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Transcript of New polymers for wet-strength – an academic perspective pptA.pdf · New polymers for wet-strength...
New polymers for wet-strength – an academic perspective
Robert PeltonInterfacial Technologies Groupte ac a ec o og es G oup
Department of Chemical EngineeringMcMaster University
1280 Main St. W., Hamilton, Ontario, Canada L8S 4L7E-mail: peltonrh@mcmaster ca
1
E-mail: [email protected]
PaperCon 2011 Page 1240
Ackno ledgementsAcknowledgements
Pengchao Ren
2
PaperCon 2011 Page 1241
Pol in laminePolyvinylamine
2000 we initiated a major project to understand 2000 we initiated a major project to understand the influence of PVAm on the mechanical properties of wet paper
A problem in wet adhesion.
3
PaperCon 2011 Page 1242
O r First Effort in Wet StrengthOur First Effort in Wet Strength
Pelton, R.; Hong, J., Some properties of newsprint impregnated with polyvinylamine. Tappi J. 2002, 1 (10), 21(10), 21– PVAm increased newsprint wet strength– More amine groups (degree of hydrolysis), the betterg p g f y y
We needed a better wet adhesion test.
4
PaperCon 2011 Page 1243
Film Delamination – A Model for Fiber-Fiber Wet AdhesionFiber Wet Adhesion
Polymer addition
Apply PolymerChemical Modification
Regenerated Cellulose(Dialysis Membrane)
89kN89kN
5
Adhere to wheel & 90° peel
Press at 89kN and dry at 23°C and
50%RH
Soaking
PaperCon 2011 Page 1244
W t Adh i T t 90° P lWet Adhesion Test – 90 Peel
20
25
m)
Direct Application
10
15
20
Peel
For
ce (N
/m
0
5
10
Nor
mal
ized
12.5 N/m
Figure: typical force vs displacement trace
0 10 20 30 40Displacement (mm)
Figure: typical force vs. displacement trace Summarized by average normalized force
– Force/width of top laminate N/m
6
f p
PaperCon 2011 Page 1245
Ho o r Method Fits InHow our Method Fits In
Surface Force ApparatusAtomic Force Microscopy, JKRPaper Testing Peel Delamination
Technical (fast) (tedious) Fundamental
SFA, AFM, JKR- gives a lot of information
Technical (fast) (tedious) Fundamental
Wet Paper Testing- standard methods
Wet Cellulose Delamination- fast, standard equipment
- requires very smooth surfaces- well defined physics
- tedious
- fast, large database- relevant substrates
- too complex for fundamental interpretation
- widely available substrate- reproducible results
- a crude model for fibers- somewhat well characterized
7
McLaren (1948)Kurosu & Pelton (2004)
PaperCon 2011 Page 1246
AFM and Peel Delamination Give Similar Res ltsSimilar Results
10
90
100
mg/m) AFM Peel
6
8
40
50
60
70
80
rbed
PVA
m-P
BA
-5
ose
Mem
bran
es /
(mm
2 )
atio
n Fo
rce
/ (N
/mAFM Peel
2
4
0
10
20
30
2 4 6 8 10 12
Max
imum
Ads
obe
twee
n Tw
o C
ellu
lo m
Del
amin
a Final pH 5.9
Final pH 5
Adsorption pH
Notley, S.; Chen, W.; Pelton, R., The extraordinary adhesion of
Chen, W.; Leung, V.; Kroener, H.; Pelton, extraordinary adhesion of phenylboronic acid derivatives of polyvinylamine to wet cellulose a colloidal probe microscopy investigation Langmuir 2009 25 (12)
R., Polyvinylamine-phenylboronic acid adhesion to cellulose hydrogel. Langmuir 2009, 25 (12), 6863
8
investigation. Langmuir 2009, 25 (12), 689
PaperCon 2011 Page 1247
S mmar Wet Adhesion TestSummary – Wet Adhesion Test
A model for fiber-fiber bonds (joints if you are Swedish).
Reproducible Reproducible Can control the amount of polymer in the
adhesive jointj
9
PaperCon 2011 Page 1248
The Bad Ne sThe Bad News
We we tried to measure PVAm wet adhesion with our new method – the forces were very small.
