Thermoplastic elastomers based on waste rubber and expanded polystyrene: Role of devulcanization and ionizing radiation

Waste rubber (WR) powder as a vulcanized one was introduced into a two-roll mill in the presence of various ratios of curatives to develop sheets of devulcanized waste rubber (DWR). Thermoplastic elastomers (TPE) were prepared by blending either WR or the obtained DWR with the waste of expanded polystyrene (EPS) at a fixed ratio of 70 rubber/30 EPS in the absence or presence of gamma irradiation at 100?kGy. Maleic anhydride (MA) 1?wt% with respect to rubber was used as coupling agent. The mechanical parameters of the blends: tensile properties, rheology, hardness (Shore D), and abrasion resistance were studied.     

Simultaneous Enhancement of Mechanical and Dynamic Mechanical Properties of Natural Rubber/Recycled Ethylene-Propylene-Diene Rubber Blends by Electron Beam Irradiation

Mechanical and dynamic mechanical properties of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends were simultanoeusly enhanced by electron beam (EB) irradiation. The cross-linking promoter, trimethylolpropane triacrylate (TMPTA), was also introduced into the blends to induce the cross-linking. By applying EB irradiation, the tensile modulus, hardness, swelling, cross-link density, and storage modulus increased with increase in the irradiation dose; an irradiation dose of 50 kGy was efficient to gain optimum tensile strength. The formation of irradiation-induced cross-links after EB irradiation is a major concern for the enhancement of mechanical, swelling resistance, and dynamic mechanical properties of the blends.     

Blending of Natural Rubber/Recycled Ethylene-Propylene-diene Rubber: Promoting the Interfacial Adhesion Between Phases by Natural Rubber Latex

This article deals with blends based on natural rubber (NR) and recycled ethylene-propylene-diene rubber (R-EPDM). Natural rubber latex (NRL) was introduced into the blends to enhance interfacial adhesion between NR and R-EPDM. A new route of compounding was also suggested. The blends were prepared by mixing R-EPDM and other additives in NRL before blending with natural rubber on a two-roll mill. By applying this method, the homogeneity of the blends and cross-linking distribution are significantly improved. The blends exhibited superior state of cure, swelling resistance, mechanical properties and dynamic mechanical properties. The degree of entanglement between NR and R-EPDM also increased after NRL modification.     

微波处理和溶胶凝胶法共同改性废胶粉及其与天然橡胶复合材料性能的研究

采用微波处理打断废胶粉(WRP)的三维网状结构用来提高WRP在有机溶剂中的溶胀性,然后采用溶胶凝胶法,将微波改性后的WRP浸入正硅酸乙酯中,通过水解反应和缩合反应,在WRP表面原位生成SiO2网络,从而制得改性废胶粉(MWRP).将制得MWRP与天然橡胶(NR)共混,制备了NR/MWRP复合材料,研究了NR/MWRP复合材料的性能.通过热重分析仪、差示扫描量热仪和力学分析表明微波处理最佳时间是20 s.由于微波处理提高了NR与WRP的相容性,原位生成的SiO2粒子起到了补强作用,所以所制备的NR/MWRP复合材料拥有较好的力学性能;随着Si69的加入,抑制了SiO2粒子聚集,提高了SiO2粒子的分散性,从而进一步提高复合材料的力学性能并降低复合材料的Payne效应;在进行频率扫描时,硫化胶的储存模量随频率的增大而增大;硫化胶的温度扫描结果表明,随着温度的升高,复合材料中SiO2粒子聚集程度加剧并且复合材料出现老化的现象.为了提高复合材料的耐老化性能,N,N-间苯撑双马来酰亚胺(BMI)作为一种防老剂加入复合材料中,BMI利用Diels-Aider反应补偿橡胶在老化过程中所损失的交联键并提高NR与WRP的界面相容性,从而提高复合材料的耐老化性能.     

Compatibilized natural rubber/recycled ethylene-propylene-diene rubber blends by biocompatibilizer

Biocompatibilizer-based refined, bleached, deodorized palm stearin was successfully used as compatibilizer for natural rubber/recycled ethylene–propylene–diene rubber (NR/R-EPDM) blends. It seems effective in improving the state of cure, tensile properties, as well as the swelling resistance and morphology of the blends, indicating an improvement in compatibility between the NR matrix and R-EPDM rendered by biocompatibilizer. This was clearly verified by the dynamic mechanical properties of the blends. The dynamic responses obtained were clearly corresponding to the swelling result. It proves that the cross-link density plays a major role in the changes of storage modulus and degree of entanglement.     

