The polyamides are long-chain polymers containing amide units. These polymers are obtained by polymerization of an acid with an amide. For example, the Polyamide 6.6 (PA 6.6) is produced by the reaction of adipic acid and hexamethylenediamine. The polyamides are the most widely used polymers in the category of engineering plastics, thanks to their excellent price/performance ratio.
The two main types of polyamide are the following:
• Polyamide 6 (PA 6);
• Polyamide 6.6 (PA 6.6).
In addition, by changing the chemical structure (length and chemical organization of the chains), many other families of polyamides may be obtained by, such as:
• Polyamide 11 (PA 11) and polyamide 12 (PA 12);
• Polyamide 4.6;
• Polyamide 6.10, 6.12 and 10.10.
The polyamide 11 (PA 11) is the only high performance polyamide produced from a renewable source, which is castor oil. It is used for a wide range of applications thanks to its outstanding properties, which are similar to those of the polyamide 12 (PA 12), such as: the excellent chemical and thermal resistance, high dimensional stability and low density.
The GRILAMID, one of the most diffused polyamides 12, is a transparent polyamide that can be treated with thermoplastic methods and based on cycloaliphatic and aromatic units. The GRILAMID belongs to the group of homo and copolyamides amorphous polymers.
Wallace Hume Carothers was the first able to synthesize polyamides. Carothers synthesized the polyhexamethylene adipamide (nylon 6.6) in a DuPont laboratory (Delaware, USA), on 28 February 1935. The nylon 6.6 synthesis process (produced by adipic acid and hexamethylene diamine) was patented in 1937 and sold in 1938. In 1940 John W.
Eckelberry of DuPont stated that the letters “nyl” were chosen at random and the suffix “-on” was adopted because it already exists in the names of other fibers (cotton and rayon). A subsequent DuPont publication explained that the name chosen initially was “no-run”, where “run” took on the meaning of “unravel”, and that was modified to improve the sound and avoid potential claims. An urban myth says that nylon stands for: Now You Lose Old Nippon.
This is because in the aftermath of World War II Japan prevented the import of silk from China to the United States that served to weave the parachute soldiers. At this point, the United States rushed out and created this new substitute material giving it exactly that acronym
EMS-GRIVORY in 1970 developed in its laboratories a new type of PA12 polymer, which became the precursor of the
transparent amorphous polyamides, hitherto unknown. GRILAMID was introduced on the market for the first time
in 1975. The first products made in GRILAMID were clothing buttons, completely transparent and able to withstand the
temperatures of a washing machine. This was a big innovation at the time, because of its high resistance to hydrolysis
was a feature unknown to a transparent polyamide at that time.
Thanks to its special characteristics, chemical resistance and impact resistance, helped the development of the data
transmission, going to accomplish the optical fibers protection tubes.
The main polyamides features are:
• Resistance to aging at high temperatures and over time;
• The high strength and rigidity;
• The functional toughness even at low temperatures;
• The high fluidity, for easy filling of the molds;
• Intrinsic resistance to the ignition;
• Excellent dielectric properties;
• A good abrasion resistance;
• An exceptional chemical resistance;
• A high barrier / resistance to chemicals such as gasoline,
fats and aromas;
• High oxygen barrier;
• An outstanding price / performance.
One of the first uses of the PA were the fibers, such as fabrics for parachutes, dresses, swimsuits. Over time later, it
spreads many other areas, such as:
• Air supply: air supply manifolds
• Systems of power transmission: gears, clutches, tensors
• Covers: engine covers
• Air ducts printed by the swelling
• Indoors: airbag containers
• Outdoors: grilles, door handles, wheel covers, mirrors
• Electricity and Electronics
• Power distribution: low-voltage switchboards
• Connectors: CEE industrial connectors, terminals
• Electrical components: switches
• General industry
• Power tools: housings and internal components
• Sports: ski bindings, inline skates
• Rail dampers
• Wheeled carts
• Furniture: various applications
• Pipelines offshore
• Packing films
• Food industry
• Components for coffee machines
• Vacuum containers
• Food containers