SAMPE Journal -September/October 2011 - 8

Figure 3. (A) First heat ramp showing the glass transition of the uncured system and the exothermic reaction peak, (B) Second heat ramp showing the glass transition temperature of the cured composite. (Figure 3b). Changes in these three features were tracked as a function of aging time. Samples were tested every seven days as ambient aging progressed. Representative changes in the glass transition of the uncured system and the exothermic cure peak are presented in Figure 4. The glass transition shifts to higher temperatures as the resin ages (Figure 4a), and the exothermic peak decreases in height (Figure 4b). These changes occur as a result of the progression of cure of the epoxy during ambient aging. Similarly, as shown in Figure 5, the glass transition temperature of the cured composite shifts higher with aging time. This trend, which has been reported for other epoxy systems8,15, results from an increased level of crosslinking, and thus an increase in the degree of cure of the system8. Data points from each day of testing were plotted for the three points of interest. The value of the area under the exothermic peak (enthalpy of reaction) was calculated using a sigmoidal tangent method. All MDSC runs were performed using prepreg, and results were not altered to take into account resin content. Such changes would result only in a relative shift in the results, not a change in the trends observed. Data fitted with linear trend lines is presented in Figure 6. From the plots in Figure 6 it is clear that the best linear relationship (R2=.94) is obtained for the glass transition of the uncured system as a function of out-time. As it is often the case that the exact outtime exposure of a roll of prepreg will be Figure 4. Changes in (A) glass transition temperature of the uncured sysunknown, it is desirable to have a simple tem and (B) exothermic reaction peak, as out-time is increased. test to predict prepreg age. It is possible Results and Discussion Prepreg Characterization Modulated DSC Modulated DCS runs were performed for two heating cycles on each sample. Full data sets from fresh prepreg are shown in Figure 3. Modulation allows for the splitting of the heat flow signal into reversing and nonreversing components. Through this process three important events can be identified. During the first heating cycle (Figure 3a) a glass transition in the uncured system can be seen in the reversing heat flow signal. The nonreversing signal shows a clear exothermic cure reaction peak. A second heat cycle was performed to determine the glass transition temperature of the cured system. This value can be seen clearly in the reversing heat flow signal for the second temperature ramp
8 SAMPE Journal, Volume 47, No. 5, September/October 2011



SAMPE Journal -September/October 2011

Table of Contents for the Digital Edition of SAMPE Journal -September/October 2011

