LOW TEMPERATURE THERMOPLASTICS (LTT)
The Invention of…
The story of Lester Larson and Dorothy Kester
Most Common Uses…
Splints - removable, comfortable casts for almost any part of the body
Foot Orthotics – custom-made shoe inserts to relieve back and knee pain
HISTORY
3000 BC - bark and palm ribs held together with egg whites or clay
860 AD - predecessor to plaster: lime/egg white mixture
Early 19th century - leather and straw treated with wine, acetate, spirits and egg whites - hardened quickly, but cast was very heavy
1835 - lighter-weight, removable bandage made of cardboard and starch - took several days to harden
Plaster of Paris - natural plaster deposits found near Paris, France - plaster powder rubbed into cotton, soaked in water and applied - cast had to be kept dry - very cumbersome
HISTORY Cont…
1970’s – fiberglass: light, durable and waterproof, still used today
Casts are not suitable for all injuries—such as tendon damage, soft tissue tears or post healing protection
LUCITE – High-temperature thermoplastic
• Rigid and clear
• Could not be molded directly on skin
• Time-consuming process involving a negative cast and a positive mold
HISTORY Cont…
The Golf Ball Connection
Lester Larson• DuPont Chemist
• Broken wrist
• Lucite Splint from
Dorothy Kester• Occupational Therapist
1963-1966
Invented Low Temperature Thermoplastics (LTT)
THE INVENTORS:
Eureka!!The Metaphor
Plastic
Must meet three conditions:
1. Main ingredient must be a polymer
2. It must be fluid at some point of processing
3. It must be “solid” in its final form
The Science of Thermoplastics
Polymers
Transpolyisoprene
Long Search/Little Apparent Progress:Short process. Aware there was a problem, but no documentation of if there was other experimentation or ideas.Precipitating Event:Visit with OT and receives uncomfortable Lucite splintEureka!Seeing the warm, moldable golf ball covers – that could be a splintTransformation:Acceptance by the OT communitySupplying the product to Orthopedic Shoe Company in NY
Lester Larson & Perkins' Model
• Swan Neck Deformity - caused by finger injury or rheumatoid arthritis
HOW LTT IS USED:
• Non-extending fingers – caused by injury or arthritis
• Re-attached fingers – comfortable support and protection
• Also used in radiation and burn treatment
One 18” x 24” sheet of LTT sells for ~$60.00
Question 2: True plastic must meet three conditions. What are they?
Question 1: What was the metaphor used by Lester Larson?
QUESTIONS
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