What are some of the basic characteristics of low temperature thermoplastic materials?

Choosing the correct LTTP is easy when we understand what makes each material unique.

Here is a glossary of terms used to describe the characteristics of LTTP’s:

  1. Rigidity refers to the strength of the material. High rigidity is necessary for large splints, specific diagnoses such as spasticity, and splints projecting large forces.
  2. Memory is the ability of the material to return to its original size and shape after being stretched. This is an important concept when frequent remolding of the splint will be necessary, as in serial splinting to increase extension or flexion over time. Memory makes the material more cost efficient. When working with materials possessing excellent memory, remember to let the splint harden sufficiently before removing or it will lose its shape rapidly. Also LTTPs with excellent memory tend to take longer to harden, so be patient!
  3. Coating is applied to certain LTTPs to make them easier to work with and less likely to adhere together where no adherence is desired.  Bonding is the ability of the material to stick to itself or to other materials. Non-Stick coated materials do not bond without having the coating removed. Non coated materials have very good bonding to themselves and other attachments. Orfit Industries calls all of its non-stick coated products “NS” (see question 9 for more info).
  4. Conformability or drapability refers to the way the material conforms to the shape of the hand. Materials with high drapability work best with gentle handling as they conform easily to the arches or bony prominences by just placing the material on the patient. These materials work with gravity. Materials with low drapability require firm handling and are recommended for larger splints where this moldability is less important.
  5. Resistance to stretch refers to the amount of resistance the material gives to being stretched when heated. High resistance means you must work slowly, firmly and steadily to stretch the material. Low resistance to stretch means you need to carefully control the material as it stretches. Too much pulling will make the material stretch out of control.
  6. Activation temperature is the temperature at which the splinting material becomes pliable for molding. If the water is too cool, the material will not become pliable. If it is too hot, the material will get overheated and sticky and become difficult to work with.  The ideal temperature for most LTTPs is between 60-70°C or 140°-160°F.  Please read the manufacturer’s instructions for use for each individual LTTP.
  7. Perforations in the splinting material allow for ventilation of the skin and make the material lighter in weight. Today we have choices ranging from percentages of perforations to various names of perforation patterns. Catalogs usually feature pictures which demonstrate the different perforation patterns. Always check to make sure the perforation style is suitable for the splint you are making.
  8. Thickness of an LTTP must be taken into consideration as well. Thinner materials such as 1.6 mm (1/16”) and 2.0 mm (1/12”) are better for smaller splints while larger splints may need thicker materials such as 2.5 mm (1/8”) or 3.2 mm (3/32”).  Thinner LTTPs are activated more quickly and also harden more quickly than thicker materials, meaning they have a shorter working time. Thicker materials take longer to become soft and pliable, but have a longer working time as well.  Thicker materials can retain a lot of heat and must be cooled slightly before placing on the patient’s skin.
  9. Working time describes the amount of time from when the material is fully heated to when it is cooled off.  Novice splint makers may want to choose materials that have a longer working time while advanced splinters can usually work quickly and accurately with LTTPs that cool and harden quickly.
  10. Pre-cuts or precut splints are ready to be heated and molded to your patient’s extremity. They are splint designs cut out of specific LTTPs and ordered by size (and/or Right and Left hand). Make sure you measure your patient correctly for each design.
  11. Prefabricated and /or preformed splints have already been molded into a specific shape.  These must be carefully fit to your patient’s extremity and some adjustments may be necessary.  The advantage in these is that the fabrication is complete and you may save time and effort.  However, you may not get as good a fit as when you custom make your own orthoses on your patients.
  12. Orfit Industries’ LTTPs are biocompatible and biodegradable. They are being tested by an external firm for biocompatibility to make sure no skin irritations will be caused. Biodegradability means that the material will degrade in nature and is therefore environmentally friendly.