共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Heat‐curable silicone rubber (HCSR) was prepared by using vinyl‐containing silicone resin (VSR) as the crosslinking agent instead of polyvinylsilicone oil (C gum). Mechanical properties and crosslink density of the vulcanizates were measured. The results indicate that VSR is a good crosslinking agent for HCSR. The tensile strength, tearing strength, elongation at break, and hardness of the vulcanizate can reach 10.2 MPa, 29.1 kN/m, 720%, and 58 SHA, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3123–3127, 2002; DOI 10.1002/app.10054 相似文献
3.
4.
Polyether‐based main‐chain‐type polytriazole elastomer with benzoxazine via a 1,3‐dipolar cycloaddition reaction 下载免费PDF全文
A novel functional polyether‐based elastomer with a benzoxazine structure in its main chain was successfully synthesized via a 1,3‐dipolar cycloaddition reaction. Benefitting from a facile one‐pot synthesis strategy, the elastomer was prepared at low temperature (80°C) and was characterized clearly afterward. The azide‐terminated polyether and acetylene‐terminated benzoxazine were used as the soft and hard segments, respectively, in the polymer chain. Because the triazole rings served as stable linkage between the soft and hard segments, the elastomer possessed good thermal stability (the 5% weight loss temperature could exceed 350°C) compared to traditional elastomers, such as polyurethane. The rigid benzoxazine rings provided the product with good mechanical properties (the tensile strength of the elastomer could exceed 30 MPa). Furthermore, the ring‐opening polymerization of oxazine rings in the structure gifted the elastomer with possibility of thermally induced structural transformation. The thermally induced structural transformation could conveniently realize the conversion of the elastomer to a thermosetting resin. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42820. 相似文献
5.
Dietmar Lenko Sandra Schlögl Armin Temel Raimund Schaller Armin Holzner Wolfgang Kern 《应用聚合物科学杂志》2013,129(5):2735-2743
At present, the most common used crosslinking process for carboxylated nitrile butadiene rubber (XNBR) latex is an accelerated sulfur curing system with zinc oxide. To avoid allergenic reactions related to residual accelerator levels in dipped XNBR latex articles such as medical gloves, a dual curing process has been developed combining thermal and photochemical crosslinking reactions. The two‐step procedure involves the formation of covalent and ionic bonds to ensure good mechanical properties of the final products. The photochemical thiol‐ene reaction is used to generate covalent crosslinks between the remaining C?C double bonds of the butadiene units whereas the carboxylic moieties are conventionally cured with divalent metal oxides (ZnO) under elevated temperature (formation of ionic crosslinks). The photochemical curing step is carried out both in the latex phase using a falling film photoreactor (prevulcanization) as well as in the solid phase by UV irradiation of dried XNBR films (postvulcanization). The mechanical properties and crosslink densities of the cured XNBR films are determined and the influence of selected curing parameters is assessed. The results give evidence that a combined approach of thermal prevulcanization and photochemical postvulcanization makes the production of latex articles (e.g., gloves) with tailored properties and good skin compatibility feasible. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
6.
The curing behavior of polydimethylsiloxane‐modified allylated novolac/4,4′‐bismaleimidodiphenylmethane resin (PDMS‐modified AN/BDM) was investigated by using Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry. The results of FTIR confirmed that the curing reactions of the PDMS‐modified AN/BDM resins, including “Ene” reaction and Diels–Alder reaction between allyl groups and maleimide groups, should be similar to those of the parent allylated novolac/4,4′‐bismaleimidodiphenylmethane (AN/BDM) resin. The results of dynamic DSC showed that the total curing enthalpy of the PDMS‐modified AN/BDM resins was lower than that of the parent resin. Incorporation of polydimethylsiloxane (PDMS) into the backbone of the allylated novolac (AN) resin favored the Claisen rearrangement reaction of allyl groups. The isothermal DSC method was used to study the kinetics of the curing process. The experimental data for the parent AN/BDM resin and the PDMS‐modified AN/BDM resins exhibited an nth‐order behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
7.
