Abstract: Described herein are polymer compositions (PC) including a polyamide (PA) and a reactive impact modifier. As explained in detail below, the polyamide (PA) is a semi-aromatic polyamide derived from the polycondensation of an aliphatic diamine, a bis(aminoalkyl)cyclohexane, terephthalic acid, and, optionally, a cyclohexanedicarboxylic acid. It was surprisingly discovered that semi-aromatic polyamides derived from the cycloaliphatic diamine bis(aminoalkyl)cyclohexane or the specific combination of the cycloaliphatic diamine bis(aminoalkyl)cyclohexane and the cycloaliphatic dicarboxylic acid cyclohexanedicarboxylic acid provided for polymer compositions (PC) having improved retention of mechanical properties (e.g. tensile strength and flexural strength) after aging in aqueous solutions, relative to analogous polyamides free of the bis(aminoalkyl)cyclohexane and the cyclohexanedicarboxylic acid.