Laser transmission welding is a well-known joining technology for welding thermoplastics. Although the process is already used industrially, fundamental process-structure-property relationships are not fully understood and are therefore the subject of current research. One aspect of these mentioned process-structure-property relationships is the interaction between the temperature field during the welding process, the weld seam morphology of semi-crystalline thermoplastics, and the weld seam strength. In this study, the influence of the line energy on the weld seam morphology of polypropylenes is analyzed. For this purpose, the size of spherulites in the weld seam is investigated, as well as different occurring phases of polypropylene (α- and β-phase). It is shown that both the spherulite size of the α-phase and the amount of β-phase increase with increasing line energy. For the explanation and discussion of the results, a temperature-dependent thermal simulation model is used to derive characteristic attributes of the temperature field (maximum temperatures, cooling rates, temperature gradients).

References

References
1.
Devrient
,
M.
,
Kern
,
M.
,
Jaeschke
,
P.
,
Stute
,
U.
,
Haferkamp
,
H.
, and
Schmidt
,
M.
,
2013
, “
Experimental Investigation of Laser Transmission Welding of Thermoplastics With Part-Adapted Temperature Fields
,”
Phys. Procedia
,
41
, pp.
59
69
.
2.
Hänsch
,
D.
,
2001
, “
Die Optischen Eigenschaften Von Polymeren Und Ihre Bedeutung Für Das Durchstrahlschweißen Mit Diodenlaser
,” Doctoral dissertation, Universität Aachen, Aachen, Germany.
3.
Russek
,
U.
,
2006
, “
Prozesstechnische Aspekte Des Laserdurchstrahlschweißens Von Thermoplasten
,” Doctoral dissertation, Universität Aachen, Aachen, Germany.
4.
Hofmann
,
A.
,
2006
, “
Hybrides Laserdurchstrahlschweißen Von Kunststoffen
,” Doctoral dissertation, Universität Erlangen-Nürnberg, Erlangen, Germany
5.
Acherjee
,
B.
,
Kuar
,
A. S.
,
Mitra
,
S.
, and
Misra
,
D.
,
2010
, “
Selection of Process Parameters for Optimizing the Weld Strength in Laser Transmission Welding of Acrylics
,”
J. Eng. Manuf.
,
224
(
10
), pp.
1529
1536
.
6.
Juhl
,
T. B.
,
Christiansen
,
J. C.
, and
Jensen
,
E. A.
,
2013
, “
Investigation on High Strength Laser Welds of Polypropylene and High-Density Polyethylene
,”
J. Appl. Polym. Sci.
,
129
(
5
), pp.
2679
2685
.
7.
Frick
,
T.
,
2007
, “
Untersuchung Der Prozessbestimmenden Strahl-Stoff-Wechselwirkungen Beim Laserstrahlschweißen Von Kunststoffen
,” Doctoral dissertation, Universität Erlangen-Nürnberg, Erlangen, Germany.
8.
Geiger
,
M.
,
Frick
,
T.
, and
Schmidt
,
M.
,
2009
, “
Optical Properties of Plastics and Their Role for the Modelling of the Laser Transmission Welding Process
,”
Prod. Eng.
,
3
(
1
), pp.
49
55
.
9.
Schmailzl
,
A.
,
Hierl
,
S.
, and
Schmidt
,
M.
,
2016
, “
Gap-Bridging During Quasi-Simultaneous Laser Transmission Welding
,”
Phys. Procedia
,
83
, pp.
1073
1082
.
10.
Herzog
,
D.
,
Fargas
,
M.
,
Meier
,
O.
, and
von Busse
,
A.
,
2007
, “
Process Monitoring System for Laser Transmission Welding of Plastics Using Direct Visualization of the Weld Seam
,”
Proc. SPIE
6530
,
pp. 65300A-1–65300A-8.
11.
Jaeschke
,
P.
,
Herzog
,
D.
