Thermoplastic elastomers based on high‐density polyethylene,ethylene–propylene–diene terpolymer,and ground tire rubber dynamically vulcanized with dicumyl peroxide

Thermoplastic vulcanizates (TPVs) based on high‐density polyethylene (HDPE), ethylene–propylene–diene terpolymer (EPDM), and ground tire rubber (GTR) were dynamically vulcanized with dicumyl peroxide (DCP). The polymer blend was composed of 40% HDPE, 30% EPDM, and 30% GTR, and the concentration of DCP was varied from 0.3 to 3.6 parts per hundred rubber (phr). The properties of the TPVs were determined by evaluation of the gel fraction content and the mechanical properties. In addition, IR spectroscopy and differential scanning calorimetry analysis were performed as a function of the DCP content. Decreases in the Young's modulus of the blends and the crystallinity of HDPE were observed when the content of DCP was greater than 1.8 phr. The results regarding the gel content indicate that the presence of DCP promoted the crosslinking of the thermoplastic matrix, and optimal properties were obtained with 1.5% DCP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39901.     

Influence of DCP content on the toughness and morphology of fully biobased ternary PLA/NR-PMMA/NR TPVs with co-continuous phase structure

ABSTRACT

Herein, the poly(lactic acid) (PLA)/poly(methyl methacrylate)-grafted natural rubber (NR-PMMA)/natural rubber (NR) blends with improved compatilibility was prepared by dicumyl peroxide induced dynamic vulcanization. Both the simple blend and the PLA/NR-PMMA/NR ternary thermoplastic vulcanizates (TPVs) exhibited co-continuous morphology. Moreover, the in situ compatibilization between PLA and rubber took place during the dynamic vulcanization. With increasing the DCP content, the toughness first increased and then decreased. With 2.5 phr DCP, the TPV displayed the highest impact strength of 760.7 J/m. Meanwhile, tensile strength of the TPVs was almost unchanged to that of the simple blend with the values of ~ 44 MPa.     

Preparation of thermoplastic vulcanizates based on waste crosslinked polyethylene and ground tire rubber through dynamic vulcanization

An environmental‐friendly approach called high‐shear mechanical milling was developed to de‐crosslink ground tire rubber (GTR) and waste crosslinked polyethylene (XLPE). The realization of partial devulcanization of GTR and de‐crosslinking of XLPE were confirmed by gel fraction measurements. Fourier transform infrared spectral studies revealed that a new peak at 1723.3 cm^?1 corresponds to the carbonyl group (? C?O) absorption was appeared after milling. The rheological properties showed that the XLPE/GTR blends represent lower apparent viscosity after mechanical milling, which means that the milled blends are easy to process. Thermoplastic vulcanizates (TPVs) could be prepared with these partially de‐crosslinked XLPE/GTR composite powders through dynamic vulcanization. The mechanical properties of the XLPE/GTR composites increased with increasing cycles of milling. The raw XLPE/GTR blends could not be processed to a continuous sheet. After 20 cycles of milling, the tensile strength and elongation at break of XLPE/GTR (50/50) composites increased to 6.0 MPa and 185.3%, respectively. The tensile strength and elongation at break of the composites have been further improved to 9.1 MPa and 201.2% after dynamic vulcanization, respectively. Re‐processability study confirmed the good thermoplastic processability of the TPVs prepared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

BR／HDPE动态硫化共混体系橡塑并用材料的研究

以硫黄和DCP为交联剂,用动态硫化方法制备了BR/HDPE共混改性材料。当橡塑比为60/40～70/30时获得的热塑性弹性体,其伸但强度为10～20MPa,扯断伸长率350～520％,永久变形20～103％,硬度(邵氏A)76～90,炭黑对TPE有明显的补强效应,硫黄体系的TPE具有较大的扯断伸长率,而DCP体系的TPE的拉伸强度高,永久形变小,DCP可交联共混物中的BR和PE,使PE的结晶度降低。S和DCP交联体系共混物中PE的结晶度、结晶温度、非等温结晶的结晶能力、n值基本上不随BR量的多寡而变化,BR不影响PE的结晶机制。     

Systematic investigation on the effect of crosslinking agent type and dosage on the performance of TPU/MVQ based thermoplastic vulcanizates

