Nanostructured Polymer Blends

550 Pages·2014·42.963 MB·550\550

by  Sabu Thomas, Robert Shanks and C. Sarathchandran (Eds.)

Nanostructured Polymer Blends
Nanostructured Polymer Blends
Editors
Sabu Thomas
Robert Shanks
Sarathchandran Chandrasekharakurup
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Preface
Polymer blends are an effective means of combining polymers to obtain desirable properties
from each constituent polymer without preparation of specific copolymers. Polymer blends
are preferably two-phase materials so that properties of constituent polymers are retained,
while in miscible polymers properties are likely to be averaged. In concert with interest in
nanotechnology, the phase dimensions of a dispersed phase in polymer blends can vary
from micrometer, to nanometer through to miscibility on a molecular scale. Polymer blends
with nanometer dispersed phase are the subject of this book.
Nanostructured polymer blends have been classified into various combinations, polymer
types and methods of preparation in developing the chapters of this book. Important
questions to be addressed are: How can phase dimensions be created in the nanometer scale
when polymers are in blends? Will a nanophase blend undergo particle growth through
diffusion to form larger particles? Are special dispersion methods required or can the blends
be created by phase separation from an initially miscible blend? Characterization techniques
are available to assess structure, morphology and properties of nanostructured polymer
blends.
Phase morphology in nanostructured blends could be obtained by shear dispersion of the
minor phase if relative viscosity and interfacial tension was such that droplets are disrupted
into smaller and smaller size until nano-dimensions are reached. Polymers that are miscible
at elevated temperature could be cooled giving spinodal decomposition into a dispersed
nano-phase. Phase separation by crosslinking of one polymer component will entropically
separate the other polymer, particularly at the gel point, which may be accompanied by
spinodal decomposition. Crystallization of one polymer will exclude and hence separate the
second polymer. If kinetics and thermodynamics are suitable a nanostructured polymer
blend can be formed. Theoretical modeling based upon solubility parameters, interactions
parameters and volume fraction theories are applicable for an understanding of
nanostructured polymer blends.
Nano-phase formation and stability can be achieved through use of compatibilisers since the
interface is critical in dispersed particle stabilization. Blends where both polymers are
thermoplastics are a convenient starting place for investigation of nanostructured blend
xv
xvi Preface
formation. Thermosetting polymers combined with block copolymers gives potential for
control of morphologies via block copolymer design and the time(cid:1)temperature(cid:1)
transformation of the thermosetting polymer. If the copolymer is of hyper-branched type
then further options are available for phase separation during cure of the thermoset.
Combinations of block copolymers allow fine tuning of blend morphology by choice,
arrangement and molar mass of the respective polymer blocks.
Specialty polymers such as hydrogels and liquid crystalline polymers can form nanophases
due to gel structures or mesogen domains within one of the phases. Hybrid materials
consisting of a disparity of size, source or composition can evolve into nanostructured
materials with unique property combinations. The materials may have specific interfaces
leading to explicit thin film properties, hierarchal structures and stimulus responsive
character. Formation of a percolation network or co-continuous structure can impart
electrical conductivity. Nano-polymer particles dispersed in a polymer can have a
disproportionate role in thermal ageing due to polymer ageing dependence on free volume
contributions. A further contribution is retardation of degradation as found for nano-
composites and fire retardation. Polymer blend systems with controlled dispersed phase size
and morphology in the nano-scale are being developed as part of the thrust into nano-
materials. Unique property combinations and specificity are leading these materials into
new applications with commercial development to follow.
