In Part 1 of this series, we examined how polymers are used in hockey skates and sticks. With the Sochi Winter Olympics underway, let’s take a look at hockey protective equipment – and that hard rubber “biscuit” that glides along the ice.

Elbow Pads and Gloves

Elbow pads are molded guards that protect a player’s elbow while providing forearm protection. They’re made of a hard, impact-resistant plastic and coated in padded fabric.  Some elbow pads use expanded polypropylene (EPP) foam because it’s lightweight, elastic, and regains its shape when deformed. This is the same foam that’s used in car seats to help protect occupants in a collision.

Hockey gloves also contain foam, especially the blocker worn by  the goalie. Built with a rectangular foam board, a goaltender’s blocking glove must fit tightly around the hand without causing discomfort or cramping. Blocker gloves may also have foam inserts that fit between the top of the goalie’s hand and the foam board. These inserts cause the board to be angled properly when the goalie faces a shooter.

Shin Guards and Shoulder Pads

Shin guards are designed to protect the shins, knees, and calves in Olympic ice hockey. Molded and contoured, this type of hockey protective equipment contains several types of polymers. The front of the shin guard is usually made of a hard plastic and lined with foam padding. High-density (HD) foam, a type of polyurethane that consists of open cells packed tightly together, is often used in the knee extension.

Hockey shin guards may also contain U-Foam, a rigid two-component urethane foam system. Thigh guards typically contain molded, removable U-Foam. The shin guard’s calf wrap section may contain molded, segmented urethane foam. Other polymeric parts for shin guards include a neoprene lock zone in the knee bed.

To protect the upper body, hockey players wear padding on critical points of the shoulder, biceps, sternum, shoulder blade, and spine. Known simply as shoulder pads, this type of hockey protective equipment is usually made of a hard, impact-resistant plastic and covered in a padded fabric. Worn under the jersey, they’re bulky but durable.

The Pucks Stops Here

Hockey pucks aren’t part of a player’s equipment, but they’re an indispensable part of the game. According to the Olympic organization, these durable disks must be made of vulcanized rubber that’s approved by the International Hockey Federation (IIHG). Predominantly black in color, Olympic hockey pucks are 2.54-cm thick, 7.62-cm in diameter, and must weigh between 156 and 179 g.

On average, as many as 80 rubber pucks are needed for an Olympic event. Moreover, before each hockey game, the pucks must be frozen in order to reduce friction and limit rebounds off the ice’s surface. In North America, the National Hockey League (NHL) follows this same rule – and even specifies that NHL pucks must be kept in a cooler at the penalty bench.

As with sticks, skates, and protective equipment, material science helps us to understand aspects of Olympic hockey that even some diehard fans don’t know. The reason that frozen hockey pucks bounce less is that rubber’s physical properties change with temperature. When a rubber puck is exposed to low temperatures, it becomes harder and slides better.

If you’ve ever been hit by a hockey puck, you probably remember how hard a “biscuit” can be. With a hardness of approximately 90 durometer (duro), pucks can move at speeds of more than 150 km/h. So when you watch the world’s greatest hockey players in the Winter Olympics next month, follow that fast-moving puck – and remember it’s not the only polymer in the game.