The objective of this work is to ascertain the characteristics of desirable (cure) and especially undesirable (scorch) crosslinking when carbon black filled ethylene propylene diene terpolymer (EPDM) is processed using different peroxide initiators. The mixing temperature and the nature of the peroxide initiator are crucial parameters affecting scorch (undesirably premature crosslinking) in this rubber. Processability and properties of EPDM prepared using various mixer set temperatures have been investigated. Dicumyl peroxide (Luperox DC), di(t‐butylperoxy) diisopropylbenzene (Luperox F), and 2,5‐dimethyl‐2,5‐di(t‐butylperoxy) hexane (Luperox 101) were used as crosslinking initiators. Higher mixing temperatures give shorter scorch times, greater scorch magnitudes, greater heterogeneities in crosslink spatial distribution and poorer tensile properties. However, extreme localization of the unwanted crosslinking at the rubber‐filler interface does have a beneficial effect. Luperox DC offers poorer processability and poorer resulting properties than do Luperox F and Luperox 101, due to its shorter half‐life and greater solubility in the rubber phase. This is the first time that the spatial heterogeneity of crosslinking and scorch has been related to the basic thermodynamics of 3‐component 2‐phase systems. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44523. 相似文献
8.
Effect of silane coupling agent on the fatigue crack propagation of silica‐filled natural rubber 下载免费PDF全文
Based on the real‐time crack tip morphology monitoring, the influence of silane coupling agent (SCA) on the crack‐growth behavior of silica‐filled natural rubber (NR) was analyzed. By using SCA, silica particles can be well dispersed and a filler–matrix network can be formed, which leads to lower crack‐growth rate. Results indicate that a dosage of 5 wt % (with respect to silica loading) is the optimal content. The real‐time observation and scanning electron microscopy (SEM) analysis proved that thin ligaments and dimples with homogeneous distribution appear on the crack tip. These crack tip morphologies reflect the low crack‐growth rate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41980. 相似文献
9.
Recycling discarded rubber is important for both environmental and economic reasons. One of the most attractive methods of recycling rubber waste is to use ground rubber (GR) as a compounding ingredient or as a replacement for raw polymers. In this study, ground natural rubber was prepared with different curing systems and compounded into the parent compounds. The cure behaviors and physical properties of the GR‐filled vulcanizates were investigated, and they were largely affected by the curing systems of the rubber matrix and GR. GR‐filled vulcanizates with GR and the rubber matrix, having a conventional curing system, showed the largest changes in the cure characteristics. The greatest decrease in the physical properties was observed for peroxide‐cured‐GR‐filled vulcanizates. The addition of GR decreased the crosslink density of the GR‐filled vulcanizates. This was thought to be the main reason for the reduction of the mechanical properties of the GR‐filled vulcanizates. However, the adhesion between the GR and rubber matrix may also have caused the differences in the physical properties of the GR‐filled vulcanizates with respect to the curing systems of the rubber matrix and GR. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
10.
Effect of a small amount of sulfur on the physical and mechanical properties of peroxide‐cured fully saturated HNBR compounds 下载免费PDF全文
Sulfur can be used as crosslink coagent in unsaturated elastomer. In this work, a fully saturated HNBR with 39 wt % nitrile content was selected to investigate the effect of a small amount of sulfur acting as crosslink coagent on the physical and mechanical properties of peroxide‐cured vulcanizates. First, selective cleavage of polysulfide (? Sx? ) and monosulfide(? S? ) bond by combined thiol‐piperidine treatment were performed and the existence of poly/monosulfide bond in sulfur‐contained HNBR compounds was verified. Then, no‐filler HNBR compounds with various content of sulfur were investigated to detect the influence of sulfur on the crosslink density and cure kinetics. The MDR results showed that the crosslink density of HNBR compounds reduced only when the amount of sulfur is 0.25 phr and above. Besides, the curing rate of no‐filler HNBR compounds increased with the increasing of the amount of sulfur and reached a maximum at a dosage of 0.25 phr sulfur. Finally, physical and mechanical properties of fully formulated compounds were evaluated and it was found that the addition of small amounts of sulfur in fully saturated HNBR compounds could improve the dynamic properties of peroxide‐cured HNBR compounds remarkably but at a cost of slightly higher compression set values and a small loss in heat aging resistance. In a conclusion, small amount of sulfur can impart the peroxide vulcanizates some “sulfide properties” like dynamic property, tensile strength, but at the same time, due to the introduction of sulfur, some “peroxide vulcanizates property” like heat‐resistance property, hot air resistance were weakened slightly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41612. 相似文献
11.