10
PaperCon 2011 Page 1249
The Sol tion O idationThe Solution - Oxidation DiFlavio applied Isogai’s
id ti i t
40
oxidation recipe to cellulose film
Adhesion increases with ll l id ti20
30
l For
ce (N
/m)
cellulose oxidation
10
20
Ave
rage
Pee
00.1 1 10 100
Oxidation Time (min)
pH 7, 10mM NaCl, ~7.5 mg/m^2
DiFlavio, JFRC: Cambridge, UK, 2005; pp 1293-1316.
11
DiFlavio, JFRC: Cambridge, UK, 2005; pp 1293 1316.
PaperCon 2011 Page 1250
Proposed MechanismProposed Mechanism
TEMPO id ti TEMPO oxidation produces aldehyde/hemiacetalsy
PVAm reacts to form imine and aminal covalent bonds withcovalent bonds with cellulose
12Diflavio et al. Cellulose 2007, 14 (3), 257
PaperCon 2011 Page 1251
TEMPO o idation on cell loseTEMPO oxidation on cellulose Primary oxidant: NaClO/NaBr Catalyst: TEMPO Selectively oxidizes primary OH – C6OH on cellulose
COOHO
COOH
O
OH
OHNaCl NaBrO
N OH
N OTEMPO
OCHO
O
OH
OH
NaClO NaBr N O
OH
OCH2OH
OOH
131 T.Saito, A.Isogai. Colloids and surfaces A: Physicochem.Eng.Aspects. 289(2006), P219
OH
OH
PaperCon 2011 Page 1252
Transition State Requires Molecular ContactContact
14Bragd, P. L. et al. Topics in Catalysis 2004, 27, (1-4), 49
PaperCon 2011 Page 1253
Practical Issues with TEMPO Applications in PapermakingApplications in Papermaking
90 g water 10 g od fiber
0 025 TEMPO (0 25%
High chemical concentrations
0.025 g TEMPO (0.25% on o.d. pulp)
0.25 g NaBr (2.5% on o.d.
High pH Chemicals in white
0.25 g NaBr (2.5% on o.d. pulp)
0.45 g NaClO (4.5% on o.d. l )
water
pulp)
Adding base to maintain Adding base to maintain pH at 10
15
PaperCon 2011 Page 1254
Cellulose Oxidation for Increased Wet Strength Rele ant Literat reStrength -Relevant Literature Luner et al. Tappi 1967, 50 (1), 3pp , ( ),
– Aldehydes, not carboxyls give wet strength– Paper must be dried for strength to develop
Kitaoka, T.; Isogai, A.; Onabe Nordic Pulp & Paper Res. J. 1999, 14 (4), , ; g , ; p p , ( ),279– Higher wet strength with PAE
Jaschinski, et al. Pat. US 6,987,181 B2, 2006– SCA patent –TEMPO oxidation to improve wet strength
Saito, T.; Isogai, A., Ind. Eng. Chem. Res. 2007, 46 (3), 773– Good series of TEMPO papersf p p– Aldehydes on pulp enhance many polymers
Many other papers and patents involving water-soluble polymers bearing aldehyde groups.
16
PaperCon 2011 Page 1255
S mmar 2008Summary - 2008 We learned a lot about PVAm adhesion to wet
cellulose– Molecular weight, pH– Hydrophobic substitution– Phenylboronic acid substitution (wet web strength)
Mi l li l– Microgels vs linear polymer Scientifically interesting but some problems with
technological applicationg pp– TEMPO – expensive, toxic (Haseloff et al 1997)– Easy to produce carboxyls instead of aldehydes
17
PaperCon 2011 Page 1256
H pothesisHypothesis
TEMPO must be in physical contact TEMPO must be in physical contact with cellulose
For covalent attachment of PVAm to cellulose we need only a few oxidized sites.
PVAm with grafted TEMPO will PVAm with grafted TEMPO will oxidize the cellulose and then form covalent bonds between the amines and the cellulose aldehydes.
18
PaperCon 2011 Page 1257
H pothesis Contin edHypothesis -Continued
Potential advantages– Much less TEMPO
A i i h– Amines react with aldehydes before further oxidation
– Only exterior fibers or other porous substrates are oxidizedare oxidized
– Immobilized TEMPO should be less toxic and not present in water.
