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

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