Study On PHBH Modified With Nano-montmorillonite Packaging Film

Traditional plastic packaging materials can not be degraded to cause serious pollution to the environment.Poly-3-hydroxybutyrate-co-3-hydroxyhexanoate(PHBH)is a third generation product of biodegradable polyhydroxy fatty acid ester(PHAs)polymers with complete biodegradability,but its Crystalline properties,thermal stability and poor mechanical properties as packaging films,narrow processing window,limiting its use.The purpose of this paper is to prepare PHBH nano composite packaging film with nano-montmorillonite modified PHBH to improve the crystallization performance,thermal stability,mechanical properties and barrier properties of PHBH,so that it can be widely used in packaging.(1)PHBH/MMT nanocomposite films were prepared by solution casting method.The effects of different nano-montmorillonite additions on the properties of PHBH nanocomposites and the nano-montmorillonite content with the best performance of PHBH nanocomposite film was selected.The results show that the barrier properties,tensile strength,elongation at break and modulus of elasticity of the composite membrane increase first and then decrease with the increase of nano-montmorillonite.PHBH/1 wt%MMT nanocomposite films have the best tensile strength and barrier properties,and the elongation and elastic modulus of PHBH/3wt%MMT nanocomposite films are the best.FTIR,SEM and XRD analysis showed that the PHBH chain was intercalated into the silicate layer of nano-montmorillonite.After adding the amount of nano-montmorillonite,the interlayer spacing(d001)and the crystallinity of the nanocomposite film increased.POM shows that the number of spherulites increased,the size of spherulite decreased,and the growth rate of spherulites increased.TGA studies have shown that the addition of nano-montmorillonite improves the thermal stability of the composite film and broadens the thermal processing window.(2)3-Aminopropyltriethoxysilane(KH550)was added into the PHBH/1 wt%/MMT.PHBH/1 wt%/MMT/KH550 nanocomposite films were prepared by solution casting method,and their properties were studied.FTIR indicates that the aminopropyl group(-NH2)of KH550 reacts with PHBH,and the silicon alcohol produced by hydrolysis of KH550 forms hydrogen bonds with Si-OH on the surface of nano-montmorillonite.SEM showed that the dispersibility of nano-montmorillonite in PHBH was improved and the compatibility of the two phases improved with the addition of KH550(1 wt%,3wt%and 5wt%).The spherulite growth rate of PHBH/1 wt%/MMT/KH550 nanocomposite films increases,the spherulite density becomes larger,the size of spherulite decreases and the crystallinity increases with the increase of KH550.The mechanical properties and barrier properties of PHBH/1 wt%/MMT/KH550 nanocomposite films were improved after KH550 was added.The mechanical properties and barrier properties of nanocomposite films are the best when the amount of KH550 was 5wt%.