Structural, thermal and X-ray shielding properties of basalt and glass fiber reinforced epoxy composites

Abstract

Composite structures are good candidates to satisfy the required demands with design flexibility and addressed to reach the aimed functionality. We compare the specifications of epoxy-based hybrid composites reinforced with glass and basalt fabrics to meet these requirements. Thermal, structural and shielding properties of multilayered composites are examined with respect to their stacking sequences. X-ray fluorescence spectograms indicate that chemical structures of basalt and glass fibers are nearly similar to each other. Radiation shielding test confirms that BBBBB stacking has a similar half-value length (HVL), tenth-value length (TVL) and mean-free path (MFP) thickness with BBGBB stacking but a higher radiation attenuation rate. Scanning electron microscopy images prove that interbonding between basalt fiber/epoxy is better than that of glass fiber/epoxy. Thermal analysis shows that mass loss per unit time is more self-consistent in case of the presence of glass fabrics as outer layers and basalt fabric as core layer in hybrid composite design. However, the mass loss of BBBBB composite is found impressively lower than GGGGG and hybrid composites. This study offers to use of BBBBB composites to fabricate lightweight and non-toxic shielders. The total cost of the BBBBB composite can be decreased by substituting the core layer with a glass layer to fabricate cost-effective and lightweight shielders.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-025-18307-0.

Introduction

Hybrid composites (HC) are functional combinations fabricated by using two or more reinforcements in a unique matrix or one reinforcement in a mixture of dissimilar matrices. Thanks to their low energy consumption, flexibility and low cost, they have been used for interior or exterior applications in many specific fields. The properties of HCs are dependent on the specifications of the constituent materials available in their compositions^1,2. In the presence of two or more fiber types in a single matrix, the fabricated composite is termed as hybrid fiber reinforced composite (HFRC). HFRCs are addressed to handle superior thermal and mechanical properties that are not met with conventional single-fiber reinforced composites. Because fiber hybridization leads to withstand higher loads by courtesy of different characteristics of fiber types and arrangement of fibrous reinforcements’ layout³.

Glass fibers are one of the popular fiber reinforcements used in composite manufacturing. Due to some advantages such as the weight, heat resistance and dimensional stability, glass fiber reinforced composites (GFRC) are the most adaptable materials for industrial and domestic demands. The design versatility, low-moderate manufacturing cost and minimal finishing needs are the reasons for the preferability of GRFCs in a wide range of application fields⁴. To handle desired characteristics in a system, glass fibers are used with combination of various types of fibers. Hybridization of glass fiber with carbon fiber generally satisfies the mechanical demands in technical applications. In terms of cost comparisons, carbon fibers are more expensive than glass fibers but the cost of basalt fiber is almost the same amount as glass fiber types⁵. Additionally, basalt fiber is known as a good candidate to overcome the drawbacks of recycling problems of GRFCs because it can be more efficiently recycled compared to glass fiber. Even though the manufacturing process of basalt fibers is seen as similar to glass fiber manufacturing, basalt fibers are fabricated with more environmentally-friendly processes because they are obtained from basalt rocks and chemical agents are not used during their production as in glass fibers⁶. When comparing the pros and cons of glass and basalt fiber, higher resistance to tensile forces, chemical agents and weathering conditions of basalt fibrous structures are outstanding properties concerning glass fibrous ones⁷. Distinctly, the use of basalt fiber in a composite structure improves the shielding property because basalt fiber facilitates the attenuation of radiation due to its inherent density and structural integrity⁸.