Preparation and characterization of polypropylene/waste tyre dust blends with addition of DCP and HVA-2 (PP/WTDP-HVA2)

Preparation of polypropylene (PP)/waste tyre dust (WTD) blends with addition of dicumyl peroxide (DCP) and N,N′-m-phenylenebismaleimide (HVA-2) (PP/WTD_P-HVA2) was described. The blends were characterized based on their tensile properties, swelling resistance and morphology, as well as thermal properties. The results reveal that the presence of both chemicals in PP/WTD_P-HVA2 blends brought about noticeable improvements in tensile properties, swelling resistance and interfacial adhesion. The thermal stability was also improved, indicating existence of some chemical interaction between WTD and the PP matrix in the presence of both DCP and HVA-2 during processing. The results imply that both chemicals had great influences on WTD destabilization, leading to the enlargement and intensification of the copolymer formation and, hence, improved the interfacial adhesion between WTD and the PP matrix. A competing reaction mechanism that may contribute to the property enhancement of PP/WTD_P-HVA2 blends was proposed.     

An investigation of dynamic mechanical, thermal, and electrical properties of housing materials for outdoor polymeric insulators

The present paper reports the results about a study of mechanical, thermal, dynamic mechanical and electrical properties of housing (weather shed) materials for outdoor polymeric insulators. Silicone rubber, ethylene-propylene-diene monomer (EPDM) and alloys of silicon-EPDM are known polymers for use as housing in high voltage insulators. The result of dynamical mechanical measurement shows that the storage modulus of blends enhances with increase EPDM in formulation. It can be seen from the result of TGA measurement that initial thermal degradation of silicone rubber improves by the effect of EPDM in blends. The blends of silicone-EPDM show good breakdown voltage strength compared to silicone rubber. Surface and volume resistance of silicone rubber improve by EPDM content. The mechanical properties of EPDM such as strength, modulus and elongation at break improve by silicone.     

Direct visualization of the nanoscopic three‐phase structure and stiffness of NBR/PVC blends by AFM nanomechanical mapping

The PeakForce Quantitative Nanomechanical Mapping based on atomic force microscope (AFM) is employed to first visualize and then quantify the elastic properties of a model nitrile rubber/poly(vinyl chloride) (NBR/PVC) blend at the nanoscale. This method allows us to consistently observe the changes in mechanical properties of each phase in polymer blends. Beyond measuring and discriminating elastic modulus and adhesion forces of each phase, we tune the AFM tips and the peak force parameters in order to reliably image samples. In view of viscoelastic difference in each phase, a three‐phase coexistence of an unmixed NBR phase, the mixed phase, and PVC microcrystallites is directly visualized in NBR/PVC blends. The nanomechanical investigation is also capable of recognizing the crosslinked rubber phase in cured rubber. The contribution of the mixed phase was quantified and it was found that the mechanical properties of blends are mainly determined by the homogeneity and stiffness of the mixed phase. This study furthers our understanding the structure–mechanical property relationship of thermoplastic elastomers, which is important for their potential design and applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 662–669     

反式异戊橡胶合金改性溶聚丁苯橡胶/顺丁橡胶轿车胎面胶

研究了反式异戊橡胶合金(TPIR)的结晶性能、加工性能和力学性能及在轿车胎面胶溶聚丁苯橡胶/顺丁橡胶(SSBR/BR)中的应用.研究结果表明,与无定形SSBR和BR相比,TPIR生胶具有常温可结晶性,因此TPIR具有较高的格林强度.毛细管挤出行为研究结果表明,TPIR具有优异的挤出性能,挤出物外观光滑,挤出涨大比小.与SSBR/BR混炼胶相比,用TPIR改性后的SSBR/BR/TPIR混炼胶的格林强度与100%定伸应力随TPIR含量的增加而提高.经150℃硫化反应后制备的SSBR/BR/TPIR硫化胶物理机械性能优异:不仅耐湿滑性能、耐磨耗性能及压缩强度较对比胶提高,其伸张疲劳性能较对比胶提高4倍以上.透射电子显微镜(TEM)及填料分散仪表征结果表明,与SSBR/BR硫化胶相比,SSBR/BR/TPIR硫化胶的填料聚集体平均尺寸降低2μm,填料分散性显著改善.表明TPIR是一种应用于高性能轿车胎面胶的理想胶料.     

