Long-chain branching polypropylene (LCB-PP)/clay nanocomposites were prepared by melt blending in a twin-screw extruder. The microstructure and melt rheology of these nanocomposites were investigated using x-ray diffraction, transmission electron microscopy, oscillatory shear rheology, and melt elongation testing. The results show that, the clay layers are intercalated by polymer molecular chains and exfoliate well in LCB-PP matrix in the presence of maleic anhydride grafted PP. Rheological characteristics, such as higher storage modulus at lowfrequency and solid-like plateau in tan-x curve, indicate that a compact and stable filler network structure is formed when clay is loaded at 4 phr (parts per hundred parts of) or higher. The response of the nanocomposite under melt extension reveals an initial decrease in the melt strength and elongational viscosity with increasing clay concentration up to 6 phr. Later, the melt strength and elongational viscosity show slight increases with further increasing clay concentration. These results might be caused by a reduction in the molecular weight of the LCB-PP matrix and by the intercalation of LCB-PP molecular chains into the clay layers. Increases in the melt strength and elongational viscosity for the nanocomposites with decreasing extrusion temperature are also observed, which is due to flow-induced crystallization under lower extrusion temperature.

The current study is to observe the effect of the locking system strengthened by biomimetic mineralized collagen putty for the treatment of senile proximal humeral osteoporotic fractures. From January 2012 to December 2015, 80 cases of senile patients with osteoporotic proximal humeral fractures were randomly divided into an observation group and a control group, each group with a total of 40 cases. The control group was simply treated with locking plate. The observation group was treated with locking plate in combination with biomimetic mineralized collagen putty. The therapeutic effect thereby was observed. The excellent and satisfactory rate was 90% in observation group and was 72.5% in control group. The difference between the two groups was statistically significant (χ2 = 5.3312, P < 0.05). The fracture healing time was 11.82 ± 3.62 weeks in observation group and 19.78 ± 5.46 weeks in control group. The shoulder joint function score was 89.63 ± 8.12 in observation group and 76.92 ± 8.18 in control group. There was significant difference between the two groups (t = 7.1272; 12.7834, P < 0.05). The complication rate was 10% in the observation group and 32.5% in the control group (χ2 = 7.3786, P < 0.05). Locking system strengthened by biomimetic mineralized collagen putty has advantages such as accelerating healing of senile proximal humeral fracture, improving the therapeutic effect, reducing the complications. As one of the optimal internal fixation method, it provides a new option for better treatment of senile osteoporotic fracture.

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