Sabu Thomas
Robert Shanks
Sarathchandran Chandrasekharakurup
List of Contributors
BlessingAtim Aderibigbe Tshwane University ofTechnology, Department ofPolymer
Technology, Lynnwoodridge, Republic ofSouth Africa
Gizelda Maria Alves Laboratory of Polymers,ChemicalEngineering Department, Engineering
School ofLorena, UniversityofSa˜o Paulo, Sa˜oPaulo, Brazil
S.M. Ashraf Materials Research Laboratory, Department ofChemistry,Jamia Millia Islamia
(A Central University), New Delhi, India
Luigi Botta Department ofCivil,Environmental, Aerospace, and Material Engineering, University
of Palermo, Palermo, Italy
Shanavas Abdul Jailani Tshwane Universityof Technology,Department ofPolymer Technology,
Lynnwoodridge,Republic of South Africa
Jaragula Jayaramudu Tshwane University ofTechnology, Department ofPolymer Technology,
Lynnwoodridge,Republic of South Africa
Golap Kalita Department ofFrontier Materials, Centerfor Fostering Young and Innovative
Researchers, Nagoya Instituteof Technology, Nagoya,Japan
Antonella Macagnano Institutefor Microelectronics andMicrosystems(cid:1)National Research
Council,Rome, Italy
Simone deFa´timaMedeiros Laboratory of Polymers, ChemicalEngineering Department,
Engineering School of Lorena, Universityof Sa˜o Paulo, Sa˜o Paulo,Brazil
Yuan Meng MOE Key Laboratoryof Macromolecular Synthesisand Functionalization,
Department ofPolymer Science and Engineering, Zhejiang University, Hangzhou China
Se´rgio Roberto Montoro Laboratory ofPolymers, ChemicalEngineering Department,
Engineering School of Lorena, Universityof Sa˜o Paulo, Sa˜o Paulo,Brazil
KoduriRamam Department ofMaterialsEngineering, FacultyofEngineering, Universityof
Concepcio´n, Concepcio´n, Chile
Goddeti Siva Mohan Reddy Tshwane Universityof Technology, Department of Polymer
Technology, Lynnwoodridge, Republic ofSouth Africa
UfanaRiaz Materials Research Laboratory, Department ofChemistry, Jamia Millia Islamia
(A Central University), New Delhi, India
Dr. Juan Rodr´ıguez-Herna´ndez Instituteof Polymer Science and Technology(ICTP-CSIC),
Chemistry and Properties of Polymeric Materials Department, Madrid,Spain
Emmanuel Rotimi Sadiku Department ofChemical andMetallurgicalEngineering,Polymer
Technology Division,Tshwane UniversityofTechnology, Republic ofSouth Africa
Gity Mir Mohamad Sadeghi Department ofPolymer Engineering andColor Technology,
AmirkabirUniversity ofTechnology, Tehran, Iran
xvii
xviii List of Contributors
Oluranti Sadiku-Agboola Tshwane University ofTechnology, Department ofChemical,
Metallurgicaland Material Engineering, Pretoria, Republic ofSouth Africa
Emmanuel Rotimi Sadiku Tshwane UniversityofTechnology,Department ofChemical,
Metallurgicaland Material Engineering, Pretoria, Republic ofSouth Africa
RotimiSadiku Tshwane Universityof Technology, Department of Polymer Technology,
Lynnwoodridge,Republic of South Africa
Sarathchandran Chandrasekharakurup Centre for Nanoscience andNanotechnology, Mahatma
GandhiUniversity, Kottayam,Kerala,India
Roberto Scaffaro Department of Civil, Environmental, Aerospace, and Material Engineering,
University ofPalermo, Palermo, Italy
Robert A. Shanks Applied Sciences, RMIT University, Melbourne,Australia
Elijah Sobalaje Ogunniran Department ofChemical andMetallurgicalEngineering,Polymer
Technology Division, Tshwane Universityof Technology, Republic ofSouthAfrica
Masaki Tanemura Department of FrontierMaterials,NagoyaInstitute ofTechnology, Nagoya,
Japan
Sabu Thomas Centrefor Nanoscience and Nanotechnology,Mahatma Gandhi University,
Kottayam, Kerala,India
Masayoshi Umeno Department of Electronicsand Information Engineering, ChubuUniversity,
Kasugai, Japan
KokkaracheduVaraprasad Tshwane University ofTechnology, Department ofPolymer
Technology, Lynnwoodridge, Republic ofSouth Africa
Xinghong Zhang MOE Key Laboratory of Macromolecular Synthesisand Functionalization,
Department ofPolymer Science andEngineering, Zhejiang University,HangzhouChina
CHAPTER 1
Polymer Blends
SarathChandran C. (cid:1),†, Robert A. Shanks† and S. Thomas(cid:1)
(cid:1)
Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, India
†Applied Sciences, RMIT University, Melbourne, Australia
Chapter Outline
1.1 Introduction 1
1.2 Polymer(cid:3)PolymerMiscibility Theory 4
1.2.1 MacromolecularSolubility 4
1.2.2 BinodalPhaseSeparation 6
1.2.3 SpinodalPhaseSeparation 7
1.2.4 NanophaseSeparation 7
1.2.5 BlendsofSemicrystallinePolymers 7
1.3 IncompatiblePolymer Blends 8
1.4 Miscible PolymerBlends 8
1.4.1 InteractionsandMiscibility 8
1.4.2 LossofDesirableProperties 9
1.5 Cross-Linking of MisciblePolymer Blends 10
1.5.1 Cross-LinkingoftheMajorPhase 10
1.5.2 Cross-LinkingoftheMinorPhase 10
1.6 CompatiblePolymerBlends 11
1.6.1 CompatiblePolymers 11
1.6.2 Shear-InducedColloidFormation 11
1.7 NanophaseBlends 12
1.7.1 PropertiesofNanoblends 12
1.8 Conclusion 12
References 13
1.1 Introduction
TheartofmixingdifferentmaterialswasknowntomankindfromtheBronzeAge.Concrete,
metalalloys,andfibercompositesthatareconsideredtobetypicalexampleswereintroduced
[1].Intheearlystagesofpolymerindustrythemajorpolymersusedwerewood,naturalrubber,
andgutta-perchaalongwithnaturalfiberssuchascellulose,proteinfibers,andleather.The
NanostructuredPolymerBlends.