Compatibilization of elastomer-based blends

The reactive compatibilization of ethylene-propylene-diene (EPDM)-based dissimilar elastomer blends has been investigated in terms of mechanical properties and swelling degree. The use of mercapto-functionalized copolymers resulted in an improvement of mechanical properties of natural rubber-EPDM blends. The mercapto-groups are able to react with the carbon-carbon double bonds of the high diene rubber, resulting in a good interaction between phases. These interactions were confirmed by the amount of insoluble material obtained in non-vulcanized blends. From dynamic mechanical properties and swelling degree, one can suggest a covulcanization process in these blends cured with sulfur-based system. Blends composed by nitrile rubber with EPDM displayed good results in terms of mechanical properties when mercapto-functionalized EVA was employed instead of functionalized EPDM, probably because of the higher polarity of the former associated to its lower viscosity. Additionally, an improvement on mechanical properties was also achieved by using EPDM functionalized with mercapto or anhydride groups in combination with nitrile rubber functionalized with epoxy or oxazoline groups.     

Physico-Mechanical Properties of Biodegradable Rubber Toughened Polymers

Summary: In this study, blends of poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT) were studied for their mechanical and thermal properties as a function of the PBAT content. Tensile testing, impact testing, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMTA) and scanning electron microscopy (SEM) were used to characterize the blends. It was observed that PLA/PBAT blends maintained quite high modulus and tensile strength compared to pure PLA. Small amounts of PBAT improved the elongation at break and the impact resistance showing a debonding effect typical of rubber toughened systems.     

Miscibility studies of PVC/Aramid blends

Blends containing PVC and aramid (Ar) matrices were probed for their miscibility. In this respect, Ar chains were synthesized by aromatic diamine and diacid chloride in amide solvent. The Ar thus synthesized was characterized through Fourier transform infrared (FTIR) spectroscopy and molecular weight determination. Blend system Ar/PVC was investigated over a range of Ar/PVC ratios. Their mechanical profiles in terms of maximum stress, maximum strain, toughness, and initial moduli have been explored. Thermal properties and morphology of the blends were estimated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). A good correlation was observed between thermal, mechanical, and morphological properties of the blends. The presence of hydrogen bonding among polymers was evaluated through FTIR spectroscopy, which is believed to be responsible for the blend miscibility. Optimal thermal and mechanical profiles were depicted by the blend containing 40-wt% PVC in the Ar matrix.     

Effect of Ground Rubber Powder on Properties of Natural Rubber

Ground rubber powder (GRP) with three different sizes was incorporated into nature rubber matrix with different loading. Cure characteristics, swelling behaviour, crosslink density, tensile fractured surface, and mechanical properties have been studied. Based on the cure characteristics, it is evident that the processability of the rubber compounds has not changed obviously with the different GRP loading. The introduction of GRP in virgin rubber leads to the increase in swelling degree and the decrease in crosslink density. Tensile strength, hardness and abrasion resistant deteriorate with the increase of GRP loading, but the tear resistance gets better. If the ground rubber particles are smaller, the properties are more similar to the virgin rubber. Because of the phase separation of the GRP and matrix, the properties get worse with the bigger ground rubber powder.     

The compatibilizing effect of epoxy resin (EP) on polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) blends

A new method was used to prepare thermoplastic elastomers based on polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) with improved mechanical properties. An epoxy resin (EP) was used as a compatibilizing agent. The effect of EP on mechanical properties, swelling percentage and morphological characteristics of the blends was investigated with different blend compositions. The results showed that the incorporation of EP has improved the tensile strength, Young's modulus and elongation at break of PP/NBRr-EP blends compared with PP/NBRr blends. The enhancement of tensile properties of PP/NBRr-EP blends is due to the better adhesion between the two phases with the incorporation of EP. This is quite evident by scanning electron microscopy of tensile fractured surfaces. PP/NBRr-EP blend exhibits lower stabilization torque and swelling percentage than PP/NBRr blends. The lower stabilization torque is an indication of better processing characteristics.     

Effect of electron beam irradiation on mechanical and thermal properties of waste polyamide copolymer blended with nitrile‐butadiene rubber

In the present study, the effect of electron beam irradiation on the morphological, thermal, and mechanical properties of waste polyamide copolymer (WPA‐66/6) blended with different contents of acrylonitrile butadiene rubber (NBR) were studied. The prepared blends were subjected to irradiation doses up to 150 kGy and the structural modifications were discussed; non‐irradiated blends were used as control. Mechanical properties, namely, tensile strength (TS), yield strength, elongation at break, and hardness, were followed up as functions of irradiation dose and degree of loading with rubber content. On the other hand, the influence of irradiation dose on the thermal parameters, melting temperature, heat of fusion, ΔH_m of the recycled PA copolymer, and its blend with NBR were also investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Compatibilizing effect of functionalized polystyrene blends: a study of morphology,thermal, and mechanical properties