Many researches have been performed on the hybridization of basalt and glass fiber. Fidan et al. (2024) studied on manufacturing of glass/basalt hybrid composites via vacuum bagging technique and showed that the wear performance of the composite improved with glass fiber reinforcement and stacking sequence had an important effect on mechanical and structural properties of hybrid composite⁹. Agrawal et al. (2024) studied on fatique behaviour of basalt/glass/epoxy hybrid composites and reported that better bonding between basalt fiber and epoxy was responsible for higher fatigue behaviour¹⁰. Zegaoui et al. (2019) fabricated glass fiber/basalt fiber reinforced epoxy composites with compression moulding technique. They proved that hybridization of basalt and glass fiber improved thermal resistance and shielding characteristics¹¹. Radiation shielding performance of basalt-based structures was studied by Ding et al. (2022). They manufactured basalt fibers from four different basalt rocks and measured the shielding performance of basalt fiber and woven basalt fabric. They concluded that the shielding performance of basalt-based structures was strictly based on chemical component of basalt rock. In addition, shielding efficiency of basalt fibers decreased with increasing radiation dose and basalt fabric exhibited excellent shield performance than fibrous-based structures¹². From the study of Ding et al. (2022), it is seen that the use of textile-based structures in the form of fabric improves shielding performance. It is well-known that specifications of a textile fabric are not only originated from which fiber it is constructed but also its weave pattern (plain, twill etc.) and fabric construction (yarn count, yarn density, type of yarn etc.)^13,14. The effect of weaving pattern on shielding performance is exmained by Camgöz and Özdemir (2017). They reported that shielding efficiency increased with the increase in fabric thickness but decrease in porosity. Besides, they pointed out that fiber type in yarn, yarn density, porosity and thickness of fabric influenced the degree of gamma ray interaction¹⁵. The study of Mikolajczyk et al. (2024) is also good agreement with previous study. Shielding performance of knitted fabrics were also affected from pattern, yarn type and fabric features (porosity, density vs.) as in woven ones¹⁶.

From literature survey, it is seen that the researchers have generally focused on improvement of composite’s mechanical properties via fiber hybridization. In case of multilayered hybridization of basalt and glass fibers and utilization of isotropic characteristics of plain-woven fabrics, it should be examined how x-ray interaction and heat flow are altered according to stacking sequence in a novel composite system. In this study, plain-woven fabrics with similar basis weight and warp/weft counts were used to fabricate non-hybrid or glass/basalt hybrid composites. By altering stacking sequence of wovens, composites were manufactured via hand lay-up/compression moulding technique for avoiding defects on surface and cross-layers of composite structures. In order to have similar thickness value after production, epoxy resin was equally applied on layers of composite to be manufactured. It is aimed to examine how thermal, structural and shielding properties of composites are affected from hybridization. This study differentiates from its counterparts by using woven fabric reinforcement in hybridization, comparison of shielding efficiency depending on various stacking sequences and determining the shielding behaviour of composites constructed with only pristine components, not by using any additives.

Experimental procedure

Materials

Glass wovens, basalt wovens, high-temperature lamination epoxy resin set (Hexion MGS L326 (Comp A) and MGS H265 (Comp B)) were supplied from Dost Kimya A.Ş. All components were used without further application. Table 1 shows the technical data of woven fabrics.

Table 1.

Specifications of woven fabrics.

	Glass fabric	Basalt fabric
Weft yarn type/count (cm)	EC9 136 / 6	BS12 110 / 9
Warp yarn type/count (cm)	EC9 136 / 8.9	BS12 110 / 10
Pattern	Plain	Plain
Basis weight	200 g/m2	210 g/m2
Ave. thickness	0.15 ± 0.03 mm	0.19 ± 0.01 mm
Density	2.62 g/cm3	2.75 g/cm3
Sizing	Silane-based agent	Silane-based agent
Resin compatibility	Epoxy, acrylic, polyester, vinylester	-

Method

Composite manufacturing

250 mm x 250 mm fabric samples were obtained by cutting glass and basalt wovens. The warp directions of samples were marked before stacking. 80 g of epoxy resin was prepared by mixing Comp A and Comp B with a ratio of 4:1 with a mechanical stirrer at 300 rpm for 3 min. 250 mm x 250 mm mold was placed on a teflon paper and each 20 g of epoxy resin was spread over each layer by hand lay-up technique. Stacking of the layers was performed by considering warp directions. Then the molds were fixed into hot press after coating the upper side of mold with another teflon paper and compression-molded at identical processing parameters (molding temperature of 100 °C, molding time of 15 min and pressure of ~ 17 MPa). Non-hybrid and hybrid composites were fabricated by hand lay-up/compression molding technique in order to remove entrapped air and decrease void occurence¹⁷. Hybrid and non-hybrid composites were constructed from 5 woven layers, as shown in Fig. 1. Views of compression-molded samples after demolding were given in Fig. 2.

