GEM-ChemGEM-ChemGEM-Chem GEM-ChemGEM-Chem

Polyurethanes > TPU > e-books

THE POLYMER BOOKSHOP®
e-books & data bases
on Polymer Technology, Engineering Science & Marketing
e-books
at reasonable prices
PU newsreel TPU Applications

Two items in this webpage:
1-TPU. e-books
2-Produce your own TPU

Thermoplastic polyurethanes (TPU)
From chemistry to marketing
ISBN 9078546018

The publication is delivered as follows:
-cd-r in a jewel box, by air mail in a padded envelope.
-USB card (for orders of 5 publications or more), by air mail in a padded envelope.
-pdf format sent by e-mail

ALL PUBLICATIONS ARE REVIEWED AND UPDATED CONTINUOUSLY
THEY ARE RE-EDITED, BEFORE DELIVERY
GEM-Chem's PUBLICATIONS ARE ALWAYS NEW
GEM-Chem's TITLES ARE NEVER OBSOLETE

A photo of a cd-book in its jewel box is shown below.
The index appears when the insert is unfolded.


For orders exceeding five publications the book is also available in USB card form, as shown below.


The outer cd insert of an edition of the cd-book is exposed below

The unfolded inner side of the cd-insert, which is shown below, exposes the contents of an edition, not necessarily a recent one, of the cd-book.


The pages appear on the PC screen as follows.
The example below is not necessarily extracted from the latest edition.


The contents of the "A course" version are shown below


To order the e-book (From chemistry to marketing, version) [ 75, payable by
bank transfer (SEPA countries only) or by credit card via PayPal] please visit
THE POLYMER BOOKSHOP
or send us an email (dk@gem-chem.net)or call (++32-2-7710649) or
click on the button below, fill in the form and send it.
The payment will be confirmed by e-mail
The fully updated e-book will be airmailed (or e-mailed) 10 to 15 days later
The "Advanced course" version, which does not include a patent survey, costs 65.
The "A course" version, which is a comprehensive account of the subject, costs 50.
The "For all" version, which is a basic introduction to the subject, costs 25.
ALL PUBLICATIONS ARE REVIEWED AND UPDATED CONTINUOUSLY.
THEY ARE RE-EDITED, BEFORE SHIPMENT
GEM-Chem's PUBLICATIONS ARE ALWAYS NEW
GEM-Chem's TITLES ARE NEVER OBSOLETE

DISCOUNTS
GEM-Chem's updated publications are strictly personal copies.
A discount of 10% is given whenever 5 copies of the same title are purchased
The discount amounts to 20% when 6 to 10 publications of the same title are purchased


If a delivery by registered mail is required, an additional 5 (five) Euros should be added to the price of each item ordered.
GEM-Chem is not responsible for any losses that result from the postal services.
Deliveries by express mail are arranged upon request.

For discounted publications
click on the text

or communicate with us

For information contact Deny Kyriacos, President & CEO, GEM-Chem,
E-mail: dk@GEM-Chem.net, phone: +32-2-7710649

Dr.Kyriacos has worked at Upjohn, GE and ICI in international TS, Sales and Marketing.
He holds a B.Sc.(Distinction, Honours, University award in Chemistry) from Alexandria,
a M.Sc.course,(ICI scholarship award) in Polymer Technology and, a Ph.D. from
Loughborough in the UK.
Deny Kyriacos is the founder of DK Business Group and GEM-Chem.

Deny Kyriacos: LinkedIn profile


Produce your own TPU

We provide formulations, at moderate prices for:
·Expanded polyester PU elastomers
·Expanded polyether PU elastomers
·Thermoplastic Polyurethanes
We also develop new formulations, offer technical &marketing support online and contribute to setting up PU & TPU systems houses as well as PU &TPU processing units

