scholarly journals The influence of water on visible-light initiated free-radical/cationic ring-opening hybrid polymerization of methacrylate/epoxy: polymerization kinetics, crosslinking structure and dynamic mechanical properties

RSC Advances ◽  
2015 ◽  
Vol 5 (95) ◽  
pp. 77791-77802 ◽  
Author(s):  
Xueping Ge ◽  
Qiang Ye ◽  
Linyong Song ◽  
Anil Misra ◽  
Paulette Spencer
Keyword(s):  
Mechanical Properties ◽  
Free Radical ◽  
Visible Light ◽  
Network Structure ◽  
Ring Opening ◽  
Crosslinking Density ◽  
Dynamic Mechanical Properties ◽  
Hydroxyl Groups ◽  
Influence Of Water ◽  
Hybrid Polymerization

During the photopolymerization, water will compete with hydroxyl groups in methacrylates to react with epoxy and reduce the apparent crosslinking density of the network structure.

scholarly journals Influence of Thermally-Accelerated Aging on the Dynamic Mechanical Properties of HTPB Coating and Crosslinking Density-Modified Model for the Payne Effect

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 403 ◽  
Author(s):  
Yongqiang Du ◽  
Jian Zheng ◽  
Guibo Yu
Keyword(s):  
Mechanical Properties ◽  
Aging Time ◽  
Loss Modulus ◽  
Accelerated Aging ◽  
Crosslinking Density ◽  
Dynamic Mechanical Properties ◽  
Maximum Elongation ◽  
Solid Rocket Motor ◽  
Payne Effect ◽  
Dynamic Mechanical

Hydroxyl terminated polybutadiene (HTPB) coating is widely used in a solid rocket motor, but an aging phenomenon exists during long-term storage, which causes irreversible damage to the performance of this HTPB coating. In order to study the effect of aging on the dynamic mechanical properties of the HTPB coating, the thermally-accelerated aging test was carried out. The variation of maximum elongation and crosslinking density with aging time was obtained, and a good linear relationship between maximum elongation and crosslinking density was found by correlation analysis. The changing regularity of dynamic mechanical properties with aging time was analyzed. It was found that with the increase of aging time, Tg of HTPB coating increased, Tα, tan β and tan α decreased, and the functional relationships between the loss factor parameters and crosslinking density were constructed. The storage modulus and loss modulus of HTPB coating increased with the increase of aging time, and decreased with the increase of pre-strain. The aging enhanced the Payne effect of HTPB coating, while the pre-strain had a weakening effect. In view of the Payne effect of HTPB coating, the crosslinking density was introduced into Kraus model as aging evaluation parameter, and the crosslinking density modified models with and without pre-strain were established. The proposed models can effectively solve the problem that the Kraus model has a poor fitting effect under the condition of small strain (generally less than 1%) and on the loss modulus, which have improved the correlations between the fitting results and the test results.

Preparation of a P(THF-co-PO)-b-PB-b-P(THF-co-PO) triblock copolymer via cationic ring-opening polymerization and its use as a thermoset polymer

RSC Advances ◽  
2015 ◽  
Vol 5 (81) ◽  
pp. 66073-66081 ◽  
Author(s):  
Wanbin Zhang ◽  
Xiaodong Fan ◽  
Wei Tian ◽  
Heng Chen ◽  
Xiuzhong Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ring Opening ◽  
Triblock Copolymer ◽  
Dynamic Mechanical Properties ◽  
Ring Opening Polymerization ◽  
Dynamic Mechanical ◽  
Thermoset Polymer ◽  
Cationic Ring Opening Polymerization

Triblock copolymer P(THF-co-PO)-b-PB-b-P(THF-co-PO) with gradient copolyether segments was synthesized, and its elastomer exhibited excellent dynamic mechanical properties.

Study on the Effects of Different Types of Carbon Black on the Performance of SBR2564S

2014 ◽  
Vol 971-973 ◽  
pp. 178-182
Author(s):  
Nai Xiu Ding ◽  
Yi Jia ◽  
Pei Yan Zuo ◽  
Li Li Wang ◽  
Hai Tao Wang
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Permanent Deformation ◽  
Poor Performance ◽  
Carbon Black Particle ◽  
Crosslinking Density ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Vulcanized Rubber ◽  
Black Particle

The curing characteristics,crosslinking density,compressive permanent deformation,the conventional mechanical properties and dynamic mechanical properties of SBR2564S filled with different carbon black were studied.The results indicated that with the increase in specific surface area of carbon black particles，Mooney viscosity of the resulting mixture increased while the scorch time decreased.As the carbon black particle size increases, tensile strength and tear strength of SBR2564S were reduced,rebound and compressive set were increased.The kinds of carbon black had little effect on the crosslinking density of vulcanized rubber of SBR2564S.It had poor performance on dynamic mechanical properties of the resulting mixture filled with small carbon black particle size.SBR2564S vulcanizates with good comprehensive properties was obtained when N330 was used.

Crosslinking density and its effect on the dynamic mechanical properties of rigid polyurethane foams

1975 ◽  
Vol 17 (11) ◽  
pp. 2824-2831 ◽  
Author(s):  
G.A. Kuznetsov ◽  
N.I. Nikiforov ◽  
R.A. Potekhin ◽  
B.A. Kalinin ◽  
O.G. Tarakanov
Keyword(s):  
Mechanical Properties ◽  
Crosslinking Density ◽  
Dynamic Mechanical Properties ◽  
Polyurethane Foams ◽  
Dynamic Mechanical ◽  
Rigid Polyurethane Foams

scholarly journals Incorporating Functionalized Cellulose to Increase the Toughness of Covalent Adaptable Networks

2020 ◽  
Author(s):  
Jeremy Swartz ◽  
William Dichtel
Keyword(s):  
Mechanical Properties ◽  
Fold Increase ◽  
Crosslinking Density ◽  
Cyclic Carbonate ◽  
Operating Conditions ◽  
Characteristic Relaxation Time ◽  
Hydroxyl Groups ◽  
Exchange Reactions ◽  
Covalent Bonds ◽  
Disulfide Exchange

<p>Covalent adaptable networks (CANs) are cross-linked polymers that have mechanical properties similar to thermosets at operating conditions, yet can be reprocessed by cross-link exchange reactions that are activated by a stimulus. Although CAN exchange dynamics have been studied for many polymer compositions, the tensile properties of these demonstration systems are often inferior compared to commercial thermosets. In this study, we explore toughening CANs capable of forming covalent bonds with a reactive filler to characterize the trade-off between improved toughness and longer reprocessing times. Polycarbonate (PC) and polyurethane (PU) CANs were toughened by incorporating cellulose modified with cyclic carbonate groups as a reactive filler with loadings from 1.3-6.6 wt%. The addition of 6.6 wt% of the cellulose derivative resulted in a 3.2-fold increase in average toughness for the PC CANs, yet only increased the characteristic relaxation time of stress relaxation (*) via disulfide exchange at 180 °C from 63 s to 365 s. The cellulose-containing samples also showed >80% recovery in crosslinking density and mechanical properties after reprocessing. The addition of 3.2 wt% of the functionalized cellulose into a PEG-based PU CAN led to a 2.3-fold increase in toughness, while increasing * at 140 °C from 106 s to 157 s. These findings demonstrate the promise of functionalized cellulose as an inexpensive, renewable, and sustainable filler that toughens CANs containing hydroxyl groups. </p>

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