SAMPE Journal - January/February 2020 - 26

FEATURE / HIGH-PRESSURE RTM (HP-RTM)

Figure 1. Measured viscosity progression.

Cure Monitoring Systems
Synthesites Optimold system enables flow and cure
to be monitored, through excitation of the resin using a constant voltage, allowing measurement of
electrical resistance. Temperature is also measured
using an integrated Pt100 RTD temperature sensor.
In this study, the Optimold system was used with
newly developed, carbon-capable DC sensors,
based on a new electrode design, enabling measurements in direct contact with carbon fibre preforms without protection.
In contrast, the Advise, Deta-Scope (DEA) system uses an alternating voltage to excite the resin, allowing measurement of resultant current.
Temperature is also measured using an integrated
J-type thermocouple. The response is post-processed by Advise's Deta-Scope software, allowing
ionic conductivity (a material property) to be determined5. As the measured response is a combination of free charge migration, dipole relaxation and
electrode polarization, which dominate at different frequencies, a compound voltage signal is required, consisting of eight frequencies in the range
2.5 - 500 Hz. A complete frequency sweep takes 1.2
seconds for each sensor, making the system suitable for the highly reactive resin used. In this study,
the Deta-Scope system was used with newly developed, carbon-capable, DEA sensors, with thermoplastic-coated electrodes, which can also be used
in direct contact with carbon fibre preforms without protection.
Electrical resistance (DC) or ionic conductivity (DEA) measured by the sensors can be directly
used to determine resin arrival and provide qualitative information about the cure (e.g. time to
minimum viscosity and end of reaction). However, real-time translation of these measurements to
viscosity, Tg and degree of cure requires calibration
of the respective monitoring software for a specific
resin system. During the early stages of cure, mea-

26

|

SAMPE JOURNAL

|

sured electrical resistance (DC), or ionic conductivity (DEA) can be directly correlated with viscosity.
Approaching gelation, this correlation begins to
diverge, as viscosity increases rapidly and the resin
can no longer flow. After gelation, measured electrical resistance (DC) or ionic conductivity (DEA)
can be directly correlated with Tg development5, 6.
In both cases, Tg was used, as it increases significantly during the last stages of cure, providing better resolution than degree of cure.
SOFTWARE CALIBRATION
The DC monitoring software was previously calibrated for Araldite LY 3585 epoxy resin, with Aradur
3475 hardener (Huntsman international LLC) and
EWOmould 3733 internal release agent (KVS Eckert
& Woelk GmbH)6. In this study, as detailed in the
following section on Viscosity Calibration, the DEA
monitoring software was also calibrated for the
same resin system based on Advise's recommended calibration procedure.
Viscosity Calibration
Viscosity development of the resin system was previously characterised and used for calibration of
DC software6. The same characterisation data was
provided to Advise, and isothermal viscosity progression at 110°C and 120°C was used for calibration of the DEA software. As shown in Figure 1, viscosity progression measured by both systems, for
pure resin at lab scale, shows excellent agreement
with the viscosity calibration data provided.
Glass Transition Temperature Calibration
Total heat of reaction provides the basis for calculation of degree of cure from isothermal DSC and
was determined using Dynamic differential scanning calorimetry (DSC). Dynamic DSC can also
be used to determine the uncured and fully cured
glass transition temperatures (Tg0 and Tg¥) required

J A N UA R Y/ F E B R UA R Y 2 0 2 0

w w w. s a m p e . o r g


http://www.sampe.org

SAMPE Journal - January/February 2020

Table of Contents for the Digital Edition of SAMPE Journal - January/February 2020