Dynamic vulcanized thermoplastic polyurethane (TPU)/methyl vinyl silicone rubber (MVQ) thermoplastic vulcanizates (TPVs) were prepared in torque rheometer. The influence of the type and amount of peroxide crosslinking agent on the mechanical properties, thermal stability, micromorphology and melt flowability was systematically investigated. The results showed that the mechanical properties of the TPVs vulcanized by 2,5-dimethyl-2,5-di (tert-butyl peroxy) hexane (DBPH) first increased and then decreased with increasing the peroxide amount, while for dicumyl peroxide (DCP) vulcanizing system the mechanical properties slowly increased. Besides, the comprehensive mechanical properties vulcanized by DBPH were better than those of DCP group. The results of the thermogravimetric analysis showed that the TPVs vulcanized by DBPH had better heat stability, corresponding to the excellent thermo-oxidative aging performance and the 38% increase in tensile strength after aging. In addition, the MVQ rubber particles showed better dispersing performance for DBPH vulcanizing system. The melt flow rate of the TPVs showed a linear relationship with increasing DBPH dosage and became worse after the amount of crosslinking agent exceeded 1.5 phr. By comprehensive comparison, the TPVs have better performance when use peroxide DBPH as the crosslinking agent and the dosage is 1.5 phr.     

Partial replacement of NR by GTR in thermoplastic elastomer based on LLDPE/NR through using reactive blending: Its effects on morphology,rheological, and mechanical properties

Attempts have been made to use different amount of ground tire rubber (GTR) powder as a partial substitute for natural rubber (NR) in thermoplastic elastomer based on linear low‐density polyethylene (LLDPE, 60 wt%) and NR (40wt%). Maleic anhydride (MA) and dicumyl peroxide (DCP) were used, during melt mixing of the compound, to modify GTR and vulcanize the rubber phases of the blends. Morphology of the blends was studied by scanning electron microscopy and rheological behavior investigated through rheomechanical spectroscopy. Mechanical properties of the blends were also measured, and the effect of GTR concentration on properties was evaluated. Obtained results showed that modification of GTR with MA and using DCP in the blends containing GTR improves the bonding between GTR and matrix. This leads to a distinctive rheological behavior and enhances tensile strength and elongation at break compared to its corresponding simple blend. It can be said that using of MA and DCP during melt mixing of thermoplastic elastomers based on LLDPE/NR containing GTR, concludes to a better dispersion of GTR and formation of morphology similar to that of a dynamic vulcanized thermoplastic elastomer, which improves interfacial bonding between phases and causes a dramatically increase in mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

POE/硅橡胶动态硫化共混物的力学性能研究

以聚烯烃弹性体(POE)/有机硅橡胶(质量比50/50)为基体,通过HAKKE密炼机制备了动态硫化热塑性弹性体,考察了硫化剂双-2,5、助交联剂(V4)、增容剂(POE-g-A151)和第三组分用量对弹性体力学性能的影响。结果表明,当硫化剂用量为0.8phr,助交联剂V4用量为0.4phr时,弹性体力学性能显著提高;加入POE-g-A151能起到一定的增容作用。第三组分的加入能有效提高弹性体的力学性能。     

Morphology and mechanical properties of ethylene‐vinyl acetate rubber/polyamide thermoplastic elastomers

High performance thermoplastic elastomers based on ethylene‐vinyl acetate rubber (EVM) and ternary polyamide copolymer (tPA) were prepared through a dynamic vulcanization process in the presence of dicumyl peroxide (DCP). The morphology, crystallization, and mechanical properties of the EVM/tPA blends were studied. A phase transition of EVM/tPA blend was observed at a weight ratio of 60/40. The presence of EVM increased the melting enthalpy at the high temperature of tPA, ascribing to the heterogeneous nucleating effect of EVM. The tensile strength of EVM/tPA (70/30) blends was increased up to 20.5 MPa as the DCP concentration increased to 3.5 phr, whereas the elongation at break of the blends kept decreasing as the DCP concentration increased. The addition of ethylene‐acrylic acid copolymer (EAA) or maleic anhydride‐grafted EVM (EVM‐g‐MAH) to the EVM/tPA blends both induced finer dispersion of the EVM particles in the tPA phase and improvement in the tensile strength and elongation at break of the blends, which were ascribed to the compatibilization of EAA or EVM‐g‐MAH. Finally, a high performance EVM/tPA (70/30) thermoplastic elastomer with Shore A hardness of 75, tensile strength of 24 MPa, elongation at break of 361%, and set at break of 20% was obtained by adding 5 wt % of EVM‐g‐MAH and 3.5 phr DCP. It has great potential in automotive and oil pipeline applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Oil resistant thermoplastic elastomers of nitrile rubber and high density polyethylene blends