Fig. 1.

Stacking sequence of fabricated composites and sample codes (created with Sketch-up 2017&3D Max 2018).

Fig. 2.

Hybrid and non-hybrid composites fabricated in this study (a) GGGGG, (b) GGBGG, (c) GBGBG, (d) BGBGB, (e) BBGBB and (f) BBBBB.

Sample characterization

Test samples were obtained by cutting fabricated hybrid composites with a Makita band saw. Structural integrity of samples was maintained as shown in Figure S1-6. The density of samples was calculated according to ASTM C271/C271 M-05 with the help of a digital gage (Mitutoyo Absolute) and analytical balance (Precisa LS-320 A). The chemical compositions of the basalt and glass fibers were tested with XRF (Bruker S8 TIGER). Structural and thermal characterization of samples were examined with SEM (Zeiss EVO LS-10), DSC (Perkin Elmer DSC-8000) and TGA (SII TGA/DTA 6300) analysis. DSC and TGA data were obtained at a heating rate of 10 ℃/min in nitrogen atmosphere in the temperature range of 30℃-450 ℃ and 30℃-800 ℃, respectively. Radiation shielding performance of 80 mm x 80 mm samples was measured with an experimental set-up consisting of an X-ray generator of GE digital X-ray medical device, PTW ion chamber as detector, Sun Nuclear electrometer and solid water phantom set as shown in Fig. 3. Further visualization of the described phenomenon is available in Supplementary Video 1. The measurements were conducted at three different tube voltages (80 kVp, 100 kVp and 120 kVp) with identical sample/source distance (100 cm), tube current (500 mA) and collimator field size (10 cm x 10 cm). Five measurements were repeated for each composition. Attenuation efficiency, linear attenuation coefficients, mass attenuation coefficients (MAC) (µ_m), half value length (HVL), tenth value length (TVL), mean free path (MFP) and lead equivalent of composites were estimated by using the following equations:

1

2

3

4

5

6

7

Fig. 3.

Experimental set-up for measuring radiation shielding efficiency.

Herein, are the attenuated and unattenuated intensities, respectively; µ is the linear attenuation coefficient (cm^-1), t is the thickness of composite (cm), is the density of sample (g/cm³) and (µ) Pb is the linear attenuation coefficient of lead (0.596 cm^-1)^18,19.

Results and discussion

XRF analysis of glass and basalt fibers

XRF method was employed to compare elemental and oxide compositions of basalt and glass fibers. In Table 2, XRF results showed that both fibers had similar contents, except boron oxide in glass fiber. The presence of boron oxide is in glass fiber is necessary in order to enhance processability and reduce dielectric constant²⁰. By means of other contents, their similar values suggest comparable structural rigidity. Both fibers contain a high amount of SiO₂ (~ 54%), which contributes to their excellent thermal and chemical resistance. Besides, it has a higher Al₂O₃ content (17.4%) than E-glass (14.6%), which enhances its mechanical strength and thermal stability and also attributes to higher corrosion resistance²¹. E-glass contains significantly more CaO (18.8%) compared to basalt fiber (7.1%). CaO acts as a fluxing agent, lowering the melting point and improving the fiber’s manufacturability. The lower CaO in basalt reflects its natural volcanic origin and contributes to its higher processing temperature. Fe₂O₃ content in basalt fiber is substantially higher (9.8%) than in E-glass (0.2%). This makes basalt fiber darker in color and denser. High iron content also increases thermal conductivity and potentially electromagnetic shielding properties^22,23. The amounts of Na₂O, K₂O and TiO₂ were found higher in basalt fiber content for enabling fiber drawing process. In literature, several studies show that high amounts of oxides such as TiO₂, Fe₂O₃, Al₂O₃ and K₂O significantly enhance the gamma-ray shielding efficiency of composite systems^24–27. From the point of literature survey, it is expected that basalt-based composites should be seen darker in color, exhibit higher shielding performance and lower thermal resistancy. However, these claims should be evaluated by means of interaction between layers and clarified for multilayer hybrid or nonhybrid basalt-containing fabric composites.

Table 2.

Chemical compositions of glass and basalt fibers.

Chemical composition	E-Glass fiber	Basalt fiber
SiO2	54.2	53.5
Al2O3	14.6	17.4
CaO	18.8	7.1
MgO	3.7	4.1
Fe2O3	0.2	9.8
Na2O	0.5	4.5
K2O	0.5	1.7
B2O3	7.3	-
Ti2O	0.2	1.9

SEM micrographs

Figure 4 shows the side, cross-sectional and top views of composites. From SEM images, it was clearly seen that filaments in glass wovens are thicker than those in basalt wovens as it was expected. The glass yarns were seen in bulky form because glass filaments (136 tex) were composed of numerous thin monofilaments (9 µ). By comparing the side views of GGGGG and BBBBB samples, it was concluded that interfacial adhesion between fiber/epoxy was better in composites with basalt wovens because of the well-impregnation of basalt filaments into epoxy matrix and closeness of matrix contour to fiber surface^28,29. In addition, the fibers were seen to be densely packed in composite structures with many basalt layers in number. This case was predictable because basalt fabrics with a higher basis weight (210 g/m²) were woven from thin filaments (110 tex) with high weft/warp density (9/10 yarn/cm). By comparing the top views of BGBGB and BBGBB composites, an increase in basalt layers on the outer surfaces of composite resulted in a decrease in superficial imperfections. This case also supported the good interaction between basalt and epoxy. The presence of voids or bubbles was not observed in different views of composites because it was reported that hand lay-up/compression molding technique was the versatile manufacturing method for basalt and glass composite systems¹⁷. Abd El-baky et al. (2018) claimed that void formations could be observed due to incomplete wetting of fibers with matrix. The absence of voids or bubbles also supports that glass and basalt fabrics are in well-corporation with epoxy matrix³⁰.

Fig. 4.

Side, cross-sectional and top views of fabricated composites; (a) BBBBB, (b) BBGBB, (c) BGBGB, (d) GBGBG, (e) GGBGG and (f) GGGGG.

Thermal characterization

Differential scanning calorimetry

DSC thermograms of composites are illustrated in Fig. 5. It is seen that thermal behaviour of epoxy system is complicated. Tg of epoxy system was detected as 135 °C. In DSC heating, two different endothermic peaks were observed in the temperature ranges of 190–220 °C and 320–350 °C which addressed to phase transition stages. GBGBG hybrid composites tend to undergo the phase transition stages at low temperatures than other composites with its low heat flow rate. Through exothermic behaviour stages, the peaks in the range of 275–290 °C, 365–395 °C and 400–450 °C were attributed to the removal of the sizing agent, main and intrinsic decomposition stages of epoxy system, respectively. Wen et al. (2019) studied on thermal degradation properties of epoxy resins under different atmospheres. They reported that several obvious characteristic peaks occurred due to heat absorption and release due to melting, exothermic behaviour, decomposition and gasification³¹. After the main decomposition stage of epoxy, the free atoms could not bond with the unbroken atoms of highly-thermal and stable nitrogen gas. The most obvious intrinsic decomposition stage was seen in BBGBB hybrid composite in which the heat flow difference was higher than that of BBBBB composites. The use of a glass layer between two-layered basalt facings contributed to the intrinsic decomposition of epoxy system but had a negative effect on heat flow rate.

Fig. 5.

Heating and cooling scans of composites (illustrated with Origin 2018).

Thermogravimetric analysis and derivative thermogravimetry

In Fig. 6, TGA and DTG thermograms are given to compare in which temperature ranges the composites are exposed to higher mass losses and how mass loss events occur. TGA revealed that the highest and the lowest mass loss were seen in GGGGG (83%) and BBBBB (56.37%) composites. In hybrid composites, % mass losses were nearly similar to each other such as; 75.48% for GGBGG, 75.50% for GBGBG, 73.62% for BGBGB and 72.81% for BBGBB. A huge percentage mass loss was available for all composites below 600 ℃ due to the evaporation of water above 100 ℃, thermal decomposition of silane-based sizing agent between 250 ℃-350 ℃^32,33 and the main thermal decomposition stage of epoxy resin between 300 ℃-600 ℃³⁴. There was no significant mass loss above 600 ℃ in BBBBB composites. However, in other composites, composite structures tend to transform to thermally stable characteristics from thermally-induced conditions³⁵.

Fig. 6.

TGA and DTG thermograms of composites (illustrated with Origin 2018).

In DTG graphs of composites, BBBBB composites revealed three different mass loss events centered at 294 ℃, 370 ℃ and 525 ℃. The two prominent peaks in BBBBB composite attributed to mass loss of epoxy matrix which was gradually decomposed in two different stages. However, six different events were observed in GGGGG composites which were centered at 92 ℃, 207 ℃, 276 ℃, 338 ℃, 398 ℃ and 468 ℃. Hybridization of basalt and glass layers caused to observation of similar mass loss events in number but at different temperatures. Hybrid composites with basalt facings, BBGBB and BGBGB, showed their mass losses at further temperatures concerning hybrid composites with glass facings, GBGBG and GGBGG. The shifts on temperature ranges suggested that the basalt layer behaved as a barrier limiting the evaporation of water-based substances³⁵. Additionally, the thermal stability of the cured epoxy system is rated by concluding both its number of decomposition stages and % mass loss³⁶. Considering that amounts of epoxy system between layers (20 g epoxy system on cross-layers of 5 layered composites), manufacturing process and epoxy type were identical for all composites, the highest thermal stability was obtained in BBBBB composites due to the lowest % mass loss, gradually decomposition of epoxy system and less number of mass loss events. BGBGB and GGBGG hybrid composites showed similar mass loss events with 3 prominent peaks but BGBGB hybrid composite was found more thermal stable because of its lower % mass loss. It was claimed that hybrid composites exhibited better thermal stability than conventional composites³⁷ but in this study, change in layer stacking sequence had a significant effect on the thermal characteristics of hybrid composites.

Characterization of shielding response

Linear attenuation coefficients and HVL, TVL, MFP values

In order to determine the unattenuated intensity (I₀), five repeated measurements were performed without composite samples at different tube voltages. Average of I₀ values for each tube voltage was calculated and then linear attenuation coefficients were determined according to Eq. (1) and then HVL, TVL and MFP values were obtained from Eq. (2), Eq. (3) and Eq. (4), respectively. The average I₀ values were denoted as 2.0038 at 80 kVp, 2.1539 at 100 kVp and 2.4116 at 120 kVp. Figure 7 illustrates the linear attenuation coefficient (µ), HVL, TVL and MFP values of fabricated composites. The average results of these parameters are also given in Table 3. The composites, especially BBBBB and BBGBB, were found effective at 100 kVp. The use of glass fabric in composite systems leads to a decrease in linear attenuation coefficient. The lowest MFP value of BBBBB supported this case because X-rays lost their energies in short distances if a composite system was constructed from one or more basalt layers. The MFPs of GGGGG composites were extremely higher than BBBBB composites which were determined as approximately 66 times at 80 kVp, 118 times at 100 kVp and 110 times at 120 kVp. Considering that HVL and TVL values refer to adequate shield thickness to lessen the initial intensity by a factor of one-half and one-tenth, respectively^38,39, similar results were obtained through HVL and TVL thickness. HVL and TVL thickness of BBBBB composites were 1/66, 1/120 and 1/110 of HVL and TVL thickness of GGGGG composites at 80 kVp, 100 kVp and 120 kVp. The results were in good agreement with the study of Osman et al. (2015) in which gamma flux was extremely high in lead-free glass systems⁴⁰. Nevertheless, hybridization did not result in obtaining lower HVL, TVL and MFP values than those of BBBBB composites.

Fig. 7.

Linear attenuation coefficient and HVL, TVL, MFP vales (depicted with Origin 2018).

Table 3.

HVL, TVL, MFP thickness and RAR% values obtained with average linear attenuation coefficients.

	Tube voltage (kVp)	HVL (cm)	TVL (cm)	MFP (cm)	RAR (%)
BBBBB	80	3,607	11,984	5,204	3,603
	100	2,176	7,230	3,140	5,900
	120	3,301	10,966	4,762	3,931
BBGBB	80	4,903	16,288	7,074	2,634
	100	2,969	9,865	4,284	4,313
	120	3,622	12,035	5,226	3,549
BGBGB	80	15,362	51,032	22,163	0,838
	100	7,096	23,575	10,238	1,806
	120	6,488	21,552	9,360	1,973
GBGBG	80	27,591	91,657	39,806	0,439
	100	11,361	37,741	16,390	1,063
	120	18,712	62,161	26,996	0,646
GGBGG	80	63,245	210,098	91,244	0,189
	100	63,008	209,310	90,902	0,190
	120	30,098	99,984	43,422	0,398
GGGGG	80	239,669	796,163	345,769	0,049
	100	257,626	855,817	371,676	0,046
	120	360,586	1197,842	520,216	0,033

Radiation shielding efficiency and lead equivalent values of composites

Shielding efficiency and lead equivalents of composites were determined with Eqs. (5) and  (6), respectively and shown in Fig. 8. It was observed that the attenuation efficiency of GGGGG composites decreased with an increase in tube voltage. The RAR values of GGGGG composites were 0.049% at 80 kVp, 0.046% at 100 kVp and 0.0331% at 120 kVp. The use of basalt fabric as the core layer caused to be observed of an increase in RAR % with an increase in tube voltage. RAR % of GGBGG and BGBGB hybrid composites were 0.189%, 0.190%, 0.398% and 0.838%, 1,806%, 1.973% at 80 kVp, 100 kVp and 120 kVp, respectively. The highest attenuation rate was obtained at 100 kVp for all different types of composites. It was noteworthy to clarify that the attenuation rate of BBBBB (5.90%) composite was 127 times higher than that of GGGGG composite at 100 kVp. The incorporation of basalt fabric into hybrid composite systems leads to a nonnegligible increase and an increase in the number of basalt layers contributes to the improvement of the attenuation rate of composite systems. The applicability of novel radiation shielders is evaluated using lead equivalence which indicates the thickness of lead that provides the same level of attenuation as the material being used. This metric is valuable for comparing the effectiveness of various radiation shielding materials and thicknesses. The thickness of lead or lead-equivalent materials directly impacts their ability to absorb and block radiation effectively⁴¹. The higher lead equivalents were obtained in composites having many glass fabrics in number. This meant that the thickness of these composites should be increased for better radiation protection. The non-linear and variable lead equivalents at different tube voltages were attributed to layered structure of hybrid composites containing fibrous layers with different K-absorption energies^42,43.

Fig. 8.

Radiation attenuation rates and lead equivalents of composites (illustrated with Origin 2018).

Density and mass attenuation coefficients

The density of composites was obtained according to ASTM C271/C271 M-05 and mass attenuations were calculated from Eq. (7) and depicted in Fig. 9. In Table 1, it is seen that the densities of basalt and glass fabrics are 2.75 g/cm³ and 2.62 g/cm³, respectively. However, the densities of BBBBB composites and hybrid composites were found lower than GGGGG composites. This case is another clue of the well-impregnation of basalt into epoxy matrix. Considering that basalt and glass filaments were treated with a silane-based sizing agent^44–46, the epoxy matrix covered the thick monofilaments (12 µ) in 110 tex basalt yarns more efficiently than the thin monofilaments (9 µ) in 136 tex glass yarns. The filaments in glass fabric behaved as a block⁴⁷, diffusion of epoxy between fabric layers should be difficult and thereby basalt-containing composites should give lower density values after compression molding than GGGGG composites. At 100 kVp, the mass attenuation coefficients (MAC) of composites were higher and MAC value increased with the increase in the number of basalt layers in the composite system. The composites were effective at 100 kVp but less effective at lower or higher tube voltages. The variation in efficiency was related with the dominant radiation interaction of the photoelectric effect in diagnostic X-ray energy ranges and different K-absorption energies of materials in a composite system⁴². In our study, we showed that BBBBB composites were inert up to 800 ℃. The results were consistent with the studies mentioned above. This case proved that basalt-containing composites were more effective due to the K-absorption energy of firm structured-basalt fiber and radiation interaction was limited between layers in the composite system. In addition, BBBBB composites in our work showed a higher degree of mass attenuation than the non-filled glass/epoxy composites studied by Jahan et al. (2024)⁴⁸. The variable MAC values concerning tube voltage are depicted in Fig. 9; Table 3 summarizes the results of studied composites at different tube voltages.

Fig. 9.

Change in MAC value in different tube voltages (created with Origin 2018).

The effects of variables on shielding characteristics were statically identified through ANOVA and Duncan comparison tests with a 95% confidence interval. Statistical datas were obtained via IBM SPSS Statisctics 25 software and interpreted in Table 4. As expected, thickness and density was found statistically important with a significance level of p < 0.001. BBBBB and GGGGG composites showed better distribution by means of thickness and density homogeneity. However, specific group differences of hybrid composites were heterogenic and homogeneity distribution of hybrids were found relevant with the homogeneity of neat composite consisted of its out-numberred layer. Increase in tube voltage lead to change in variation and homogeneity value. The significance levels of lineer and mass attenuation coefficients of composites were found more important at 100 kVp than those of other tube voltages. The applied X-ray intensity at a certain tube voltage was found statistically unimportant for different tube voltages (p > 0.05). Hybridization caused to variations in significant differences and specific group differences were observed in hybrid composites but not in neat composites.

Table 4.

Analysis of variance and homogeneity.

Sample	t	ρ	80 kVp				100 kVp				120 kVp
			I0	I	µ	µm	I0	I	µ	µm	I0	I	µ	µm
BBBBB	1.910b (0,00873)	1.091a (0.09183)	2.0038a (0.02248)	1.9316a (0.08108)	0.1956a (0.18694)	0.1872b (0.18099)	2.1538a (0.03584)	2.0268a (0.08392)	0.3212c (0.18889)	0.2936a (0.16293)	2.4116a (0.05797)	2.3168a (0.05579)	0.2098a (0.12869)	0.1876c (0.10562)
BBGBB	1.889b (0,05030)	1.112a (0.04609)	2.0038a (0.02248)	1.9506a (0.07706)	0.1432a, b (0.15471)	0.1272a, b (0.13558)	2.1538a (0.03584)	2.0610a, b (0.04211)	0.2362b, c (0.16817)	0.2114a (0.14967)	2.4116a (0.05797)	2.3262a, b (0.04559)	0.1900a (0.09222)	0.1730b, c (0.08809)
BGBGB	1.866b (0.09317)	1.1420a, b (1.03501)	2.0038a (0.02248)	1.9866a (0.02680)	0.0456a, b (0.02128)	0.0404a (0.01962)	2.1538a (0.03584)	2.1148b, c (0.02330)	0.0992a, b (0.06276)	0.0872a, b (0.05439)	2.4116a (0.05797)	2.3640a, b (0.06236)	0.1076a (0.05110)	0.0948a, b,c (0.04620)
GBGBG	1.752a (0.01891)	1.187b (0.02026)	2.0038a (0.02248)	1.9950a (0.4122)	0.0256b (0.07046)	0.0216a (0.059)	2.1538a (0.03584)	2.1306b, c (0.05060)	0.0636a, b (0.18105)	0.0528a, b (0.15151)	2.4116a (0.05797)	2.3958a, b (0.07317)	0.0382a (0.04504)	0.0318a, b,c (0.03847)
GGBGG	1.7322a (0.04110)	1.2984c (0.02901)	2.0038a (0.02248)	2.000a (0.02060)	0.0112b (0.02668)	0.0088a (0.02058)	2.1538a (0.03584)	2.1498c (0.03631)	0.0108a (0.02111)	0.0080b, c (0.01557)	2.4116a (0.05797)	2.4018a, b (0.05747)	0.0226a (0.14688)	0.0158a, b (0.11314)
GGGGG	1.7256a (0.04312)	1.3458c (0.00763)	2.0038a (0.02248)	2.0028a (0.02060)	0.0034b ((0.12757)	0.0026a (0.08589)	2.1538a (0.03584)	2.1528c (0.06819)	0.0048a (0.13068)	0.0036c (0.09693)	2.4116a (0.05797)	2.4108b (0.05915)	0.0002a (0.27223)	0.0010a (0.20259)
Sig.	p < 0.001	p < 0.001	p > 0.05	p > 0.05	p > 0.05	0.01 < p < 0.05	p > 0.05	p > 0.05	0.001 < p < 0.01	0.001 < p < 0.01	p > 0.05	p > 0.05	p > 0.05	0.01 < p < 0.05

Conclusion

This study reports the effect of basalt/glass hybridization on thermal, morphological and radiation shielding characteristics. SEM images confirmed that glass and basalt filaments were successively impregnated into epoxy matrix via hand lay-up/hot compression molding which was reported as the most versatile and appropriate manufacturing technique for composite fabrication. It was seen that hybridization had a significant effect on the thermal characteristics of composites and intrinsic decomposition of epoxy matrix was triggered when glass fabric was used as the core layer. BBGBB hybrid composites showed the most obvious peaks attributing intrinsic decomposition stages of epoxy matrix. Even though undergoing phase transition stages at lower temperatures, GBGBG hybrid composites yielded more controllable heat flow among studied hybrid composites. Despite majority of basalt fabric in the composite system caused to increase in thermal conductivity, the % mass loss of the composite system was decreased with the incorporation of basalt layers into the composite. BGBGB hybrid composites granted the lowest % mass loss among hybrids. However, number of mass loss events were fewer in GGBGG and GBGBG hybrid composites. Radiation shielding tests were performed at three different tube voltage and fabricated composites gave the highest radiation shielding efficiency at 100 kVp tube voltage. At 100 kVp, the radiation shielding rate (RAR) of BBBBB composite was 127 times higher than that of GGGGG composites. In addition, HVL, TVL and MFP values of BBBBB dropped down to 1/120 of GGGGG composite. An impressive decrease was also observed in TVL, HVL and MFP values when the majority of the basalt layer increased in the hybrid composite system. MAC value of BBBBB composite was 145 times higher than that of GGGGG composites. Hybridization contributed to handling higher attenuation characteristics with a negligible increase in composite thickness than that of neat glass composites. % RAR and lead equivalent values of BBGBB hybrid composites were closest to BBBBB composites at different tube voltages. Besides, mass attenuation coefficient of BBGBB hybrid composites was nearly similar to neat basalt composites at 120 kVp. The results show that performance of studied composites is strictly based on chemical, structural and physical properties of constituents in composite system. The shielding results suggest potential uses in medical shielding applications of studied composites in which radiation shielding efficiency can be obtained without the incorporation of any additive into the composite system. This study will route the researchers focusing on non-toxic and sustainable shielders.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

Hayriye Hale AYGÜN: Conceptualization, Fabrication, Writing-review & editing, SupervisionUlviye BAY: Fabrication, Formal analysis, Data curationMehmet Hakkı ALMA: Supervision.

Data availability

The data will be made available on request from corresponding author, Dr. Aygün.

Declarations

Competing interests

The authors declare no competing interests.