, and
Hustedt
,
M.
,
2008
, “
Thermography Enhances the Capabilities of Laser Transmission Welding
,”
InfraMation
, Reno, Nevada, Nov. 3–7, pp.
209
220.
12.
Wippo
,
V.
,
Devrient
,
M.
,
Kern
,
M.
,
Jaeschke
,
P.
,
Frick
,
T.
,
Stute
,
U.
,
Schmidt
,
M.
, and
Haferkamp
,
H.
,
2012
, “
Evaluation of a Pyrometric-Based Temperature Measuring Process for the Laser Transmission Welding
,”
Phys. Procedia
,
39
, pp.
128
136
.
13.
Acherjee
,
B.
,
Kuar
,
A. S.
,
Mitra
,
S.
,
Misra
,
D.
, and
Acharyya
,
S.
,
2012
, “
Experimental Investigation on Laser Transmission Welding of PMMA to ABS via Response Surface Modeling
,”
Opt. Laser Technol.
,
44
(
5
), pp.
1372
1383
.
14.
Kaiser
,
W.
,
2006
,
Kunststoffchemie Für Ingenieure
,
Carl Hanser Verlag
,
München Wien, Munich, Germany
.
15.
Romankiewicz
,
A.
,
Sterzynski
,
T.
, and
Brostow
,
W.
,
2004
, “
Structural Characterization of α- and β-Nucleated Isotactic Polypropylene
,”
Polym. Int.
,
53
(
12
), pp.
2086
2091
.
16.
Koltzenburg
,
S.
,
Maskos
,
M.
, and
Nuyken
,
O.
, :
2014
,
Polymere: Synthese, Eigenschaften Und Anwendungen
,
Springer Verlag
,
Berlin
.
17.
Tjordeman
,
P.
,
Robert
,
C.
,
Marin
,
G.
, and
Gerard
,
P.
,
2001
, “
The Effect of α, β Crystalline Structure on the Mechanical Properties of Polypropylene
,”
Eur. Phys. J. E
,
4
(
4
), pp.
459
465
.
18.
Ehrenstein
,
G. W.
,
2011
,
Polymer Werkstoffe: Struktur – Eigenschaften – Anwendungen, 3
,
Auflage, Hanser Verlag
,
München, Germany
.
19.
Ohlberg
,
S. M.
,
Roth
,
J.
, and
Raff
,
R. A. V.
,
1959
, “
Relationship Between Impact Strength and Spherulite Growth in Linear Polyethylene
,”
Appl. Polym.
,
1
(
1
), pp.
114
120
.
20.
Wright
,
D. G. M.
,
Dunk
,
R.
,
Bouvart
,
D.
, and
Autran
,
M.
,
1988
, “
The Effect of Crystallinity on the Properties of Injection Moulded Polypropylene and Polyacetal
,”
Polymer
,
29
(
5
), pp.
793
796
.
21.
Perkins
,
W. G.
,
1999
, “
Polymer Toughness Impact Resistance
,”
Polym. Eng. Sci.
,
39
(
12
), pp.
2445
2460
.
22.
Remaly
,
L. S.
,
1970
, “
Time-Dependent Effect of Spherulite Size on the Tensile Behavior of Polypropylene
,”
J. Appl. Polym. Sci.
,
14
(
7
), pp.
1871
1877
.
23.
Way
,
J. L.
,
Atkinson
,
J. R.
, and
Nutting
,
J.
,
1974
, “
The Effect of Spherulite Size on the Fracture Morphology of Polypropylene
,”
J. Mater. Sci.
,
9
(
2
), pp.
293
299
.
24.
van Erp
,
T. B.
,
Balzano
,
L.
, and
Peters
,
G. W. M.
,
2012
, “
Oriented Gamma Phase in Isotactic Polypropylene Homopolymer
,”
ACS Macro Lett.
,
1
(
5
), pp.
618
622
.