Different grades of oil resistant thermoplastic elastomers (TPE) based on blends of nitrile rubber (NBR) and high density polyethylene (HDPE) have been developed. Chemical treatment of HDPE to evolve compatibility with NBR and dynamic vulcanization with different curatives have been studied. Determination of physico‐mechanical and thermal properties and relative crystallinity of these blends have been carried out. Oil resistance characteristics of the blends have been evaluated in different commercially used oils and fuels for applications as a substitute for NBR/polyvinyl chloride (PVC) blends.     

Thermoplastic vulcanizates based on poly(methyl methacrylate)/epoxidized natural rubber blends: Mechanical,thermal, and morphological properties

Epoxidized natural rubbers (ENRs) with epoxide levels of 10, 20, 30, 40 and 50 mol % were prepared. The ENRs were later used to prepare thermoplastic vulcanizates (TPVs) by blending them with poly(methyl methacrylate) (PMMA) using various formulations. Dynamic vulcanization, using sulfur as a vulcanizing agent, was performed during the mixing process. The mixing torque increased as the ENR contents and epoxide molar percentage increased. This was because of an increasing chemical interaction between the polar groups of the blend components, particularly at the interface between the elastomeric and thermoplastic phases. The ultimate tensile strength of the TPVs with ENR‐20 was high because of strain‐induced crystallization. ENRs with epoxide levels >30 mol % exhibited an increase of tensile strength because of increasing levels of chemical interaction between the molecules and the different phases. The hardness of the TPVs also increased with increased epoxide levels but decreased with increased contents of ENRs. Two morphology phases with small domains of vulcanized ENR particles dispersed in the PMMA matrix were observed from scanning electron microscopy micrographs. The TPVs based on ENR‐20 and ENR‐50 showed smaller dispersed rubber domains than those of the other types of ENRs. Furthermore, the size of the vulcanized rubber domain decreased with increasing amounts of PMMA in the blends. The decomposition temperature of the TPVs also increased as both the levels of ENRs in the blends and the epoxide molar percentage increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1251–1261, 2005     

交联剂用量对BR/EVA热塑性硫化胶性能的影响

采用动态硫化法制备了BR/EVA热塑性硫化胶(TPV),考查了硫化体系中硫黄用量对混炼胶的硫化行为、静态硫化胶的溶出物含量及性能的影响,并对BR/EVA型TPV的力学性能及微观结构进行了研究。结果表明,随着硫黄用量的提高,混炼胶硫化历程中的平坦期较长,但t90趋于明显降低,静态硫化胶溶出物含量及力学性能均呈下降趋势;当硫黄用量为0.5份时,静态硫化胶及BR/EVA TPV表现出良好的综合性能。显微镜照片表明,BR硫化胶的粒状物平均尺寸为5～10μm左右,较均匀地分散在EVA树脂基体中;FE-SEM的测试表明,TPV的断面平滑,TPV具有良好的形变回复性。     

Influence of phenolic curative on crosslink density and other related properties of dynamically cured NR/HDPE blends

Dynamically cured 60/40 NR/HDPE blends with various amounts of phenolic curative were prepared in an internal mixer at 160°C. A simple blend (i.e., the blend without curative) was also prepared using the same materials and blend proportion for comparison purposes. Mechanical, dynamic, and morphological properties; swelling resistance and crosslink density of the blends were investigated. It was found that the thermoplastic vulcanizates (TPVs) gave superior mechanical and dynamic properties than the simple blend. Furthermore, the mechanical properties in terms of elongation at break, modulus and tensile strength and elastic response in dynamic test in terms of storage modulus increased with increased loading amount of the curative. The complex viscosity also increased but the tan δ and tension set decreased with increased loading level of the curative. The crosslink density of the TPVs was estimated based on the elastic shear modulus. It was found that the crosslink density of the blends increased with increased loading levels of the curative while the degree of swelling decreased. This correlated well with the trend of mechanical and dynamic properties. SEM micrographs were used to confirm the level of mechanical and dynamic properties. It was found that the simple blend at a given blend ratio exhibited co‐continuous phase morphology. However, the TPVs showed micron scale of vulcanized rubber domains dispersed in a continuous HDPE matrix. The size of vulcanized rubber domains decreased with increasing amounts of the curative. This led to greater interfacial adhesion between the phase and hence superior mechanical and dynamic properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermoplastic dynamic vulcanisates containing LDPE,rubber, and thermochemically reclaimed ground tyre rubber