Six chiral monomers ( M 1? M 6), and their corresponding polymers ( P 1, P 4) and elastomers ( P 2, P 3, P 5, P 6) derived from chiral mesogenic crosslinking agent were synthesized. The chemical structures of M 1? M 6 were confirmed by FTIR and 1H NMR spectroscopy. The structure‐property relationships of M 1? M 6 and P 1? P 6 were discussed. Their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), polarizing optical microscopy (POM), and X‐ray diffractometer (XRD) measurements. All monomers obtained, except M 2 and M 5, showed typical oily streaks texture and focal conic texture of cholesteric phase on heating and cooling cycles. The selective reflection of cholesteric monomers and elastomers shifted to the short wavelength region with increasing temperature. The elastomers P 2 and P 5 did not reveal the mesomorphic properties, and P 3 and P 6 showed cholesteric phase. TGA showed that P 1? P 6 had a high thermal stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
12.
Cure efficiency of dodecyl succinic anhydride as a cross‐linking agent for elastomer blends based on epoxidized natural rubber 下载免费PDF全文
Blends of a highly epoxidized natural rubber (ENR50) with unmodified natural rubber (NR) and ethylene propylene elastomers (EPDM) were produced to evaluate the mixing and curing characteristics. Dodecyl succinic anhydride was used to cross‐link the ENR50 component and the reactivity was assessed by monitoring the evolution of the torque in an oscillatory co‐axial cylinder rheometer, as well as by DSC thermal analysis. A physical model was used to obtain a single parameter for the reactivity of the system, which corresponds to the rate constant for first order curing reactions. Although the blends were thermodynamically immiscible, displaying no significant change in Tg, the components were well dispersed at microscopic level. Better mechanical properties were obtained for blends with EPDM. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41448. 相似文献
13.
Reethamma Joseph Rosamma Alex K. N. Madhusoodanan C. K. Premalatha Baby Kuriakose 《应用聚合物科学杂志》2004,92(6):3531-3536
To obtain good reinforcement by silica filler in nonpolar rubbers, it is almost essential to use coupling agents, such as bis(triethoxy silyl propyl) tetrasulfane (TESPT). Chemicals that can interact with the silanol groups on the silica particles and reduce their network formation are also expected to enhance reinforcement. We made a comparative evaluation of TESPT, epoxidized rubber seed oil (ERSO), and their combination as a coupling agent and a plasticizer in silica‐filled natural rubber compounds. The results indicate that compounds containing ERSO showed physical and mechanical properties between that of TESPT and naphthenic oil. The action of ERSO in the improvement of the properties was expected to be bifunctional and similar to that of TESPT; that is, it caused the hydrophobation of silica, which increased its degree of dispersion and the formation of chemical bonds with the rubber, thereby ensuring strong polymer–filler interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3531–3536, 2004 相似文献
14.
Chemical crosslinking is possibly the most significant factor affecting the mechanical behavior of rubbers. In this study, we investigated the evolution of network structures (the crosslinking degree and crosslinking density) during the thermooxidative aging of a nitrile–butadiene rubber (NBR) using characterization methods such as low‐dimensional NMR, solvent extraction, solvent swelling, IR spectroscopy, and mechanical property measurements. The NMR and solvent extraction results show the change of the crosslinking degree. The solvent swelling results show the change of the crosslinking density. The IR results show the chemical changes relating to crosslinking and chain scissions. Therefore, a comprehensive picture of the thermal oxidative aging of the NBR compound was drawn by the integration of various results from these methods. Crosslinking occurred throughout the aging process, whereas chain scissions took place and competed with crosslinking in the later stage. The crosslinking density increased at a nearly constant rate, whereas the increase in the crosslinking degree slowed down in the later stage. The crosslinking density was closely correlated with the hardness and Young's modulus. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41319. 相似文献
15.
The hydrosilation‐cured vulcanizates (HCV) of silicone rubber were prepared by using hydrogen‐containing silicone resin (HSR) as the crosslinking agent. The influences of both the amount and structure of HSR on hydrosilation‐curing silicone rubber (HCSR) were discussed. The results indicate that HSR is a good crosslinking agent for HCSR. The tensile strength, tearing strength, elongation at break, and hardness of the vulcanizates can reach 9.6 MPa, 37.8 kN/m, 870% and 56 SHA, respectively. The aging stability of the vulcanizates can be improved greatly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3066–3069, 2003 相似文献
16.