Table of Contents
SAMPE Journal - January/February 2020 - Cover1
SAMPE Journal - January/February 2020 - Cover2
SAMPE Journal - January/February 2020 - Table of Contents
SAMPE Journal - January/February 2020 - 2
SAMPE Journal - January/February 2020 - 3
SAMPE Journal - January/February 2020 - 4
SAMPE Journal - January/February 2020 - 5
SAMPE Journal - January/February 2020 - 6
SAMPE Journal - January/February 2020 - 7
SAMPE Journal - January/February 2020 - 8
SAMPE Journal - January/February 2020 - 9
SAMPE Journal - January/February 2020 - 10
SAMPE Journal - January/February 2020 - 11
SAMPE Journal - January/February 2020 - 12
SAMPE Journal - January/February 2020 - 13
SAMPE Journal - January/February 2020 - 14
SAMPE Journal - January/February 2020 - 15
SAMPE Journal - January/February 2020 - 16
SAMPE Journal - January/February 2020 - 17
SAMPE Journal - January/February 2020 - 18
SAMPE Journal - January/February 2020 - 19
SAMPE Journal - January/February 2020 - 20
SAMPE Journal - January/February 2020 - 21
SAMPE Journal - January/February 2020 - 22
SAMPE Journal - January/February 2020 - 23
SAMPE Journal - January/February 2020 - 24
SAMPE Journal - January/February 2020 - 25
SAMPE Journal - January/February 2020 - 26
SAMPE Journal - January/February 2020 - 27
SAMPE Journal - January/February 2020 - 28
SAMPE Journal - January/February 2020 - 29
SAMPE Journal - January/February 2020 - 30
SAMPE Journal - January/February 2020 - 31
SAMPE Journal - January/February 2020 - 32
SAMPE Journal - January/February 2020 - 33
SAMPE Journal - January/February 2020 - 34
SAMPE Journal - January/February 2020 - 35
SAMPE Journal - January/February 2020 - 36
SAMPE Journal - January/February 2020 - 37
SAMPE Journal - January/February 2020 - 38
SAMPE Journal - January/February 2020 - 39
SAMPE Journal - January/February 2020 - 40
SAMPE Journal - January/February 2020 - 41
SAMPE Journal - January/February 2020 - 42
SAMPE Journal - January/February 2020 - 43
SAMPE Journal - January/February 2020 - 44
SAMPE Journal - January/February 2020 - 45
SAMPE Journal - January/February 2020 - 46
SAMPE Journal - January/February 2020 - 47
SAMPE Journal - January/February 2020 - 48
SAMPE Journal - January/February 2020 - 49
SAMPE Journal - January/February 2020 - 50
SAMPE Journal - January/February 2020 - 51
SAMPE Journal - January/February 2020 - 52
SAMPE Journal - January/February 2020 - 53
SAMPE Journal - January/February 2020 - 54
SAMPE Journal - January/February 2020 - 55
SAMPE Journal - January/February 2020 - 56
SAMPE Journal - January/February 2020 - 57
SAMPE Journal - January/February 2020 - 58
SAMPE Journal - January/February 2020 - 59
SAMPE Journal - January/February 2020 - 60
SAMPE Journal - January/February 2020 - 61
SAMPE Journal - January/February 2020 - 62
SAMPE Journal - January/February 2020 - 63
SAMPE Journal - January/February 2020 - 64
SAMPE Journal - January/February 2020 - Cover3
SAMPE Journal - January/February 2020 - Cover4
https://www.nxtbook.com/nxtbooks/sampe/journal_20240304
https://www.nxtbook.com/nxtbooks/sampe/journal_20240102
https://www.nxtbook.com/nxtbooks/sampe/journal_20231112
https://www.nxtbook.com/nxtbooks/sampe/journal_20230910
https://www.nxtbook.com/nxtbooks/sampe/journal_20230708
https://www.nxtbook.com/nxtbooks/sampe/journal_20230506
https://www.nxtbook.com/nxtbooks/sampe/journal_20230304
https://www.nxtbook.com/nxtbooks/sampe/journal_20230102
https://www.nxtbook.com/nxtbooks/sampe/journal_20221112
https://www.nxtbook.com/nxtbooks/sampe/journal_20220910
https://www.nxtbook.com/nxtbooks/sampe/journal_20220708
https://www.nxtbook.com/nxtbooks/sampe/journal_20220506
https://www.nxtbook.com/nxtbooks/sampe/journal_20220304
https://www.nxtbook.com/nxtbooks/sampe/journal_20220102