Abstract

Thermochemically devulcanised ground tyre rubber (GTR^DL) was added to fresh rubber compositions, which were then melt blended with low density polyethylene (LDPE). Styrene/butadiene rubber (SBR), natural (NR), and ethylene/propylene/diene (EPDM) rubbers were selected as the fresh rubbers. During blending, dynamic curing was achieved using sulphuric, phenolic, and peroxide curing agents. Some of the GTR was decomposed in the presence of 6 phr Regen^TM Agent-S reclaiming compound before being incorporated into the blends. The resulting thermoplastic dynamic vulcanisates had constant compositions, namely LDPE/rubber/GTR=50:25:25. Sulphuric and phenolic curing agents proved to be most suitable for dynamic curing. The thermoplastic dynamic vulcanisates with the best mechanical performance contained SBR and EPDM rubbers. The observed improvements in mechanical performance were attributed to chain entanglement and co-crosslinking in the interphase between the GTR^DL particles and the surrounding matrix (i.e. with the fresh rubber and/or LDPE). The phase morphology, which was assessed using scanning electron microscopy on the etched surfaces of cryogenically fractured thermoplastic dynamic vulcanisate compositions, is discussed.     

Effect of acrylonitrile content of acrylonitrile butadiene rubber on mechanical and thermal properties of dynamically vulcanized poly(lactic acid) blends

We report here the morphology, thermal and tensile properties of poly(lactic acid) (PLA) blends composed of acrylonitrile butadiene rubber (NBR) with different acrylonitrile contents with/without dynamic vulcanization by dicumyl peroxide (DCP). The interfacial tension of PLA and NBR measured by contact angle measurement decreased as the acrylonitrile content of NBR decreased. Likewise, SEM images showed that the rubber particle size reduced with decreasing acrylonitrile content owing to the stronger interfacial adhesion between the PLA matrix and NBR domains. Incorporation of DCP at 1.0 phr for dynamic vulcanization led to higher crosslink density and, in turn, optimal tensile strength and tensile toughness as a result of the action of PLA‐NBR copolymer as a reactive compatibilizer. The dynamic vulcanization of the blends containing low acrylonitrile NBR gave the most improved tensile properties because the free radicals from DCP decomposition preferentially attacked the allylic hydrogen atoms or double bonds of the butadiene backbone. Accordingly, more NBR macroradicals were generated and probably more PLA‐NBR copolymers were produced. Moreover, further addition of DCP at 2.0 phr provided a large amount of crosslinked NBR gel, which significantly degraded the tensile properties. From the DSC results, dynamic vulcanization lowered the cold crystallization temperature, implying an improvement of cold crystallization. Finally, TGA results showed a higher degradation temperature as a function of DCP content, which suggested that thermal stability increased due to stronger interfacial adhesion as well as higher gel content. © 2019 Society of Chemical Industry     

Dynamic properties of rubber vibration isolators and antivibration performance of ethylene–propylene–diene monomer/nylon 6 blend systems

This article examines thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs) as two types of elastomers from melt-blended and dynamically vulcanized ethylene–propylene–diene monomer (EPDM) rubber materials and nylon 6 plastic materials. A series of investigations were conducted on the mechanical properties, morphology, dynamic mechanical properties, hysteresis behavior, and dynamic antivibration properties with different nylon 6 contents. The experimental results showed that the incompatibility between EPDM and nylon 6 led to the easy destruction of the TPV materials in two interfacial polymers upon the application of an external force. Thus, after a dynamic vulcanization process, the mechanical properties of the EPDM/nylon 6 blends were not as good as those of the TPE materials. In terms of morphology, nylon 6 plastics were uniformly distributed in the EPDM/nylon 6 blends during the EPDM rubber phase before vulcanization was performed. After the dynamic vulcanization, phase inversion was produced in which rubber microparticles were formed and dispersed in the nylon 6 plastic phase. The results of dynamic mechanical analysis, compression vibration hysteresis behavior, and dynamic property antivibration experiments showed that the blends provided better vibration isolation and antivibration performance after the amount of nylon 6 was increased and EPDM and nylon 6 were blended through dynamic vulcanization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Design and properties of a series of high‐temperature thermoplastic elastomeric blends from polyamides and functionalized rubbers

