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