The phrase "brittle plastic" means that the plastic material is hard, rigid, and likely to break easily when pressure or force is applied to it. Full definition
All of those clear, brittle plastics used in baby bottles, food ware, and small kitchen appliances (like food - processor bowls) are made from polycarbonates. (sciencenews.org)
We rapid cool the bone broth then cold - fill BPA - Free 32oz standup plastic pouches for maximum freshness and to eliminate spills, leaks, or cracks possible in other, more brittle plastic containers or glass. (aubonbrothbonebroth.com)
The interior uses better materials than older Kias, but you'll still find some rather brittle plastics that are absent in, say, a Skoda Octavia. (carbuyer.co.uk)