Fracture and impact properties of modified nylon 11

The steric hindrance formed by polyether side chains is the key factor determining the dispersion performance of polycarboxylate superplasticizer (PCE).While with the increase of the side chain length, the coiled conformation of side chain will prevent the dispersion ability of PCE from being further improved. In this work, the methallyl polyoxyethylene ether (HPEG) was esterified with tricarballylic acid (TA) to obtain dicarboxyl terminated macromonomer, and further used to synthesize polycarboxylate (PCETA). The fluidity tests show that compared with ordinary PCE-B2400 with short side chain, the dispersion performance of PCETA-2400 was slightly improved. While for the PCEs with long side chain, the dispersion ability of PCETA-4000 was significantly improved than that of ordinary PCE-B4000. The adsorption layer thickness of PCETA-4000 adsorbed on the surface of SiO 2 sphere measured by dynamic light scattering is 7.93 nm, which is 1.3 times that of PCE-B4000. Due to electrostatic repulsion between the carboxylic groups, the stretching of long side-chain forms stronger steric hindrance and enhancing the dispersion of cement particles. In addition, PCETA also shows good slump retention and clay resistance properties, and it is an excellent multi-functional concrete admixture with great application potential.

Section: Resultsmentioning

confidence: 99%

Study on the dispersion performance and mechanism of polycarboxylate superplasticizer by the long side‐chain dicarboxyl terminated

Zhou

Liu

et al. 2023

“…Compared with α‐cyclodextrin (α‐CD) and γ‐cyclodextrin (γ‐CD), it has higher thermal and chemical stability, and has the advantages of green production and low cost 16 . β‐CD and its derivatives have been widely combined into dendrimer, block or star copolymers, which can better interact with cement particles and other additives to form a stable dispersion system and improve the water reduction effect of concrete 17,18 . Therefore, it is worthwhile to study the introduction of β‐CD into the molecular structure design of PCE.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of multi‐armed polycarboxylate superplasticizer modified by β‐cyclodextrin

Yuan,

Yuan

2023

The polycarboxylate superplasticizer with a multi‐armed structure (multi‐armed‐PCE) was synthesized via RAFT polymerization of pentaerythritol triacrylate, acrylic acid, macro‐monomer polyethylene glycol ether (GPEG) and a certain amount of β‐cyclodextrin esterified by maleic anhydride (MA‐β‐CD). The precise structure of the multi‐armed‐PCE was characterized by NMR, FTIR, and GPC. Benefitting from the stronger steric hindrance effect provided by the multi‐armed topology and MA‐β‐CD side chains, the polymer exhibited efficient dispersion and fluidity retention properties. As a result, the water reduction rate of the polymer multi‐armed‐PCE can reach 32.5% under the condition of 0.28% dosage. Compared with comb‐like PCE‐B, the cement paste containing multi‐armed‐PCE exhibited better fluidity retention of 2 hours. Moreover, the multi‐armed‐PCE can significantly increase the mechanical strength of cement hydration products, which can provide potential prospect for the design of high‐strength concrete products.

Steady flow and dynamic viscoelastic behavior of nylon 1313 using parallel‐plate rheometer and capillary rheometer

Wang

Zhao

Wang

et al. 2005