Effect of dicumyl peroxide and phenolic resin as a mixed curing system on the mechanical properties and morphology of TPVs based on HDPE/ground tire rubber

Thermoplastic vulcanizates (TPVs) are a special group of thermoplastic elastomer with the characteristic that consists of rubber elasticity and the processability of thermoplastic polymers. TPVs based on high density polyethylene (HDPE)/ground tire rubber (GTR) with phenolic resin (HY‐2045) and dicumyl peroxide (DCP) as vulcanizing agents are prepared through dynamic vulcanization in this article. The blends consisting of 40/60 HDPE/GTR are melt‐mixed in an internal mixer and then pressed with a compression molding machine. The aim of this experiment is to study the influence of a compound curing agent system on the mechanical properties of the HDPE/GTR composites. The results indicate that the mechanical properties of the HDPE/GTR blends are improved significantly by adding 4 phr HY‐2045 and 0.3 phr DCP than those of TPVs without any vulcanizing agents after dynamic vulcanization. The X‐ray photoelectron spectroscopy study and the FTIR‐ATR analysis confirmed that the crosslinking phenomenon occurred in the preparation of TPVs; and the gel fraction analysis indicates that the GTR components and the HDPE components of the HDPE/GTR blends are all moderately crosslinked. In addition, the morphology of the HDPE/GTR blends has been investigated by scanning electron microscopy. POLYM. COMPOS., 36:1907–1916, 2015. © 2014 Society of Plastics Engineers     

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.     

Multifunctional peroxide as alternative crosslink agents for dynamically vulcanized epoxidized natural rubber/polypropylene blends

Commonly used dicumyl peroxide (DCP) in combination with coagent, triallyl cyanurate (TAC), as a crosslinking agent is well acceptable for dynamically vulcanized rubber phase of thermoplastic vulcanizates (TPVs). However, it generally produces volatile decomposition products, which cause a typical unpleasant smell and a blooming phenomenon. In this work, influence of two types of multifunctional peroxides: 2,4‐diallyloxy‐6‐tert‐butylperoxy‐1,3,5‐triazine (DTBT) and 1‐(2‐tert‐butylperoxyisopropyl)‐3‐isopropenyl benzene (TBIB), on properties of TPVs based on epoxidized natural rubber (ENR)/polypropylene (PP) blends were investigated. The conventional peroxide/coagent combinations, i.e., DCP/TAC and tert‐butyl cumyl peroxide (TBCP)/α‐methyl styrene (α‐MeS) were also used to prepare the TPVs for a comparison purpose. The TPVs with multifunctional peroxide, DTBT, provided good mechanical properties and phase morphology of small dispersed vulcanized rubber domains in the PP matrix which were comparable with the DCP/TAC cured TPVs. However, the TPVs with TBIB/α‐MeS and TBCP/α‐MeS showed comparatively low values of the tensile properties as well as rather large phase morphology. The results were interpreted by three main factors: the kinetic aspects of the various peroxides, solubility parameters of respective peroxide/coagent combinations in the ENR and PP phases, and the tendency to form unpleasantly smelling byproducts. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

硫化剂对陶瓷化耐火硅橡胶性能的影响

研究了2,5-二甲基-2,5-二（叔丁基过氧基）己烷（俗称双二五）、2,4-二氯过氧化苯甲酰（俗称双二四）、过氧化二异丙苯（DCP）3种硫化剂对陶瓷化耐火硅橡胶力学性能和烧结性能的影响。结果表明,一次硫化和二次硫化后,使用DCP做硫化剂的硅橡胶的硬度都是最大,使用双二五做硫化剂的硅橡胶的拉断伸长率都是最高,采用双二四做硫化剂的硅橡胶拉伸强度都是最大;使用双二四做硫化剂的硅橡胶烧结硬度最高。综合来看,使用双二四作硫化剂时陶瓷化耐火硅橡胶的力学性能最好,其最佳用量为1.25份。     

聚醚型聚氨酯混炼胶性能研究

研究了炭黑补强剂和过氧化物（DCP,BIPB）对混炼型聚醚聚氨酯橡胶力学性能的影响,讨论了DCP和补强剂用量变化以及热空气老化对性能的影响。结果表明,DCP硫化胶拉断伸长率高,BIPB硫化胶永久变形低;当DCP用量为1.6份时,拉伸强度和撕裂强度最高,分别为25.3MPa和47.5kN/m;随补强剂用量的增加,混炼橡胶硬度增加,拉伸强度变化不明显,拉伸永久变形变大。     

