The effects of temperature, pressure and flow on relaxation times, nucleation density, spherulitic growth rate, as well as the interrelation among these quantities and the distributions of deformation rate and cooling time during the process, determine the morphology distribution in the final polymeric part. Each of the effects mentioned above was experimentally analyzed and described by a model for the iPP grade considered in this work. The combination of all these specific models becomes a model for the morphology evolution during polymer processing and its application to the injection molding process was numerically developed into the UNISA code.

Injection molded samples were obtained with a fast evolution of cavity surface temperatures technique allowing to keep, for assigned time intervals, the cavity surface temperature at intermediate values between injection and cooling channels temperatures. A modulation of the level of the cavity surface temperature and of the time, it was kept active, allowed to control the final sample morphology all the way from the complexity of a standard injection molded part down to a completely (skin and shear layers free) spherulitic structure.

The fibrillar layer morphology was related to the achievement of critical values of both the molecular stretch and the mechanical work, the latter being performed after the achievement of the critical molecular stretch. The dependence of the morphological layers (skin, shear, spherulitic layers, the latter including the transition from the shear zone) thicknesses upon the heating conditions was satisfactorily described by the models adopted.

1.
H.
Zhou
,
Computer Modeling for Injection Molding: Simulation, Optimization, and Control.
2013
.
2.
R.
Pantani
,
F.
De Santis
,
V.
Speranza
, and
G.
Titomanlio
, “
Modelling morphology evolution during solidification of ipp in processing conditions
,”
AIP Conf. Proc. PPS-29
, vol.
1593
, pp.
636
640
,
2014
.
3.
R.
Pantani
,
V.
Speranza
, and
G.
Titomanlio
, “
Effect of flow-induced crystallization on the distribution of spherulite dimensions along cross section of injection molded parts
,”
Eur. Polym. J.
, vol.
97
, pp.
220
229
, Dec.
2017
.
4.
R.
Pantani
,
V.
Speranza
, and
G.
Titomanlio
, “
Thirty Years of Modeling of Injection Molding. A Brief Review of the Contribution of UNISA Code to the Field
,”
Int. Polym. Process.
, vol.
31
, no.
5
, pp.
655
663
, Nov.
2016
.
5.
S.
Liparoti
,
A.
Sorrentino
, and
G.
Titomanlio
, “
Fast cavity surface temperature evolution in injection molding: control of cooling stage and final morphology analysis
,”
RSC Adv.
, vol.
6
, no.
101
, pp.
99274
99281
,
2016
.
6.
O. O.
Mykhaylyk
,
P.
Chambon
,
C.
Impradice
,
J. P. A.
Fairclough
,
N. J.
Terrill
, and
A. J.
Ryan
, “
Control of Structural Morphology in Shear-Induced Crystallization of Polymers
,”
Macromolecules
, vol.
43
, no.
5
, pp.
2389
2405
, Mar.
2010
.
7.
O. O.
Mykhaylyk
,
P.
Chambon
,
R. S.
Graham
,
J. P. A.
Fairclough
,
P. D.
Olmsted
, and
A. J.
Ryan
, “
The Specific Work of Flow as a Criterion for Orientation in Polymer Crystallization
,”
Macromolecules
, vol.
41
, no.
6
, pp.
1901
1904
, Mar.
2008
.
8.
S.
Liparoti
,
A.
Sorrentino
,
V.
Speranza
, and
G.
Titomanlio
, “
Multiscale mechanical characterization of iPP injection molded samples
,”
Eur. Polym. J.
, vol.
90
, no.
March
, pp.
79
91
, May
2017
.
9.
R.
Pantani
,
V.
Speranza
, and
G.
Titomanlio
, “
A criterion for the formation of fibrillar layers in injection molded parts
,”
Int. Polym. Process.
, vol.
33
, no.
3
, pp.
355
362
,
2018
.
10.
R.
Pantani
,
V.
Nappo
,
F.
De Santis
, and
G.
Titomanlio
, “
Fibrillar morphology in shear-induced crystallization of polypropylene
,”
Macromol. Mater. Eng.
, vol.
299
, no.
12
, pp.
1465
1473
,
2014
.
11.
F.
De Santis
,
S.
Adamovsky
,
G.
Titomanlio
, and
C.
Schick
, “
Scanning Nanocalorimetry at High Cooling Rate of Isotactic Polypropylene
,”
Macromolecules
, vol.
39
, no.
7
, pp.
2562
2567
, Apr.
2006
.
12.
R.
Pantani
,
I.
Coccorullo
,
V.
Speranza
, and
G.
Titomanlio
, “
Modeling of morphology evolution in the injection molding process of thermoplastic polymers
,”
Prog. Polym. Sci.
, vol.
30
, no.
12
, pp.
1185
1222
, Dec.
2005
.
13.
F.
De Santis
,
R.
Pantani
, and
G.
Titomanlio
, “
Effect of shear flow on spherulitic growth and nucleation rates of polypropylene
,”
Polymer
, vol.
90
, pp.
102
110
,
2016
.
14.
R.
Pantani
,
V.
Speranza
, and
G.
Titomanlio
, “
Simultaneous morphological and rheological measurements on polypropylene: Effect of crystallinity on viscoelastic parameters
,”
J. Rheol.
, vol.
59
, no.
2
, pp.
377
390
, Mar.
2015
.
15.
S.
Liparoti
,
G.
Landi
,
A.
Sorrentino
,
V.
Speranza
,
M.
Cakmak
, and
H. C.
Neitzert
, “
Flexible Poly(Amide-Imide)-Carbon Black Based Microheater with High-Temperature Capability and an Extremely Low Temperature Coefficient
,”
Adv. Electron. Mater.
, vol.
2
, no.
6
, p.
1600126
, Jun.
2016
.
16.
S.
Liparoti
,
G.
Titomanlio
, and
A.
Sorrentino
, “
Analysis of asymmetric morphology evolutions in iPP molded samples induced by uneven temperature field
,”
AIChE J.
, vol.
62
, no.
8
, pp.
2699
2712
, Aug.
2016
.
17.
V.
Speranza
,
S.
Liparoti
,
M.
Calaon
,
G.
Tosello
,
R.
Pantani
,
G.
Titomanlio
, “
Replication of micro and nano-features on iPP by injection molding with fast cavity surface temperature evolution
,”
Mater. Des.
, vol.
133
, pp.
559
569
,
2017
.
This content is only available via PDF.