Geotechnical article, and process for making it, the article having coefficient of thermal expansion less than about 150 ppm/.degree. C. at ambient; resistance to acidic media greater than polyamide 6 resin and/or resistance to basic media greater than PET resin; resistance to hydrocarbons greater than that of HDPE; creep modulus of at least 400 MPa at 25.degree. C., at 20% of yield stress load for 60 minutes (ISO 899-1); and 1 percent secant flexural modulus at least 700 MPa at 25.degree. C. (ASTM D790); the article including a composition including (a) from about 1 to about 95% by weight of the composition of at least one functional group containing polymer or oligomer; and (b) from about 5 to about 99% by weight of the composition of at least one engineering thermoplastic, and optionally containing a filler and optionally containing an unmodified polyolefin, ethylene copolymer or ethylene terpolymer.