Application of Molecular Weight Regulators for the Synthesis of Sodium Polyacrylate Thinners of Mineral Suspensions

The synthesis of additives for thinning mineral suspensions based on sodium polyacrylate was carried out. The effect of molecular weight regulators on the molecular weight characteristics of the polymer and the effect of such polymers on the rheological properties of suspensions was studied. Sodium acrylate polymers are synthesized by free radical polymerization in aqueous solution using molecular weight regulators. The molecular weight characteristics of the polymeric samples were estimated by viscometry using Mark-Houwink-Kuhn-Sakurada (MHKS) equation. Synthesized polymers were used as thinners ceramic slurries, prepared according to the recipe of the enterprises producing ceramic products. The thinning ability of polymer samples with different molecular weights was estimated using an Engler viscometer from the time of the ceramic slurry flow. The influence of the type and amount molecular weight regulator on polyacryates was revealed. It was found that molecular weight synthesized samples was in the range of 21000 - 91000. It was determined that samples with a molecular weight of 28000 - 35000 synthesized using mercaptoethanol (at a dosage of 0.5-1.5% by weight of the monomer) provide optimal fluidity to the ceramic slurry.

Synthesis and Application of a Thermoplastic Plate of Poly(lactide-ε-caprolactone) for Radiation Therapy

In this study, the poly(lactide-ε-caprolactone) (P(LA-CL)) copolymer is synthesized by ring-opening polymerization with glycol used as a molecular weight regulator to adjust the molecular weight of the polymer. The proton nuclear magnetic resonance spectroscopy and gel permeation chromatography (GPC) results demonstrate that the P(LA-CL) copolymer is successfully synthesized, and that the molecular weight can be controlled by the glycol content. The thermoplastic plate is processed with triallyl isocyanurate as a cross-linking agent by a single-screw extruder followed by γ-ray irradiation. Shape memory test results show that the material had the desired shape memory effect, with deformation recovery rates reaching 100%. After secondary stretching of samples, deformation recovery rates are unchanged. The results of mechanical property measurements indicate that with added lactide, the tensile strength is improved and shore hardness is increased by 20%–30%. Data from clinical trials also reveal that the material has good clinical effects in thermoplastic membrane fixation.

Prediction of the Styrene Butadiene Rubber Performance by Emulsion Polymerization Using Backpropagation Neural Network

The effect of the amounts of initiator, emulsifier, and molecular weight regulator on the styrene butadiene rubber performance was investigated, based on the industrial original formula. It was found that the polymerization rate was increased with the increased dosage of initiator and emulsifier, and together with replenishing molecular weight regulator will make the Mooney viscosity of rubber meet the national standard when the conversion rate reaches 70%. The backpropagation neural network was trained by the original formula and ameliorated formula on the basis of Levenberg-Marquardt algorithm, and the relative error between the simulation results and experimental data is less than 1%. The good consistency shows that the BP neural network could predict the product performances in different formula conditions. It would pave the way for adjustment of the SBR formulation and prediction of the product performances.

Study on Increasing Conversion of Styrene/Butadiene Co-Polymerization by Adjusting Basic Recipe

The effects of initiator, modifier, electrolyte, and emulsifier on emulsion polymerization of styrene butadiene rubber were investigated. The results showed that the conversion could reach up to 70% within 12 hour with the same properties as conversion 62% without changing the kinds and specification by using the adjusted recipe: the amount of initiator was 10%, the mass ratio of initial amount to addition amount of molecular weight regulator was 100/20, addition time was at polymerization beginning 2 hour, the initial amount of electrolyte was 110%-115%, the total amount of emulsifier was 110%, the addition amount of emulsifier was 10% and adding time was at polymerization beginning 2 hour. the raw and vulcanizate properties of rubber crumb high monomer conversion of 70% by adjusting recipe were satisfied to meet the requirements of the superior product standard of styrene butadiene rubber.

Preparation and Cement Fluidity of Slow-Release Polycarboxylate-Type Superplasticizer

High performance polycarboxylate-type superplasticizer (PCSP) was synthesized with acrylic acid (AA), polyethylene glycol allyl ether (APEG) and one monomer of methyl acrylate (MA), methacrylate acid (MAA), acrylamide (AM), and ethyleneglycol dimethacrylate (EGDMA). Ammonium persulfate and thioglycolic acid, as an initiator and a molecular weight regulator respectively, were used for radical polymerization in aqueous solution. Influence of superplasticizer on the cement fluidity of grout was investigated. The results showed that plasticizer admixture compounded with EGDMA-APEG-AA had excellent dispersibility and slump retention.