https://www.nxtbook.com/nxtbooks/sampe/journal_20211112
https://www.nxtbook.com/nxtbooks/sampe/journal_20210910
https://www.nxtbook.com/nxtbooks/sampe/journal_20210708
https://www.nxtbook.com/nxtbooks/sampe/journal_20210506
https://www.nxtbook.com/nxtbooks/sampe/journal_20210304
https://www.nxtbook.com/nxtbooks/sampe/journal_20210102
https://www.nxtbook.com/nxtbooks/sampe/journal_20201112
https://www.nxtbook.com/nxtbooks/sampe/journal_20200910
https://www.nxtbook.com/nxtbooks/sampe/journal_20200708
https://www.nxtbook.com/nxtbooks/sampe/journal_20200506
https://www.nxtbook.com/nxtbooks/sampe/journal_20200304
https://www.nxtbook.com/nxtbooks/sampe/journal_20200102
https://www.nxtbook.com/nxtbooks/sampe/journal_20191112
https://www.nxtbook.com/nxtbooks/sampe/journal_20190910
https://www.nxtbook.com/nxtbooks/sampe/journal_20190708
https://www.nxtbook.com/nxtbooks/sampe/journal_20190506
https://www.nxtbook.com/nxtbooks/sampe/journal_20190304
https://www.nxtbook.com/nxtbooks/sampe/journal_20190102
https://www.nxtbook.com/nxtbooks/sampe/journal_20181112
https://www.nxtbook.com/nxtbooks/sampe/journal_20180910
https://www.nxtbook.com/nxtbooks/sampe/journal_20180708
https://www.nxtbook.com/nxtbooks/sampe/journal_20180506
https://www.nxtbook.com/nxtbooks/sampe/journal_20180304
https://www.nxtbook.com/nxtbooks/sampe/journal_20180102
https://www.nxtbook.com/nxtbooks/sampe/journal_20171112
https://www.nxtbook.com/nxtbooks/sampe/journal_20170910
https://www.nxtbook.com/nxtbooks/sampe/journal_20170708
https://www.nxtbook.com/nxtbooks/sampe/journal_20170506
https://www.nxtbook.com/nxtbooks/sampe/journal_20170304
https://www.nxtbook.com/nxtbooks/sampe/journal_20170102
https://www.nxtbook.com/nxtbooks/sampe/journal_20161112
https://www.nxtbook.com/nxtbooks/sampe/journal_20160910
https://www.nxtbook.com/nxtbooks/sampe/journal_20160708
https://www.nxtbook.com/nxtbooks/sampe/journal_20160506
https://www.nxtbook.com/nxtbooks/sampe/journal_20160304
https://www.nxtbook.com/nxtbooks/sampe/journal_20160102
https://www.nxtbook.com/nxtbooks/sampe/journal_20151112
https://www.nxtbook.com/nxtbooks/sampe/journal_20150910
https://www.nxtbook.com/nxtbooks/sampe/journal_20150708
https://www.nxtbook.com/nxtbooks/sampe/journal_20150506
https://www.nxtbook.com/nxtbooks/sampe/journal_20150304
https://www.nxtbook.com/nxtbooks/sampe/journal_20150102
https://www.nxtbook.com/nxtbooks/sampe/journal_20141112
https://www.nxtbook.com/nxtbooks/sampe/journal_20140910
https://www.nxtbook.com/nxtbooks/sampe/journal_20140708
https://www.nxtbook.com/nxtbooks/sampe/journal_20140506
https://www.nxtbook.com/nxtbooks/sampe/journal_20140304
https://www.nxtbook.com/nxtbooks/sampe/journal_20140102
https://www.nxtbook.com/nxtbooks/sampe/journal_20131112
https://www.nxtbook.com/nxtbooks/sampe/journal_20130910
https://www.nxtbook.com/nxtbooks/sampe/journal_20130708
https://www.nxtbook.com/nxtbooks/sampe/journal_20130506
https://www.nxtbook.com/nxtbooks/sampe/journal_20130304
https://www.nxtbook.com/nxtbooks/sampe/journal_20130102
https://www.nxtbook.com/nxtbooks/sampe/journal_20121112
https://www.nxtbook.com/nxtbooks/sampe/journal_20120910
https://www.nxtbook.com/nxtbooks/sampe/journal_20120708
https://www.nxtbook.com/nxtbooks/sampe/journal_20120506
https://www.nxtbook.com/nxtbooks/sampe/journal_20120304
https://www.nxtbook.com/nxtbooks/sampe/journal_20120102
https://www.nxtbook.com/nxtbooks/sampe/journal_20111112
https://www.nxtbook.com/nxtbooks/sampe/journal_20110910
https://www.nxtbook.com/nxtbooks/sampe/journal_20110708
https://www.nxtbook.com/nxtbooks/sampe/journal_20110506
https://www.nxtbook.com/nxtbooks/sampe/journal_20110304
https://www.nxtbook.com/nxtbooks/sampe/journal_20110102
https://www.nxtbookmedia.com