Page 211 - Carrahers_Polymer_Chemistry,_Eighth_Edition

174 Carraher’s Polymer Chemistry

(a)

(b)

(c)

FIGURE 5.5 Space-filling models of syndiotactic (a), isotactic (b), and atactic (c) forms of polypropylene.

(My children and now grandchildren believe that the isotactic polypropylene is really a chorus-line of dancing
teddy bears.)

TABLE 5.4
General Physical Properties of iPP

o
Heat deflection temperature (1,820 kPa; C) 55
o
Maximum resistance to continuous heat ( C) 100

Coefficient of linear expansion (cm/cm- C, 10 ) 9
–5
o
Flexural strength (kPa) 5 × 10 4
Impact strength (Izod: cm-N/cm of notch) 27
Tensile strength (kPa) 3.5 × 10 4
Ultimate elongation (%) 100
Density (g/mL) 0.90
from another speaker calling one another various unkind words. It was later learned that each of the
groups had different catalytic systems that gave different products. Thus, the presenters were most
probably giving accurate information but based on slightly differing catalyst systems.

Jumping from a laboratory-scale production to mass production is difficult and is made espe-

cially difficult because of the need to control the structure of the catalyst because only one form
of the catalyst gave the desired iPP and PE while other forms would give mixtures of PP and PE
structures. The first Marlex pellets came off the production line at the Adams plant and they were

varied in color and size, and off specification. It was hard for the sales staff to convince buyers that
this was the miracle material that they had promised. The realization that the catalysts form was so
important became painfully evident. The material was better than the old PE and PP but it was not
as good as that obtained in the laboratory. Warehouse after warehouse of somewhat inferior mate-
rial was produced with few buyers.
Relief was spelled, not “R-E-L-I-E-F,” but rather “H-U-L-A H-O-O-P” which was reinvented by
Richard Knerr and Arthur “Spud” Melin who founded the Wham-O company that also reinvented

9/14/2010 3:39:11 PM
K10478.indb 174 9/14/2010 3:39:11 PM
K10478.indb 174