Sodyum pentaborat, kalsiyum karbonat ve doğal reçine katkılı polilaktik asit filmlerin üretimi ve özelliklerinin incelenmesi
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Tarih
2022
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info:eu-repo/semantics/openAccess
Özet
Günümüzde petrol kaynaklarının azalması nedeniyle geleneksel plastikler yerine biyoesaslı plastik malzemelerin kullanımına ciddi bir ihtiyaç duyulmaktadır. Yenilenebilir kaynaklardan üretilen biyobozunur ve biyouyumlu bir polimer olan polilaktik asit (PLA) ve kopolimerleri giderek daha fazla önem kazanmaktadır, ancak zayıf mekanik özellikleri ve neme karşı aşırı hassasiyetleri nedeniyle gıda ambalajlarında kullanımları sınırlıdır. Bu çalışmanın amacı, geleneksel koruyucu malzemelere alternatif olarak ultraviyole (UV) ve görünür ışınlarından koruyucu, nanopartikül ve doğal reçine takviyesi ile PLA polimerinin özelliklerini iyileştirmek, yeni, şeffaf ve esnek film üretimi ile ambalaj malzemesi olarak kullanılabilirliğini araştırmaktır. Bu çalışmada, UV ışınlarından koruyucu bir biyofilm üretebilmek amacıyla PLA polimeri içerisine sodyum pentaborat anhidrit (SP), yumurta kabuğu (CC) nanopartikülleri ve doğal reçine katkıları eklenmiştir. PLA/SP, PLA/CC, PLA/doğal reçine, PLA/SP/doğal reçine ve PLA/CC/doğal reçine biyofilmlerinin üretiminde, serbest döküm (solvent-casting) ve ultrasonik homojenizatör kullanılarak döküm olmak üzere iki yöntem kullanılmış ve karakterizasyonu gerçekleştirilmiştir. İlaveten, her iki nanopartiküle doğal reçine eklenmesiyle PLA/SP/doğal reçine ve PLA/CC/doğal reçine filmlerin üretimi ve karakterizasyonu ile elde edilen PLA filmlerinde, UV koruma bölgesinin genişletilmesi hedeflenmektedir. PLA polimerinin olumsuz özelliklerinin farklı katkılar ile iyileştirildiği bu çalışma; termal özelliği, mekanik özelliği, temas açısı değerleri, UV-görünür bölge ışınlarının geçirgenliği ve mikroyapı analiz sonuçlarına göre değerlendirilmiştir. Taramalı elektron mikroskobu görüntülerinde, nanopartiküllerin topaklandığı görülmüştür. Bu durum filmlerin mekanik özelliklerinin olumsuz bir şekilde etkilendiğini açıklamaktadır. Nanopartikül katkılı filmlerin mekanik özelliklerinin saf PLA filmine göre düştüğü, ağırlıkça %5 ve artan katkı oranlarında çekme ve kopma uzama değerlerinin neredeyse aynı kaldığı ve bu yüzden ideal katkı oranlarının ağırlıkça %5 olduğu görülmüştür. Reçinelerin kattığı süneklik etkisi ile çekme direncinde düşüş, kopmada uzama değerlerinde artış gözlenmiştir. Saf PLA filmine göre; ağırlıkça %7,5 saf reçine (SR) katkısı için %11 artış elde edilirken, ağırlıkça %1 esterleştirilmiş reçine (ER)kaKatkısıçin %71 artış sağlamıştır. Hibrit biyokompozit filmlerin mekanik özelliklerinde ağırlıkça %5 SR ve %1 ER katkıları en iyi gerilme direncini sergilemişlerdir. ER katkısı, SR' ye göre mekanik direnci arttırmaktadır. Katkı oranı artışına göre gerilme mukavemetinde düşüş gözlemlenirken kopmada uzama değerlerinde artışa yol açmıştır. Partiküller çözelti içinde homojen olarak dağıldığında, polimer döküm yöntemiyle üretilen filmlere kıyasla mekanik özellikler iyileşmiştir. Ambalajların, taşınmasında ve depolanmasında nem, buhar, ıslanma gibi sıvıya maruz kalabileceği durumlarda sıvının ambalajdan geçişine izin vereceğinden hidrofobik özellikler istenmektedir. Temas açısı ölçümleri sonucunda, ağırlıkça %40 SR ve ER katkılı hibrit biyokompozit filmlerin su ile temas açısının arttığı ve ıslanma oranını azaltan bir yüzey elde edildiği görülmüştür. SP katkılı biyofilmlerin ıslanabilirliği, CC katkılı biyofilmlere göre daha düşük çıkmıştır. Homojen partikül dağılımına sahip filmlerde, CC katkılı filmlerin temas açısı değerlerinin saf PLA filme göre azaldığı, SP katkılı filmlerde ise arttığı gözlenmiştir. UV korumada, nanopartiküllerin polimer matrisinde iyileşme sağladığı ve reçinelerin ise daha çok etkili olduğu görülmüştür. Ayrıca hibrit biyokompozitlerde reçine katkısının ağırlıkça oranı arttıkça geçirgenliği azaltıcı etkisi olduğu görülmüştür. Ağırlıkça %40 reçine katkısı, tüm filmlerin geçirgenliğini azaltan en iyi oran olmuştur. FTIR spektrumu analizinde saf PLA filmi ile uyumlu oldukları, sadece fiziksel bir etkileşim olduğu kimyasal yeni bir bağ oluşmadığı görülmüştür. Saf PLA polimerinin kristalleşme davranışı üzerine olan etkilerini anlamak için ağırlıkça %2,5 ve %7,5 nanopartikül katkılı PLA/CC ve PLA/SP filmlerin ve ağırlıkça %5 ve %40 reçine katkılı hibrit biyofilmlerin termal özellikleri incelenmiştir. Sonuçlara göre, PLA/CC filmlerin camsı geçiş sıcaklığı (Tg) ve kristal oranı (ꭓc) değerlerinde artış gözlemlenirken, PLA/SP filmlerin Tg değerlerinin arttığı ve (ꭓc) değerlerinin düştüğü görülmüştür. Ayrıca, SR ve ER katkısı ile oluşan hibrit biyofilmlerin Tg ve (ꭓc) değerlerinin düştüğü gözlenmiştir.
