Biodegradation screws

Jagodzinski M, Geiges B, von Falck C, Knobloch K, Haasper C, Brand J, Hankemeier S, Krettek C, Meller R (2010) Biodegradable screw versus a press-fit bone plug fixation for hamstring anterior cmciate ligament reconstruction a prospective randomized study. Am J Sports Med 38(3) 501-508... 

Compared with metal interference screws, these biodegradable interference screws are expected to dissolve concerns such as the need to pull out the fixatimi device, the adverse effect on MRI images, and injury risks of the transplanted tendon. Some other biomechanical studies indicated that the primary fixatimi property of biodegradable screws and biosynthetic screws has a similar strength and stiffness as the metal screws. 

Fig. 8 Histological sections of an ACL reconstruction in a sheep model after 6 weeks. An expandable SMP cylinder was used in (a) whereas a biodegradable screw was used in (b)...

Matsusue, Y, Yainaniuro, T., Yoshii, S., Oka, M., Ikada, Y., Hyon.. 8., Jhikinami, Y. (1991) Biodegradable screw fixation of rabbit tibia proximal osteotomies. /. App. Biomat.,2, 1-12. 

Single-screw extmsion in general is the most important conversion process for biodegradable plastics. Only injection-molded and injection-stretch blow molded rigid containers like closures and bottles are not produced by a continuous extmsion process. 

The Sesame is designed so that molders can use a smaller runner and sprue, which gives them more control over the amount of plastic and pressure used to form the part itself. A smaller runner and sprue also means less material waste. While screw-and-barrel systems waste as much as 99.7% of the shot material, the Sesame wastes less than 80%. This is particularly important when molding expensive materials like biodegradable plastics, which cost as much as 10 per gram. The Sesame can handle any type of moldable plastic, as well as silicone rubber. Super-small medical parts that have been molded by the machine include ... 

Coal slurry feeding into pressurized gasification reactors Optimisation of rotor geometries in mbber mixers Extrasion cooking of food and feed Closed loop quality control in extrasion Twin-screw extmders for recycling Compounding of biodegradable plastics... 

Multilayer co-extrusion is another technique used in the preparation of starch/ synthetic sheets or films [164, 263-266], in which TPS is laminated with appropriate biodegradable polymers to improve the mechanical, water-resistance and gas-barrier properties of final products. These products have shown potential for applications such as food packaging and disposable product manufacture. Three-layer co-extrusion is most often practiced, in which a co-extrusion line consists of two single-screw extruders (one for the inner starch layer and the other for the outer polymer layers) a feedblock a coat-hanger-type sheet die and a three-roll calendering system [164]. Biodegradable polyesters such as PCL [164, 264], PLA [164, 263], and polyesteramide, PBSA and poly(hydroxybutyrate-co-valerate) [164] are often used for the outer layers. These new blends and composites are extending the utilization of starch-based materials into new value-added products. 

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