Foam injection molding with physical blowing agents

191 Pages·2013·5.43 MB·English

Foam injection molding with
physical blowing agents

Valentina Volpe

Unione Europea UNIVERSITÀ DEGLI
STUDI DI SALERNO

FONDO SOCIALE EUROPEO
Programma Operativo Nazionale 2007/20013
“Ricerca Scientifica, Sviluppo Tecnologico, Alta Formazione”
Regioni dell’Obiettivo 1 – Misura III.4
“Formazione superiore ed universitaria”

Department of Industrial Engineering
Ph.D. Course in “Scienza e tecnologie per
l’industria chimica, farmaceutica e alimentare”
(XI Cycle-New Series)

Foam Injection molding with physical blowing
agents

Supervisor Ph.D. student
Prof. Giuseppe Titomanlio Valentina Volpe
Prof. Roberto Pantani

Scientific Referees
Prof. Lih-Sheng (Tom) Turng
Prof. Volker Altstädt

Ph.D. Course Coordinator
Prof. Paolo Ciambelli

Acknowledgments

At the end of these three years, full of challenges but also of moments of joy
and of satisfaction, I must thank all those who, in different ways, have
allowed to accomplish my work in the best way.
A special thanks to Prof. Giuseppe Titomanlio for guided and helped me
from the beginning.
I cannot find the right words to express my gratitude and the enormous
esteem for Prof. Roberto Pantani. In more than 7 years we have shared
many experiences but above all he taught me many things, both from the
academic and from the human point of view. Today, that with sadness and a
little fear I realized that the time to leave “I1” is getting closer, I want to say
thank to him because, if I have arrived so far, it is mainly due to him!
Special thanks to Prof. Turng and Prof. Altstadt for their availability and
their valuable advice.
Thanks to all those who have put their knowledge at my disposal: Prof.
Berenika Hausnerova, Prof. Tom Sedlacek and Ing. Paolo Addesso.
All these years would not have been so intense and pleasant without Andrea
Sorrentino, Vito Speranza, Felice De Santis, Umberto Vietri and Ivano
Coccorullo. Thank you for helping me and supported ... I will miss you!
A virtual hug to Luigi Dello Ioio, Gemma De Nicola and the “erasmus
boys” Armando Rafael Macedo da Mota, Maria Alexandra Ronda Escudero,
Marcelo Passos Da Costa and Rui Nuno Ferreira Pinto, who in recent years
have worked with me, making work less tiring and more enjoyable.
Thanks to all the boys and girls who in these years have gone in our lab to
make it more cheerful and interesting.
I conclude by thanking my family and Vincenzo for their support in all these
years.

Publication list

 “Shear-Induced Nucleation and Growth in Isotactic Polypropylene”, R.
Pantani, I. Coccorullo, V. Volpe, G. Titomanlio, Macromolecules 2010,
43, 9030–9038

 “Mutual effect of flow and crystallization: investigations in flow-
induced crystallization and crystallization induced solidification”, R.
Pantani, I. Coccorullo, V.Speranza, V. Volpe, S. Di Domenico,
G.Titomanlio, Polymer Processing Society 26th Annual Meeting, July
4-8, 2010 Banff (Canada)

 “Injection molding of microcellular polymers”, V. Volpe*, A.
Sorrentino, R. Pantani, G. Titomanlio, XVI Scuola Nazionale di Scienza
dei Materiali – INSTM, 27 settembre-2 ottobre 2010 Bressanone (BZ)

 “Injection molding of microcellular polymers”, V. Volpe*, A.
Sorrentino, R. Pantani, G. Titomanlio, proceedings EPF 5th Summer
School - “Fundamental and developments in polymer processing science
and technology”, 15-20 Maggio 2011, Gargnano (BS)

 “Injection molding of microcellular PLA”, V. Volpe*, A. Sorrentino, R.
Pantani, G. Titomanlio, proceedings Third International Conference on
Biofoams, Capri (Na) 21-23 settembre 2011

 “Foam injection molding of poly(lactic acid) with physical blowing
agents”, R. Pantani, A. Sorrentino, V. Volpe, G.Titomanlio, Polymer
Processing Society 29th Annual Meeting, Nuremberg (Germany) 15-19
Luglio 2013.

