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The proppant equilibrium height is the basis of investigating proppant distributions in artificial fractures and has a great significant influence on hydraulic fracturing effect. There are two shortcomings of current research on proppant equilibrium heights, one of which is that the effect of fracture widths is neglected when calculating the settling velocity and another of which is that the settling bed height is a constant when building the settling bed height growth rate model. To fill those two shortcomings, this work provides a novel model for the proppant equilibrium height in hydraulic fractures for slickwater treatments. A comparison between the results obtained from the novel model and the published model and experimental results indicates that the proposed model is verified. From the sensitivity analysis, it is concluded that the proppant equilibrium height increases with an increasing proppant density. The proppant equilibrium height decreases with an increase in the slickwater injection rate and increases with an increase in the proppant injection rate. The increase in proppant diameter results in an increasing the friction factor, which makes proppant equilibrium heights decrease. Meanwhile, the increase in proppant sizes results in an increase in proppant settling rates, which makes the proppant equilibrium height increase. When the effect of the proppant diameter on settling rates is more significant than that on friction factors, the equilibrium height increases with an increasing proppant size. This work provides a research basis of proppant distributions during the hydraulic fracture.

In view of the present situation that the recovery of waste thermosetting plastics and products is difficult and the utilization rate is low, regeneration mechanism, regeneration methods and recycling process of waste thermosetting plastics under mechanical thermal coupling fields are proposed. Regeneration powders of Thermosetting Phenolic plastic are obtained by mechanochemical activated regeneration methods, the molecular structure, properties and crosslink density of phenol regeneration materials are analyzed. Analysis results show that network crosslinked molecular structure was destroyed, reactive groups produced and the crosslink density decreased. The activity of regeneration powders was reinforced and its plasticity was also improving, so the utilization rate was improved. Regeneration composite plastics were manufactured by hot press molding or extrusion compression molding. The microstructure of regeneration composite plastics was analyzed, and its mechanical strength was tested. Results showed that the tensile strength and bending strength of samples (weight ratio ≥ 50%) respectively exceed 15.88 MPa and 33.49 MPa. At last process parameters for regeneration effects were discussed, and these parameters were optimized. When particle size was 80 mesh (size ≤ 0.18 mm), quality proportion was 50~70%, pressure was 10Mpa, heating temperature was 180~190°C, the optimal effects for regenerated composite were achieved.

Various mechanical forces are used to promote the waste thermosetting phenol resin to produce the physical decomposition process. The molecular structure and physicochemical properties change, thus it obtains the reversible thermos plasticity and restore the processing performance. The paper proposes the regeneration principle based on physical methods, and smashing and regeneration experiments have been carried out. The optimized design for important factors of rotational speed, crushing time, feed, feed size and other parameters which impact crushing and regenerating effects has been carried out after experiments. Multivariate quadratic simulation equations are established and the order of significantly affecting the regeneration is determined.

Through the combined mechanical forces of sheer, friction and squeezing, the rigid polyurethane powder particles get certain plasticity. Based on the principles of mechanical and physical methods, an orthogonal test is designed, and then characterization analysis under conditions of different parameters is carried out through ATR-FTIR. The test indicates that when the rotate speed is 2400r/min, test time is 120min and inlet amount is 24g, the carbamic acid ester groups break down at the place of C-O bond and the cross-linked network structure is destroyed, then the best degradation effect is gained. This article provides theoretical basis for the recycle of thermosetting plastic.

Propose a recycling technology of waste thermosetting phenolic resin based on mechanical and physical method,use the range and variance analysis of orthogonal test of four factors at three different levels, obtain the affection of speed ,time, feeding material weight ,feeding particle size on degradation efficiency of thermosetting phenolic resin. According to the affection ,the influencing factors could be arranged as follows : speed>feeding particle size> time>feeding material weight,and optimal technology parameters are determined as follows: speed is 3000 r / min, time is 90 min, feeding material weight is 50 g, feeding particle size is 0.425 mm.

Pulverizing the waste thermosetting phenol-formaldehyde resins by the self-developed machine which is used to recycle thermosetting plastics, studying the variable laws of fractions of different particle changing with the pulverization time, and establishing a pulverizing dynamic model by regression analysis. The results show that the particle distribution parameters b and m are not constants but the functions of pulverization time; the established equation of regression dynamic is high accurate which clearly describes the pulverization process.

Using adjustable speed crushing regeneration test device for the recovery experiment of thermosetting phenolic plastic waste, this paper analyses the principle of recovery process. Through particle size analytical technique, FTIR, XRD and SEM etc. various testing method is analyzed mechanochemical effects of crushing process. Research the speed, time, temperature process parameters of the influence of recycling process conditions. According to the experimental results, it established the mechanochemical model and analyzed the degradation and regeneration mechanism of thermosetting phenolic plastic waste.

PPO was a better intensifier and charred material for High-impact polystyrene (HIPS), it could make HIPS achieve UL94V-0 with APP, MC, RDP. Especially, RDP not only improved the flame-retarded property but also controlled the hole producing, and had the best consistent with matrix which could improve the mechanical properties. SBS and SEBS were better consistent with matrix, especially SEBS was tiny granule, which could be dispersed in matrix easily. The properties of SEBS toughened the non-halogen flame-retarded HIPS was followed: tensile strength: 18.83MPa; izod notch impact strength: 15.7kJ/m2; UL94V-0.

Waste thermosetting plastics are considered to be a difficulty of recycling of polymeric materials due to its three-dimensional reticular cross-linkage structure and the complexity of the types of materials. Take the hard thermosetting polyurethane plastic which is widely used in the market as the research object and deferent from the traditional methods, this paper puts forward waste thermosetting plastics recycling process based on mechanical and physical methods. Through strong shear, extrusion, grinding and other mechanical forces combined with the frictional heat generated, not only the physical properties and morphology of the material change, but also the molecular structure and chemical properties of the material change and produce degradation. The paper has analyzed the degradation mechanism of polyurethane and influencing factors based on mechanical and physical methods. At last the reasonable parameters of effective degradation are obtained, which are combined with the actual experimental results.