Polymer blends polylactide

SMP based on miscible blends of semicrystalline polymer/amorphous polymer was reported by the Mather research group, which included semicrystalline polymer/amorphous polymer such as polylactide (PLA)/poly vinylacetate (PVAc) blend [21,22], poly(vinylidene fluoride) (PVDF)/PVAc blend [23], and PVDF/polymethyl methacrylate (PMMA) blend [23]. These polymer blends are completely miscible at all compositions with a single, sharp glass transition temperature, while crystallization of PLA or PVDF is partially maintained and the degree of crystallinity, which controls the rubbery stiffness and the elasticity, can be tuned by the blend ratios. Tg of the blends are the critical temperatures for triggering shape recovery, while the crystalline phase of the semicrystalline PLA and PVDF serves well as a physical cross-linking site for elastic deformation above Tg, while still below T ,. 

Tsuji, H. (2002) Autocatalytic hydrolysis of amorphous-made polylactides effects of L-lactide content, tacticity, and enantiomeric polymer blending. Polymer, 43,1789-1796. 

Another example of rubber-modified glassy polymer was given by the study of polylactide blends (Kowalczyk and Piorkowska 2012). Blending polylactide (PLA) with poly(l,4-cA-isoprene), which is immiscible with PLA, can lead to a substantial improvement of drawability and impact strength without a decrease in Tg. In contrast to HIPS reported by Bubeck et al. (1991), the mbbery particles initiated crazing in PLA matrix at the early stages of deformation. Crazing was accompanied by cavitation inside mbber particles, which further... 

A patent from Germany [12] describes a method for producing construction materials made from a polymer blend. The blend consists of alkali lignin and protein. The product is used to house electrical and electronic devices. Polylactide with high impact strength is used. Chitin or natural starch may also be used. 

The amount of the degradable impact modifier required to realize the desired film properties depends upon the degree of miscibility of the modifier in the polylactide. The properties of polymer blends are strongly dependent upon the degree of compatibility and/or miscibility of the components. Only a few blends are truly miscible at the microscopic level while most are semi-miscible. Typically, the amount of modifier in the film ranges from about 10 to about 25% by weight of the film. 

The most common strategy to decrease the price or improve the properties of polylactide to fulfill the requirements of different applications is blending. Polylactide has been blended with degradable and inert polymers, natural and synthetic polymers, plasticizers, natural fibers and inorganic fillers. The most common blends include blends with other polyesters such as polycaprolactone or PLA/starch blends. Usually the compatibility between the two components has to be improved by addition of compatibilizers such as polylactide grafted with starch or acrylic acid (114,115). Recently a lot of focus was concentrated on the development of polylactide biocomposites, nanocomposites and stereocomplex materials. In addition various approaches have been evaluated for toughening of polylactide. 

In this section, the structure, preparation, miscibility and properties of different polymer blends based on biodegradable polyesters are reviewed. Polylactide-based blends are first revisited and discussed, and the miscibility behaviors of other commercially available biopolymers of great interest such as poly(E-caprolactone) (PCL), poly(3-hydroxybutyrate) (PHB), poly(p-dioxanone) (PPDO) and polyglyco-lide (PGA) are briefly reviewed. Finally, Appendix 2.A provides a brief outline of the investigations used to develop the miscibility study presented here. In this recap, it is possible to find the chemical structures of the polymers and their solubility parameters, and also some brief comments summarizing the research studies. 

These polymers, some of which are listed next are used to modify the atmosphere within packaged foods, beverages, pharmaceuticals and cosmetics and to control the ingress of, for example, oxygen, ethylene-vinyl alcohol, perfectly alternating polyketones, thermoformable ethylene-vinyl, alcohol blends, polylactide, and polyethylene terephthalate. 

Takagi, Y., Yasuda, R., Yamaoka, M. and Yamane, T. 2004. Morphologies and mechanical properties of polylactide blends with medium chain length poly(3-hydroxyalkanoate) and chemically modified poly(3-hydroxyalkanoate). Journal of Applied Polymer Science 93 2363-2369. 

The above mentioned scaffolds were made completely of the ceramic materials. Other potential materials which could be used to fabricate a novel construct for the repair of ciitical-sized bone defects is a novel material made of biodegradable polymer reinforced with ceramics particles. The properties of such a composite depend on 1) properties of the polymer used for the matrix and properties of the ceramics used for the reinforcement, 2) composition of the composite (i.e. content of ceramic particles) and 3) size, shape and arrangement of the particles in the matrix. Several polymer-composite composites have been used for scaffolds fabrication including polylactide (PLA) and polycaprolacton (PCL) reinforced with calcium phosphate (CaP) micro and nanoparticles. Authors proposed a novel composite material by blending copolymer -Poly(L-lactide-co-D,E-lactide) (PLDLLA) a copolymer with a ceramic - Tri-Calcium Phosphate... 

M. Peesan, R. Rujiravanit, P. Supaphol, Electrospinning of hexanoyl chitosan/polylactide blends, J. Biomater. Sci. Polym. Ed. 17 (2006) 547-565. 

Thibaut, G., Tatiana, B. Morphology and molten-state rheology of polylactide and polyhydroxyalkanoate blends. Eur. Polym. J. 48(6), 1110-1117 (2012)... 

Anderson, K.S., Lim, S.H., Hillmyer, M.A. Toughening of polylactide by melt blending with linear low-density polyethylene. J. Appl. Polym. Sci. 89, 3757-3768 (2003)... 

Pluta, M., Galeski, A., Alexandre, M., Paul, M.A., Dubois, P. Polylactide/montmorillonite nanocomposites and microcomposites piepaied by melt blending Structure and some physical properties. J. Appl. Polym. Sci. 86, 1497—1506 (2002)... 

---