相容剂对LDPE/MVQ并用胶热老化性能的影响

以低密度聚乙烯（LDPE）、相容剂、甲基乙烯基硅橡胶（MVQ）混炼胶为主要原料,加入自由基捕捉剂和硫化剂过氧化二异丙苯（DCP）,在双辊上将各组分进行熔融共混,通过平板硫化机将共混物硫化,制备出了LDPE／MVQ并用胶。本文重点研究了相容剂对LDPE／MVQ并用胶的力学性能和热老化性能的影响。结果表明,适量相容剂可以改善并用胶中LDPE和MVQ的相容性,提高材料的力学性能,而过多相容剂会阻碍LDPE与MVO共硫化反应的进行,降低并用胶机械强度和热老化性能。随着相容剂用量的增加,并用胶的拉伸强度、断裂伸长率和撕裂强度及热老化系数先增大后减小,其用量为15hpr时并用胶的综合性能最好。     

炭黑对动态硫化POE/PP热塑性弹性体性能的影响

采用动态硫化法制备POE/PP共混物,研究了过氧化二异丙苯（DCP）对POE/PP体系熔体流动速率（MFR）和力学性能的影响。交联助剂硫磺（S）的加入有效地提高了交联效果,当m（DCP）/m（S）=2/0.2时,体系的综合力学性能最佳。通过不同加工工艺制备POE/PP/炭黑共混物,并研究了炭黑用量对体系力学性能和老化性能的影响。结果表明,母料法制备的共混物更有利于炭黑的分散,体系性能更好,炭黑的加入使体系的耐热老化性和抗紫外性能明显改善。     

硅橡胶/聚氨酯热塑性弹性体的制备

采用过氧化物硫化体系制备了硅橡胶(VSR)与聚氨酯(TPU)质量比为50/50的VSR/TPU热塑性弹性体。考察了VSR的硫化条件,研究了抑制剂4-羟基2,2,6,6-四甲基哌啶氧(TEMPO)用量对VSR/TPU体系动态硫化过程及性能的影响。结果表明,当Hakke流变仪转速为110 r/min、硫化温度为180℃、硫化剂2,5-二甲基-2,5双(过氧化叔丁基)己烷用量为1.0份(质量,下同)、抑制剂TEMPO用量为0.3份时,制备的VSR/TPU热塑性弹性体具有较精细的相态,分散相VSR在TPU连续相中分散较均匀,热塑性弹性体的拉伸强度及扯断伸长率分别达到4.4 MPa及291%,流变性能较好,压缩永久变形最小。     

ACM/PA6耐油热塑性弹性体的制备及性能

研究了不同硫化体系、硫化剂含量及橡塑比对动态硫化丙烯酸酯橡胶/尼龙6(ACM/PA6)热塑性弹性体加工性能、力学性能和耐油性的影响。结果表明:3号硫化剂(N,N-二次肉桂基-1,6-己二胺)作为硫化剂最合适,其用量为2 phr或橡塑比为70/30时,热塑性弹性体性能最好。     

马来酸酐和苯乙烯接枝改性对天然橡胶/聚丙烯共混物物理机械性能的影响

用动态硫化法制备了天然橡胶(NR)/聚丙烯(PP)热塑性弹性体(TPV)。研究了马来酸酐/苯乙烯/过氧化二异丙苯(MAH/St/DCP)多单体熔融接枝交联改性及纳米二氧化硅用量对NR/PP TPV物理机械性能的影响,讨论了NR/PP TPV的重复加工性能。结果表明,当MAH/St/DCP用量为3.750/1.875/0.375质量份、纳米二氧化硅用量为3质量份时,NR/PP TPV的物理机械性能最好,达到了国内外有关通用橡胶/PP TPV的水平,并且具有较好的重复加工性能。     

DCP／MgO复合硫化体系的PUR／CR共混物硫化特性

采用硫化特性参数、溶胀指数和DSC谱图等表征了聚氨酯橡胶(PUR)/氯丁橡胶(CR)共混胶的共硫化性能,并研究了PUR/CR的共混比、补强体系与软化体系等对共混胶的硫化特性的影响.结果表明,采用过氧化二异丙苯/氧化镁(DCP/MgO)复合硫化体系,可以使PUR/CR共混胶达到共硫化;增加PUR和炭黑的用量,减少软化剂的用量,则共混胶料的转矩增大;增加PUR用量,可以加快共混胶料的硫化速度,其它因素对硫化速度的影响不明显.当PUR/CR共混比为20/80、DCP 3份、MgO 4份、炭黑N550 30份、软化剂聚异丁烯(PIB)5份时,共混硫化胶有较好的综合性能.     

