low temperature thermoplastics (ltt) the invention of… the story of lester larson and dorothy...
TRANSCRIPT
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