Polystyrene (PS), being an amorphous polymer is immiscible with other polymers. To engender miscible blends, PS has been functionalized with an active amino‐functional group on the molecular chains of PS to yield amino‐substituted polystyrene (APS), which serves as a reactive compatibilizer. The compatibilization effect of amino functionalized polystyrene on the rubber toughening was explored and results were compared in terms of morphology, thermal, and mechanical properties of PS/SEBS‐g‐MA versus APS/SEBS‐g‐MA blends. In addition, the effect of rubber content on the blend morphology and mechanical properties were investigated. An appreciable change in the thermal stability of APS blends in comparison with PS blend has been probed. A marked correlation has been observed between phase morphology and thermal stability. Use of APS produced the compatibilized blends which render improved blend morphology, enhanced thermal and mechanical properties. Optimal thermal, morphological and mechanical profiles were depicted by 20‐wt% APS blend. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC

This research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and ¹H-NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque-time curves of the materials.     

Development and characterization of reactive extruded PVC/polyacrylate blends

This paper describes a method to obtain polymer blends by the absorption of a liquid solution of monomer, initiator, and a crosslinking agent in suspension type porous poly(vinyl chloride) (PVC) particles, forming a dry blend. These PVC/monomer dry blends are reactively polymerized in a twin‐screw extruder to obtain the in situ polymerization in a melt state of various blends: PVC/poly(methyl methacrylate) (PVC/PMMA), PVC/poly(vinyl acetate) (PVC/PVAc), PVC/poly(butyl acrylate) (PVC/PBA) and PVC/poly(ethylhexyl acrylate) (PVC/PEHA). Physical PVC/PMMA blends were produced, and the properties of those blends are compared to reactive blends of similar compositions. Owing to the high polymerization temperature (180°C), the polymers formed in this reactive polymerization process have low molecular weight. These short polymer chains plasticize the PVC phase reducing the melt viscosity, glass transition and the static modulus. Reactive blends of PVC/PMMA and PVC/PVAc are more compatible than the reactive PVC/PBA and PVC/PEHA blends. Reactive PVC/PMMA and PVC/PVAc blends are transparent, form single phase morphology, have single glass transition temperature (T_g), and show mechanical properties that are not inferior than that of neat PVC. Reactive PVC/PBA and PVC/PEHA blends are incompatible and two discrete phases are observed in each blend. However, those blends exhibit single glass transition owing to low content of the dispersed phase particles, which is probably too low to be detected by dynamic mechanical thermal analysis (DMTA) as a separate T_g value. The reactive PVC/PEHA show exceptional high elongation at break (～90%) owing to energy absorption optimized at this dispersed particle size (0.2–0.8 µm). Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of an efficient bio-based plasticizer derived from waste cooking oil and its performance testing in PVC

In order to develop an efficient and sustainable plasticizer, the waste cooking oil and malic acid were used as the main raw materials in this study to synthesize a bio-based plasticizer (acetylated-fatty acid methyl ester-malic acid ester, AC-FAME-MAE) by environment-friendly methods, and the structure was characterized by FTIR and ¹H NMR. The properties of the poly (vinyl chloride) (PVC) with AC-FAME-MAE were tested and compared with those of the PVC plasticized with DOP (di-2-ethylhexyl phthalate) and EFAME (epoxy fatty acid methyl ester), respectively. The results of tensile test, TGA and leaching test showed that the mechanical properties, thermal stability and overall solvent resistance of PVC films with AC-FAME-MAE were significantly better than those of PVC films plasticized by DOP or EFAME. From the results of DMA, the plasticized efficiency of AC-FAME-MAE was as good as DOP. The application of AC-FAME-MAE has higher safety in the food industry based on the results of food simulation fluids experiment.     

Study of the properties of rigid and plasticized PVC/PMMA blends

The aim of this work is to study the structure-properties relationship of rigid and plasticized PVC/PMMA blends. For that purpose, blends of variable compositions were prepared in the absence and in the presence of a plasticizer di (ethyl-2 hexyl) phtalate or DEHP. The miscibility of the two polymers was investigated by differential scanning calorimetric analysis (DSC) and Fourier transform infrared spectroscopy. The weight loss from 30 to 600°C was investigated by thermogravimetric analysis (TGA). The thermal degradation under nitrogen at 185°C was studied and the amount of HCl released from PVC was measured by the pH method. Furthermore, the variation of mechanical properties such as tensile behavior, hardness and impact resistance was investigated for all blend compositions.