25.
Raab
,
M.
,
Scudla
,
J.
, and
Kolarik
,
J.
,
2004
, “
The Effect of Specific Nucleation on Tensile Mechanical Behaviour of Isotactic Polypropylene
,”
Eur. Polym. J.
,
40
(
7
), pp.
1317
1323
.
26.
Varga
,
J.
,
1992
, “
Supermolecular Structure of Isotactic Polypropylene
,”
J. Mater. Sci.
,
27
(
10
), pp.
2557
2579
.
27.
Varga
,
J.
,
2002
, “
β-Modification of Isotactic Polypropylene: Preparation, Structure, Processing, Properties and Applications
,”
J. Macromol. Sci., Part B—Phys.
,
41
(
4–6
), pp.
1121
1171
.
28.
Varga
,
J.
,
1995
, “
Crystallization, Melting and Supermolecular Structure of Isotactic Polypropylene
,”
Polypropylene: Structure, Blends and Composites
,
J.
Karger-Kocsis
, ed., Vol.
1
,
Chapman & Hall
,
London
, pp.
56
115
.
29.
Brückner
,
S.
,
Meille
,
S. V.
,
Petraccone
,
V.
, and
Pirozzi
,
B.
,
1991
, “
Polymorphism in Isotactic Polypropylene
,”
Prog. Polym. Sci.
,
16
(
2–3
), pp.
361
404
.
30.
Lotz
,
B.
,
1991
, “
Single Crystals of γ Phase Isotactic Polypropylene: Combined Diffraction and Morphological Support for a Structure With Non-Parallel Chains
,”
Polymer
,
32
(
16
), pp.
2902
2910
.
31.
De Rosa
,
C.
,
De Rosa
,
C.
,
Auriemma
,
F.
,
de Ballesteros
,
O. R.
,
Resconi
,
L.
, and
Camurati
,
I.
,
2007
, “
Crystallization Behavior of Isotactic Propylene−Ethylene and Propylene−Butene Copolymers:  Effect of Comonomers Versus Stereodefects on Crystallization Properties of Isotactic Polypropylene
,”
Macromolecules
,
40
(
18
), pp.
6600
6616
.
32.
Klein
,
M.
,
2001
, “
Laserschweißen Von Kunststoffen in Der Mikrotechnik
,” Doctoral dissertation, Universität Aachen, Aachen, Germany.
33.
Piccarolo
,
S.
,
1992
, “
Morphological Changes in Isotactic Polypropylene as a Function of Cooling Rate
,”
J. Macromol. Sci., Part B: Phys.
,
31
(
4
), pp.
501
511
.
34.
Reiter
,
G.
,
2007
,
Progress in Understanding of Polymer Crystallization
,
Springer Verlag, Berlin
.
35.
Geißler
,
B.
,
Laumer
,
T.
,
Wübbeke
,
A.
,
Lackemeyer
,
P.
,
Frick
,
T.
,
Schöppner
,
V.
, and
Schmidt
,
M.
,
2017
, “
Analysis of the Interaction Between the Temperature Field and the Weld Seam Morphology in Laser Transmission Welding by Using Two Different Discrete Laser Wavelengths
,”
34st International Congress on Applications of Lasers and Electro-Optics (ICALEO 2017)
, Atlanta, Georgia, Oct. 22–26.
36.
Bonefeld
,
D.
,
2012
, “
Eigenspannungen, Spaltüberbrückbarkeit Und Strahloszillation Beim Laserdurchstrahlschweißen
,” Doctoral dissertation, Universität Paderborn, Paderborn, Germany.
37.
Mayboudi
,
L. S.
,
2008
, “
Heat Transfer Modelling and Thermal Imaging Experiments in Laser Transmission Welding of Thermoplastics
,”
Doctoral dissertation
, Queen's University, Kingston, ON, Canada.https://qspace.library.queensu.ca/handle/1974/1551
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