Dynamics of Associative Polymers with High Density of Reversible Bonds

We design and synthesize unentangled associative polymers carrying unprecedented high fractions of stickers, up to eight per Kuhn segment, that can form strong pairwise hydrogen bonding of $\sim20k_BT$ without microphase separation. The reversible bonds significantly slow down the polymer dynamics but nearly do not change the shape of linear viscoelastic spectra. Moreover, the structural relaxation time of associative polymers increases exponentially with the fraction of stickers and exhibits a universal yet non-Arrhenius dependence on the distance from polymer glass transition temperature. These results cannot be understood within the framework of the classic sticky-Rouse model but are rationalized by a renormalized Rouse model, which highlights an unexpected influence of reversible bonds on the structural relaxation rather than the shape of viscoelastic spectra for associative polymers with high concentrations of stickers.Comment: 4 figure

COMPARATIVE STUDY OF ON-SITE SORTING FOR C&D IN CHINA AND EUROPE

Construction and demolition waste (CDW) accounts for 40% of urban municipal waste in China and around 25% in the European Union (EU). Since the EU is more developed and urbanized than China, its experience with managing CDW may be helpful to China. This study therefore compared China and the EU with respect to the flow of CDW materials and the policies, laws and regulations for CDW management. The results reveal that the CDW management practices and facilities in China are relatively underdeveloped with a large amount of low-value inert material going to landfill compared with the EU. The study also reveals the important role of government involvement in CDW management, including the use of punitive measures and preferential policies; most EU members states achieved their waste recovery rates by 2016 due to mature CDW legalization. To improve the management of CDW in China, a series of suggestions are proposed including waste prevention strategies, establishment of supervision mechanisms, and financial support. </jats:p

Infinitely Many Nontrivial Solutions of Resonant Cooperative Elliptic Systems with Superlinear Terms

We study a class of resonant cooperative elliptic systems and replace the Ambrosetti-Rabinowitz superlinear condition with general superlinear conditions. We obtain ground state solutions and infinitely many nontrivial solutions of this system by a generalized Nehari manifold method developed recently by Szulkin and Weth