DOI:http://dx.doi.org/10.1016/B978-1-4557-3159-6.00001-8 1
©2014ElsevierInc.Allrightsreserved.
2 Chapter 1
year1846witnessedthefirstpolymerblend(naturalrubberblendedwithgutta-percha)which
wasreportedinthepatentsofHancockandParkes[1].Asinglerotormasticatingmachinewas
usedfortheblendingprocess.Thiswasfollowedbytheslowdevelopmentofblending
technology.Inthefirsthalfofthetwentiethcenturygreatprogressinthepolymerindustryled
tothedevelopmentofawiderangeofnewpolymers.Laterthedepletionofeconomicwaysto
developnewmonomers,andthefactthatnewlydevelopedmonomersgaverisetopolymers
withintermediatepropertiesascomparedwiththeexistingpolymers,ledtothedevelopmentof
polymerblending[2].Thelast80yearsshowanexponentialincreaseinthenumberofpolymer
blendpatentsandliterature;thenumberalmostdoubledafter1993[3].Thus,polymerblends
areaclassofmaterialsinwhichatleasttwopolymersarecombinedtogetherresultinginanew
materialwithdifferentphysicalproperties[4].
The important advantages of polymer blending can be summarized as:
(cid:129) Development of new properties or improvement of existing properties to meet specific
needs
(cid:129) Material cost reduction with little or no loss of properties
(cid:129) Material processability improvement
(cid:129) Meeting the needs of emerging industries by surpassing the polymerization step
Polymer blends can broadly be classified into three categories:
1. Miscible polymer blends
2. Compatible polymer blends
3. Immiscible polymer blends
The main differences and the important conditions for miscibility are shown in Table 1.1.
The success of developing a polymer blend depends on the effectiveness with which the
following inherent limitations are overcome [4].
(cid:129) The high interfacial tension (Γ between 1.531023 and 1.531022J(cid:4)m22) making
12
the dispersion of one polymer in another phase extremely difficult
(cid:129) Poor interfacial adhesion resulting in narrow interphase width
(cid:129) Instability of immiscible polymer blends
Table1.1:The Variation of Properties for Polymer Blends in Relation totheir Miscibility
MiscibleBlends PartiallyMiscibleBlends ImmiscibleBlends
Homogenous Partialphaseseparation Completephaseseparation
Mechanicalpropertiesof Mechanicalpropertiesof individual Poorinterfaceleadingto
componentsaveraged componentpolymersmostlyretained mechanicalproperties
ΔG,0 ΔG.0 ΔG.0
Theyshowasingleglass Theyshowtwoglasstransition Theyshowthetwoglasstransition
transitiontemperature temperatures,intermediatetothe temperaturesofthecomponent
componentpolymers polymers
Polymer Blends 3
When a polymer is made by the union of two or more different “mers” (the smallest repeat
unit of a polymer chain) it is called a copolymer.
Copolymers include:
(cid:129) Alternating copolymers, in which the individual “mers” appear in an alternating manner
(cid:129) Random copolymers, in which the individual mers are repeated randomly
(cid:129) Block copolymers, in which the polymer chain consists of repeating blocks of
individual mers
(cid:129) Graft copolymers, in which the side chains are structurally different from the main
chain; a common example of this is the free radical polymerization of styrene in the
presence of poly(butadiene) (with active double bonds), which results in a polystyrene
chain with poly(butadiene) branches
In a polymer blend the interactions between the different monomers are predominantly
interactions such as hydrogen bonding, Van der Waals interaction, or dipole(cid:3)dipole
interactions, whereas in a copolymer the interaction is predominantly covalent in nature. In
a copolymer the structural arrangement of molecular units plays an important role in
properties such as melting temperature, glass transition temperature, modulus, and tensile
strength. In a random copolymer these properties are averaged; a block copolymer gives
superiority in individual properties [5]. The variation of the properties for polymer blends is
shown in Figure 1.1.
100
Composition
S yn ergistic vcaormiapbaletibility
Intermediate
y
pert Additive incompatibility
o
Pr
Incompatible
0 100
Composition
Figure1.1
Variation of theproperties ofpolymer blends as a function ofcomposition.