SPATIAL HIERARCHY AND INTERFACIAL STRUCTURE IN INJECTION-MOLDED BARS OF POLYPROPYLENE-BASED BLENDS AND COMPOSITES

The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.

Reactive TiO_(2) Nanoparticles Compatibilized PLLA/PBSU Blends:Fully Biodegradable Polymer Composites with Improved Physical,Antibacterial and Degradable Properties

The fully biodegradable polymer blends remain challenges for the application due to their undesirable comprehensive performance.Herei n,remarkable combi nation of superior mechanical performa nee,bacterial resista nee,and con trollable degradability is realized in the biodegradable poly(L-lactide)/poly(butylene succinate)(PLLA/PBSU)blends by stabilizing the epoxide group modified titanium dioxide nan oparticles(m-TiO_(2))at the PLLA-PBSU in terface through reactive blending.The m-TiO_(2) can not only act as in terfacial compatibilizer but also play the role of photodegradation catalyst:on the one hand,binary grafted nanoparticles were in situ formed and stabilized at the interface to enhance the compatibility between polymer phases.As a consequence,the mechanical properties of the blend,such as the elongation at break,notched impact strength and tensile yield strength,were simultaneously improved.On the other hand,antibacterial and photocatalytic degradation performance of the composite films was synergistically improved.It was found that the m-TiO_(2 )incorporated PLLA/PBSU films exhibit more effective antibacterial activity than the neat PLLA/PBSU films.Moreover,the analysis of photodegradable properties revealed that that m-TiO_(2) nan oparticles could act as a photocatalyst to accelerate the photodegradati on rate of polymers.This study paves a new strategy to fabricate advaneed PLLA/PBSU blend materials with excellent mechanical performance,antibacterial and photocatalytic degradation performance,which enables the potential utilization of fully degradable polymers.

A Simple and Effective Method to Fabricate Separation Membranes for Dehydration of Natural Gas

PBT/PEG_(1000)composite membranes were prepared by the phase inversion method and were used to dehydrate natural gas.In this study,evaporation time,coagulation bath concentration,and additives in casting solution were investigated,respectively,on the selectivity and permeability of separation membranes,and optimal conditions were found to include an evaporation time of 30 sec,an 100%PEG400-containing coagulation bath and 2%of PVA used as the additive.The H_(2)O/CH_(4)selectivity reached over 3600,which is about 20 times more selective than the original membrane.It provides a simple and effective preparation method to fabricate membranes for dehydration of methane gas.

A single-level composite structure optimization method based on a blending tapered model

In order to decrease the number of design variables and improve the efficiency of com- posite structure optimal design, a single-level composite structure optimization method based on a tapered model is presented. Compared with the conventional multi-level composite structure opti- mization method, this single-level method has many advantages. First, by using a distance variable and a ply group variable, the number of design variables is decreased evidently and independent with the density of sub-regions, which makes the single-level method very suitable for large-scale composite structures. Second, it is very convenient to optimize laminate thickness and stacking sequence in the same level, which probably improves the quality of optimal result. Third, ply con-tinuity can be guaranteed between sub-regions in the single-level method, which could reduce stress concentration and manufacturing difficulty. An example of a composite wing is used to demonstrate the advantages and competence of the single-level method proposed.