Effects of reactive and non-reactive tackifying agents on mechanical neat resin and composite performance for preforming processes and Liquid Resin Infusion (LRI) techniques

Figures & data

Figure 1. Tackifying agents; (a) Powder binder, e.g. E5390; (b) Textile veil, e.g. PA1541; (c) Adhesive film, e.g. SAER; (d) Hot-melt binder, e.g. PR685; (e) Spray adhesive, e.g. AIR2E.

Table 1. Description of tackifying agents characterized within this study.

Name	Abbreviation	Supplier	Type	Appearance	Chem. Composition	Activation Temperature [°C]
EPIKOTE 05311	E5311	HEXION	Reactive	Powder	Bisphenol A	97–107
EPIKOTE 05390	E5390	HEXION	Reactive	Powder	Bisphenol A	75–105
Araldite LT3366	LT3366	HUNTSMAN	Reactive	Powder	Bisphenol A	160–200
Spunfab PA1541	PA1541	Spunfab	Non-Reactive	Veil	Copolyamide	87–100
SAERfix EP	SAER	SAERTEX	Reactive	Veil / Transfer Film	Bisphenol A	RT
EPIKOTE MGS PR685	PR685	HEXION	Reactive	Hot-Melt	Bisphenol A	120 / RT
AIRTAC 2E	AIR2E	AIRTECH	Non-Reactive	Spray	Rubber based	RT

Table 2. Curing cycles applied for different epoxy resins.

Resin	Post-curing	Tg^1 [°C]
RIMR135/RIMH137	8 h 70 °C	90
Biresin C120/120-6	12 h 120 °C	115
Resoltech 1500/1504	3 h 50 °C + 3 h 100 °C + 3 h 150 °C	141

¹ Values obtained from corresponding TDS.

Figure 2. Manufacturing of CFRP specimen via LRI (a) Schematic VARI set-up (b) Experimental VARI-setup.

Table 3. Description of CFRP specimen.

Specimen	Thickness² [mm]	Binder fraction [wt%]	Fiber volume fraction [%]
CF-NR	1.93	–	59.22
CF-E5311	2.13	4.5	54.52
CF-E5390	2.02	4.5	56.06
CF-LT3366	2.29	4.5	51.52
CF-PA1541	2.59	7.4	42.36
CF-SAER	1.99	4.8	57.62
CF-PR685	2.08	16.1^1	57.22
CF-AIR2E	2.01	3.7	57.36

¹ Due to manual application, BAW of 5 wt% was not achieved.

² Average STD: 0.02 mm.

Figure 3. Tensile testing of neat resin samples acc. DIN EN ISO 527-2 (a) Test set-up (b) Detailed view of valid test specimen.

Figure 4. ILSS testing acc. DIN EN ISO 14130 (a) Test set-up before load application (b) Detailed cross-sectional view.

Figure 5. Reactive binder solubility analysis (a) LT3366 (b) PR685.

Figure 6. Non-reactive binder solubility analysis (a) PA1541 (b) AIR2E.

Table 4. DSC analysis of neat resin samples.

Specimen	RIM135		CR120		Resoltech1500
	Tg^1 [°C]	STD	Tg^1 [°C]	STD	Tg^1 [°C]	STD
DSC-NR	86.40	1.89	121.53	0.98	140.84	0.47
DSC-E5311	84.61	0.59	117.01	2.32	136.81	1.18
DSC-E5390	83.54	0.57	109.65	0.75	139.22	0.60
DSC-LT3366	83.88	0.66	120.41	0.50	139.11	0.60
DSC-PA1541	86.07	0.75	117.15	1.76	142.21	0.99
DSC-SAER	85.86	0.30	124.21	1.57	140.52	1.25
DSC-PR685	86.30	0.71	112.65	1.56	141.46	0.70
DSC-AIR2E	77.34	0.68	103.90	5.08	131.42	0.43

¹ Average Values were obtained from 6 DSC measurements.

Figure 7. DSC analysis neat resin samples and effect of tackifying agents.

Figure 8. Conditioning acc. DIN EN ISO 175 of 8 different CFRP specimens.

Table 5. Water absorption test analysis acc. Fick’s Law.

