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Porous materials show low Young's moduli and excellent bonding to living bone. However, the strength of such materials is often insufficient in the initial stage of implantation. Thus, the objective of this study was to increase strength and Young's modulus of porous titanium by filling the pores with a biodegradable mixture of polyglycolide (PGA) and calcium carbonate (CaCO3). The mixture was introduced into porous Ti (porosity: 60%) using a heat injection technique. When the pores were filled with PGA-CaCO3, compressive strength and Young's moduli were drastically increased and influenced by the content of CaCO3. In an animal test, unfavourable autopsy findings could not be confirmed in rats and no bone was observed in the pores of the Ti-PGA composite. Decomposition of PGA lowered the surrounding pH, it was found to inhibit bone formation in the pores. Addition of CaCO3 to PGA could suppress the decrease in pH. [ABSTRACT FROM AUTHOR]

This review touches on recent trials for producing microbial polyhydroxyalkanoates (PHAs), which are used as a bio-based plastic, from renewable and non-edible ligoocellulosic biomass. Lignocellulose is composed of cellulose, hemicellulose and lignin, which form a persistent complex. Thus, for the efficient saccharification of lignocellulose, the physical,chemical processes for removing lignin and unstiffening cellulose fibers are required. The obtained sugar is typically a mixture of glucose and xylose, and contains a certain inpurity derived from lignocellulose and,or byproduct generated during pretreatment and subsequent saccharification processes. The microbes used for PHA production need to utilize the mixed sugar and to be resistant to the impurities. This review introduces several examples for addressing this issue. Moreover, an important direction is to design the polymer with better properties. Metabolic and enzyme engineering are powerful tools to biosynthesize various useful polymers from non-related sugar carbon sources. In particular, microbial production of lactate-based polymer from xylose is a potent platform. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are bio-based and biodegradable polyester synthesized by a wide variety of bacteria. To enhance the usability of PHA, we need to improve the material performance for wide-ranging applications and reduce the production cost during fermentation. We have developed biosynthesis methods for a novel PHA copolymer consisting of 3-hydroxybutyrate (3HB) and 3-hydroxy-4-methylvalerate (3H4MV) [P(3HB-co-3H4MV)], which shows improved long-term stability and processability than other known PHA copolymers. P(3HB-co-3H4MV) has the potential to broaden the use of PHA if it can be produced from inexpensive sugars with controlled 3H4MV fraction. This article summarizes recent advances in the study of P(3HB-co-3H4MV) biosynthesis. [ABSTRACT FROM AUTHOR]

Biodegradable polyester emulsion adhesives were investigated with respect to preparation methods and adhesive properties using phys-ico-chemical considerations. Polybutylenesuccinate-co-adipate (PBSA) and polycaprolactone(PCL) were emulsified with PVA as an emulsifier using an extruder in a melt emulsification system and colloidal properties of the resulting emulsions were as follows: particle diameter 1–2 μm, solid concentration ≧ 50 wt%, and viscosity ≧ 1000 mPa·s/23°C. The PBSA emulsion and the PCL's both were evaluated to have similar potentiality as adhesives as PVAc emulsions from the view point of surface chemistry. Water dispersible aliphatic poly-isocyanate was recognized as an effective additive for the adhesion enhancement through a comparatively small number of chemical bonds formed between the polymer emulsion film as glue lines and adherends. Besides, a formula to estimate the life span of those emulsion adhesives was introduced, since aliphatic polyester emulsions are generally hydrolyzed easily and their adhesive properties will deteriorate, even in indoor atmosphere. Therefore, the development of the atmosphere-friendly-biodegradable polyester emulsion adhesives will be stimulated by this study, leading to more adequate and wider applications. [ABSTRACT FROM AUTHOR]

The new linear polyurethanes were synthesized by the reaction of methyl(S)-2,6-diisocyanatohexanoate (LDI) with bis(2-hydroxyethyl) terephthalate (BHET) and polycaprolactone diols (PCC2000 or PCL2000). The polymers were obtained in relatively high yields (90-95%) and possessed high inherent viscosities ([η] = 0.41-0.52). The polymers were soluble in dimethyl sulfoxide and dimethyl formamide. The mechanical properties such as tensile strength, adhesion strength, and hardness were better than the standard values. We have examined the biodegradability of the polymers by enzymes. The copolymers were found to have good enzymatic degradation (max. 80%, 30 days). The SEM micrographs, showed countless holes and hollow structures on the film surface. [ABSTRACT FROM AUTHOR]