A-INTRODUCTION
Thermoplastic polyurethanes for injection moulding and extrusion are easy to formulate because of the
-Absence of any foaming process during the formation of the polymer
-Dependence of the technology on a specific polymer morphology
The main constituents of TPU's are linear or difunctional. They comprise
-A diisocyanate
-A high molecular weight diol. This is a polyester or a polyether with a MW = 2000
-A chain extender which consists of a low molecular weight diol such as 1,4 butane diol
The properties of the final product depend on the chemical structure of the above components.
B-CHEMISTRY & MORPHOLOGY
TPU's are elastomers which result from the aggregation and subsequent precipitation of hard segments formed from the reaction of MDI with the chain extender in the soft MDI/high MW diol chains
During the reaction, one -NCO equivalent adds to one -OH equivalent. When equivalent amounts of NCO groups and OH groups are present in the mixture, the isocyanate index is 100.
The resulting chains consist of short, hard segments made of carbamate (urethane) bonds linking the low molecular weight diol with the isocyanate as well as, long flexible (soft) segments made of urethane bonds linking the isocyanate with the high molecular weight diol (macroglycol)
Below the melting point (ca.220ºC), the hard segments, aggregate through hydrogen bonding and precipitate in the soft segment matrix. Those segments constitute physical crosslinks which reinforce the structure of the polymer
Schematically, the above interaction can be represented as follows:
C-STRUCTURE/PROPERTY RELATIONS
A basic formulation for the synthesis of a polyester TPU consists of
-0.16 equivalents of polyethylene glycol adipate (eq. weight = 1000, functionality = 2)
-0.32 equivalents of butanediol
-0.52 equivalents of an isocyanate
1-Isocyanates
MDI is the workhorse of the technology. The diagram below shows the effect of various isocyanates on the hardness of TPU's resulting from the formulation outlined above
Large and rigid aromatic rings, symmetrical structures and the absence of methyl substituents favour high modulus, tear strength and hardness.
Aliphatic diisocyanates, such as hexamethylene diisocyanate, result in products with high UV stability. 2-Polyols/Macrodiols
Diols used in the synthesis of TPU elastomers fall in two categories
-Polyesters (MW = 2000)
-Polyethers (MW = 2000)
TPUs based on polyester polyols are stiffer, have good oil/solvent resistance, and have better abrasion, UV, and heat resistance than polyether based TPU’s.
Polyether-polyol based TPUs are lower specific gravity, softer polymers, with excellent hydrolytic stability, good acid/base resistance, and good low temperature flexibility.
a-Polyester polyols
The diagram below shows the effect of various polyester polyols on the tear strength of TPU's based on MDI and extended with butane diol.
Polyethylene as well as polybutylene adipates are commonly used in the synthesis of polyester TPU's. However, elastomers with optimum properties are obtained from polycaprolactone derived polyester polyols
b-Polyether polyols
The most commonly used polyether polyols are
-Polytetrahydrofuran or polytetramethylene ether glycol (PTMEG)
-Polypropylene glycol
-Polyethylene glycol
3-Chain extenders
The choice of the chain extender depends on the following factors
-The properties required from the final product
-The price of the formulation
The most widely used chain extenders are
-Butane diol(BD)
-Ethylene glycol(EG)
As shown on the graph below, the hardness, as well as other physical properties change by varying the ratio of macrodiol to chain extender, in the fomulation
Other chain extenders comprise, but are not limited to
-Hydroquinone bis(2-hydroxylethyl)ether (HQEE)
-Trimethylene glycol (TriMEG)
-1,6 Hexane diol (HD)
The following graph compares the effect of different chain extenders on the tensile strength of various polyether (PTMEG) and polyester (polybutylene adipate)elastomers
Novel chain extenders include
-Linear dodecane diol. It results in TPU's with better mechanical and thermal properties than 1, 4 butane diol. Furthermore it improves the resilience as well as the moisture resistance of the elastomers.
-Cyclodecane diol. It results in elastomers which are soft (Shore A 60), and have lower compressive strengths & hardness, but have a high softening temperature. They show very low hysteresis & excellent compression set. Soft PU elastomers can be used in printing wheels, sealants, medical applications, synthetic leathers, fibers, etc.

4-Additives
a-Catalysts
The production of TPU's by reactive extrusion (see below) does not necessarily require the presence of catalyst to effect the reaction. The heat and shear of the twin screw extruder are good enough to carry the polymerisation process to completion. Catalysts and particularly metal salts may have a negative role as far as hydrolysis resistance is concerned especially when polyester macrodiols are used. It is well known that metal salts catalyse the hydrolysis and subsequently degrade the polyesters. In extremis, suitable catalysts are tertiary amine compounds.
b-Antioxidants
Sterically hindered phenolic antioxidants are effective, non discoloring stabilizers. They protect the substrates against thermo-oxidative degradation which may occur during the processing of the polymer.
Other antioxidants have an organophosphite structure
On the other hand, sterically hindered amine light stabilizers (HALS) form stable nitroxyl radicals, with oxygen, when exposed to light.

