In this study, a series of poly(ethylene glycol)/collagen (PEG/Col) double network (DN) hydrogel is fabricated from PEG and Col. Results of the compressive strength test indicate that the strength and toughness of these DN hydrogels are significantly enhanced. The fracture strength of PEG/ Col DN hydrogels increases by 9-to 12-fold compared with that of PEG single network (SN) hydrogel, and by 36-to 48-fold compared with that of Col SN hydrogel. Taking advantage of both PEG and Col building blocks, the PEG/Col DN hydrogels possess a strengthened skeleton. Moreover, the water-storage capability and favorable biocompatibility of Col are effectively maintained. Given that the DN hydrogels can provide the appropriate environment for the adhesion, growth, and proliferation of MC3T3-E1 cells, PEG/Col DN hydrogels have potential as a load-bearing tissue repair material.
Fiber-reinforced single-polymer composites were fabricated through the compression molding of sheathcore bicomponent fibers consisting of low and high molecular weight poly(ethylene terephthalate), LMPET and HMPET, as the sheath and core components, respectively. The LMPET/HMPET bicomponent fibers were prepared through the high-speed melt spinning process. When the take-up velocity exceeded a certain level, orientation-induced crystallizaion started to occur in the HMPET while the LMPET remained in an amorphous state. After the starting of the crystallization of the HMPET in the melt spinning process, orientation relaxation of the LMPET proceeded. Accordingly, the sheath-core fibers consisting of the highly oriented and crystallized core component (HMPET) and the amorphous and low oriented sheath component (LMPET) were obtained. Compression molding of such sheath-core fibers was conducted at a temperature above the glass transition temperature and below the melting temperature of PET where the rubbery softening of the amorphous phase was utilized for the fusion of the sheath component to form matrix phase while maintaining the well-developed fiber structure of the core component intact. The fabricated fiber-reinforced single-polymer composites showed fairly high mechanical properties. Good recyclability of the composites is expected because the composites are consisting of only pure PET.
Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.