are you wanting the categories info the product is in? Like all the categories the product is in? The data is already available on product page.
Its available with $this->product->categoryItem
The code below isnt exactly what you want, but you can see the variables and how i do it.
foreach ($this->product->categoryItem as $category){
if ($category['published']==0)continue;
if ($category['virtuemart_category_id']==85)continue;
$caturl = JRoute::_ ( 'index.php?option=com_virtuemart&view=category&virtuemart_category_id=' . $category['virtuemart_category_id'] );
$catname=$category['category_name'];
$categoriescombined[]= array($caturl,$catname,$category['virtuemart_category_id']);
$skip2[]=$category['virtuemart_category_id'];
}