Nowadays, there is a serious need to use bio-based plastic materials instead of traditional plastics due to the decrease in petroleum resources. Polylactic acid (PLA), a biodegradable and biocompatible polymer produced from renewable resources, and its copolymers are gaining more and more importance, but their use in food packaging is limited due to their poor mechanical properties and extreme sensitivity to moisture. The aim of this study is to improve the ultraviolet (UV) and visible rays protection properties of PLA polymer using nanoparticle and natural resin reinforcements, as an alternative to traditional protective materials, to produce new, transparent and flexible film and to investigate its usability as a packaging material. In this study, sodium pentaborate anhydride (SP), eggshell (CC) nanoparticles and natural resin additives were introduced to PLA polymer in order to produce a biofilm protecting from UV rays. In the production of PLA/SP, PLA/CC, PLA/natural resin, PLA/SP/natural resin and PLA/CC/natural resin biofilms, two methods, solvent-casting and casting using ultrasonic homogenizer, were used and their characterization was carried out. In addition, it is aimed to expand the UV protection zone in PLA films obtained by the production and characterization of PLA/SP/natural resin and PLA/CC/natural resin films by adding natural resin to both nanoparticles. This study, in which the negative properties of PLA polymer were improved with different additives; thermal properties, mechanical properties, contact angle values, transmittance of UV-visible rays and microstructure were evaluated according to the analysis results. In scanning electron microscopy images, it was observed that the nanoparticles were agglomerated. This explains that the mechanical properties of the films are adversely affected. It was observed that the mechanical properties of the nanoparticle added films decreased compared to the pure PLA film, the tensile and breaking elongation values remained almost the same at 5% by weight and increasing additive ratios, and therefore the ideal additive ratio was determined as 5% by weight. On the other hand, a decrease in tensile strength and an increase in elongation at break were observed due to the ductility effect added by the resins. According to pure PLA film, while an increase of 11% was obtained for 7.5% by weight of crude resin (SR), it provided an increase of 71% for 1% by weight of esterified resin (ER). In the mechanical properties of hybrid biocomposite films, 5 wt.% SR and 1 wt.% ER additives exhibited the best tensile strength value. ER filler increased the mechanical resistance compared to SR. While a decrease was observed in the tensile strength according to the increase in the additive ratio, it led to an increase in the elongation at break values. When the particles were homogeneously dispersed in the solution, the mechanical properties were improved compared to the films produced by the polymer casting method. Hydrophobic properties are required as it will allow the liquid to pass through the package in cases where the packages may be exposed to liquids such as moisture, steam, and wetting during transportation and storage.As a result of the contact angle measurements, it was observed that the contact angle of hybrid biocomposite films containing 40 wt.% SR and ER was increased and a surface that reduced the wetting rate was obtained. The wettability of SP filled biofilms was lower than CC filled biofilms. In films with homogeneous particle distribution, it was observed that the contact angle values of the CC-filled films decreased compared to the pure PLA film, but increased in the SP-filled films. In UV protection, it was observed that nanoparticles improved the properties of polymer matrix and that resins were more effective. In addition, for hybrid biocomposites, it was observed that the permeability reduction effect was increased as the weight ratio of resin additive increased. The 40 wt.% resin filled film was the best ratio reducing the permeability of all films. In the FTIR spectrum analysis, it was observed that they were compatible with the pure PLA film, there was only a physical interaction, and no new chemical bond was formed. In order to understand the effects of pure PLA polymer on the crystallization behavior, the thermal properties of 2.5 wt.% and 7.5 wt.% nanoparticle added PLA/CC and PLA/SP films and 5 wt.% and 40 wt.% resin filled hybrid biofilms were studied. According to the results, it was observed that the glass transition temperature (Tg) and crystal ratio (ꭓc) values of PLA/CC films increased, while the Tg values of PLA/SP films increased and (ꭓc) values decreased. Furthermore, it was observed that the Tg and (ꭓc) values of the hybrid biofilms formed with the addition of SR and ER were decreased.