过氧化物硫化聚醚型聚氨酯混炼橡胶力学性能的研究

研究了过氧化物过氧化二异丙苯（DCP）、双叔丁基过氧化异丙基苯（BIPB）和补强剂（炭黑或白炭黑）对聚醚型聚氨酯混炼橡胶力学性能的影响,讨论了DCP和补强剂用量变化及不同硫化条件对混炼橡胶力学性能的影响。结果表明,DCP硫化混炼胶定伸应力高,永久变形小;BIPB硫化混炼胶硬度和强度高;当DCP用量在1．6份时,混炼胶拉伸强度和撕裂强度最高;提高补强剂用量,混炼胶硬度和定伸应力增加,拉伸强度变化不明显,但永久变形变大。     

Exploring a novel cyclic monofunctional peroxide for curing of silicone rubber at elevated temperature

The curing characteristics of silicone rubber (polydimethylsiloxane [PDMS]) in the presence of structurally different peroxides, namely dicumyl peroxide (DCP) and 3,3,5,7,7‐pentamethyl‐1,2,4‐trioxepane (PMTO), have been studied in details. At moderate temperature, DCP is more prominent for curing the silicone rubber but at high temperatures it suffers from low scorch safety. An inhibitor 2,2,6,6‐tetramethylpiperidinyloxyl (TEMPO) was added with DCP to stabilize the radicals in order to increase the scorch safety time. On the other hand, PMTO showed a prolonged scorch safety and better crosslinking efficiency rather than (DCP + TEMPO) mix at higher temperatures. PMTO‐crosslinked PDMS shows better crosslinking efficiency as indicated by a higher gel content and low swelling index value. Also the mechanical properties, thermal stability, and dynamic mechanical behavior of PMTO‐crosslinked PDMS are much superior than (DCP + TEMPO)‐crosslinked PDMS. Apart from thermoplastic vulcanizates (TPVs) made from PMTO‐crosslinked PDMS show better physicomechanical behavior compared to the TPVs made from (DCP + TEMPO)‐crosslinked PDMS. Moreover, DCP undergoes decomposition reactions at a higher temperature and forms acetophenone, which leads to an unpleasant smell in the final products whereas no such phenomenon is observed for PMTO. Therefore, PMTO turns out to be the suitable peroxide for crosslinking of PDMS at higher temperature. POLYM. ENG. SCI., 57:1073–1082, 2017. © 2016 Society of Plastics Engineers     

Mechanical properties of thermoplastic elastomers based on silicone rubber and an ethylene–octene copolymer by dynamic vulcanization

Thermoplastic vulcanizates (TPVs) are a special class of thermoplastic elastomers that are generally produced by the simultaneous mixing and crosslinking of a rubber with a thermoplastic polymer at an elevated temperature. Novel peroxide‐cured TPVs based on blends of silicone rubber and the thermoplastic Engage (an ethylene–octene copolymer) have been developed. These TPVs exhibit very good overall mechanical and electrical properties. With an increasing concentration of dicumyl peroxide, the tensile strength, modulus, and hardness of the TPVs increase, whereas the elongation at break decreases. Significant correlations have been obtained from oscillating disc rheometer torque values with various physical properties, such as the modulus and tension set of the TPVs. The aging characteristics and recyclability of the silicone‐based TPVs are also excellent. Scanning electron microscopy photomicrographs of the TPVs have confirmed a dispersed phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of various crosslinking systems on the mechanical properties of gas phase EPDM/PP thermoplastic vulcanizates

Dynamically cured thermoplastic elastomers or thermoplastic vulcanizates (TPVs) are widely used nowadays for their unique characteristics. In this paper, gas phase ethylene–propylene–diene terpolymer (GEPDM)/Polypropylene (PP) TPVs with various crosslinking systems have been extensively studied to optimize the curative level in each crosslinking system with special reference to their mechanical properties. Optimized systems were compared for heat aging, recyclability, crosslink density, morphology studies, and dynamic mechanical analysis. Crosslinking by peroxide in the presence of triallyl cyanurate as a coagent gives best overall performance with reference to excellent heat aging behavior, tension set, and compatibility between GEPDM and PP. Conventional EPDM/PP system was also compared with GEPDM/PP system. GEPDM/PP system was found to exhibit better behavior in all respects. Significant correlations were obtained between delta torque values obtained from Moving Die Rheometer and modulus or cross link density of TPVs irrespective of the nature of crosslinking agent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5463–5471, 2006     

动态硫化三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性弹性体的力学性能

研究了双螺杆挤出机制备EPDM/PP热塑性弹性体的工艺条件对其力学性能的影响,结果显示,当橡塑比为60/40.EPDM与PP预混合两次,双螺杆挤出机转速约9.5Hz,硫化剂的量为10份时,热塑性弹性体有较好的力学性能。     

硫化剂对硅橡胶性能的影响

考察硫化剂TX-29、双2,5、双2,4和DCP对硅橡胶硫化特性和物理性能的影响。试验结果表明:采用硫化剂DCP的硅橡胶的综合物理性能最佳;可根据生产工艺、成本和性能要求,选用不同的硫化剂来实现产品性能目标。     

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     

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 .     

硅橡胶／EPDM／ⅡR共混的研究

研究了硅橡胶/三元乙丙橡胶/丁基橡胶的共混技术与硫化体系。对增容剂、共混比例等对共混胶的力学性能的影响进行了探讨。KH570适宜于作为共混增容剂;共混胶宜于采用DCP硫化,也可以采用硫黄硫化,随着丁基橡胶含量的增加,其力学性能有大幅度提高,并出现最佳值点。