Plant press slag (PPS) containing abundant cellulose and starch is a byproduct in the deep processing of fruits, cereals, and tuberous crops products. PPS can be modified by using caustic soda and chloroacetic acid to obtain an inexpensive and environmentally friendly filtrate reducer of drilling fluids. The optimum mass ratio of mNaOH:mMCA:mPPS is 1:1:2, the optimum etherification temperature is 75 °C, and the obtained product is a natural mixture of carboxymethyl cellulose and carboxymethyl starch (CMCS). PPS and CMCS are characterized by using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, X-ray photoelectron spectroscopy, and elemental analysis. The filtration loss performance of CMCS is stable before and after hot-rolling aging at 120 °C in 4.00% NaCl and saturated NaCl brine base slurry. The minimum filtration loss value of CMCS is 5.28 mL/30 min at the dosage of 1.50%. Compared with the commercial filtrate reducers with a single component, i.e., carboxymethyl starch (CMS) and low viscosity sodium carboxymethyl cellulose (LV-CMC), CMCS have a better tolerance to high temperature of 120 °C and high concentration of NaCl. The filtration loss performance of low-cost CMCS can reach the standards of LV-CMC and CMS of the specification of water-based drilling fluid materials in petroleum industry.

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Fumaric acid sludge (FAS) by-produced from phthalic anhydride production wastewater treatment contains a large amount of refractory organic compounds with a complex composition, which will cause environmental pollution unless it is treated in a deep, harmless manner. FAS included saturated carboxylic acid, more than 60%, and unsaturated carboxylic acid, close to 30%, which accounted for the total mass of dry sludge. A new oil well drilling fluid filtrate loss reducer, poly(AM-AMPS-FAS) (PAAF), was synthesized by copolymerizing FAS with acrylamide (AM) and 2-acrylamide-2-methyl propane sulfonic acid (AMPS). Without a refining requirement for FAS, it can be used as a polymerizable free radical monomer for the synthesis of PAAF after a simple drying process. The copolymer PAAF synthesis process was studied, and the optimal monomer mass ratio was determined to be AM:AMPS:FAS = 1:1:1. The temperature resistance of the synthesized PAAF was significantly improved when 5% sodium silicate was added as a cross-linking agent. The structural characterization and evaluation of temperature and complex saline resistance performance of PAAF were carried out. The FT-IR results show that the structure of PAAF contained amide groups and sulfonic acid groups. The TGA results show that PAAF has good temperature resistance. As an oilfield filtrate loss reducer, the cost-effective copolymer PAAF not only has excellent temperature and complex saline resistance, the API filtration loss (FL) was only 13.2 mL/30 min after 16 h of hot rolling and aging at 150 °C in the complex saline-based mud, which is smaller compared with other filtrate loss reducer copolymers, but it also has little effect on the rheological properties of drilling fluid.

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Dental mold gypsum materials require fine powder, appropriate liquidity, fast curing, and easy-to-perform clinical operations. They require low linear expansion coefficient and high strength, reflecting the master model and facilitating demolding. In this article, the suitable accelerators and reinforcing agents were selected as additives to modify dental gypsum. The main experimental methods used were to compare the trends of linear expansion coefficients of several commercially available dental gypsum products over 72 h and to observe the cross-sectional microstructure of cured bodies before and after dental gypsum modification using scanning electron microscopy. By adjusting the application of additives, the linear expansion coefficient of dental gypsum decreased from 0.26% to 0.06%, while the flexural strength increased from 6.7 MPa to 7.4 MPa at 2 h. Formulated samples showed good stability and gelation properties with linear expansion completed within 12 h. It is indicated that the performance of dental gypsum materials can be improved by adding additives and nanomaterials, which provided a good reference for clinical preparation of high-precision dental prosthesis.