Nowadays, there is a serious need to use bio-based plastic materials instead of traditional plastics due to the decrease in petroleum resources. Polylactic acid (PLA), a biodegradable and biocompatible polymer produced from renewable resources, and its copolymers are gaining more and more importance, but their use in food packaging is limited due to their poor mechanical properties and extreme sensitivity to moisture. The aim of this study is to improve the ultraviolet (UV) and visible rays protection properties of PLA polymer using nanoparticle and natural resin reinforcements, as an alternative to traditional protective materials, to produce new, transparent and flexible film and to investigate its usability as a packaging material. In this study, sodium pentaborate anhydride (SP), eggshell (CC) nanoparticles and natural resin additives were introduced to PLA polymer in order to produce a biofilm protecting from UV rays. In the production of PLA/SP, PLA/CC, PLA/natural resin, PLA/SP/natural resin and PLA/CC/natural resin biofilms, two methods, solvent-casting and casting using ultrasonic homogenizer, were used and their characterization was carried out. In addition, it is aimed to expand the UV protection zone in PLA films obtained by the production and characterization of PLA/SP/natural resin and PLA/CC/natural resin films by adding natural resin to both nanoparticles. This study, in which the negative properties of PLA polymer were improved with different additives; thermal properties, mechanical properties, contact angle values, transmittance of UV-visible rays and microstructure were evaluated according to the analysis results. In scanning electron microscopy images, it was observed that the nanoparticles were agglomerated. This explains that the mechanical properties of the films are adversely affected. It was observed that the mechanical properties of the nanoparticle added films decreased compared to the pure PLA film, the tensile and breaking elongation values remained almost the same at 5% by weight and increasing additive ratios, and therefore the ideal additive ratio was determined as 5% by weight. On the other hand, a decrease in tensile strength and an increase in elongation at break were observed due to the ductility effect added by the resins. According to pure PLA film, while an increase of 11% was obtained for 7.5% by weight of crude resin (SR), it provided an increase of 71% for 1% by weight of esterified resin (ER). In the mechanical properties of hybrid biocomposite films, 5 wt.% SR and 1 wt.% ER additives exhibited the best tensile strength value. ER filler increased the mechanical resistance compared to SR. While a decrease was observed in the tensile strength according to the increase in the additive ratio, it led to an increase in the elongation at break values. When the particles were homogeneously dispersed in the solution, the mechanical properties were improved compared to the films produced by the polymer casting method. Hydrophobic properties are required as it will allow the liquid to pass through the package in cases where the packages may be exposed to liquids such as moisture, steam, and wetting during transportation and storage.As a result of the contact angle measurements, it was observed that the contact angle of hybrid biocomposite films containing 40 wt.% SR and ER was increased and a surface that reduced the wetting rate was obtained. The wettability of SP filled biofilms was lower than CC filled biofilms. In films with homogeneous particle distribution, it was observed that the contact angle values of the CC-filled films decreased compared to the pure PLA film, but increased in the SP-filled films. In UV protection, it was observed that nanoparticles improved the properties of polymer matrix and that resins were more effective. In addition, for hybrid biocomposites, it was observed that the permeability reduction effect was increased as the weight ratio of resin additive increased. The 40 wt.% resin filled film was the best ratio reducing the permeability of all films. In the FTIR spectrum analysis, it was observed that they were compatible with the pure PLA film, there was only a physical interaction, and no new chemical bond was formed. In order to understand the effects of pure PLA polymer on the crystallization behavior, the thermal properties of 2.5 wt.% and 7.5 wt.% nanoparticle added PLA/CC and PLA/SP films and 5 wt.% and 40 wt.% resin filled hybrid biofilms were studied. According to the results, it was observed that the glass transition temperature (Tg) and crystal ratio (ꭓc) values of PLA/CC films increased, while the Tg values of PLA/SP films increased and (ꭓc) values decreased. Furthermore, it was observed that the Tg and (ꭓc) values of the hybrid biofilms formed with the addition of SR and ER were decreased.
Açıklama
Anahtar Kelimeler
Polilaktik Asit, Doğal Reçine, UV Koruma, Kalsiyum Karbonat, Sodyum Pentaborat, Polylactic Acid, Natural Resin, UV Protection, Calcium Carbonate, Sodium Pentaborate
