Effects of Dynamic Crosslinking on Crystallization, Structure and Mechanical Property of Ethylene-Octene Elastomer/EPDM Blends

The dynamic crosslinking method has been widely used to prepare rubber/plastic blends with thermoplastic properties, and the rubber phase is crosslinked in these blends. Both polyolefin elastomer (POE) and ethylene-propylene-diene monomer rubber (EPDM) can be crosslinked, which is different from usual dynamic crosslinking components. In this paper, dynamic crosslinked POE/EPDM blends were prepared. For POE/EPDM blends without dynamic crosslinking, EPDM can play a nucleation role, leading to POE crystallizing at a higher temperature. After dynamic crosslinking, the crosslinking points hinder the mobility of POE chains, resulting in smaller crystals, but having too many crosslinking points suppresses POE crystallization. Synchrotron radiation studies show that phase separation occurs and phase regions form in non-crosslinked blends. After crosslinking, crosslinking points connecting EPDM and part of POE chains, enabling more POE to enter the EPDM phase and thus weakening phase separation, indicates that dynamic crosslinking improves the compatibility of POE/EPDM, also evidenced by a lower β conversion temperature and higher α conversion temperature than neat POE from dynamic mechanical analysis. Moreover, crosslinking networks hinder the crystal fragmentation during stretching and provide higher strength, resulting in 8.3% higher tensile strength of a 10 wt% EPDM blend than neat POE and almost the same elongation at break. Though excessive crosslinking points offer higher strength, they weaken the elongation at break.

Seven quick tips for beginners in protein crystallography

The aim of this brief review is to provide a roadmap for beginning crystallographers who have little or no experience in structural biology and yet are keen to produce protein crystals and analyze their 3D structures to understand their biological roles. To achieve this goal it is crucial to perform crystallization, structure determination, visualization and analysis of the protein’s structural features related to its biological function. Keeping that objective in mind, tips presented herein cover the most important steps in a crystallographic endeavor and present a selection of databases and software which can aid and accelerate the whole process. We hope that this short overview will help novices coming from different disciplines to navigate a protein crystallography project and, hopefully, allow avoiding some costly mistakes, even though being a crystallographer means learning by trial and error.

KLn(MoO4)2 micro/nanocrystals (Ln = La-Lu, Y): systematic hydrothermal crystallization, structure, and the performance of doped Eu3+ for optical thermometry

Systematic crystallization of KLn(MoO4)2 double molybdate micro/nanocrystals was achieved in this work for the family of lanthanide elements (excluding Pm) and Y via hydrothermal reaction under the optimized conditions of...