallization, clarity is better than neat nylon, making nanocomposites ideal for films. Taking into account their improved strength, nanocomposites can be run at higher line speeds. Add to this the benefit of better print hold-out, and they become a superior, low cost film material.

Nylon nanocomposites find application in mono and multi-layer films as well as thin-wall structures. All are amenable to down-gauging, especially in instances where gas barrier is the dominating requirement. In mono-layer applications one has the obvious option of maintaining film thickness and taking advantage of additional barrier performance. In thin-wall structures and packages where stiffness is important, i.e. stand-up pouches, nanocomposites offer a low cost solution, particularly in high humidity environments.

Ultra-High Barrier Nanocomposites

The inexorable movement of plastics into packages formerly dominated by glass and
aluminum creates demand for very low gas barrier plastics, which are easy to process in
conjunction with common resins such as polyester. One such material is Nylon MXD6*. This semi-crystalline resin exhibits very good gas barrier. Its barrier is exceptionally good at high humidity. Converting MXD6 to a nanocomposite further enhances barrier, making it superior to EVOH, the most commonly used high barrier resin. MXD6 nanocomposites were developed in conjunction with Eastman Chemical Company and are available directly from Nanocor under the tradename, ImpermTM.

Imperm is appropriate for films, as well as multi-layer beverage and food containers.
Oxygen barrier for films improves by 80% (5X) compared to neat MXD6. The barrier
improvement in multi-layer PET containers is somewhat lower due to less-than-perfect platelet alignment during the bottle blowing process. Bottle oxygen barrier improves about 70% (3.8X) with bottle side-wall CO2 improvement of 60% (2.5X) at ambient pressure. When the bottle is pressurized at 3 volumes CO2 barrier improvement drops to slightly better than 40%. (1.7X)

Polyolefin Nanocomposites

This area includes polypropylene and co-polymers, TPO’s and TPE’s. In contrast to nylon 6 nanocomposites, commercial products are not available through resin producers. Rather they are offered by independent compounders or produced at customer locations, using masterbatches supplied by masterbatch producers. Masterbatches are available from Clariant Corporation and RTP Company, among others.

Masterbatches typically consist of 40-50 wt% Nanomer and a nanocomposite usually
contains 6 wt% loading for an average let-down ratio of 8:1. Polyolefin-type materials represent a wide range of hydrophobicity. Often a specific grade of Nanomer must be matched to a specific resin grade. Nanocor assists with Nanomer selection and then works with the compounder or masterbatch producer.

Both mechanical and barrier improvements drive nanocomposite use. Low melt-flow homopolymer polypropylenes (MF 2-15) yield the best mechanicals with increases ranging from 75-95% of neat resin. HDT’s improve 30%. Part densities are slightly above neat resin (0.93 vs 0.90). Co-polymers, TPO’s and TPE’s demonstrate mechanical increases from 40-65%. HDT’s for co-polymers and TPO’s are somewhat lower than homopolymer.

Mechanical Properties of Injection Molded HPP Nanocomposites

Process	PP Type	Addition level (%)	Tensile Mod Mpa	Flextural Mod (Mpa)	HDT (°C)
Injection Moulding	Homopolymer	-	1412	1148	87
	(Low melt flow)	6%	2804	2043	116
Injection Moulding	Homopolymer	-	1327	1196	86
	(Medium melt flow)	6%	2180	1777	109

Depending on the polyolefin, gas permeability reductions range from 25-50% (1.3-2X).
Polyolefins are low water vapor transmitters. Nanocomposites improve WVTR a more modest 10-15%.

Unsaturated Polyester Nanocomposites

Unsaturated polyester (UPE) nanocomposites find application in fiber reinforced products used in the marine, transportation and construction industries. UPE nanocomposite formulations are available from Polymeric Supply, Inc., Fort Pierce, FL. These formulations provide greater chemical resistance, especially to corrosive chemicals and sea water. Depending on the specific corrosive tested, ASTM D 543 Relative Uptakes can be reduced by 70%. UPE nanocomposites are also more dimensionally stable and fire resistant.

UPE/fiberglass nanocomposites are being used for boat accessories. In addition to the
above benefits, accessories are less prone to color fading. Sag control is another major benefit, also seen in epoxy formulations. Sag control is the ability of the liquid resin to properly wet out and adhere to fiberglass matting prior to curing. Fumed silica has traditionally been used for sag control. Nanomers bring to thermosets the same type of rheology as fumed silica, and therefore provide sag control in addition to cured property improvements. Nanomers are easier to disperse and they are less costly, delivering the cured resin benefits at little-to-no cost increase compared to existing formulations.