تهیه فیلم کامپوزیت زیست تخریب‌پذیر کربوکسی متیل سلولز- صمغ عربی و ارزیابی خصوصیات فیزیکی، مکانیکی و حرارتی آن

در این پژوهش اثر ترکیب دو پلیمر کربوکسی متیل سلولز و صمغ عربی به‌منظور بهبود خواص فیزیکی و مکانیکی فیلم‌های زیست تخریب‌پذیر مورد مطالعه قرار گرفت. بدین منظور ابتدا فیلم‌های کربوکسی متیل سلولز و صمغ عربی به‌صورت جداگانه تهیه و در ادامه این دو پلیمر به نسبت‌های مختلف (75:25، 50:50 و 25:75) با یکدیگر ترکیب شده و خصوصیات فیزیکی، مکانیکی و حرارتی آنها ارزیابی گردید. میزان نفوذپذیری به بخار آب در فیلم‌های ترکیبی دو پلیمر با افزایش سطح صمغ عربی به‌طور معنی‌داری کاهش یافت (0.05>p) و کمترین میزان عبور بخار آب در تیمار 75:25 (کربوکسی متیل سلولز: صمغ عربی) 2.2567 (g pas1 m1 s1) مشاهده شد. میزان آب‌گریزی فیلم‌ها با اضافه کردن صمغ عربی به ماتریس فیلم کربوکسی متیل سلولز به‌طور معنی‌داری از 41.33 درجه به 61.10 درجه افزایش یافت (0.05>p). مقاومت کششی فیلم‌های تولید شده با افزایش سطح صمغ عربی از 51.10 مگاپاسکال به 3.16 مگاپاسکال کاهش یافت. میزان عبور نور از فیلم‌های تولید شده با افزایش نسبت صمغ عربی کاهش نشان داد (0.05>p). بیشترین و کمترین میزان دمای انتقال ذوب به‌ترتیب در تیمارهای کربوکسی متیل سلولز (265.29 درجه سانتی‌گراد) و صمغ عربی (241.9 درجه سانتی‌گراد) مشاهده شد. به‌طورکلی، از نتایج حاضر دریافت می‌شود که تهیه فیلم‌های ترکیبی از کربوکسی متیل سلولز و صمغ عربی باعث بهبود برخی از ویژگی‌های فیلم‌های تولید شده از قبیل خواص فیزیکی، حرارتی و میزان عبور نور گردید.

Preparation of biodegradable carboxymethyl cellulose-Arabic gum composite film and evaluation of its physical, mechanical and thermal properties

Introduction: Films with appropriate mechanical properties and low permeability are very important for food packaging. Natural polymers have gained increasing attention for the development of biodegradable films due to the environmental problems caused by petroleumbased polymers. Carboxymethyl cellulose (CMC) is a linear polysaccharide that exhibited good film forming properties. Gum Arabic (GA) is another polysaccharide that can be used for preparing the edible and biodegradable films. However, several studies have shown that biopolymers like CMC and GA films have high water vapor permeability and poor mechanical properties in moist conditions. One of the strategies that can be used for improving the properties of biopolymers films is blending the different polymers and formation the composite films. Various studies on the preparation of biocomposite films have been performed, however, to the best of our knowledge, studies on combinations of the CMC and AG have not been reported yet. Thus, the main objectives of this study were to prepare CMC/AG composite films using solvent casting method and investigate the effect of different CMC/AG blending ratio on the physical (water vapor permeability (WVP), water contact angle (WCA), color, opacity and lightbarrier properties), mechanical and thermal properties. Furthermore, in order to determine the structural characteristics of the films, fouriertransform infrared spectroscopy (FTIR) and xray diffraction (XRD) measurements were also performed.   Material Method: The CMC and AG solutions were prepared by dissolving 1 g in 100 mL of distilled water at 45 °C for 24 h under magnetic stirring. The prepared solutions were then blended in different proportions (75:25, 50:50, and 25:75). After mixing, glycerol (0.3% w/w) was added as a plasticizer and the solution was stirred for 15 min. The prepared solutions were poured into a glass plate, then dried at 45 °C for 24 h in the oven. Finally, the properties of CMC, GA and composite films were determined.   Result and Discussion: In this study, biodegradable films composed of CMC and AG were successfully prepared. Results showed that some properties of the composite films were greatly influenced by addition of AG. So that, WVP of films was decreased significantly in the blend films and the lowest WVP was observed in the 25:75 (AG: CMC) films (p < 0.05). The films hydrophobicity was significantly increased from 41.33o to 61.10o by addition of AG to the CMC films (p < 0.05). With increasing the ratio of AG, the tensile strength (TS) of blend films decreased. Opacity and light transmission of the composite films increased and decreased, respectively with increasing the AG ratio. The differential scanning calorimetry (DSC) test demonstrated that the thermal properties of blend films improved with increasing the AG content. The FTIR analysis indicated that new interaction was generated between the components of the blend films. Generally, it can be concluded that blending the AG and CMC can improve some of the physicomechanical properties of the blend films