c-UV absorbers
Aromatic polyurethanes and their primary photo-degradation products are sensitive to light
UV absorbers have the property to convert the energy absorbed from UV light into heat
Suitable UV absorbers are benzotriazole derivatives.

d-Biocides
Polyester based TPU suffer from microbiological attack when used in conditions of heat and humidity.
Antimicrobial agents suitable for incorporation into thermoplastic materials include: maleimides, isoindole dicarboximides, isothiazolinone compounds, silver compounds.

e-Other additives
Depending on the specifications of the end product, a TPU formulation may also include the following additives:
-Carbodiimides. They improve the resistance to hydrolysis.
-Lubricants. They lower the inherent tackiness and coefficient of friction of TPU.
-Flame retardants.
-Nanoparticles. They improve the strength of the product.
-Antistatic agents.
-Pigments.
-Antiblocking agents. TPU films have a tendency to adhere together. Antiblocking additives can be added to the polymer to minimise this adhesion.
-Silanes.They improve the adhesion of the elastomer on glass fibre reinforcement.
-Plasticisers.It is not common practice to use plasticisers in TPU formulations. Recent advances in the plasticization of TPU's have shown that liquid plasticizers based on alkylated and esterified with a monocarboxylic acid, polyether-polyols from EO and PO units are used for the manufacture thermoplastic polyurethanes with shore A hardness as low as 40.
D-TPU PRODUCTION
TPU granules for injection or extrusion are manufactured on an industrial scale according to the following methods
1-Casting
It consists of mixing all components in stoichiometric amounts and pouring or casting the mix onto a moving belt (belt process). The polymer is then diced and passed through an oven where the reaction is completed. A variant of the above process consists of removing the material from the belt and feeding it into an extruder for completion of the reaction and homogenisation of the product.
2-Reactive extrusion
The method consists of introducing the liquefied reactants in the feed zone of a twin-screw extruders. The reaction mixture is then homogenized very rapidly in the extruder. In conventional processes, special measures must be taken in order to combine the reactants (relatively high molecular weight polyol, chain extender and diisocyanate) in such a way that a homogeneous mixture is formed before the polyurethane formation begins to any significant extent. If the reactants are mixed too slowly, the polyurethanes formed are inhomogeneous and contain completely or substantially insoluble or infusible gel particles. In order to ensure the stoichiometry of the components in the mix, the individual reactants are first fed stoichiometrically in a special mixing unit and it is only the homogeneous reaction melt which is introduced into the twin screw extruder. The residence times of the reaction melt in the twin screw extruder are ca. 4 minutes. The temperature of the screw barrel is in the range from 240C to 280 C ( 250 C in the feed zone; 280C in the middle of the extruder and 250C in the discharge zone). The melt issuing from the extruder is quenched in water and then pelletised. The length of the screw corresponds to ~ 42 times the screw diameter.
E-TPU APPLICATIONS
The properties which attract designers, technologists and OEM's to use TPU in their products are:
-Resistance to abrasion especially polyester TPU.
-Flexibility at low temperatures and toughness especially polyethers.
-Resistance to greases and oils (polyester grades).
-Tear strength.
TPU’s find applications in the following fields:
-Sportswear, such as soles, heels, boots
-Medical, especially FDA approved grades, used in tapes, blood bags,coats.
-Automotive, such as sleeves, gear stick handles,key parts, air bumps, spokes of airless tires, spring tops.
-Belts, cables and hoses.
-Garnments and apparel.

For information contact Deny Kyriacos, President & CEO, GEM-Chem,
E-mail: dk@GEM-Chem.net, phone: +32-2-7710649

Dr.Kyriacos has worked at Upjohn (Polyurethanes &PU chemicals), GE (Eng. thermoplastics) and ICI (PU) in international TS, Sales and Marketing.
He holds a B.Sc.(Distinction, Honours, University award in Chemistry) from Alexandria,
a M.Sc.course,(ICI scholarship award) in Polymer Technology and, a Ph.D. from
Loughborough in the UK.
Deny Kyriacos is the founder of DK Business Group and GEM-Chem.

Deny Kyriacos: LinkedIn profile

GEM-Chem compose & publish e-books and data bases
on Polymer Science, Engineering, Technology and Marketing.
GEM-Chem initiate, develop, market and direct new projects on company
organisation, international marketing, engineering, technology and science.

GEM-ChemGEM-ChemGEM-Chem GEM-ChemGEM-Chem