Related Experiment Video
Updated: Jul 29, 2025

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application
Published on: March 8, 2019
Effects of the Addition of Amino-Terminated Highly Branched Polyurea on Curing Properties of Phenol-Formaldehyde
Shiguan Lian1,2, Huali Lin1,2, Wenbin Zhang1,2
1Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products, Southwest Forestry University, Kunming 650224, China.
Abstract:
In this work, a highly branched polyurea (HBP-NH2) similar to urea structure was introduced to phenol-formaldehyde (PF) resin to accelerate itscuring speed The results of gel time and bonding strength were combined to obtain a good modified additional stage and amount of HBP-NH2. The relative molar mass changes of HBP-NH2-modified PF resin were investigated by gel permeation chromatography (GPC). The effects of HBP-NH2 on the curing of PF resin were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The effect of HBP-NH2 on the structure of PF resin was also investigated by nuclear magnetic resonance carbon spectroscopy (13C-NMR). The test results show that the gel time of the modified PF resin was reduced by 32% and 51% at 110 °C and 130 °C, respectively. Meanwhile, the addition of HBP-NH2 increased the relative molar mass of PF resin. The bonding strength test showed that the bonding strength of modified PF resin increased by 22% after soaking in boiling water (93 °C ± 2) for 3 h. The DSC and DMA analysis indicated that the curing peak temperature decreased from 137 °C to 102 °C, and the curing rate of the modified PF resin was also faster than that of the pure PF resin. The 13C-NMR results showed that HBP-NH2 in the PF resin reacted to produce a co-condensation structure. Finally, the possible reaction mechanism of HBP-NH2 for the modification of PF resin was given.
Related Concept Videos
Polymer Classification: Architecture
Radical Chain-Growth Polymerization: Chain Branching
Step-Growth Polymerization: Overview
Many natural and synthetic polymers are produced by...
Accelerated Curing of Concrete
Free-Radical Chain Reaction and Polymerization of Alkenes
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...

