Preparations And Performances Of Wear Resistant And Heat Insulating Polymer Composites For Tubing Lining

Eccentric wear of sucker rod-tube and the tubing waxing are two technical bottlenecks in the process of crude oil exploitation,which seriously affect the normal production and operation,and increase the cost of crude oil exploitation.In this thesis,ultra-high molecular weight polyethylene(UHMWPE)and polypropylene(PP)composites were prepared by the filling of the composite filler of carbon fiber and silica nano spheres,hollow glass beads and/or styrene-butadiene rubber.The mechanical properties,thermal properties and tribological properties of the composites were characterized and tested,and their structure-performance relationships were studied.A composite with excellent tribological and thermal insulation properties was developed to meet the requirement of tubing lining,which can solve the problem of rod and tube eccentric wear and wellbore wax.1.Tribological and thermal insulation properties of UHMWPE composites filled with CF-SNSFirstly,the synergistic effect of carbon fiber(CF)and SiO2 nanosphere(SNS)on ultra-high molecular weight polyethylene(UHMWPE)composites were studied.CFN-SNS composites filler were prepared by a sol gel method,in which CFN denotes carbon fibers treated with dilute HNO3.UHMWPE/CF and UHMWPE/CFN-SNS composites were prepared by a mechanical mixing followed by a heat molding process.The results showed that the mechanical properties of CF-filled UHMWPE composites were improved.Their tensile moduli were significantly increased,and the composites maintained a high toughness.Compared with pure UHMWPE,the friction coefficient and wear loss of UHMWPE/CF composites decreased significantly,and abrasive wear was found dominating on them.Slurry abrasion wear loss of the optimal UHMWPE/CF composite was decease to about 80%of that of the pure UHMWPE.UHMWPE composites filled with CFN-SNS had more excellent mechanical properties and tribological properties,With respect to UHMWPE/CF composites,the elastic modulus of the UHMWPE/CFN-SNS composites increased slightly,and its capability of deformation resistance was enhanced.The friction coefficient of the UHMWPE/CFN-SNS composites were further decreased and presented an enhanced stability;the wear mechanism was mainly abrasive wear.The slurry wear loss was 50%lower than that of pure UHMWPE.Furthermore,nanosized SNS could promote the crystallization of UHMWPE matrix,and UHMWPE/CFN-SNS composites exhibited higher heat resistance and lower coefficient of linear expansion.The tribological properties and mechanical properties of the UHMWPE/CFN-SNS composites were further improved by a coupling treatment of the composite filler CFN-SNS.2.Tribological and thermal insulation properties of UHMWPE composites filled with HGBSecondly,the tribological properties and thermal insulation properties of the UHMWPE matrix composites filled with hollow glass beads(HGB)were investigated.In this section,UHMWPE/HGB composites were prepared by a sequential mechanical mixing and hot pressing method.It was found that there was a good interaction between the coupled hollow glass beads and UHMWPE,and the HGB was highly dispersed in the matrix.The tensile modulus and hardness of the UHMWPE composites filled with hollow glass beads were higher than those of pure UHMWPE,and the toughness of the UHMWPE/HGB composites was maintained.The average linear expansion coefficient of the UHMWPE/HGB composites was reduced by 50%,and the thermal conductivity of the composites was obviously lower than that of the raw material.The friction coefficient of UHMWPE/HGB was decreased to 20%at room temperature and water lubrication conditions,and the wear loss was reduced by 90%,the dominating wear mechanism was abrasive wear.An improvement of abrasion resistance of the UHMWPE/HGB composites at high temperature was confirmed by a slurry wear test at 80 °C.3.Tribological and thermal insulation properties of PP composites filled with HGB and SEBSThis thesis also prepared PP/HGB and PP/SEBS/HGB composites by a melt blending method using the polypropylene(PP)with smaller thermal conductivity as matrix resin,hollow glass beads(HGB)as the filling material,and the styrene butadiene rubber(SEBS)as toughening agent,and the mechanical properties,thermal insulation properties and tribological properties of the resulting composites were characterized and tested.PP/HGB composites still maintained a high toughness,and the tensile modulus and hardness of the composites were obviously improved.The linear expansion coefficient and thermal conductivity of PP/HGB composites obviously decreased,which was beneficial to the usage of composites as tubing lining.The friction coefficient and wear loss of PP/HGB composites with optimum content was 50%and 20%of that of pure PP,respectively,and the slurry wear loss was reduced by more than 20%.The toughness of PP/HGB composites was improved by introduction of SEBS as a toughening agent,and its friction coefficient and wear loss were further decreased significantly.The wear mechanism the PP/SEBS/HGB composite was mainly abrasive wear.The slurry wear loss of PP/SEBS/HGB composite was decreased to 55%of pure PP.In summary,UHMWPE/C[CF-SNS]compo sites,UHMWPE/HGB composites,PP/SEBS/HGB composites were prepared by a physical filling method,in which UHMWPE/C[CF-SNS]composites exhibited the most excellent friction and wear properties except a relatively high thermal conductivity.UHMWPE/HGB composites presented a better thermal insulation property than UHMWPE/C[CF-SNS]and a similar tribological property.PP/SEBS/HGB composites exhibited the best heat insulation performance among the investigated composites.Three kinds of composites can be used in the tubing lining of sucker rod pumping wells with different requirements,which can prevent eccentric wear and wax deposition.