This study focused on exploring the feasibility of green composites made from biodegradable and renewable materials as potential alternatives to petroleum polymer composites and understanding the reinforcing mechanisms in composites containing kenaf fibers (KF). KF-reinforced poly(lactide) acid (PLA) composites were made using melt compounding and injection molding, and their properties were compared to that of KF-reinforced polypropylene (PP) composites. The flexural properties and thermomechanical behavior were determined as a function of the fiber content, the crystallization of PLA and PP was studied using X-ray diffraction and differential scanning calorimetry, and the composites’ morphology was investigated using scanning electron microscopy. It was concluded that PLA exhibits higher modulus and Tg compared to those of neat PP. The modulus of the composites at 40 wt% fibers is 6.64 GPa and 2.96 GPa for PLA and PP, respectively. In general, addition of kenaf results in larger property enhancement in PP due to better wetting of the fibers by the low melt viscosity PP and the crystallization behavior of PP that is significantly altered by the fibers. The novelty of this work is that it provides one-to-one comparison of PLA and PP composites, and it explores the feasibility of fabricating green composites with enhanced properties using a simple scalable process.

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Purpose: The present study was undertaken to examine whether periodontal probe visibility (PV) accurately reflects gingival thickness (GT) and to identify factors affecting PV using cluster and multivariate analyses. Methods: The clinical characteristics of the maxillary central incisors (n=90 subjects) were examined. Clinical photographs, sex, PV, probing depth, gingival width, papilla height, GT as measured with an ultrasonic device, and the ratio of crown width to crown length were recorded. Multivariate analysis, using multinomial baseline-category logistic regression, was used to identify factors predictive of PV. Cluster analysis was used to identify gingival biotypes. Results: In the multivariate analysis, sex was the only significant predictor of PV (odds ratio, 6.48). Two clusters of subjects were created based on morphometric parameters. The mean GT among cluster A subjects was significantly lower than that among cluster B subjects (P=0.015). No significant difference was found between cluster A and B subjects in terms of PV score (P=0.583). Conclusions: Periodontal PV was not associated with GT as measured directly using an ultrasonic device. Sex was a highly significant predictor of periodontal PV. GT was found to be correlated with morphological characteristics of the periodontium.

In order to investigate the adsorption behaviour of cellobiohydrolase I in combination with cellobiohydrolase II (CBH I and CBH II) purified from Trichoderma reesei cellulase on Avicel 101, CBH I and II and their various compositions were adsorbed at 5–35 C. All adsorptions were found to apparently obey the Langmuir isotherm, and the thermodynamic parameters, DHa, DSa and DGa were calculated from the adsorption equilibrium constant, Kad. CBH I had a higher adsorption affinity (Kad) and tightness (‐DHa) for Avicel than CBH II. This indicates that CBH I showed stronger preferential adsorption than CBH II. The reconstituted CBH I and II mixture showed maximum affinity and tightness at a weight ratio of 1:4. The CBH I and II mixture displayed a significant synergistic degradation of Avicel, with a maximum found at a proportion of CBH I and II of 1:4. The increase of affinity (Kad) and tightness (‐ DHa) for the adsorption of CBH I combined with CBH II goes in parallel with their maximum synergistic degradation. It indicates that tightness and affinity of adsorption play a crucial role in synergistic degradation of the microcrystalline cellulose. At a specific weight ratio of CBH I and II, the maximum affinity and tightness of these components existed, and the degree of synergism was maximized at this condition. The synergism of two CBHs can be explained by assuming the formation of a partial complex of CBH I and II, which has higher adsorption affinity and tightness than the individual components, and different specificity in the cellulose attack at a specific optimum ratio of CBHs.

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To improve the mechanical properties of polypropylene (PP) biocomposites reinforced with sulfuric acidtreated green algae (SGA), SGA/graphite nanoplatelets (GNP)/PP biocomposites were prepared and their properties were evaluated depending on the particle size and content of GNP. The flexural and impact strength of SGA/GNP/PP biocomposites decreased with the addition of GNP, whereas the flexrual and storage moduli were greatly improved with increasing GNP loading. SGA/GNP/PP biocomposites reinforced with GNP5 showed generally better mechanical properties compared to that reinforced with GNP15 mainly due to the improved dispersion of the smaller GNP. SGA/GNP/ PP biocomposites reinforced with GNP5 showed a lower resistance to the thermal expansion because the relatively uniform dispersion of smaller GNP was responsible for the effective heat transfer to the polymer matrix. As a result, SGA/ GNP/PP biocomposite was acceptable for the general purpose application due to the improved flexural resistance, storage moduli, and damping characteristics.