19
PaperCon 2011 Page 1258
Preparation of PVAm TEMPOPreparation of PVAm-TEMPOAmidation reaction catalyzed by EDC/Sulfo-NHSAmidation reaction catalyzed by EDC/Sulfo NHS
COOH
CH2 CHEDC/Sulfo-NHS
CH2 CH CH2 CH
N
O
2
NH2
nC 2 C C 2
NHm
C O
C
NH2
n-m
N 0 29 TEMPO moieties per amine N
O
0.29 TEMPO moieties per amine such high contents are unnecessary measured by conductometric titration activity confirmed by soluble molecule oxidation
20
y y
PaperCon 2011 Page 1259
Stability of PVAm-TEMPO under oxidation diticonditions
PT after 8hs hydrolysis100ce Peak ratio to quantify TEMPO content:
1040020406080
%Tr
ansm
ittan
1240 cm-1: C-N stretching vibration, from PVAm
1040 cm-1: N-O vibration from TEMPO- PT after 4hs hydrolysis
20406080
100
ansm
ittan
ce
%
Samples Peak Ratio (1040 /1240 cm-1)
1040 cm : N O vibration, from TEMPOCOOH
406080
100 PVAm-TEMPO
mitt
ance
0
%Tr
a /1240 cm )
Original PT 0.874
PT, after 4hs’ 0.809
4000 3500 3000 2500 2000 1500 1000 500
02040
%Tr
ansm
Wavenumbers
hydrolysis 0.809
PT, after 8hs’ hydrolysis 0.809
21PVAm-TEMPO is stable under oxidation
conditions!
PaperCon 2011 Page 1260
Direct coating methodExperimental procedure
Direct coating method
PVAm-TEMPO oxidation in aqueous solution, pH 10.3 2h NaBr PVAm-
ONaClO Coated
AAverage
Wet adhesion of treated cellulose films
, p
Oxidized films were
TrialsNaBr
(mg/L)TEMPO(mg/L)
(mmol/g cellulose)
PVAm(mg/m2)
peel force (N/m)
1 0 0 0 6.25 1.9O d ed s e erinsed with water and
laminated with additional PVAm,
then pressed
1 0 0 0 6.25 1.9
2 82.5 0 1.8 6.25 2.9
then pressed
Laminated films were
3 82.5 66.7 1.8 6.25 25.2
PVAm-TEMPO works well as a catalyst!
22
conditioned and peel force was tested
PVAm TEMPO works well as a catalyst!
PaperCon 2011 Page 1261
Infl ence of O idation TimeInfluence of Oxidation Time
Soluble TEMPO40
m)
Soluble TEMPO diffuses into film interior and 20
30
tion
Forc
e (N
/m
Soluble TEMPO Oxidation Diflavio et al. 2005
weakens whole film10
20
Wet
Del
amin
at PVAm-TEMPO Oxidation
Cellulose Film
Grafted TEMPO gives similar ki ti ith t
0 0.1 1 10 100
W
Oxidation Time (min) 0
Cellulose Film Failure
kinetics without oxidizing film interior poresinterior pores
23Jieyi (Jerry) Liu
PaperCon 2011 Page 1262
Comparing Soluble to Tethered TEMPOTEMPO
Assume:– Adsorbed density PVAm-g-TEMPO 1mg/m2– Adsorbed layer thickness 5 nm– TEMPO conc. On cellulose surface 5 M/L
T th d TEMPO t ti 1000> Tethered TEMPO concentration 1000> Saito and Isogai solution concentration.
Much scope to lower TEMPO grafting andMuch scope to lower TEMPO grafting and optimization.
24
PaperCon 2011 Page 1263
Concl sionsConclusions
PVAm-TEMPO does oxidize cellulose Many potential advantages
L TEMPO– Less TEMPO– No soluble TEMPO effluent
No fiber strength loss (exterior oxidation only)– No fiber strength loss (exterior oxidation only) Scope for optimization Ultimate goal self-catalyzing adhesive with no g y g
other chemical additions.
25
PaperCon 2011 Page 1264
See Pelton, R.; Ren, P. R.; Liu, J.; Mijolovic, D., Polyvinylamine-graft-tempo adsorbs onto, oxidizes and covalently bonds to wet cellulose. Biomacromolecules , y2011, on-line. http://dx.doi.org/10.1021/bm200101b
That’s AllThat s All
Bioactivepaper.comPapersci.mcmaster.ca
PaperCon 2011 Page 1265