Specimen	cs [wt%]	D [mm²/s]	TM∞ [d]
WAT-NR	1.01	2.93 * 10^−7	39
WAT-E5311	0.84	2.76 * 10^−7	28
WAT-E5390	0.86	3.91 * 10^−7	27
WAT-LT3366	0.79	4.26 * 10^−7	28
WAT-PA1541	1.07	5.21 * 10^−7	30
WAT-SAER	0.96	5.86 * 10^−7	27
WAT-PR685	1.38	2.93 * 10^−7	41
WAT-AIR2E	0.95	3.61 * 10^−7	28

Figure 9. Ultimate tensile strength acc. DIN EN ISO 527.

Figure 10. Elongation at break acc. DIN EN ISO 527.

Figure 11. Young’s modulus E of neat resin samples and effect of tackifying agents.

Table 6. Analysis of neat resin tensile properties acc. DIN EN ISO 527.

Specimen	Tensile strength		Fracture strain		Tensile modulus
	${\sigma }_{\max }$^1 [MPa]	STD	${\epsilon }_{\max }$^1 [%]	STD	E^1 [MPa]	STD
RIM135-NR	65.70	0.25	8.05	0.47	2724.56	32.75
RIM135-5311	51.39	1.26	2.24	0.10	2757.70	64.40
RIM135-5390	43.43	4.11	1.75	0.21	2825.76	115.86
RIM135-LT3366	35.82	1.82	1.38	0.08	2746.70	74.84
RIM135-PA1541	61.71	2.12	3.43	0.40	2794.60	92.10
RIM135-SAER	61.10	0.58	3.75	0.16	2729.70	81.48
RIM135-PR685	67.20	0.51	6.03	0.29	2884.56	53.55
RIM135-AIR2E	66.52	0.23	6.23	0.65	2813.34	104.13
CR120-NR	63.01	4.30	3.91	0.65	2614.70	114.98
CR120-5311	50.83	1.03	2.37	0.07	2749.52	54.27
CR120-5390	30.06	10.65	1.23	0.48	2728.40	120.69
CR120-LT3366	42.90	2.24	1.86	0.15	2788.68	133.93
CR120-PA1541	59.55	0.98	2.86	0.09	2802.06	47.12
CR120-SAER	51.02	6.25	2.69	0.59	2523.52	103.64
CR120-PR685	59.99	3.75	3.18	0.39	2741.94	34.09
CR120-AIR2E	45.99	2.37	2.02	0.15	2711.92	22.98
RES1500-NR	55.17	7.27	1.75	0.28	3517.54	39.78
RES1500-5311	40.84	3.91	1.21	0.14	3596.68	39.77
RES1500-5390	32.10	1.07	4.61	4.52	3431.78	133.48
RES1500-LT3366	35.12	1.32	1.04	0.06	3456.34	159.25
RES1500-PA1541	43.37	3.05	1.25	0.09	3693.24	45.27
RES1500-SAER	51.76	2.40	1.67	0.10	3397.36	120.61
RES1500-PR685	39.24	3.62	1.16	0.13	3636.22	163.68
RES1500-AIR2E	57.34	4.28	1.82	0.18	3574.14	13.79

Neat polymer samples without binder are marked in bold for reference.

¹ Average Values were obtained from 5 measurements.

Figure 12. Graphical ILSS assessment acc. DIN EN ISO 14130.

Table 7. ILSS assessment acc. DIN EN ISO 14130.

Specimen	Dry specimen				Conditioned specimen
	Fmax^1 [kN]	STD	${\tau }^1\mathrm{ }$ [MPa]	STD	Fmax^1 [kN]	STD	${\tau }^1\mathrm{ }$ [MPa]	STD
ILSS-NR	1.61	0.02	62.29	0.70	1.51	0.03	58.24	0.97
ILSS-E5311	1.65	0.02	58.99	0.97	1.62	0.02	56.39	0.63
ILSS-E5390	1.56	0.02	58.95	0.70	1.52	0.03	56.58	0.73
ILSS-LT3366	1.69	0.02	58.84	0.82	1.74	0.04	56.71	0.89
ILSS-PA1541	1.92	0.08	49.89	2.11	1.57	0.03	45.30	0.78
ILSS-SAER	1.51	0.01	57.44	0.56	1.48	0.02	55.84	0.69
ILSS-PR685	0.84	0.07	30.50	2.48	0.70	0.11	26.64	4.41
ILSS-AIR2E	1.20	0.02	45.18	0.62	1.12	0.02	41.81	0.62

¹ Average Values were obtained from 8 ILSS measurements.

Data availability statement

The data that support the findings of this study are available from the corresponding author, FH, upon reasonable request.