SAMPE Journal - September/October 2011
Table of Contents
President’s Message
Technical Director’s Corner
Out-Time Effects on VBO (Vacuum Bag Only) Prepreg and Laminate Properties
Corporate Partners
SAMPE Tech 2011 Conference
SAMPE Tech 2011 Exhibition
Europe News & Views
SAMPE Europe’s SETEC 2011, Leiden
SAMPE Europe’s SEICO 2012, Paris
SAMPE China 2011
12th Japan International SAMPE Symposium and Exhibition – JISSE-12
SAMPE Books & CD’s Order Form
SAMPE Proceedings
Welcome SAMPE’s Newest Members
The SAMPE Foundation
Adhesive Characterization Using NIAR-Modified KGR Extensometer
Industry News
SAMPE LinkedIn Communities
SAMPE 2012 Call for Papers
SAMPE 2012 Exhibition
Materials & Products
SAMPE Asia 2012|Kuala Lumpur, Malaysia
SAMPE Materials Forecast Forum: Final Report
SAMPE Tech 2012 Call for Papers
SAMPE Journal Editorial Calender
Advertiser’s Index
Resource Center
Membership Application
Industry Events Calendar
Chapter Meetings Dates and Contacts
SAMPE Journal -September/October 2011 - SAMPE Journal - September/October 2011
SAMPE Journal -September/October 2011 - Cover2
SAMPE Journal -September/October 2011 - Table of Contents
SAMPE Journal -September/October 2011 - President’s Message
SAMPE Journal -September/October 2011 - 3
SAMPE Journal -September/October 2011 - 4
SAMPE Journal -September/October 2011 - Technical Director’s Corner
SAMPE Journal -September/October 2011 - Out-Time Effects on VBO (Vacuum Bag Only) Prepreg and Laminate Properties
SAMPE Journal -September/October 2011 - 7
SAMPE Journal -September/October 2011 - 8
SAMPE Journal -September/October 2011 - 9
SAMPE Journal -September/October 2011 - 10
SAMPE Journal -September/October 2011 - 11
SAMPE Journal -September/October 2011 - 12
SAMPE Journal -September/October 2011 - 13
SAMPE Journal -September/October 2011 - 14
SAMPE Journal -September/October 2011 - Corporate Partners
SAMPE Journal -September/October 2011 - SAMPE Tech 2011 Conference
SAMPE Journal -September/October 2011 - SAMPE Tech 2011 Exhibition
SAMPE Journal -September/October 2011 - Europe News & Views
SAMPE Journal -September/October 2011 - 19
SAMPE Journal -September/October 2011 - SAMPE Europe’s SETEC 2011, Leiden
SAMPE Journal -September/October 2011 - 21
SAMPE Journal -September/October 2011 - SAMPE Europe’s SEICO 2012, Paris
SAMPE Journal -September/October 2011 - 23
SAMPE Journal -September/October 2011 - SAMPE China 2011
SAMPE Journal -September/October 2011 - 25
SAMPE Journal -September/October 2011 - 12th Japan International SAMPE Symposium and Exhibition – JISSE-12
SAMPE Journal -September/October 2011 - SAMPE Books & CD’s Order Form
SAMPE Journal -September/October 2011 - SAMPE Proceedings
SAMPE Journal -September/October 2011 - 29
SAMPE Journal -September/October 2011 - Welcome SAMPE’s Newest Members
SAMPE Journal -September/October 2011 - 31
SAMPE Journal -September/October 2011 - 32
SAMPE Journal -September/October 2011 - 33
SAMPE Journal -September/October 2011 - The SAMPE Foundation
SAMPE Journal -September/October 2011 - 35
SAMPE Journal -September/October 2011 - 36
SAMPE Journal -September/October 2011 - Adhesive Characterization Using NIAR-Modified KGR Extensometer
SAMPE Journal -September/October 2011 - 38
SAMPE Journal -September/October 2011 - 39
SAMPE Journal -September/October 2011 - 40
SAMPE Journal -September/October 2011 - 41
SAMPE Journal -September/October 2011 - 42
SAMPE Journal -September/October 2011 - 43
SAMPE Journal -September/October 2011 - 44
SAMPE Journal -September/October 2011 - 45
SAMPE Journal -September/October 2011 - Industry News
SAMPE Journal -September/October 2011 - 47
SAMPE Journal -September/October 2011 - 48
SAMPE Journal -September/October 2011 - SAMPE LinkedIn Communities
SAMPE Journal -September/October 2011 - SAMPE 2012 Call for Papers
SAMPE Journal -September/October 2011 - SAMPE 2012 Exhibition
SAMPE Journal -September/October 2011 - Materials & Products
SAMPE Journal -September/October 2011 - 53
SAMPE Journal -September/October 2011 - SAMPE Asia 2012|Kuala Lumpur, Malaysia
SAMPE Journal -September/October 2011 - 55
SAMPE Journal -September/October 2011 - SAMPE Materials Forecast Forum: Final Report
SAMPE Journal -September/October 2011 - 57
SAMPE Journal -September/October 2011 - 58
SAMPE Journal -September/October 2011 - 59
SAMPE Journal -September/October 2011 - 60
SAMPE Journal -September/October 2011 - 61
SAMPE Journal -September/October 2011 - 62
SAMPE Journal -September/October 2011 - SAMPE Tech 2012 Call for Papers
SAMPE Journal -September/October 2011 - SAMPE Journal Editorial Calender
SAMPE Journal -September/October 2011 - 65
SAMPE Journal -September/October 2011 - Advertiser’s Index
SAMPE Journal -September/October 2011 - 67
SAMPE Journal -September/October 2011 - Resource Center
SAMPE Journal -September/October 2011 - 69
SAMPE Journal -September/October 2011 - 70
SAMPE Journal -September/October 2011 - 71
SAMPE Journal -September/October 2011 - 72
SAMPE Journal -September/October 2011 - 73
SAMPE Journal -September/October 2011 - 74
SAMPE Journal -September/October 2011 - Membership Application
SAMPE Journal -September/October 2011 - Chapter Meetings Dates and Contacts
SAMPE Journal -September/October 2011 - Cover3
SAMPE Journal -September/October 2011 - 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