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.

Structural Composition Explains Differences in Stretchability for Compression-Molded Arabinoxylan-Based Thermoplastic Films

<div><div><div><p>Valorization of argi-waste polymers into value-added materials is essential for sustainable development of polymeric industry. Reported herein is a 1-step and 2-step strategy for fabrication of flexible and stretchable thermoplastics prepared by compression molding from two structurally different arabinoxylans (AX). The synthesis was accomplished using n-butyl glycidyl ether whose epoxide ring opened on hydroxyl group and resulted in introduction of alkoxide sidechains for the 1-step synthesis. AX was preactivated by periodate oxidation as 1st step for the 2-step synthesis. Two structurally different AXs, i.e. wheat bran extracted arabinoxylan (AXWB, araf/xylp=3/4) and barley husk extracted arabinoxylan (AXBH, araf/xylp=1/4) were used to understand the effects of the araf/xylp on thermoplastic properties because melt processability has been rare for low araf/xylp AXs. AXBH-derived samples demonstrated melt compression processability. AXWB and AXBH derived thermoplastics featured dual and single glass transition (Tg) characteristics respectively as confirmed by DSC and DMA, but AXBH derived thermoplastics had lower stretchability (maximum 160%) compared to AXWB samples (maximum 300 %). Higher araf/xylp and thus in turn longer alkoxide side chains in AXWB derived thermoplastics explained differences in stretchability.</p></div></div></div>

Structural Composition Explains Differences in Stretchability for Compression-Molded Arabinoxylan-Based Thermoplastic Films

<div><div><div><p>Valorization of argi-waste polymers into value-added materials is essential for sustainable development of polymeric industry. Reported herein is a 1-step and 2-step strategy for fabrication of flexible and stretchable thermoplastics prepared by compression molding from two structurally different arabinoxylans (AX). The synthesis was accomplished using n-butyl glycidyl ether whose epoxide ring opened on hydroxyl group and resulted in introduction of alkoxide sidechains for the 1-step synthesis. AX was preactivated by periodate oxidation as 1st step for the 2-step synthesis. Two structurally different AXs, i.e. wheat bran extracted arabinoxylan (AXWB, araf/xylp=3/4) and barley husk extracted arabinoxylan (AXBH, araf/xylp=1/4) were used to understand the effects of the araf/xylp on thermoplastic properties because melt processability has been rare for low araf/xylp AXs. AXBH-derived samples demonstrated melt compression processability. AXWB and AXBH derived thermoplastics featured dual and single glass transition (Tg) characteristics respectively as confirmed by DSC and DMA, but AXBH derived thermoplastics had lower stretchability (maximum 160%) compared to AXWB samples (maximum 300 %). Higher araf/xylp and thus in turn longer alkoxide side chains in AXWB derived thermoplastics explained differences in stretchability.</p></div></div></div>

THE INFLUENCE OF TECHNOLOGICAL PARAMETERS OF THE EXTRUSION PROCESS AND TECHNICAL PARAMETERS OF AN EXTRUDER WITH ELASTIC SCREW ELEMENTS ON THE EXPANSION INDEX OF THE EXTRUDATE

The processing of feed by extrusion improves the level of absorption by animals. In the extruder, due to frictional forces, the grain mass is heated to a temperature of 120 ... 150 ° C and acquires thermoplastic properties. Due to the transition of the heated mass from the high-pressure zone to the atmospheric zone, adiabatic expansion occurs, as a result of which the volume of the extrudate increases due to the destruction of the granular structure of starch at the cellular level. The extrudate acquires a microporous structure, which contributes to a more complete absorption of nutrients by the animal body. The purpose of the work is to determine the rational values of the factors that most significantly influence the extrusion process and to evaluate the degree of their influence on the extrusion index of the grain mixture of cereals. The studies were performed using a sample of the model extruder section structure, the coils of the screw extruder can oscillate along its axis. A blend of corn, barley and winter wheat in a 5: 3: 2 ratio was used as the study object. The effect of the extruder parameters and modes on the extrudate expansion index was studied using the multivariate experiment planning method. The extrudate expansion index was defined as the ratio of the extrudate diameter to the diameter of the die. To study the process, the following factors were selected that most significantly influence the extrusion process and the extrudate expansion index: die diameter X1 (d, mm), relative humidity of the grain mixture X2 (W,%) and temperature of the extrusion process X3 (T, 0C). The levels of variation of the factors were as follows (initially recorded the zero level of factors, and after the interval of variation): X1 (6; 2 mm), X2 (16; 4%) and X3 (135; 25 0C). As a result of the conducted researches the following rational parameters and modes of operation of the extruder were established: diameter of die d = 4.9… 5.9 mm; humidity of grain mixture W = 17,7… 20%; the temperature of the extrusion process T = 140… 145 0C, and a die diameter of 4.9 ... 5, 9mm.

Basic Characteristics and Industrial Application of Styrene Copolymer-Based Thermoplastic Elastomers (Overview)

Thermoplastic elastomers (TPEs) have elastic properties that are similar to rubber but capable of melting and all thermoplastic properties. Block copolymers are also widely used, in which there are links of different polymers in the structure of their macromolecules. So styrene-ethylene-butylene- styrene (SEBS) belongs to the second generation, the products of which have high physical and mechanical properties, and biocompatibility allows it to be used in the medical field. The main characteristics and analysis of advantages of TPE on the example of SBSS in comparison with traditional materials are presented in the paper.