The effect of peroxide crosslinking on the dynamic modulus of a silica‐reinforced silicone [poly(dimethylsiloxane)] elastomer was investigated. Three different peroxides (t‐butyl peroxide, t‐butyl perbenzoate, and benzoyl peroxide) were employed at various practical loadings and differences in the nonlinear behavior of the dynamic modulus were found. Results are discussed with respect to changes in crosslinking density and the identity of the peroxide. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1504–1512, 2005 相似文献
17.
We investigated the effect of polyvinylsilicone oil (C gum) as a crosslinker and 2,5‐bis(tert‐butyl peroxy)‐2,5‐dimethyl hexane (DBPMH) as a curing agent on the conductivity of conductive silicone rubber with two different kinds of conducting mechanisms. The experimental results show that the volume resistivity of conductive silicone rubber changed with its degree of crosslinking. When the carbon black loading was 25 parts per hundred rubber (phr) and a completely continuous conducting network had not formed, the volume resistivity of the vulcanizates decreased with increasing crosslink density. The volume resistivity of the vulcanizate with a suitable amount of C gum decreased to 53%, and the tensile strength increased by 0.8 MPa compared to the vulcanizate without C gum. When the carbon black loading was 40 phr and a completely continuous conducting network had formed, the crosslink density of vulcanizates changed as the amount of DBPMH changed. The volume resistivity of vulcanizates first decreased and then increased with increasing crosslink density. There was a valley value in the resistivity–crosslink density curve. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3471–3475, 2003 相似文献
18.
19.
An intercrosslinked network of unsaturated polyester–bismaleimide modified epoxy matrix systems was developed. Epoxy systems modified with 10, 20, and 30% (by weight) of unsaturated polyester were made by using epoxy resin and unsaturated polyester with benzoyl peroxide and diaminodiphenylmethane as curing agents. The reaction between unsaturated polyester and epoxy resin was confirmed by IR spectral studies. The unsaturated polyester toughened epoxy systems were further modified with 5, 10, and 15% (by weightt) of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were performed to determine the glass transition temperature (Tg) and thermal degradation temperature of the systems, respectively. Mechanical properties, viz: tensile strength, flexural strength, and plain strain fracture toughness of intercrosslinked epoxy systems, were studied by ASTM methods. Data obtained from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improves toughness but with a reduction in glass transition, whereas the incorporation of bismaleimide into epoxy resin improved both mechanical strength and thermal behavior of epoxy resin. The introduction of bismaleimide into unsaturated polyester‐modified epoxy resin altered thermomechanical properties according to their percentage concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2853–2861, 2002 相似文献
20.
Effects of EPDM‐g‐MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology 下载免费PDF全文
Jeefferie Abd Razak Sahrim Haji Ahmad Chantara Thevy Ratnam Mazlin Aida Mahamood Juliana Yaakub Noraiham Mohamad 《应用聚合物科学杂志》2015,132(27)
This study evaluates the effects of ethylene‐propylene‐diene‐monomer grafted maleic anhydride (EPDM‐g‐MAH) and internal mixer melt compounding processing parameters on the properties of natural rubber/ethylene‐propylene‐diene rubber (NR/EPDM) blends. Using Response Surface Methodology (RSM) of 25 two‐level fractional factorial, we studied the effects of NR/EPDM ratio, mixing temperature, Banbury rotor speed, mixing period, and EPDM‐g‐MAH contents in NR/EPDM blends. The study found that the presence of EPDM‐g‐MAH in NR/EPDM blends had a predominant role as a compatibilizing agent, which affected the processability and properties of the final material. We also determined the model fitting with constant determination, R2 of 99.60% for tensile strength (TS) response with a suggested combination of mixing process input parameters. The reproducibility of the proposed mixing strategy was then confirmed through model validation with a minor deviation at +2.303% and higher desirability of 0.960. This study is essential in providing a process design reference for NR/EPDM blends preparation by melt‐blending and the role of a compatibilizer from the systematic Design of Experiment (DOE) approach. The experimental findings were further supported with swelling and cross‐link density measurements, differential scanning calorimetry analysis, and observation of fracture morphology using a scanning electron microscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42199. 相似文献