Multilayer sheet and methods of making and articles comprising the multilayer sheet

A method of making an article, comprising:

• co-extruding a core layer formed from a core composition comprising a core thermoplastic polymer and a first cap layer formed from a first cap composition comprising an intumescent flame retardant material to form a multilayer sheet;
• and
• thermoforming the multilayer sheet to form the article, wherein the first cap layer and the core layer have an adhesion test value of greater than 2A as measured according to ASTM D3359-02 before thermoforming to form the article;
• wherein, if a core layer and a cap layer formed from the same core composition and the same first cap composition are formed by another method to form another multilayer sheet, a thermoformed article of the another multilayer sheet will have an adhesion of less than 2A as measured according to ASTM D3359-02 before thermoforming to form another article.

A multilayer sheet, comprising:

• an extruded first cap layer formed from a first cap composition comprising an intumescent flame retardant material;
• and
• a co-extruded core layer formed from a core composition comprising a thermoplastic polymer, wherein the first cap layer is disposed upon and in intimate contact with a surface of the core layer;
• wherein the first cap layer and the second cap layer have an adhesion test value of greater than 2 as measured according to ASTM D3359-02 before thermoforming the first cap layer and the second cap layer.