This study is aimed at investigating the feasibility of using facile forced assembly methods (temperature and shear strain-induced orientation of the dispersed phase) to create novel in situ low-density polyethylene (LDPE) composites containing fibrillar inorganic phosphate glass (P-glass) reinforcing phase during the composite fabrication. Clearly, the experimental results show that unique thermo-rheological conditions exist under which the in situ LDPE composites containing fibrillar P-glass with potential enhanced benefits can be prepared. DSC results showed that the P-glass has a moderate nucleating effect on the LDPE crystallization that restricts in situ deformation of the P-glass during the composite fabrication. Rheo-optical data showed that a 5% P-glass/95% LDPE hybrid composition, subjected to a shear rate of 20 s-1 in the parallel plate configuration and 130 degrees C gave in situ LDPE composite samples with the largest amount of P-glass fibers in the limited range of experimental conditions used. This study may spur interests in a better understanding of the potential for the in situ reinforcement of engineering plastics with inorganic P-glasses, at the molecular level, to produce novel in situ polymer composites with very high aspect ratios of the reinforcing inorganic phase. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers