To prepare the CMC films (Figure, 1), 2g batches of CMC were dissolved in 100ml of distilled water under stirring at 80 °C. Glycerol (1% v/v) was incorporated into the solu- tion as a plasticizer to enhance film properties. The result- ing mixture was cast into Petri dishes and dried in a 40 °C hot air oven until a constant weight was achieved. Follow- ing a 48-hour stabilization period at room temperature, the peeled films were exposed to gamma radiation at doses of 0, 1, 2, and 3 kGy (Abdel-Ghaffar and Ali, 2022).

The irradiation process (0, 1, 2 and 3 kGy) was performed using a 60Co Russian gamma chamber (dose rate: 395.1 Gy/h) at the Cyclotron Project, Nuclear Research Center, Egyptian Atomic Energy Authority, Egypt.

The thickness of the CMC films was determined using a hand-held micrometer (Mitsutoyo Co., Kanagawa, Japan), which had a 0.001 mm precision. Six random positions around each film were measured (10 specimens).

The following equation was utilized to calculate the trans- parency value of the CMC films (Han et al., 1997) by utiliz- ing a UV-Vis spectrophotometer (Biochrome, Libra S60, B, Cambridge, England) to measure light transmittance at 600 nm.,

Transparency = − log T600x

Where, x is the film thickness (mm) and T600 is the frac- tional transmittance at 600 nm.

Mechanical properties were performed in accordance with ASTM D 882-02 (2010) guidelines using Brookfield tex-

ture analyzer (CT3) with a 5-kg load cell. Films specimens (20 x 50 mm) were fixed on grips (50 mm apart) and sub- jected to a tensile speed of 5 mm/min. The relationship between the load and the film’s initial cross-sectional area determines the stress at break. TS value was calculated us- ing the following formula (Properties, 1995):

TS (MPa) = Maximum force / (Film thickness × Film width)

Elongation (%) = [(Length after breaking − Initial Length) / Initial Length] × 100

Fourier-Transform Infrared (FTIR) analysis was per- formed using a Jasco FTIR-4100 spectrophotometer (Ja- pan) across a spectral range of 400 - 4000 cm-¹.

Thermogravimetric analysis (TGA) was conducted using a TA Instruments Q50 V20.13. Samples were heated to a maximum temperature of 491°C at a constant ramp rate of 10°C/min under a nitrogen purge (80 mL/min). Differ- ential scanning calorimetry (DSC) was conducted using a DSC2A-00181 unit. The thermal cycle consisted of a heating phase from 25 to 500 °C at a rate of 10 °C/min, followed by a cooling phase back to 25 °C. The melting temperature (Tm) was identified from the resulting DSC heating thermogram. All data acquired from both TGA and DSC measurements were processed using TA Instruments’ Universal Analysis software (Grande Tovar et al., 2019) (Grande Tovar et al., 2020). Thermomechanical analysis (TMA) was performed using a TMA 450 (Waters) in film tension mode. Samples with dimensions of 30 mm × 2 mm × 50 µm were analyzed. The testing protocol in- volved heating from -50 °C to 180 °C at a constant rate of 2 °C/min. Dynamic parameters included a static strain of 0.67% and a 20-micron amplitude at a frequency of 1 Hz. Before testing, all specimens were preconditioned at 25 °C and 60% relative humidity (RH) for at least of 48 hours.

WVTR of CMC films was measured gravimetrically ac- cording to the standard method of ASTM E96-92 method (ASTM, 1995) and (Guillard et al., 2003). The films (20 cm diameter), free of physical defects, were sealed on the top of Al cup containing 10 ml distilled water, and placed in a desiccator containing 80 g of calcium chloride (0 %, RH). The cups were weighed every 1 h for 5 h, and again after 24 h. The weight loss of the permeation cell was used to calculate the amount of water vapour that was adsorbed by the desiccant and transferred through the film. A tiny fan inside the desiccator maintained continuous air circulation outside the test cup, thereby ensuring a steady, uniform water pressure. Using linear regression, the slope of the weight loss versus time curve was determined (McHugh et al., 1993) and WVTR was calculated and expressed as (g H2O/hr.cm2.d). All samples were investigated at 25 °C under inside humidity of 90 %. Oxygen and Carbon dioxide Transmission Rate (O2TR, CO2TR) O2TR and CO2TR was measured with Gas Permeability Tester G103H within measuring range from 0.01 to 50,000 cm3/m2·day, at temperature of 25 °C and humidity 90 % (ASTM, 2015) and (ASTM et al., 2016)

Table (1) includes the measured values for thickness and transparency of the film samples. The thickness of CMC films was in the range of 0.0124 to 0.0127mm, which is in the range of film thickness reported for industrial plastic and represents a suitable application field in food packaging aspects. No significant differences were found between irradiated and non-irradiated CMC films. Transparency is a crucial characteristic, particularly when the film is used for see through packaging. Transparency of control CMC film was 2.45 (Table 1) and it was increased to 2.79 for 3 KG irradiated films, which means that low dose irradiation slightly increases transparency of the CMC films, which agrees with the results reported by (Algethami and Sci- ences, 2025).

FTIR spectral analysis - in the range between 4,000 and 450 cm−1 - of nonirradiated and irradiated CMC/Glyc films at doses 1, 2 and 3 kGy are shown in Figure 2(a and b). Nonirradiated peak of CMC/Glyc illustrated around 3282 cm-1 corresponding the hydrogen bonding O-H stretching region (Zaïdi et al., 2011), the small hump around 2928 and 2880 cm-1 belongs to the C-H stretching vibration. The sharp peak observed at 1591 cm-1 confirms the presence of COO- is assigned to stretching of the carboxyl group (Su et al., 2010). The bands around 1412 cm-1 and 1320 cm-1 are assigned to O-H stretching in-plane and C-H stretching in the symmetric mode of CMC/Glyc (Abou Taleb et al., 2009). The FTIR spectrum of CMC/Glyc showed that the bands at 1105 cm−1 and 1028 cm−1 which were characteristic of the C-O stretching on polysaccharide skeleton (Chai and Isa, 2013).

As illustrated, the overall spectral profiles of the sample films remained unchanged following gamma irradiation, with no emergence of new characteristic bands. This sta- bility confirms that the primary functional groups were preserved despite exposure to ionizing radiation. These observations align with the findings of (Choi et al., 2009), who previously noted that the functional integrity of CMC is maintained under irradiation.

All materials display characteristic thermal degradation temperature profiles. TGA analysis offers essential infor- mation about material purity and heat tolerance, making it indispensable in materials research. Figure 3(a and b) show the thermal decomposition behavior of edible films before and after irradiation treatment. The thermogravi- metric profile of the control sample film (Figure, 3a) ex- hibited an initial weight loss of 30.08% as temperatures reached 246.61°C, a phase primarily attributed to the evaporation of absorbed water. Upon reaching 323.43°C, the cumulative weight loss increased to 44.84%. By the conclusion of the thermal heating at 491.26°C, the final re- corded weight loss reached 6.858%. The extended dehydra- tion phase observed in glycerol-containing films may be due to the formation of a surface oily layer, which acts as a barrier to moisture loss, as previously suggested by (Atta et al., 2022).

As shown in Figure 3(a and b), irradiation treatments at different dose of 1, 2, and 3 kGy showed many different stages of thermal degradation phases. In the case of 1 kGy there were for thermal degradation phases started from 120.96 oC where the weight loss was 16.12% and the sec- ond phase at 251.05 oC and weight loss was 15.48%. while the last phase was 490.81 oC and the weight loss was 5.68%. like 1 kGy, 2 and 3 kGy showed different stage of thermal degradation phases, where 2 kGy started from 64.57 oC in the first stage and ended with 489.93 oC where the weight losses were 3.4% and 7.7%, respectively. And 3 kGy started from 67.68 oC and ended with 489.48 oC. The results illustrated that irradiated CMC/Glyc is ther- mally stable than unirradiated one. So, our obtained data are in agreement with those in previous studies (Abdel Ghaffar et al., 2019), (Abdel-Ghaffar and Ali, 2022) who found that increasing thermal stability is accompanied with increasing of irradiation dose levels. Furthermore, (Ali et al., 2015) found that the thermal stability of bio- blend CMC/TiO2 increased with increasing the irradiation dose up to 10 kGy. A sort of crosslinking process occurred after irradiation treatment of CMC, that increase thermal stability compared with CMC (Senna et al., 2000), (Ibra- him et al., 2013) and (Ibrahim et al., 2014).

One of the most notable differences is the residue left at 491°C (Figure 3, a andb). The unirradiated sample (0kGy) has the lowest thermal stability in terms of final mass, leav- ing only about 18.4% of its weight. All irradiated samples (1, 2, and 3 kGy) show a higher residual mass (between 24% and 26%). This indicates that irradiation promotes the formation of a more thermally stable carbonaceous char, which is a common effect of gamma irradiation on poly- saccharide derivatives. However, The TGA data suggests that while low-dose irradiation (1–3 kGy) does not dras- tically change the primary decomposition temperature of your CMC films, it does improve the overall thermal sta- bility at high temperatures by increasing the residual char.

Differential scanning colometry (DSC) curves were plot- ted for CMC/Glyc before and after gamma irradiation to different doses as shown in Figure 4(a and b). These curves track the heat flow of both irradiated and unirra- diated samples as they are heated from room temperature to nearly 500°C. Since the “Exo Up” indicator is present, peaks pointing upward represent exothermic events (re- leasing heat), while dips represent endothermic events (absorbing heat, such as melting).

The DSC curve shows endothermic peaks; at 307 °C (from 251.5 to 362.5 °C), 306.11 °C (from 253.27 to 358.95 °C),303.00 °C (from 254.61 to 351.39 °C) and 307.44 °C (from

250.17 to 364.71 °C) for 0, 1, 2 and 3 kGy, respectively which is attributed to the dehydration/decomposition of CMC. This behavior is associated to the complete decom- position of CMC, leading to a minute solid residue (El- Sherbiny et al., 2009). Our finding is in agreement with (El-Sakhawy et al., 2019) who found that CMC have two endothermic curves.

Furthermore, increasing the dose to 2 kGy slightly increases this temperature (from 251.50 °C to 254.61°C), suggesting that moderate irradiation may slightly stabilize the crystal- line structure. However, at 3 kGy, this temperature drops back down to 250.17 °C, which might indicate the onset of polymer degradation or “chain scission” outweighing the benefits of cross-linking. Compared to unirradiated CMC/Glyc, the maximum melting temperature (Tm) 307

°C, shifted slightly to the left after irradiation treatment.

Where Tm values were 298.95, 300.06 and 296.44 °C for 1, 2 and 3 kGy, respectively. Irradiation of CMC/Glyc shows a narrow endothermic band, probably attributed to the higher thermal stability of CMC. Additionally, the enthal- py change (ΔH) significantly decreases from the Control (614.7 mJ) to the 2 kGy sample (421.1 mJ). This suggests that the 2 kGy irradiation has already “pre-cured” or cross- linked the material, leaving less residual reactive energy to be released during the DSC scan.

There is a sharp rebound in enthalpy at 3 kGy (594.4 mJ). This often indicates that the higher radiation dose has bro- ken polymer chains (degradation), creating new reactive sites that release more energy when heated.

The combined TGA and DSC results indicate a ‘dual-mode’ transition within the CMC/glycerol matrix following 1–3 kGy irradiation. While thermal analysis highlights the frag- mentation and scission of the polymer backbone, the me- chanical behavior is primarily governed by the reorganiza- tion and cross-linking of these fragments into a more rigid, albeit thermally susceptible, network. This simultaneous occurrence of structural degradation and the formation of a more brittle architecture is a recognized characteristic of irradiated polysaccharides (Mahmud et al., 2026).

By using TMA method for CMC-Glycerol films, the thermal fingerprint of the films expresses the film stability under the influence of heat and ionizing radiation. Thermomechanical analysis (TMA) involves placing a sample in a furnace un- der constant stress (compression, tension, or flexure) while systematically changing its temperature. The technique de- tects any deformation that occurs at specific temperatures, making it especially useful for characterizing viscoelastic materials like organic polymers, including CMC. Such ma- terials display both viscous and elastic behavior, which gov- erns their mechanical response under stress.

Based on the Thermomechanical Analysis (TMA) shown in Figure (5), irradiation doses (from 0 kGy to 3 kGy) in- fluence the dimensional stability of the sample as a func- tion of temperature. Regarding low doses, often show the highest structural stability. In mechanical testing, this is where the material shows the smallest displacement, mean- ing it is more resistant to deformation. A common trend across all samples is a contraction (dimensional change) as temperature increases, which is characteristic of materials with internal stresses or those undergoing a specific phase transitions/cross-linking effect. The “slope, rate of dimen- sional change” or the rate of contraction changes at specific temperature intervals, often indicating a softening point. Control sample shows a very gradual, smooth contraction starting around 40 °C and accelerating until 100 °C, how- ever irradiated films at dose 1 kGy showed a much sharper initial drop between 30 °C and 50 °C, then stabilizes sig- nificantly compared to the 0 kGy sample (James, 2017).

On the other hand, samples irradiated at doses 2 kGy and 3 kGy show a more linear, steady rate of contraction. In- terestingly, the 3 kGy sample shows a slight upward turn (expansion) after 100°C, which suggests the irradiation might have induced enough cross-linking to provide some structural “spring-back, effect of the cross-linked network resisting the thermal collapse of the polymer chains” or thermal expansion once the initial contraction phase is over. Films irradiated at dose 1 kGy, seem to be stabilize more rapidly. After the initial drop, the curve is flatter be- tween 60 °C and 120 °C than the 0 kGy control.

Irradiation usually does one of two things: it creates cross- links (strengthening) or causes chain scission (weakening). The transition in the 3 kGy plot - where it stops contract- ing and starts slightly expanding at high heat - is a strong indicator of an increased cross-link density. In addition, in viscoelastic materials, gradually increasing temperature leads to changes in properties such as shrinkage, expan- sion, swelling, and softening. This restricts the polymer chains from collapsing further. Thus, Irradiation appears to be shifting the onset of dimensional change. While the 0 kGy sample begins its major descent around 50°C, the ir- radiated samples (especially 1 kGy) show earlier sensitivity but reach a “plateau” sooner. (Bhattacharya, 2000).

To extend the shelf life of food products, the barrier prop- erties of packaging films are essential. These properties are measured by water vapor and gas permeability, which depend on the film’s internal structure—specifically the amorphous regions where permeation occurs. Additives like plasticizers play a dual role; they modify the film’s mo- lecular chain mobility and diffusion coefficients, thereby impacting both its protective capabilities and its physical durability (García et al., 2009).

The rate of water vapor transmission (WVTR) is a crucial property of edible films. The results for WVRT values are illustrated in Figure (6–B). At a radiation dose of 1 kGy, the treatment did not yield significant differences in the WVTR of irradiated CMC/Glyc films. However, at doses of 2 and 3 kGy, there was a notable decrease in WVTR com- pared to the control. Furthermore, CMC/Glyc films can help prolong the shelf life of fresh foods by reducing dehy- dration, oxidative rancidity, and surface browning. Conse- quently, low gamma irradiation dose reduces the WVTR because the new cross-links create a denser “mesh” that molecules can’t easily pass through (Beghetto et al., 2026) and (Mahmud et al., 2026). Nevertheless, their hydrophilic nature limits their effectiveness as barriers against water vapor (Nelida Lucia del, 2016). Therefore, The transmis- sion of water vapor through a film typically takes place via its hydrophilic portions, with the rate dependent on the balance between hydrophilic and hydrophobic compo- nents within the film (Rojas-Graü et al., 2007).