Index

ACKNOWLEDGMENTS
PUBBLICATION LIST
INDEX..................................................................................................................... I
FIGURES INDEX ..................................................................................................... V
TABLES INDEX ...................................................................................................... XI
ABSTRACT .......................................................................................................... XIII
CHAPTER 1
STATE OF THE ART ................................................................................................ 1
1.1 INJECTION MOLDING ...................................................................................... 1
1.2 CELLULAR MATERIALS ..................................................................................... 2
1.2.1 FOAMING PROCESS ........................................................................................ 4
Homogeneous nucleation .............................................................................. 5
Heterogeneous nucleation ............................................................................. 7
Cell growth.................................................................................................... 9
Stabilization of the structure ......................................................................... 9
1.3 BLOWING AGENTS .........................................................................................10
1.3.1 PHYSICAL BLOWING AGENTS ............................................................................10
1.3.2 CHEMICAL BLOWING AGENTS ...........................................................................12
1.4 BATCH FOAMING PROCESS ............................................................................15
1.5 FOAM INJECTION MOLDING ...........................................................................17
1.6 BIODEGRADABLE POLYMERS..........................................................................22
1.6.1 BIODEGRADABLE POLYMER: POLY(LACTIC) ACID ...................................................23
1.7 FOAM INJECTION MOLDING OF BIODEGRADABLE POLYMERS........................26
1.8 EFFECT OF GAS ON THE RHEOLOGY OF A POLYMER .......................................27
1.9 MONITORING OF CAVITY PRESSURE AND TEMPERATURE PROFILES ..............29
CHAPTER 2
MATERIALS AND METHODS .................................................................................31
2.1 CONVENTIONAL POLYMERS FOR INJECTION MOLDING ..................................31
2.1.1 POLYPROPYLENE HIFAX BA 238 G3 ................................................................31
2.1.2 POLYSTYRENE PS 678E..................................................................................32
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2.2 BIODEGRADABLE POLYMERS FOR INJECTION MOLDING ................................ 34
2.2.1 POLY(LACTIC) ACID PLA 2002D ...................................................................... 34
2.2.2 POLY(LACTIC) ACID PLA 4032D ...................................................................... 34
2.3 BLOWING AGENT: NITROGEN ........................................................................ 35
2.4 BATCH FOAMING EQUIPMENT ....................................................................... 35
2.5 FOAM INJECTION MOLDING EQUIPMENT ...................................................... 36
2.6 SLIT RHEOMETER ........................................................................................... 38
2.7 DENSITY MEASUREMENTS: ARCHIMEDES’ PRINCIPLE .................................... 42
2.8 CROSS-VOGEL MODEL .................................................................................... 44
2.9 TEST METHOD FOR TENSILE PROPERTIES ....................................................... 46
2.10 TEST METHOD FOR IMPACT RESISTANCE ..................................................... 50
Unnotched specimens .................................................................................. 50
2.11 TEST METHOD FOR FLEXURAL PROPERTIES .................................................. 50
2.12 SKYSCAN 1174 FOR TOMOGRAPHY .............................................................. 53
CHAPTER 3
BATCH FOAMING PROCESS .................................................................................. 55
3.1 SAMPLE IDENTIFICATION ............................................................................... 58
3.2 EXPERIMENTAL CONDITIONS ......................................................................... 59
3.3 EXPERIMENTAL RESULTS ................................................................................ 60
3.3.1 FOAMING TEMPERATURE EFFECT ...................................................................... 60
3.3.2 COOLING BY WATER ...................................................................................... 63
3.3.3 SOLUBILIZATION TIME EFFECT .......................................................................... 66
3.3.4 COMPARISON BETWEEN COOLING RATE AND SOLUBILIZATION TIME .......................... 67
3.3.5 COMPARISON BETWEEN PS WITH PLA ............................................................... 68
CHAPTER 4
POLYPROPYLENE ................................................................................................. 71
HIFAX BA 238 G3 ................................................................................................. 71
4.1 EXPERIMENTAL CONDITIONS ......................................................................... 72
4.2 ANALYSIS WITH CROSS MODEL ...................................................................... 73
4.3 RHEOLOGICAL MEASUREMENTS .................................................................... 73
4.4 MORPHOLOGICAL ANALYSIS .......................................................................... 75
CHAPTER 5
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