SAMPE Journal - July/August 2022 - 62

FEATURE / BENZOXAZINE FORMULATION
Resin
Storage
Modules
(MPa)
35610
35700
35900
5292B-PPA
28% BMI
32% BMI
38% BMI
BisA-PPA
15% BMI
BisM-PPA
15% BMI
5292B-FA
BisA-FA
Thio-FA
2314
1319
2774
3059
3037
3075
3029
2176
2966
1467
2199
2594
1771
3220
E' onset Tg
(o
C)
163
170
183
274
222
270
243
276
246
256
243
255
272
274
Loss
Modulus
Peak (o
179
186
196
286
255
281
268
292
268
187
260
275
286
276
C)
Tan δ
Peak (o
196
209
218
303
288
308
291
311
307
312
301
313
>295
297
C)
5% Weight
Loss
(o
C, in N2
329
337
317
366
)
Char Yield
at 800o
(%, in N2
42
54
55
41
C
)
344
363
399
377
328
Table 5. Curing result of benzoxazine and matrimid 5292A (33% except noted).
most samples, a 2:1 benzoxazine/BMI molar ratio
or weight ratio used. The initial mix temperature is
around 90°C, and the cool down solid was grinded,
and DSC was taken from such sample. The mixture
would be continued heated to 130°C, at that
temperature, most sample could be completed.
The aniline benzoxazine mixture doesn't
shown any peaks after 270°C, indicate the
reaction between benzoxazine and BMI, for other
functionalized benzoxazines, most show a bimodal
pattern. There is an endo-thermo peak just before
the exotherm at around 120-145°C. it is related to
the retro Diels-Alder reaction between either the
furan ring and double bond or among the triple
bond and double bond.
With the addition of BMI into the aniline derived
and propargyl amine derived benzoxazine, the Tg
of the co-polymer could be increased by compared
to the homo-polymerization of benzoxazines
depends on the primary resin of the structure.
For example, when mixed with Matrimid 5292B,
the storage Tg of the polymer from bisphenol A
propargylamine increased from 232°C (Table 1)
to 246°C (15% BMI) or 276°C (33% BMI), but for
bisphenol M propargylamine benzoxazine, the Tg
actually decreases from 257°C to 243°C. In limited
example here, that the Tg increase maximized at
certain amount of BMI added, for example, when
co-polymerized with 5292B propargylamine
benzoxazine, 32-33% BMI will have a Tg above
270°C, however, when the BMI increased to 38%,
49
47
46
46
58
Figure 4. FT-IR of furfuryl amine benzoxazine with matrimid 5292A.
the Tg decreased to 243°C. On the other hand, Tg
of the polymer are reduced when Matrimid 5292A
added into furfuryl amine based benzoxazines,
For BisA-FA and BisF-FA, the Tg reduced from over
300°C (Table 2) to 272°C and 265°C respectively, for
thio-FA from 287°C to 274°C. It could be explained
by the possibility of the network degradation in the
furfuryl amine system before the potential network
establishment. A FT-IR monitoring of the heat
process is shown below.
The co-polymerization of benzoxazine and
bismaleimide happened at the beginning as the
hydroxy group attack the maleic double bond.
But when the temperature raised to 250°C, the
temperature that most furfuryl amine needed for
62 | SAMPE JOURNAL | JULY AUGUST 2022
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