A series of high‐temperature thermoplastic elastomers (TPEs) and thermoplastic vulcanisates (TPVs) were successfully developed based on two different types of heat resistant polyamide (PA) (25 parts by weight)—PA‐12 and PA‐6, in combination with three different functionalized rubbers (75 parts by weight) of varying polarity, e.g., maleic anhydride grafted ethylene propylene diene terpolymer (MA‐g‐EPDM), sulphonated ethylene propylene diene terpolymer, and carboxylated acrylonitrile butadiene rubber, by melt mixing method. These rubbers have low level of unsaturation in its backbone, and the plastics showed high melting range. Thus, the developed TPEs and TPVs were expected to be high temperature resistant. Resol type resin was used for dynamic vulcanization to further increase the high temperature properties of these blends. Interestingly, initial degradation temperature of the prepared blends was much higher (421 °C for MA‐g‐EPDM/PA‐12) than the other reported conventional TPEs and TPVs. Fourier transform infrared analysis described the interactive nature of the TPEs and TPVs, which is responsible for their superior properties. The maximum tensile strength with lowest tension set was observed for the carboxylated acrylonitrile butadiene rubber/PA‐12 TPV. Mild increase in mechanical properties without any degradation was observed after recycling. Dynamic mechanical analysis results showed two distinct glass transition temperatures and indicated the biphasic morphology of the blends, as evident from the scanning electron microscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45353.     

Peroxide cured natural rubber/fluoroelastomer/high‐density polyethylene via dynamic vulcanization

In this work, blends of fluoroelastomer (FKM), natural rubber (NR) along with high‐density polyethylene (HDPE) by dynamic vulcanization using peroxide (DBPH, DCP) as a curing agent were prepared. HDPE was melt‐mixed with NR and FKM at different compositions (HDPE/FKM/NR i.e. 30/60/10, 30/55/15, 30/50/20, and 30/35/35%wt) using an internal mixer at 150°C and 50 rpm rotor speed. The mechanical properties and oil swelling resistances of these blends were analyzed according to ISO 37 (Type 1) and ASTM D471, respectively. The results suggest that DBPH works better as a curing agent for the dynamic vulcanization system than DCP. The optimum mechanical properties and oil resistance were revealed in 30/50/20 and 30/60/10 HDPE/FKM/NR, being dynamic vulcanized with DBPH, respectively. In addition, was found that a dispersed HDPE phase shows the percent crystallinity in the range of 53% to 55% upon increasing the NR content. The SEM micrographs reveal the NR phase is well dispersed in FKM as small particles. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers .     

管材用回收高密度聚乙烯/胶粉复合材料的研究

采用一步法活化增容制备了回收高密度聚乙(烯RHDPE/)胶粉管材专用料,并研究了引发剂过氧化二异丙苯强度从37.5 kJ/m2提高到48 kJ/m2;弯曲强度从10.5 MPa提高到12.9 MPa;弯曲模量从356 MPa提高到405(DCP)、接枝单体马来酸酐(MAH用)量对体系力学性能的影响。结果表明:当DCP、MAH用量分别为0.1份、1.0份时,RHDPE/胶粉体系获得最佳的力学性能,与简单共混物比较,拉伸强度从18.8 MPa提高到23.8 MPa;缺口冲击MPa。通过流变性能测试结果和扫描电(镜SEM)照片分析活,化增容对RHDPE/胶粉体系有效。     

聚氯乙烯/丁腈胶粉共混型热塑性弹性体

将聚氯乙烯与废丁腈胶粉经高温机械共混，制备了动态交联的共混型热塑性弹性体。讨论了共混比，硫化体系及其用量，废胶粉品种（丁腈胶粉，轮胎胶粉）等因素对热塑性弹性体性能的影响，同时将聚氯乙烯／丁腈胶粉与聚氯乙烯／轮胎胶粉制备的共混型热塑性弹性体的性能进行了比较。结果表明，以聚氯乙烯100份（质量份，下同），邻苯二甲酸二辛酯50份，丁腈胶粉80份，丁腈橡胶20份，过氧化二异丙苯0．5份，氧化锌5份及适量其他助剂可制得综合性能较好的共混型热塑性弹性体。扫描电镜结果显示该共混型热塑性弹性体具有较好的相容性。