Basic polymer engineering data

266 Pages·2017·22.263 MB·English

by  Rao, Natti S

Natti S. Rao
Basic Polymer
Engineering Data
Rao
Basic Polymer Engineering Data

Natti S. Rao
Basic Polymer
Engineering Data
Hanser Publishers, Munich Hanser Publications, Cincinnati
The Author:
Dr. Natti S. Rao, Schieferkopf 6, 67434 Neustadt, Germany
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Preface
Mechanical, thermal, and rheological properties of polymers form the basic group
of property values required for designing polymer machinery. In addition, knowl-
edge of the properties of the resin, such as stock temperature of the melt, is neces-
sary for optimizing the process. Furthermore, while designing a plastic part, per-
formance properties of the resin, depending on the application, are to be considered.
Examples of which are flammability, weather resistance, and optical properties, to
name a few. Hence, a variety of property values is needed to accomplish machine
design, part design, and process optimization.
The bulk of polymer machinery is comprised of extruders and injection molding
machines. Their designs can be accomplished empirically by trial and error proce-
dures based on experiments. However, these methods are costly and time-consum-
ing and not always feasible if one has to work with large units like a high speed
blown film line or a sheet making unit of a thermoforming plant.
As a result, the use of software based on numerical analysis of the processes occur-
ring in these machine elements has found more applications and become a state-
of-the-art design tool. The property data required to perform design calculations
using software exists in databanks, which are available on the market. However,
for a number of practical applications, these databanks are too extensive to justify
their use; for example, to obtain a quick estimate of the dimensions of an extrusion
die or the cooling of a part in an injection molding die.
The intent of this book, first of all, is to create an easy to use quick reference that
covers basic design data on resin, machine, part, and process, and second, to show
how this data can be applied to solve practical problems. With this aim in mind,
numerous examples are given to illustrate the use of this data. The calculations
involved in these examples can be easily handled with the help of handheld cal-
culators.
Chapters 1 to 5 deal with the description of physical properties—mechanical, ther-
mal, rheological, electrical, and optical—of polymers and principles of their meas-
urement. In Chapter 6 the effect of external influences on the performance of poly-
mers is treated. General property data for different materials such as liquid crystal
VI Preface
polymers, structural foams, thermosetting resins, and reinforced plastics are given
at the end of this chapter.
In Chapter 7 the processing properties and machine related data are presented for
continuous extrusion processes; namely, blown film, pipe, and flat film extrusion.
Resin and machine parameters for thermoforming and compounding have also
been included in this chapter.
Chapter 8 deals with blow molding and the influence of resin and machine varia-
bles on different kinds of blow molding processes. Finally, Chapter 9 covers
resin-dependent and machine-related parameters concerning the injection mold-
ing process.
Machine element design, covered in Chapters 7 to 9, includes screw design for
extruders and injection molding machines, die design for extruders, mold design
for molding and forming operations, and downstream equipment for extrusion.
Wherever appropriate, the properties and machine related parameters are de-
scribed by mathematical formulas that are, as already mentioned, illustrated by
worked-out examples. The solution procedure used in these examples describes
the application of polymer data to solve practical problems. On the basis of this
approach, the importance of polymer data in dealing with design and process opti-
mization is explained.
Thanks are due to Dr. Benjamin Dietrich of The Karlsruhe Institute of Technology
for his cooperation in preparing the manuscript, and to Prof. Stephen Orroth of the
University of Massachusetts at Lowell, for his fruitful suggestions.
I am extremely grateful to Dr. Mark Smith of Hanser for his careful review of the
manuscript and corrections needed to attain compatibility with the printing re-
quirements. Thanks are also due to Cheryl Hamilton for her great help in editing
the text. The careful proofreading and various suggestions for improving the manu-
script by Julia Diaz, associate editor of Hanser, are also thankfully acknowledged.
Natti S. Rao, Ph. D.
About the Author
Natti S. Rao obtained his B. Tech (Hons) in Mechanical Engineering and M. Tech in
Chemical Engineering from the Indian Institute of Technology Kharagpur, India.
After receiving his Ph. D. in Chemical Engineering from the University of Karls-
ruhe, Germany, he worked for many years as a senior research assistant with the
BASF AG. Later, he served as a technical advisor to the leading machine and resin
manufacturers in various countries.
Dr. Rao has published over 70 papers and authored six books on designing poly-
mer machinery with the help of computer programs. Prior to starting his consult-
ing company in 1987, he worked as a visiting professor at the Indian Institute of
Technology, Madras. Besides consulting, he conducts seminars on the computer-
aided design of polymer machinery. Dr. Rao has given lectures on polymer engi-
neering at the University of Texas, Austin, and he is presently involved in the
Continuing Education Department of UMASS Lowell, MA.
Dr. Rao is a Fellow of the Society of Plastics Engineers USA.

Contents
Preface ......................................................... V
About the Author ............................................... VII
1 Mechanical Properties of Solid Polymers .................... 1
1.1 Ideal Solids .................................................. 1
1.2 Tensile Properties ............................................. 2
1.2.1 Stress-Strain Behavior .................................. 3
1.2.2 Tensile Modulus ....................................... 5
1.2.3 Effect of Temperature on Tensile Strength .................. 7
1.3 Shear Properties .............................................. 7
1.3.1 Shear Modulus ........................................ 8
1.3.2 Effect of Temperature on Shear Modulus ................... 8
1.4 Compressive Properties ........................................ 10
1.4.1 Bulk Modulus ......................................... 11
1.5 Time Related Properties ....................................... 12
1.5.1 Creep Modulus ........................................ 12
1.5.2 Creep Rupture ......................................... 14
1.5.3 Relaxation Modulus .................................... 14
1.5.4 Fatigue Limit .......................................... 15
1.6 Hardness .................................................... 18
1.7 Impact Strength .............................................. 19
1.8 Coefficient of Friction ......................................... 19
1.9 References ................................................... 24
2 Thermal Properties of Solid and Molten Polymers ............ 25
2.1 Specific Volume .............................................. 25
2.2 Specific Heat ................................................. 28