相关实验视频
Updated: Jul 7, 2025
09:06
Preparation of DNA-crosslinked Polyacrylamide Hydrogels
Published on: August 27, 2014
14.6K
分子添加剂和交叉链密度对交叉链聚合物的细分动力学和机械性质的竞争影响
Wenjian Nie1, Jack F Douglas2, Wenjie Xia3
1Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States.
ACS engineering Au
|December 25, 2023
概括
将分子添加剂添加到热固体中会影响其性能. 这项研究表明,增加添加剂含量降低了玻璃过渡温度和脆弱性,而增加交叉链密度则具有相反的效果,证明了对材料性质的竞争影响.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 分子添加剂改变热稳定性动力学和机械性能,对于涂料和复合材料等应用至关重要.
- 对添加剂如何影响聚合物中的玻璃形成的基本理解仍然有限.
- 玻璃形成是各种玻璃成型材料的重要研究领域.
研究的目的:
- 为了研究分子添加剂对玻璃形成动态和热的机械性能的影响.
- 开发一个理论参考点,以理解添加剂效应,使用简化的粗粒度模型.
- 探索添加剂度和交叉链密度对热性行为的竞争效应.
主要方法:
- 采用简化粗粒度 (CG) 模型,用于表示热固体的聚合物网络.
- 引入了一种具有与聚合物矩阵相同的刚性和相互作用强度的聚合物添加剂.
- 系统地改变添加剂质量百分比 (m) 和交叉链密度 (c) 以分析对动力学和机械学的影响.
主要成果:
- 增加添加剂质量百分比 (m) 降低了玻璃过渡温度 (Tg) 和脆性.
- 越来越多的交叉链密度 (c) 显示出与增加 (m) 相反的趋势,表明竞争效应.
- 机械性能 (模块) 与m和c有竞争性的变化,与德拜-沃勒参数 (u2) 相对应.
结论:
- 添加度和交叉链密度对耐热玻璃的形成和机械性能产生竞争的影响.
- 这些发现为交联聚合物中的结构性质关系提供了基础.
- 这项研究可以指导设计具有针对特定应用量身定制物理性质的耐热材料.
相关概念视频
01:14Polymer Classification: Architecture
2.7K
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
2.7K
01:08Molecular Weight of Step-Growth Polymers
2.2K
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
2.2K
01:26Polymer Classification: Stereospecificity
2.4K
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
2.4K
01:30Superplasticizers
85
Superplasticizers are advanced admixtures that enhance the workability of concrete by lowering the water content without compromising the strength of the material. These substances are highly effective water reducers, improving concrete flow, making it easier to work with, and enabling concrete to reach inaccessible areas or densely reinforced sections without mechanical vibration. The key components in superplasticizers are either sulfonated melamine or naphthalene formaldehyde condensates,...
85
01:31Plasticizers
75
Water-reducers, or plasticizers, are chemical admixtures used in concrete to improve strength and workability. These additives reduce the water-cement ratio without compromising workability, lower the cement content while maintaining the same workability, or increase workability to assist concrete placement in inaccessible areas.
Plasticizers function by using surface-active agents to create repulsive electrostatic forces between cement particles. This dispersion enhances the concrete's...
Plasticizers function by using surface-active agents to create repulsive electrostatic forces between cement particles. This dispersion enhances the concrete's...
75
01:21Polymer Classification: Crystallinity
2.9K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
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...
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...
2.9K