Although CMC is inherently hydrophilic, its incorporation into blend films unexpectedly reduced the water vapor transmission rate. This phenomenon in CMC/Glyc films can be attributed to: (1) the robust intermolecular interac- tions between CMC and glycerol create tighter molecular packing and greater film compactness, and (2) the crys- talline regions of CMC force water molecules to navigate around insoluble crystals, slowing their diffusion through the matrix (Zivanovic et al., 2007).

Assessing the permeability of films or coatings to CO2 and O2 is vital for evaluating the physiological quality of coated fruits during storage. Researchers often simplify this mea- surement by testing isolated films rather than the coated food products themselves. This approach is supported by the findings of (Garcia et al., 2006), which demonstrate that water vapor permeability (WVP) values remain con- sistent between standalone films and applied coatings. The design of protective coatings must be tailored to the spe- cific needs of the food item. For fresh produce, a coating should provide a strong water vapor barrier to maintain texture while allowing for moderate CO2 and O2 exchange to support natural respiration. In contrast, for dried fruits and nuts, the priority shifts to a strict barrier against both moisture (to preserve crispness) and oxygen (to prevent lipid oxidation) (Nelida Lucia del, 2016). Maintaining gas barrier properties is fundamental to preventing food deg- radation. Specifically, regulating O2 and CO2 levels is criti- cal for managing respiration and oxidation without trig- gering anaerobic spoilage or excessive gas buildup. Beyond these functional traits, an ideal coating should preserve the fresh quality of produce, enhance its visual gloss without creating off-flavors, and remain both low-viscosity and cost-effective for commercial application (Dhall, 2013). In general, CO2 passes through films more easily than O2, as shown in Figure (6, A and C). While O2 is techni- cally smaller (3.1Å) than CO2 (3.4Å), the chemical “com- patibility” or solubility of CO2 within the film material is much higher. This higher solubility allows CO2 to perme- ate faster, even though its larger size slightly slows down its physical movement (diffusion) through the polymer chains (Robertson et al., 2013). Permeability of both CO2 and O2 in unirradiated CMC/Glyc was 43.42 and 0.51 cm3/ m2·day, respectively. The CMC/Glyc film should regulate gas exchange effectively, ensuring that CO2 levels do not reach inhibitory concentrations or trigger anaerobic res- piration within the fruit’s internal environment. As well as, did not deplete the O2 (Chakravartula et al., 2019). Ir- radiation treatment (low doses) reduces the gas perme- ability (O2 and CO2 ) and the reduction increased with irradiation dose level increased, because the new cross- links create a denser “mesh” that molecules can’t easily pass through (Beghetto et al., 2026) and (Mahmud et al., 2026). However, at 3 kGy of irradiation, CO2 and O2 were

35.32 and 0.44 cm3/m2·day, respectively. The process of gas permeation through polymer matrices is multifaceted, involving a complex interplay of variables. These factors are categorized into gas-specific attributes—including molecular size, polarity, and chemical inertness—and material-specific characteristics, such as the degree of crystallinity, the extent of cross-linking, and the inherent stiffness of the polymer chains (Chakravartula et al., 2019). The results indicate that CMC/Glyc films subjected to ir- radiation treatment maintain favorable gas permeability. This performance facilitates the development of an opti- mal modified atmosphere, which extends product shelf life while successfully avoiding the risk of anaerobic condi- tions.

The findings confirm that CMC/Glycerol films treated with an irradiation dose of 3 kGy represent a high-poten- tial, eco-friendly candidate for the food packaging indus- try. These films offer a rare combination of high transpar- ency, improved mechanical durability, and tuned gas bar- rier properties, making them effective for extending the shelf life of both fresh produce and moisture-sensitive food products.