Packaging Materials

Petroleum Based Plastics

PC – polycarbonate

Polyester containing carbonate groups, made from bisphenol A and phosgene.

Clear, heat resistant, and durable. Harsh cleaning detergents catalyze the release of bisphenol A and are potential health hazard.

PE – polyethylene

Polyolefin made from ethylene, a gaseous hydrocarbon, using catalysts.

Classified by density:

LDPE: flexible, strong, tough, easy to seal, and resistant to moisture, relatively transparent.

HDPE: stiff, strong, tough, resistant to chemicals and moisture, permeable to gas, easy to process, and easy to form.

PET – polyethylene terephthalate

Polyester made from ethylene glycol and dimethyl terephthalate or terephthalic acid.

Good gas and moisture barrier, good resistance to heat, mineral oils, solvents, and to acids, but not to bases. Glass-like transparency, light weight, shatter resistant.

PP – polypropylene

Polyolefin made from propylene, a gaseous hydrocarbon, using catalysts.

Harder, denser, and more transparent than polyethylene.

PS – polystyrene

Aromatic polymer made from styrene monomers by polymerization.

Clear, hard, and brittle with a relatively low melting point. Foaming produces an opaque, rigid, lightweight material with impact protection and thermal insulation properties.

PSP: Polystyrene Paper

Polystyrene foam in sheet form produced by an extruding process.

OPS: Oriented polystyrene

BOPS: Biaxially oriented polystyrene

Formed by stretching a polystyrene film. Increases transparency, but also stiffness.

PVC – polyvinyl chloride

Polymer made from vinyl chloride monomers by polymerization.

Polyvinyl chloride is a heavy, stiff, ductile, medium strong, amorphous, transparent material. Excellent resistance to chemicals (acids and bases), grease, and oil.

Natural Source Materials

Bioplastics

PLA: polylactic acid

Thermoplastic polyester obtained by condensation or polymerisation of lactic acid.

The lactic acid monomer is obtained from fermented plant starch (corn, sugarcane, etc.). Mechanical properties range from soft and elastic to stiff and high strength. Heat-resistant, non-toxic, biodegradable.

Paper

Made primarily from cellulose fibers of various origin (wood, rags, certain grasses) that are suspended in water. Thin sheets are formed by draining the water through a screen. When untreated, paper has poor barrier properties. Coating, lamination, or impregnation with other materials (waxes, resins, lacquers) improve the protective properties.

Kraft paper: Wood chips are treated with alkaline sulfide, removing lignin and hemicellulose, to isolate almost pure cellulose fibers.

Qualities: natural brown, if unbleached, heavy duty. White color if bleached.

Sulfite paper: Treatment with sulfites produces a lighter and weaker paper than kraft paper. Glazed to improve appearance and increase wet strength and oil resistance, coated for higher print quality.

Greaseproof paper: Prolonged hydration period causes cellulose fibers to become gelatinous and pack densely. Surface becomes resistant to oils but not wet agents.

Glassine: Further hydration and mechanical treatment produce very dense sheets. Highly smooth and glossy surface.

Parchment paper: Acid-treatment of pulp modifies the cellulose to make it smoother and resistant to water and oil, and to increase wet strength.

Paperboard

A thick, more rigid form of paper with a higher weight per square meter.

White board: Made from several thin layers of bleached chemical pulp, may be coated with wax, or laminated with polyethylene for heat sealability. Recommended for direct food contact.

Solid board: Multiple layers of bleached sulfate board, may be laminated with polyethylene to produce liquid containers.

Chipboard: Made from recycled paper. May contain blemishes and impurities. Unsuitable for direct food contact, printing, and folding.

Fiberboard: Solid (inner white board layer and outer kraft layer, can be laminated with plastics or aluminium), Corrugated (both surfaces of central corrugating material covered with kraft paper layers)

Pulp Fiber

Sugar Cane Bagasse: Pulp produced from sugar cane after juice extraction.